Python2/PyMuPDF: mupdf-source/thirdparty/leptonica/src/pix5.c comparison

comparison mupdf-source/thirdparty/leptonica/src/pix5.c @ 2:b50eed0cc0ef upstream

ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.

author	Franz Glasner <fzglas.hg@dom66.de>
date	Mon, 15 Sep 2025 11:43:07 +0200
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-:1d09e1dec1d9
+:b50eed0cc0ef
+/*====================================================================*
+-  Copyright (C) 2001 Leptonica.  All rights reserved.
+-
+-  Redistribution and use in source and binary forms, with or without
+-  modification, are permitted provided that the following conditions
+-  are met:
+-  1. Redistributions of source code must retain the above copyright
+-     notice, this list of conditions and the following disclaimer.
+-  2. Redistributions in binary form must reproduce the above
+-     copyright notice, this list of conditions and the following
+-     disclaimer in the documentation and/or other materials
+-     provided with the distribution.
+-
+-  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+-  ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+-  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+-  A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL ANY
+-  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+-  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+-  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+-  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+-  OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+-  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+-  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*====================================================================*/
+/*!
+* \file pix5.c
+* <pre>
+*
+*    This file has these operations:
+*
+*      (1) Measurement of 1 bpp image properties
+*      (2) Extract rectangular regions
+*      (3) Clip to foreground
+*      (4) Extract pixel averages, reversals and variance along lines
+*      (5) Rank row and column transforms
+*
+*    Measurement of properties
+*           l_int32     pixaFindDimensions()
+*           l_int32     pixFindAreaPerimRatio()
+*           NUMA       *pixaFindPerimToAreaRatio()
+*           l_int32     pixFindPerimToAreaRatio()
+*           NUMA       *pixaFindPerimSizeRatio()
+*           l_int32     pixFindPerimSizeRatio()
+*           NUMA       *pixaFindAreaFraction()
+*           l_int32     pixFindAreaFraction()
+*           NUMA       *pixaFindAreaFractionMasked()
+*           l_int32     pixFindAreaFractionMasked()
+*           NUMA       *pixaFindWidthHeightRatio()
+*           NUMA       *pixaFindWidthHeightProduct()
+*           l_int32     pixFindOverlapFraction()
+*           BOXA       *pixFindRectangleComps()
+*           l_int32     pixConformsToRectangle()
+*
+*    Extract rectangular regions
+*           PIX        *pixExtractRectangularRegions()
+*           PIXA       *pixClipRectangles()
+*           PIX        *pixClipRectangle()
+*           PIX        *pixClipRectangleWithBorder()
+*           PIX        *pixClipMasked()
+*           l_int32     pixCropToMatch()
+*           PIX        *pixCropToSize()
+*           PIX        *pixResizeToMatch()
+*
+*    Select a connected component by size
+*           PIX        *pixSelectComponentBySize()
+*           PIX        *pixFilterComponentBySize()
+*
+*    Make special masks
+*           PIX        *pixMakeSymmetricMask()
+*           PIX        *pixMakeFrameMask()
+*
+*    Generate a covering of rectangles over connected components
+*           PIX        * pixMakeCoveringOfRectangles()
+*
+*    Fraction of Fg pixels under a mask
+*           l_int32     pixFractionFgInMask()
+*
+*    Clip to foreground
+*           PIX        *pixClipToForeground()
+*           l_int32     pixTestClipToForeground()
+*           l_int32     pixClipBoxToForeground()
+*           l_int32     pixScanForForeground()
+*           l_int32     pixClipBoxToEdges()
+*           l_int32     pixScanForEdge()
+*
+*    Extract pixel averages and reversals along lines
+*           NUMA       *pixExtractOnLine()
+*           l_float32   pixAverageOnLine()
+*           NUMA       *pixAverageIntensityProfile()
+*           NUMA       *pixReversalProfile()
+*
+*    Extract windowed variance along a line
+*           NUMA       *pixWindowedVarianceOnLine()
+*
+*    Extract min/max of pixel values near lines
+*           l_int32     pixMinMaxNearLine()
+*
+*    Rank row and column transforms
+*           PIX        *pixRankRowTransform()
+*           PIX        *pixRankColumnTransform()
+* </pre>
+*/
+#ifdef HAVE_CONFIG_H
+#include <config_auto.h>
+#endif  /* HAVE_CONFIG_H */
+#include <string.h>
+#include <math.h>
+#include "allheaders.h"
+static const l_uint32 rmask32[] = {0x0,
+0x00000001, 0x00000003, 0x00000007, 0x0000000f,
+0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
+0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
+0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
+0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
+0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
+0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
+0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff};
+#ifndef  NO_CONSOLE_IO
+#define  DEBUG_EDGES         0
+#endif  /* ~NO_CONSOLE_IO */
+/*-------------------------------------------------------------*
+*                 Measurement of properties                   *
+*-------------------------------------------------------------*/
+/*!
+* \brief   pixaFindDimensions()
+*
+* \param[in]    pixa
+* \param[out]   pnaw [optional] numa of pix widths
+* \param[out]   pnah [optional] numa of pix heights
+* \return  0 if OK, 1 on error
+*/
+l_ok
+pixaFindDimensions(PIXA   *pixa,
+NUMA  **pnaw,
+NUMA  **pnah)
+{
+l_int32  i, n, w, h;
+PIX     *pixt;
+if (pnaw) *pnaw = NULL;
+if (pnah) *pnah = NULL;
+if (!pnaw && !pnah)
+return ERROR_INT("no output requested", __func__, 1);
+if (!pixa)
+return ERROR_INT("pixa not defined", __func__, 1);
+n = pixaGetCount(pixa);
+if (pnaw) *pnaw = numaCreate(n);
+if (pnah) *pnah = numaCreate(n);
+for (i = 0; i < n; i++) {
+pixt = pixaGetPix(pixa, i, L_CLONE);
+pixGetDimensions(pixt, &w, &h, NULL);
+if (pnaw)
+numaAddNumber(*pnaw, w);
+if (pnah)
+numaAddNumber(*pnah, h);
+pixDestroy(&pixt);
+}
+return 0;
+}
+/*!
+* \brief   pixFindAreaPerimRatio()
+*
+* \param[in]    pixs    1 bpp
+* \param[in]    tab     [optional] pixel sum table, can be NULL
+* \param[out]   pfract  area/perimeter ratio
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) The area is the number of fg pixels that are not on the
+*          boundary (i.e., are not 8-connected to a bg pixel), and the
+*          perimeter is the number of fg boundary pixels.  Returns
+*          0.0 if there are no fg pixels.
+*      (2) This function is retained because clients are using it.
+* </pre>
+*/
+l_ok
+pixFindAreaPerimRatio(PIX        *pixs,
+l_int32    *tab,
+l_float32  *pfract)
+{
+l_int32  *tab8;
+l_int32   nfg, nbound;
+PIX      *pixt;
+if (!pfract)
+return ERROR_INT("&fract not defined", __func__, 1);
+*pfract = 0.0;
+if (!pixs || pixGetDepth(pixs) != 1)
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (!tab)
+tab8 = makePixelSumTab8();
+else
+tab8 = tab;
+pixt = pixErodeBrick(NULL, pixs, 3, 3);
+pixCountPixels(pixt, &nfg, tab8);
+if (nfg == 0) {
+pixDestroy(&pixt);
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+pixXor(pixt, pixt, pixs);
+pixCountPixels(pixt, &nbound, tab8);
+*pfract = (l_float32)nfg / (l_float32)nbound;
+pixDestroy(&pixt);
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+/*!
+* \brief   pixaFindPerimToAreaRatio()
+*
+* \param[in]    pixa   of 1 bpp pix
+* \return  na   of perimeter/arear ratio for each pix, or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This is typically used for a pixa consisting of
+*          1 bpp connected components.
+* </pre>
+*/
+NUMA *
+pixaFindPerimToAreaRatio(PIXA  *pixa)
+{
+l_int32    i, n;
+l_int32   *tab;
+l_float32  fract;
+NUMA      *na;
+PIX       *pixt;
+if (!pixa)
+return (NUMA *)ERROR_PTR("pixa not defined", __func__, NULL);
+n = pixaGetCount(pixa);
+na = numaCreate(n);
+tab = makePixelSumTab8();
+for (i = 0; i < n; i++) {
+pixt = pixaGetPix(pixa, i, L_CLONE);
+pixFindPerimToAreaRatio(pixt, tab, &fract);
+numaAddNumber(na, fract);
+pixDestroy(&pixt);
+}
+LEPT_FREE(tab);
+return na;
+}
+/*!
+* \brief   pixFindPerimToAreaRatio()
+*
+* \param[in]    pixs    1 bpp
+* \param[in]    tab     [optional] pixel sum table, can be NULL
+* \param[out]   pfract  perimeter/area ratio
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) The perimeter is the number of fg boundary pixels, and the
+*          area is the number of fg pixels.  This returns 0.0 if
+*          there are no fg pixels.
+*      (2) Unlike pixFindAreaPerimRatio(), this uses the full set of
+*          fg pixels for the area, and the ratio is taken in the opposite
+*          order.
+*      (3) This is typically used for a single connected component.
+*          This always has a value <= 1.0, and if the average distance
+*          of a fg pixel from the nearest bg pixel is d, this has
+*          a value ~1/d.
+* </pre>
+*/
+l_ok
+pixFindPerimToAreaRatio(PIX        *pixs,
+l_int32    *tab,
+l_float32  *pfract)
+{
+l_int32  *tab8;
+l_int32   nfg, nbound;
+PIX      *pixt;
+if (!pfract)
+return ERROR_INT("&fract not defined", __func__, 1);
+*pfract = 0.0;
+if (!pixs || pixGetDepth(pixs) != 1)
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (!tab)
+tab8 = makePixelSumTab8();
+else
+tab8 = tab;
+pixCountPixels(pixs, &nfg, tab8);
+if (nfg == 0) {
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+pixt = pixErodeBrick(NULL, pixs, 3, 3);
+pixXor(pixt, pixt, pixs);
+pixCountPixels(pixt, &nbound, tab8);
+*pfract = (l_float32)nbound / (l_float32)nfg;
+pixDestroy(&pixt);
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+/*!
+* \brief   pixaFindPerimSizeRatio()
+*
+* \param[in]    pixa   of 1 bpp pix
+* \return  na   of fg perimeter/(2*(w+h)) ratio for each pix,
+*                  or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This is typically used for a pixa consisting of
+*          1 bpp connected components.
+*      (2) This has a minimum value for a circle of pi/4; a value for
+*          a rectangle component of approx. 1.0; and a value much larger
+*          than 1.0 for a component with a highly irregular boundary.
+* </pre>
+*/
+NUMA *
+pixaFindPerimSizeRatio(PIXA  *pixa)
+{
+l_int32    i, n;
+l_int32   *tab;
+l_float32  ratio;
+NUMA      *na;
+PIX       *pixt;
+if (!pixa)
+return (NUMA *)ERROR_PTR("pixa not defined", __func__, NULL);
+n = pixaGetCount(pixa);
+na = numaCreate(n);
+tab = makePixelSumTab8();
+for (i = 0; i < n; i++) {
+pixt = pixaGetPix(pixa, i, L_CLONE);
+pixFindPerimSizeRatio(pixt, tab, &ratio);
+numaAddNumber(na, ratio);
+pixDestroy(&pixt);
+}
+LEPT_FREE(tab);
+return na;
+}
+/*!
+* \brief   pixFindPerimSizeRatio()
+*
+* \param[in]    pixs    1 bpp
+* \param[in]    tab     [optional] pixel sum table, can be NULL
+* \param[out]   pratio  perimeter/size ratio
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) We take the 'size' as twice the sum of the width and
+*          height of pixs, and the perimeter is the number of fg
+*          boundary pixels.  We use the fg pixels of the boundary
+*          because the pix may be clipped to the boundary, so an
+*          erosion is required to count all boundary pixels.
+*      (2) This has a large value for dendritic, fractal-like components
+*          with highly irregular boundaries.
+*      (3) This is typically used for a single connected component.
+*          It has a value of about 1.0 for rectangular components with
+*          relatively smooth boundaries.
+* </pre>
+*/
+l_ok
+pixFindPerimSizeRatio(PIX        *pixs,
+l_int32    *tab,
+l_float32  *pratio)
+{
+l_int32  *tab8;
+l_int32   w, h, nbound;
+PIX      *pixt;
+if (!pratio)
+return ERROR_INT("&ratio not defined", __func__, 1);
+*pratio = 0.0;
+if (!pixs || pixGetDepth(pixs) != 1)
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (!tab)
+tab8 = makePixelSumTab8();
+else
+tab8 = tab;
+pixt = pixErodeBrick(NULL, pixs, 3, 3);
+pixXor(pixt, pixt, pixs);
+pixCountPixels(pixt, &nbound, tab8);
+pixGetDimensions(pixs, &w, &h, NULL);
+*pratio = (0.5f * nbound) / (l_float32)(w + h);
+pixDestroy(&pixt);
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+/*!
+* \brief   pixaFindAreaFraction()
+*
+* \param[in]    pixa   of 1 bpp pix
+* \return  na  of area fractions for each pix, or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This is typically used for a pixa consisting of
+*          1 bpp connected components.
+* </pre>
+*/
+NUMA *
+pixaFindAreaFraction(PIXA  *pixa)
+{
+l_int32    i, n;
+l_int32   *tab;
+l_float32  fract;
+NUMA      *na;
+PIX       *pixt;
+if (!pixa)
+return (NUMA *)ERROR_PTR("pixa not defined", __func__, NULL);
+n = pixaGetCount(pixa);
+na = numaCreate(n);
+tab = makePixelSumTab8();
+for (i = 0; i < n; i++) {
+pixt = pixaGetPix(pixa, i, L_CLONE);
+pixFindAreaFraction(pixt, tab, &fract);
+numaAddNumber(na, fract);
+pixDestroy(&pixt);
+}
+LEPT_FREE(tab);
+return na;
+}
+/*!
+* \brief   pixFindAreaFraction()
+*
+* \param[in]    pixs    1 bpp
+* \param[in]    tab     [optional] pixel sum table, can be NULL
+* \param[out]   pfract  fg area/size ratio
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) This finds the ratio of the number of fg pixels to the
+*          size of the pix (w * h).  It is typically used for a
+*          single connected component.
+* </pre>
+*/
+l_ok
+pixFindAreaFraction(PIX        *pixs,
+l_int32    *tab,
+l_float32  *pfract)
+{
+l_int32   w, h, sum;
+l_int32  *tab8;
+if (!pfract)
+return ERROR_INT("&fract not defined", __func__, 1);
+*pfract = 0.0;
+if (!pixs || pixGetDepth(pixs) != 1)
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (!tab)
+tab8 = makePixelSumTab8();
+else
+tab8 = tab;
+pixGetDimensions(pixs, &w, &h, NULL);
+pixCountPixels(pixs, &sum, tab8);
+*pfract = (l_float32)sum / (l_float32)(w * h);
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+/*!
+* \brief   pixaFindAreaFractionMasked()
+*
+* \param[in]    pixa    of 1 bpp pix
+* \param[in]    pixm    mask image
+* \param[in]    debug   1 for output, 0 to suppress
+* \return  na of ratio masked/total fractions for each pix,
+*                  or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This is typically used for a pixa consisting of
+*          1 bpp connected components, which has an associated
+*          boxa giving the location of the components relative
+*          to the mask origin.
+*      (2) The debug flag displays in green and red the masked and
+*          unmasked parts of the image from which pixa was derived.
+* </pre>
+*/
+NUMA *
+pixaFindAreaFractionMasked(PIXA    *pixa,
+PIX     *pixm,
+l_int32  debug)
+{
+l_int32    i, n, full;
+l_int32   *tab;
+l_float32  fract;
+BOX       *box;
+NUMA      *na;
+PIX       *pix;
+if (!pixa)
+return (NUMA *)ERROR_PTR("pixa not defined", __func__, NULL);
+if (!pixm || pixGetDepth(pixm) != 1)
+return (NUMA *)ERROR_PTR("pixm undefined or not 1 bpp", __func__, NULL);
+n = pixaGetCount(pixa);
+na = numaCreate(n);
+tab = makePixelSumTab8();
+pixaIsFull(pixa, NULL, &full);  /* check boxa */
+box = NULL;
+for (i = 0; i < n; i++) {
+pix = pixaGetPix(pixa, i, L_CLONE);
+if (full)
+box = pixaGetBox(pixa, i, L_CLONE);
+pixFindAreaFractionMasked(pix, box, pixm, tab, &fract);
+numaAddNumber(na, fract);
+boxDestroy(&box);
+pixDestroy(&pix);
+}
+LEPT_FREE(tab);
+if (debug) {
+l_int32  w, h;
+PIX     *pix1, *pix2;
+pixGetDimensions(pixm, &w, &h, NULL);
+pix1 = pixaDisplay(pixa, w, h);  /* recover original image */
+pix2 = pixCreate(w, h, 8);  /* make an 8 bpp white image ... */
+pixSetColormap(pix2, pixcmapCreate(8));  /* that's cmapped ... */
+pixSetBlackOrWhite(pix2, L_SET_WHITE);  /* and init to white */
+pixSetMaskedCmap(pix2, pix1, 0, 0, 255, 0, 0);  /* color all fg red */
+pixRasterop(pix1, 0, 0, w, h, PIX_MASK, pixm, 0, 0);
+pixSetMaskedCmap(pix2, pix1, 0, 0, 0, 255, 0);  /* turn masked green */
+pixDisplay(pix2, 100, 100);
+pixDestroy(&pix1);
+pixDestroy(&pix2);
+}
+return na;
+}
+/*!
+* \brief   pixFindAreaFractionMasked()
+*
+* \param[in]    pixs    1 bpp, typically a single component
+* \param[in]    box     [optional] for pixs relative to pixm
+* \param[in]    pixm    1 bpp mask, typically over the entire image from
+*                       which the component pixs was extracted
+* \param[in]    tab     [optional] pixel sum table, can be NULL
+* \param[out]   pfract  fg area/size ratio
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) This finds the ratio of the number of masked fg pixels
+*          in pixs to the total number of fg pixels in pixs.
+*          It is typically used for a single connected component.
+*          If there are no fg pixels, this returns a ratio of 0.0.
+*      (2) The box gives the location of the pix relative to that
+*          of the UL corner of the mask.  Therefore, the rasterop
+*          is performed with the pix translated to its location
+*          (x, y) in the mask before ANDing.
+*          If box == NULL, the UL corners of pixs and pixm are aligned.
+* </pre>
+*/
+l_ok
+pixFindAreaFractionMasked(PIX        *pixs,
+BOX        *box,
+PIX        *pixm,
+l_int32    *tab,
+l_float32  *pfract)
+{
+l_int32   x, y, w, h, sum, masksum;
+l_int32  *tab8;
+PIX      *pix1;
+if (!pfract)
+return ERROR_INT("&fract not defined", __func__, 1);
+*pfract = 0.0;
+if (!pixs || pixGetDepth(pixs) != 1)
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (!pixm || pixGetDepth(pixm) != 1)
+return ERROR_INT("pixm not defined or not 1 bpp", __func__, 1);
+if (!tab)
+tab8 = makePixelSumTab8();
+else
+tab8 = tab;
+x = y = 0;
+if (box)
+boxGetGeometry(box, &x, &y, NULL, NULL);
+pixGetDimensions(pixs, &w, &h, NULL);
+pix1 = pixCopy(NULL, pixs);
+pixRasterop(pix1, 0, 0, w, h, PIX_MASK, pixm, x, y);
+pixCountPixels(pixs, &sum, tab8);
+if (sum == 0) {
+pixDestroy(&pix1);
+if (!tab) LEPT_FREE(tab8);
+return 0;
+}
+pixCountPixels(pix1, &masksum, tab8);
+*pfract = (l_float32)masksum / (l_float32)sum;
+if (!tab) LEPT_FREE(tab8);
+pixDestroy(&pix1);
+return 0;
+}
+/*!
+* \brief   pixaFindWidthHeightRatio()
+*
+* \param[in]    pixa   of 1 bpp pix
+* \return  na of width/height ratios for each pix, or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This is typically used for a pixa consisting of
+*          1 bpp connected components.
+* </pre>
+*/
+NUMA *
+pixaFindWidthHeightRatio(PIXA  *pixa)
+{
+l_int32  i, n, w, h;
+NUMA    *na;
+PIX     *pixt;
+if (!pixa)
+return (NUMA *)ERROR_PTR("pixa not defined", __func__, NULL);
+n = pixaGetCount(pixa);
+na = numaCreate(n);
+for (i = 0; i < n; i++) {
+pixt = pixaGetPix(pixa, i, L_CLONE);
+pixGetDimensions(pixt, &w, &h, NULL);
+numaAddNumber(na, (l_float32)w / (l_float32)h);
+pixDestroy(&pixt);
+}
+return na;
+}
+/*!
+* \brief   pixaFindWidthHeightProduct()
+*
+* \param[in]    pixa   of 1 bpp pix
+* \return  na of width*height products for each pix, or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This is typically used for a pixa consisting of
+*          1 bpp connected components.
+* </pre>
+*/
+NUMA *
+pixaFindWidthHeightProduct(PIXA  *pixa)
+{
+l_int32  i, n, w, h;
+NUMA    *na;
+PIX     *pixt;
+if (!pixa)
+return (NUMA *)ERROR_PTR("pixa not defined", __func__, NULL);
+n = pixaGetCount(pixa);
+na = numaCreate(n);
+for (i = 0; i < n; i++) {
+pixt = pixaGetPix(pixa, i, L_CLONE);
+pixGetDimensions(pixt, &w, &h, NULL);
+numaAddNumber(na, w * h);
+pixDestroy(&pixt);
+}
+return na;
+}
+/*!
+* \brief   pixFindOverlapFraction()
+*
+* \param[in]    pixs1, pixs2   1 bpp
+* \param[in]    x2, y2         location in pixs1 of UL corner of pixs2
+* \param[in]    tab            [optional] pixel sum table, can be null
+* \param[out]   pratio         ratio fg intersection to fg union
+* \param[out]   pnoverlap      [optional] number of overlapping pixels
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) The UL corner of pixs2 is placed at (x2, y2) in pixs1.
+*      (2) This measure is similar to the correlation.
+* </pre>
+*/
+l_ok
+pixFindOverlapFraction(PIX        *pixs1,
+PIX        *pixs2,
+l_int32     x2,
+l_int32     y2,
+l_int32    *tab,
+l_float32  *pratio,
+l_int32    *pnoverlap)
+{
+l_int32  *tab8;
+l_int32   w, h, nintersect, nunion;
+PIX      *pixt;
+if (pnoverlap) *pnoverlap = 0;
+if (!pratio)
+return ERROR_INT("&ratio not defined", __func__, 1);
+*pratio = 0.0;
+if (!pixs1 || pixGetDepth(pixs1) != 1)
+return ERROR_INT("pixs1 not defined or not 1 bpp", __func__, 1);
+if (!pixs2 || pixGetDepth(pixs2) != 1)
+return ERROR_INT("pixs2 not defined or not 1 bpp", __func__, 1);
+if (!tab)
+tab8 = makePixelSumTab8();
+else
+tab8 = tab;
+pixGetDimensions(pixs2, &w, &h, NULL);
+pixt = pixCopy(NULL, pixs1);
+pixRasterop(pixt, x2, y2, w, h, PIX_MASK, pixs2, 0, 0);  /* AND */
+pixCountPixels(pixt, &nintersect, tab8);
+if (pnoverlap)
+*pnoverlap = nintersect;
+pixCopy(pixt, pixs1);
+pixRasterop(pixt, x2, y2, w, h, PIX_PAINT, pixs2, 0, 0);  /* OR */
+pixCountPixels(pixt, &nunion, tab8);
+if (!tab) LEPT_FREE(tab8);
+pixDestroy(&pixt);
+if (nunion > 0)
+*pratio = (l_float32)nintersect / (l_float32)nunion;
+return 0;
+}
+/*!
+* \brief   pixFindRectangleComps()
+*
+* \param[in]    pixs        1 bpp
+* \param[in]    dist        max distance allowed between bounding box
+*                           and nearest foreground pixel within it
+* \param[in]    minw, minh  minimum size in each direction as a requirement
+*                           for a conforming rectangle
+* \return  boxa of components that conform, or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This applies the function pixConformsToRectangle() to
+*          each 8-c.c. in pixs, and returns a boxa containing the
+*          regions of all components that are conforming.
+*      (2) Conforming components must satisfy both the size constraint
+*          given by %minsize and the slop in conforming to a rectangle
+*          determined by %dist.
+* </pre>
+*/
+BOXA *
+pixFindRectangleComps(PIX     *pixs,
+l_int32  dist,
+l_int32  minw,
+l_int32  minh)
+{
+l_int32  w, h, i, n, conforms;
+BOX     *box;
+BOXA    *boxa, *boxad;
+PIX     *pix;
+PIXA    *pixa;
+if (!pixs || pixGetDepth(pixs) != 1)
+return (BOXA *)ERROR_PTR("pixs undefined or not 1 bpp", __func__, NULL);
+if (dist < 0)
+return (BOXA *)ERROR_PTR("dist must be >= 0", __func__, NULL);
+if (minw <= 2 * dist && minh <= 2 * dist)
+return (BOXA *)ERROR_PTR("invalid parameters", __func__, NULL);
+boxa = pixConnComp(pixs, &pixa, 8);
+boxad = boxaCreate(0);
+n = pixaGetCount(pixa);
+for (i = 0; i < n; i++) {
+pix = pixaGetPix(pixa, i, L_CLONE);
+pixGetDimensions(pix, &w, &h, NULL);
+if (w < minw || h < minh) {
+pixDestroy(&pix);
+continue;
+}
+pixConformsToRectangle(pix, NULL, dist, &conforms);
+if (conforms) {
+box = boxaGetBox(boxa, i, L_COPY);
+boxaAddBox(boxad, box, L_INSERT);
+}
+pixDestroy(&pix);
+}
+boxaDestroy(&boxa);
+pixaDestroy(&pixa);
+return boxad;
+}
+/*!
+* \brief   pixConformsToRectangle()
+*
+* \param[in]    pixs       1 bpp
+* \param[in]    box        [optional] if null, use the entire pixs
+* \param[in]    dist       max distance allowed between bounding box and
+*                          nearest foreground pixel within it
+* \param[out]   pconforms  0 (false) if not conforming;
+*                          1 (true) if conforming
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) There are several ways to test if a connected component has
+*          an essentially rectangular boundary, such as:
+*           a. Fraction of fill into the bounding box
+*           b. Max-min distance of fg pixel from periphery of bounding box
+*           c. Max depth of bg intrusions into component within bounding box
+*          The weakness of (a) is that it is highly sensitive to holes
+*          within the c.c.  The weakness of (b) is that it can have
+*          arbitrarily large intrusions into the c.c.  Method (c) tests
+*          the integrity of the outer boundary of the c.c., with respect
+*          to the enclosing bounding box, so we use it.
+*      (2) This tests if the connected component within the box conforms
+*          to the box at all points on the periphery within %dist.
+*          Inside, at a distance from the box boundary that is greater
+*          than %dist, we don't care about the pixels in the c.c.
+*      (3) We can think of the conforming condition as follows:
+*          No pixel inside a distance %dist from the boundary
+*          can connect to the boundary through a path through the bg.
+*          To implement this, we need to do a flood fill.  We can go
+*          either from inside toward the boundary, or the other direction.
+*          It's easiest to fill from the boundary, and then verify that
+*          there are no filled pixels farther than %dist from the boundary.
+* </pre>
+*/
+l_ok
+pixConformsToRectangle(PIX      *pixs,
+BOX      *box,
+l_int32   dist,
+l_int32  *pconforms)
+{
+l_int32  w, h, empty;
+PIX     *pix1, *pix2;
+if (!pconforms)
+return ERROR_INT("&conforms not defined", __func__, 1);
+*pconforms = 0;
+if (!pixs || pixGetDepth(pixs) != 1)
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (dist < 0)
+return ERROR_INT("dist must be >= 0", __func__, 1);
+pixGetDimensions(pixs, &w, &h, NULL);
+if (w <= 2 * dist || h <= 2 * dist) {
+L_WARNING("automatic conformation: distance too large\n", __func__);
+*pconforms = 1;
+return 0;
+}
+/* Extract the region, if necessary */
+if (box)
+pix1 = pixClipRectangle(pixs, box, NULL);
+else
+pix1 = pixCopy(NULL, pixs);
+/* Invert and fill from the boundary into the interior.
+* Because we're considering the connected component in an
+* 8-connected sense, we do the background filling as 4 c.c. */
+pixInvert(pix1, pix1);
+pix2 = pixExtractBorderConnComps(pix1, 4);
+/* Mask out all pixels within a distance %dist from the box
+* boundary.  Any remaining pixels are from filling that goes
+* more than %dist from the boundary.  If no pixels remain,
+* the component conforms to the bounding rectangle within
+* a distance %dist. */
+pixSetOrClearBorder(pix2, dist, dist, dist, dist, PIX_CLR);
+pixZero(pix2, &empty);
+pixDestroy(&pix1);
+pixDestroy(&pix2);
+*pconforms = (empty) ? 1 : 0;
+return 0;
+}
+/*-----------------------------------------------------------------------*
+*                      Extract rectangular regions                      *
+*-----------------------------------------------------------------------*/
+/*!
+* \brief   pixExtractRectangularRegions()
+*
+* \param[in]    pixs
+* \param[in]    boxa  regions to extract
+* \return  pix  with extracted regions, or NULL on error
+*
+* <pre>
+* Notes:
+*     (1) The returned pix has the rectangular regions clipped from
+*         the input pixs.
+*     (2) We could equally well do this operation using a mask of 1's over
+*         the regions determined by the boxa:
+*           pix1 = pixCreateTemplate(pixs);
+*           pixMaskBoxa(pix1, pix1, boxa, L_SET_PIXELS);
+*           pixAnd(pix1, pix1, pixs);
+* </pre>
+*/
+PIX *
+pixExtractRectangularRegions(PIX   *pixs,
+BOXA  *boxa)
+{
+l_int32  w, h;
+PIX     *pix1;
+PIXA    *pixa1;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (!boxa)
+return (PIX *)ERROR_PTR("boxa not defined", __func__, NULL);
+if ((pixa1 = pixClipRectangles(pixs, boxa)) == NULL)
+return (PIX *)ERROR_PTR("pixa1 not made", __func__, NULL);
+pixGetDimensions(pixs, &w, &h, NULL);
+pix1 = pixaDisplay(pixa1, w, h);
+pixaDestroy(&pixa1);
+return pix1;
+}
+/*!
+* \brief   pixClipRectangles()
+*
+* \param[in]    pixs
+* \param[in]    boxa  requested clipping regions
+* \return  pixa consisting of requested regions, or NULL on error
+*
+* <pre>
+* Notes:
+*     (1) The boxa in the returned pixa has the regions clipped from
+*         the input pixs.
+* </pre>
+*/
+PIXA *
+pixClipRectangles(PIX   *pixs,
+BOXA  *boxa)
+{
+l_int32  i, n;
+BOX     *box, *boxc;
+PIX     *pix;
+PIXA    *pixa;
+if (!pixs)
+return (PIXA *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (!boxa)
+return (PIXA *)ERROR_PTR("boxa not defined", __func__, NULL);
+n = boxaGetCount(boxa);
+pixa = pixaCreate(n);
+for (i = 0; i < n; i++) {
+box = boxaGetBox(boxa, i, L_CLONE);
+pix = pixClipRectangle(pixs, box, &boxc);
+pixaAddPix(pixa, pix, L_INSERT);
+pixaAddBox(pixa, boxc, L_INSERT);
+boxDestroy(&box);
+}
+return pixa;
+}
+/*!
+* \brief   pixClipRectangle()
+*
+* \param[in]    pixs
+* \param[in]    box    requested clipping region; const
+* \param[out]   pboxc  [optional] actual box of clipped region
+* \return  clipped pix, or NULL on error or if rectangle
+*              doesn't intersect pixs
+*
+* <pre>
+* Notes:
+*
+*  This should be simple, but there are choices to be made.
+*  The box is defined relative to the pix coordinates.  However,
+*  if the box is not contained within the pix, we have two choices:
+*
+*      (1) clip the box to the pix
+*      (2) make a new pix equal to the full box dimensions,
+*          but let rasterop do the clipping and positioning
+*          of the src with respect to the dest
+*
+*  Choice (2) immediately brings up the problem of what pixel values
+*  to use that were not taken from the src.  For example, on a grayscale
+*  image, do you want the pixels not taken from the src to be black
+*  or white or something else?  To implement choice 2, one needs to
+*  specify the color of these extra pixels.
+*
+*  So we adopt (1), and clip the box first, if necessary,
+*  before making the dest pix and doing the rasterop.  But there
+*  is another issue to consider.  If you want to paste the
+*  clipped pix back into pixs, it must be properly aligned, and
+*  it is necessary to use the clipped box for alignment.
+*  Accordingly, this function has a third (optional) argument, which is
+*  the input box clipped to the src pix.
+* </pre>
+*/
+PIX *
+pixClipRectangle(PIX   *pixs,
+BOX   *box,
+BOX  **pboxc)
+{
+l_int32  w, h, d, bx, by, bw, bh;
+BOX     *boxc;
+PIX     *pixd;
+if (pboxc) *pboxc = NULL;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (!box)
+return (PIX *)ERROR_PTR("box not defined", __func__, NULL);
+/* Clip the input box to the pix */
+pixGetDimensions(pixs, &w, &h, &d);
+if ((boxc = boxClipToRectangle(box, w, h)) == NULL) {
+L_WARNING("box doesn't overlap pix\n", __func__);
+return NULL;
+}
+boxGetGeometry(boxc, &bx, &by, &bw, &bh);
+/* Extract the block */
+if ((pixd = pixCreate(bw, bh, d)) == NULL) {
+boxDestroy(&boxc);
+return (PIX *)ERROR_PTR("pixd not made", __func__, NULL);
+}
+pixCopyResolution(pixd, pixs);
+pixCopyColormap(pixd, pixs);
+pixCopyText(pixd, pixs);
+pixRasterop(pixd, 0, 0, bw, bh, PIX_SRC, pixs, bx, by);
+if (pboxc)
+*pboxc = boxc;
+else
+boxDestroy(&boxc);
+return pixd;
+}
+/*!
+* \brief   pixClipRectangleWithBorder()
+*
+* \param[in]    pixs
+* \param[in]    box       requested clipping region; const
+* \param[in]    maxbord   maximum amount of border to include
+* \param[out]   pboxn     box in coordinates of returned pix
+* \return  under-clipped pix, or NULL on error or if rectangle
+*              doesn't intersect pixs
+*
+* <pre>
+* Notes:
+*      (1) This underclips by an amount determined by the minimum of
+*          %maxbord and the amount of border that can be included
+*          equally on all 4 sides.
+*      (2) If part of the rectangle lies outside the pix, no border
+*          is included on any side.
+* </pre>
+*/
+PIX *
+pixClipRectangleWithBorder(PIX     *pixs,
+BOX     *box,
+l_int32  maxbord,
+BOX    **pboxn)
+{
+l_int32  w, h, bx, by, bw, bh, bord;
+BOX     *box1;
+PIX     *pix1;
+if (!pboxn)
+return (PIX *)ERROR_PTR("&boxn not defined", __func__, NULL);
+*pboxn = NULL;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (!box)
+return (PIX *)ERROR_PTR("box not defined", __func__, NULL);
+/* Determine the border width */
+pixGetDimensions(pixs, &w, &h, NULL);
+boxGetGeometry(box, &bx, &by, &bw, &bh);
+bord = L_MIN(bx, by);
+bord = L_MIN(bord, w - bx - bw);
+bord = L_MIN(bord, h - by - bh);
+bord = L_MIN(bord, maxbord);
+if (bord <= 0) {  /* standard clipping */
+pix1 = pixClipRectangle(pixs, box, NULL);
+pixGetDimensions(pix1, &w, &h, NULL);
+*pboxn = boxCreate(0, 0, w, h);
+return pix1;
+}
+/* There is a positive border */
+box1 = boxAdjustSides(NULL, box, -bord, bord, -bord, bord);
+pix1 = pixClipRectangle(pixs, box1, NULL);
+boxDestroy(&box1);
+*pboxn = boxCreate(bord, bord, bw, bh);
+return pix1;
+}
+/*!
+* \brief   pixClipMasked()
+*
+* \param[in]    pixs    1, 2, 4, 8, 16, 32 bpp; colormap ok
+* \param[in]    pixm    clipping mask, 1 bpp
+* \param[in]    x, y    origin of clipping mask relative to pixs
+* \param[in]    outval  val to use for pixels that are outside the mask
+* \return  pixd, clipped pix or NULL on error or if pixm doesn't
+*              intersect pixs
+*
+* <pre>
+* Notes:
+*      (1) If pixs has a colormap, it is preserved in pixd.
+*      (2) The depth of pixd is the same as that of pixs.
+*      (3) If the depth of pixs is 1, use %outval = 0 for white background
+*          and 1 for black; otherwise, use the max value for white
+*          and 0 for black.  If pixs has a colormap, the max value for
+*          %outval is 0xffffffff; otherwise, it is 2^d - 1.
+*      (4) When using 1 bpp pixs, this is a simple clip and
+*          blend operation.  For example, if both pix1 and pix2 are
+*          black text on white background, and you want to OR the
+*          fg on the two images, let pixm be the inverse of pix2.
+*          Then the operation takes all of pix1 that's in the bg of
+*          pix2, and for the remainder (which are the pixels
+*          corresponding to the fg of the pix2), paint them black
+*          (1) in pix1.  The function call looks like
+*             pixClipMasked(pix2, pixInvert(pix1, pix1), x, y, 1);
+* </pre>
+*/
+PIX *
+pixClipMasked(PIX      *pixs,
+PIX      *pixm,
+l_int32   x,
+l_int32   y,
+l_uint32  outval)
+{
+l_int32   wm, hm, index, rval, gval, bval;
+l_uint32  pixel;
+BOX      *box;
+PIX      *pixmi, *pixd;
+PIXCMAP  *cmap;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (!pixm || pixGetDepth(pixm) != 1)
+return (PIX *)ERROR_PTR("pixm undefined or not 1 bpp", __func__, NULL);
+/* Clip out the region specified by pixm and (x,y) */
+pixGetDimensions(pixm, &wm, &hm, NULL);
+box = boxCreate(x, y, wm, hm);
+pixd = pixClipRectangle(pixs, box, NULL);
+/* Paint 'outval' (or something close to it if cmapped) through
+* the pixels not masked by pixm */
+cmap = pixGetColormap(pixd);
+pixmi = pixInvert(NULL, pixm);
+if (cmap) {
+extractRGBValues(outval, &rval, &gval, &bval);
+pixcmapGetNearestIndex(cmap, rval, gval, bval, &index);
+pixcmapGetColor(cmap, index, &rval, &gval, &bval);
+composeRGBPixel(rval, gval, bval, &pixel);
+pixPaintThroughMask(pixd, pixmi, 0, 0, pixel);
+} else {
+pixPaintThroughMask(pixd, pixmi, 0, 0, outval);
+}
+boxDestroy(&box);
+pixDestroy(&pixmi);
+return pixd;
+}
+/*!
+* \brief   pixCropToMatch()
+*
+* \param[in]    pixs1   any depth, colormap OK
+* \param[in]    pixs2   any depth, colormap OK
+* \param[out]   ppixd1  may be a clone
+* \param[out]   ppixd2  may be a clone
+* \return  0 if OK, 1 on error
+*
+* <pre>
+* Notes:
+*      (1) This resizes pixs1 and/or pixs2 by cropping at the right
+*          and bottom, so that they're the same size.
+*      (2) If a pix doesn't need to be cropped, a clone is returned.
+*      (3) Note: the images are implicitly aligned to the UL corner.
+* </pre>
+*/
+l_ok
+pixCropToMatch(PIX   *pixs1,
+PIX   *pixs2,
+PIX  **ppixd1,
+PIX  **ppixd2)
+{
+l_int32  w1, h1, w2, h2, w, h;
+if (!ppixd1 || !ppixd2)
+return ERROR_INT("&pixd1 and &pixd2 not both defined", __func__, 1);
+*ppixd1 = *ppixd2 = NULL;
+if (!pixs1 || !pixs2)
+return ERROR_INT("pixs1 and pixs2 not defined", __func__, 1);
+pixGetDimensions(pixs1, &w1, &h1, NULL);
+pixGetDimensions(pixs2, &w2, &h2, NULL);
+w = L_MIN(w1, w2);
+h = L_MIN(h1, h2);
+*ppixd1 = pixCropToSize(pixs1, w, h);
+*ppixd2 = pixCropToSize(pixs2, w, h);
+if (*ppixd1 == NULL || *ppixd2 == NULL)
+return ERROR_INT("cropped image failure", __func__, 1);
+return 0;
+}
+/*!
+* \brief   pixCropToSize()
+*
+* \param[in]    pixs   any depth, colormap OK
+* \param[in]    w, h   max dimensions of cropped image
+* \return  pixd cropped if necessary or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) If either w or h is smaller than the corresponding dimension
+*          of pixs, this returns a cropped image; otherwise it returns
+*          a clone of pixs.
+* </pre>
+*/
+PIX *
+pixCropToSize(PIX     *pixs,
+l_int32  w,
+l_int32  h)
+{
+l_int32  ws, hs, wd, hd, d;
+PIX     *pixd;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+pixGetDimensions(pixs, &ws, &hs, &d);
+if (ws <= w && hs <= h)  /* no cropping necessary */
+return pixClone(pixs);
+wd = L_MIN(ws, w);
+hd = L_MIN(hs, h);
+if ((pixd = pixCreate(wd, hd, d)) == NULL)
+return (PIX *)ERROR_PTR("pixd not made", __func__, NULL);
+pixCopyResolution(pixd, pixs);
+pixCopyColormap(pixd, pixs);
+pixCopyText(pixd, pixs);
+pixCopyInputFormat(pixd, pixs);
+pixRasterop(pixd, 0, 0, wd, hd, PIX_SRC, pixs, 0, 0);
+return pixd;
+}
+/*!
+* \brief   pixResizeToMatch()
+*
+* \param[in]    pixs   1, 2, 4, 8, 16, 32 bpp; colormap ok
+* \param[in]    pixt   can be null; we use only the size
+* \param[in]    w, h   ignored if pixt is defined
+* \return  pixd resized to match or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This resizes pixs to make pixd, without scaling, by either
+*          cropping or extending separately in both width and height.
+*          Extension is done by replicating the last row or column.
+*          This is useful in a situation where, due to scaling
+*          operations, two images that are expected to be the
+*          same size can differ slightly in each dimension.
+*      (2) You can use either an existing pixt or specify
+*          both %w and %h.  If pixt is defined, the values
+*          in %w and %h are ignored.
+*      (3) If pixt is larger than pixs (or if w and/or d is larger
+*          than the dimension of pixs, replicate the outer row and
+*          column of pixels in pixs into pixd.
+* </pre>
+*/
+PIX *
+pixResizeToMatch(PIX     *pixs,
+PIX     *pixt,
+l_int32  w,
+l_int32  h)
+{
+l_int32  i, j, ws, hs, d;
+PIX     *pixd;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (!pixt && (w <= 0 || h <= 0))
+return (PIX *)ERROR_PTR("both w and h not > 0", __func__, NULL);
+if (pixt)  /* redefine w, h */
+pixGetDimensions(pixt, &w, &h, NULL);
+pixGetDimensions(pixs, &ws, &hs, &d);
+if (ws == w && hs == h)
+return pixCopy(NULL, pixs);
+if ((pixd = pixCreate(w, h, d)) == NULL)
+return (PIX *)ERROR_PTR("pixd not made", __func__, NULL);
+pixCopyResolution(pixd, pixs);
+pixCopyColormap(pixd, pixs);
+pixCopyText(pixd, pixs);
+pixCopyInputFormat(pixd, pixs);
+pixRasterop(pixd, 0, 0, ws, hs, PIX_SRC, pixs, 0, 0);
+if (ws >= w && hs >= h)
+return pixd;
+/* Replicate the last column and then the last row */
+if (ws < w) {
+for (j = ws; j < w; j++)
+pixRasterop(pixd, j, 0, 1, h, PIX_SRC, pixd, ws - 1, 0);
+}
+if (hs < h) {
+for (i = hs; i < h; i++)
+pixRasterop(pixd, 0, i, w, 1, PIX_SRC, pixd, 0, hs - 1);
+}
+return pixd;
+}
+/*---------------------------------------------------------------------*
+*                Select a connected component by size                 *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixSelectComponentBySize()
+*
+* \param[in]    pixs          1 bpp
+* \param[in]    rankorder     in decreasing size: 0 for largest.
+* \param[in]    type          L_SELECT_BY_WIDTH, L_SELECT_BY_HEIGHT,
+*                             L_SELECT_BY_MAX_DIMENSION,
+*                             L_SELECT_BY_AREA, L_SELECT_BY_PERIMETER
+* \param[in]    connectivity  4 or 8
+* \param[out]   pbox          [optional] location of returned component
+* \return  pix of rank order connected component, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) This selects the Nth largest connected component, based on
+*          the selection type and connectivity.
+*      (2) Note that %rankorder is an integer.  Use %rankorder = 0 for
+*          the largest component and %rankorder = -1 for the smallest.
+*          If %rankorder >= number of components, select the smallest.
+*/
+PIX *
+pixSelectComponentBySize(PIX     *pixs,
+l_int32  rankorder,
+l_int32  type,
+l_int32  connectivity,
+BOX    **pbox)
+{
+l_int32  n, empty, sorttype, index;
+BOXA    *boxa1;
+NUMA    *naindex;
+PIX     *pixd;
+PIXA    *pixa1, *pixa2;
+if (pbox) *pbox = NULL;
+if (!pixs || pixGetDepth(pixs) != 1)
+return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", __func__, NULL);
+if (type == L_SELECT_BY_WIDTH)
+sorttype = L_SORT_BY_WIDTH;
+else if (type == L_SELECT_BY_HEIGHT)
+sorttype = L_SORT_BY_HEIGHT;
+else if (type == L_SELECT_BY_MAX_DIMENSION)
+sorttype = L_SORT_BY_MAX_DIMENSION;
+else if (type == L_SELECT_BY_AREA)
+sorttype = L_SORT_BY_AREA;
+else if (type == L_SELECT_BY_PERIMETER)
+sorttype = L_SORT_BY_PERIMETER;
+else
+return (PIX *)ERROR_PTR("invalid selection type", __func__, NULL);
+if (connectivity != 4 && connectivity != 8)
+return (PIX *)ERROR_PTR("connectivity not 4 or 8", __func__, NULL);
+pixZero(pixs, &empty);
+if (empty)
+return (PIX *)ERROR_PTR("no foreground pixels", __func__, NULL);
+boxa1 = pixConnComp(pixs, &pixa1, connectivity);
+n = boxaGetCount(boxa1);
+if (rankorder < 0 || rankorder >= n)
+rankorder = n - 1;  /* smallest */
+pixa2 = pixaSort(pixa1, sorttype, L_SORT_DECREASING, &naindex, L_CLONE);
+pixd = pixaGetPix(pixa2, rankorder, L_COPY);
+if (pbox) {
+numaGetIValue(naindex, rankorder, &index);
+*pbox = boxaGetBox(boxa1, index, L_COPY);
+}
+numaDestroy(&naindex);
+boxaDestroy(&boxa1);
+pixaDestroy(&pixa1);
+pixaDestroy(&pixa2);
+return pixd;
+}
+/*!
+* \brief   pixFilterComponentBySize()
+*
+* \param[in]    pixs          1 bpp
+* \param[in]    rankorder     in decreasing size: 0 for largest.
+* \param[in]    type          L_SELECT_BY_WIDTH, L_SELECT_BY_HEIGHT,
+*                             L_SELECT_BY_MAX_DIMENSION,
+*                             L_SELECT_BY_AREA, L_SELECT_BY_PERIMETER
+* \param[in]    connectivity  4 or 8
+* \param[out]   pbox          [optional] location of returned component
+* \return  pix with all other components removed, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) See notes in pixSelectComponentBySize().
+*      (2) This returns a copy of %pixs, with all components removed
+*          except for the selected one.
+*/
+PIX *
+pixFilterComponentBySize(PIX     *pixs,
+l_int32  rankorder,
+l_int32  type,
+l_int32  connectivity,
+BOX    **pbox)
+{
+l_int32  x, y, w, h;
+BOX     *box;
+PIX     *pix1, *pix2;
+if (!pixs || pixGetDepth(pixs) != 1)
+return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", __func__, NULL);
+pix1 = pixSelectComponentBySize(pixs, rankorder, type, connectivity, &box);
+if (!pix1) {
+boxDestroy(&box);
+return (PIX *)ERROR_PTR("pix1 not made", __func__, NULL);
+}
+/* Put the selected component in a new pix at the same
+* location as it had in %pixs */
+boxGetGeometry(box, &x, &y, &w, &h);
+pix2 = pixCreateTemplate(pixs);
+pixRasterop(pix2, x, y, w, h, PIX_SRC, pix1, 0, 0);
+if (pbox)
+*pbox = box;
+else
+boxDestroy(&box);
+pixDestroy(&pix1);
+return pix2;
+}
+/*---------------------------------------------------------------------*
+*                         Make special masks                          *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixMakeSymmetricMask()
+*
+* \param[in]    w, h    dimensions of output 1 bpp pix
+* \param[in]    hf      horizontal fraction of half-width
+* \param[in]    vf      vertical fraction of half-height
+* \param[in]    type    L_USE_INNER, L_USE_OUTER
+* \return  pixd 1 bpp, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) This is a convenience function for generating masks with
+*          horizontal and vertical reflection symmetry, over either
+*          the inner or outer parts of an image.
+*      (2) Using L_USE_INNER to generate a mask over the inner part
+*          of the image, the mask is a solid rectangle, and the fractions
+*          describe the distance between the boundary of the image and
+*          the rectangle boundary.  For example, with hf == vf == 0.0,
+*          the mask covers the full image.
+*      (3) Using L_USE_OUTER to generate a mask over an outer frame
+*          of the image, the mask touches the boundary of the image,
+*          and the fractions describe the location of the inner
+*          boundary of the frame.  For example, with hf == vf == 1.0,
+*          the inner boundary is at the center of the image, so the
+*          mask covers the full image.
+*      (4) More examples:
+*           * mask covering the inner 70%: hf = vf = 0.3, type = L_USE_INNER
+*           * frame covering the outer 30%: hf = vf = 0.3, type = L_USE_OUTER
+* </pre>
+*/
+PIX *
+pixMakeSymmetricMask(l_int32    w,
+l_int32    h,
+l_float32  hf,
+l_float32  vf,
+l_int32    type)
+{
+if (w <= 0 || h <= 0)
+return (PIX *)ERROR_PTR("mask size 0", __func__, NULL);
+if (hf < 0.0 || hf > 1.0)
+return (PIX *)ERROR_PTR("invalid horiz fractions", __func__, NULL);
+if (vf < 0.0 || vf > 1.0)
+return (PIX *)ERROR_PTR("invalid vert fractions", __func__, NULL);
+if (type == L_USE_INNER)
+return pixMakeFrameMask(w, h, hf, 1.0, vf, 1.0);
+else if (type == L_USE_OUTER)
+return pixMakeFrameMask(w, h, 0.0, hf, 0.0, vf);
+else
+return (PIX *)ERROR_PTR("invalid type", __func__, NULL);
+}
+/*!
+* \brief   pixMakeFrameMask()
+*
+* \param[in]    w, h  dimensions of output 1 bpp pix
+* \param[in]    hf1   horizontal fraction of half-width at outer frame bdry
+* \param[in]    hf2   horizontal fraction of half-width at inner frame bdry
+* \param[in]    vf1   vertical fraction of half-width at outer frame bdry
+* \param[in]    vf2   vertical fraction of half-width at inner frame bdry
+* \return  pixd 1 bpp, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) This makes an arbitrary 1-component mask with a centered fg
+*          frame, which can have both an inner and an outer boundary.
+*          All input fractional distances are measured from the image
+*          border to the frame boundary, in units of the image half-width
+*          for hf1 and hf2 and the image half-height for vf1 and vf2.
+*          The distances to the outer frame boundary are given by hf1
+*          and vf1; to the inner frame boundary, by hf2 and vf2.
+*          Input fractions are thus in [0.0 ... 1.0], with hf1 <= hf2
+*          and vf1 <= vf2.  Horizontal and vertical frame widths are
+*          thus independently specified.
+*      (2) Special cases:
+*           * full fg mask: hf1 = vf1 = 0.0, hf2 = vf2 = 1.0.
+*           * empty fg (zero width) mask: set  hf1 = hf2  and vf1 = vf2.
+*           * fg rectangle with no hole: set hf2 = vf2 = 1.0.
+*           * frame touching outer boundary: set hf1 = vf1 = 0.0.
+*      (3) The vertical thickness of the horizontal mask parts
+*          is 0.5 * (vf2 - vf1) * h.  The horizontal thickness of the
+*          vertical mask parts is 0.5 * (hf2 - hf1) * w.
+* </pre>
+*/
+PIX *
+pixMakeFrameMask(l_int32    w,
+l_int32    h,
+l_float32  hf1,
+l_float32  hf2,
+l_float32  vf1,
+l_float32  vf2)
+{
+l_int32  h1, h2, v1, v2;
+PIX     *pixd;
+if (w <= 0 || h <= 0)
+return (PIX *)ERROR_PTR("mask size 0", __func__, NULL);
+if (hf1 < 0.0 || hf1 > 1.0 || hf2 < 0.0 || hf2 > 1.0)
+return (PIX *)ERROR_PTR("invalid horiz fractions", __func__, NULL);
+if (vf1 < 0.0 || vf1 > 1.0 || vf2 < 0.0 || vf2 > 1.0)
+return (PIX *)ERROR_PTR("invalid vert fractions", __func__, NULL);
+if (hf1 > hf2 || vf1 > vf2)
+return (PIX *)ERROR_PTR("invalid relative sizes", __func__, NULL);
+pixd = pixCreate(w, h, 1);
+/* Special cases */
+if (hf1 == 0.0 && vf1 == 0.0 && hf2 == 1.0 && vf2 == 1.0) {  /* full */
+pixSetAll(pixd);
+return pixd;
+}
+if (hf1 == hf2 && vf1 == vf2) {  /* empty */
+return pixd;
+}
+/* General case */
+h1 = 0.5f * hf1 * w;
+h2 = 0.5f * hf2 * w;
+v1 = 0.5f * vf1 * h;
+v2 = 0.5f * vf2 * h;
+pixRasterop(pixd, h1, v1, w - 2 * h1, h - 2 * v1, PIX_SET, NULL, 0, 0);
+if (hf2 < 1.0 && vf2 < 1.0)
+pixRasterop(pixd, h2, v2, w - 2 * h2, h - 2 * v2, PIX_CLR, NULL, 0, 0);
+return pixd;
+}
+/*---------------------------------------------------------------------*
+*     Generate a covering of rectangles over connected components     *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixMakeCoveringOfRectangles()
+*
+* \param[in]   pixs       1 bpp
+* \param[in]   maxiters   max iterations: use 0 to iterate to completion
+* \return  pixd, or NULL on error
+*
+* <pre>
+* Notes:
+*      (1) This iteratively finds the bounding boxes of the connected
+*          components and generates a mask from them.  Two iterations
+*          should suffice for most situations.
+*      (2) Returns an empty pix if %pixs is empty.
+*      (3) If there are many small components in proximity, it may
+*          be useful to merge them with a morphological closing before
+*          calling this one.
+* </pre>
+*/
+PIX *
+pixMakeCoveringOfRectangles(PIX     *pixs,
+l_int32  maxiters)
+{
+l_int32  empty, same, niters;
+BOXA    *boxa;
+PIX     *pix1, *pix2;
+if (!pixs || pixGetDepth(pixs) != 1)
+return (PIX *)ERROR_PTR("pixs undefined or not 1 bpp", __func__, NULL);
+if (maxiters < 0)
+return (PIX *)ERROR_PTR("maxiters must be >= 0", __func__, NULL);
+if (maxiters == 0) maxiters = 50;  /* ridiculously large number */
+pixZero(pixs, &empty);
+pix1 = pixCreateTemplate(pixs);
+if (empty) return pix1;
+/* Do first iteration */
+boxa = pixConnCompBB(pixs, 8);
+pixMaskBoxa(pix1, pix1, boxa, L_SET_PIXELS);
+boxaDestroy(&boxa);
+if (maxiters == 1) return pix1;
+niters = 1;
+while (niters < maxiters) {  /* continue to add pixels to pix1 */
+niters++;
+boxa = pixConnCompBB(pix1, 8);
+pix2 = pixCopy(NULL, pix1);
+pixMaskBoxa(pix1, pix1, boxa, L_SET_PIXELS);
+boxaDestroy(&boxa);
+pixEqual(pix1, pix2, &same);
+pixDestroy(&pix2);
+if (same) {
+L_INFO("%d iterations\n", __func__, niters - 1);
+return pix1;
+}
+}
+L_INFO("maxiters = %d reached\n", __func__, niters);
+return pix1;
+}
+/*---------------------------------------------------------------------*
+*                 Fraction of Fg pixels under a mask                  *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixFractionFgInMask()
+*
+* \param[in]    pix1    1 bpp
+* \param[in]    pix2    1 bpp
+* \param[out]   pfract  fraction of fg pixels in 1 that are
+*                       aligned with the fg of 2
+* \return  0 if OK, 1 on error.
+*
+* <pre>
+* Notes:
+*      (1) This gives the fraction of fg pixels in pix1 that are in
+*          the intersection (i.e., under the fg) of pix2:
+*          |1 & 2|/|1|, where |...| means the number of fg pixels.
+*          Note that this is different from the situation where
+*          pix1 and pix2 are reversed.
+*      (2) Both pix1 and pix2 are registered to the UL corners.  A warning
+*          is issued if pix1 and pix2 have different sizes.
+*      (3) This can also be used to find the fraction of fg pixels in pix1
+*          that are NOT under the fg of pix2: 1.0 - |1 & 2|/|1|
+*      (4) If pix1 or pix2 are empty, this returns %fract = 0.0.
+*      (5) For example, pix2 could be a frame around the outside of the
+*          image, made from pixMakeFrameMask().
+* </pre>
+*/
+l_ok
+pixFractionFgInMask(PIX        *pix1,
+PIX        *pix2,
+l_float32  *pfract)
+{
+l_int32  w1, h1, w2, h2, empty, count1, count3;
+PIX     *pix3;
+if (!pfract)
+return ERROR_INT("&fract not defined", __func__, 1);
+*pfract = 0.0;
+if (!pix1 || pixGetDepth(pix1) != 1)
+return ERROR_INT("pix1 not defined or not 1 bpp", __func__, 1);
+if (!pix2 || pixGetDepth(pix2) != 1)
+return ERROR_INT("pix2 not defined or not 1 bpp", __func__, 1);
+pixGetDimensions(pix1, &w1, &h1, NULL);
+pixGetDimensions(pix2, &w2, &h2, NULL);
+if (w1 != w2 || h1 != h2) {
+L_INFO("sizes unequal: (w1,w2) = (%d,%d), (h1,h2) = (%d,%d)\n",
+__func__, w1, w2, h1, h2);
+}
+pixZero(pix1, &empty);
+if (empty) return 0;
+pixZero(pix2, &empty);
+if (empty) return 0;
+pix3 = pixCopy(NULL, pix1);
+pixAnd(pix3, pix3, pix2);
+pixCountPixels(pix1, &count1, NULL);  /* |1| */
+pixCountPixels(pix3, &count3, NULL);  /* |1 & 2| */
+*pfract = (l_float32)count3 / (l_float32)count1;
+pixDestroy(&pix3);
+return 0;
+}
+/*---------------------------------------------------------------------*
+*                           Clip to Foreground                        *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixClipToForeground()
+*
+* \param[in]    pixs   1 bpp
+* \param[out]   ppixd  [optional] clipped pix returned
+* \param[out]   pbox   [optional] bounding box
+* \return  0 if OK; 1 on error or if there are no fg pixels
+*
+* <pre>
+* Notes:
+*      (1) At least one of {&pixd, &box} must be specified.
+*      (2) If there are no fg pixels, the returned ptrs are null.
+* </pre>
+*/
+l_ok
+pixClipToForeground(PIX   *pixs,
+PIX  **ppixd,
+BOX  **pbox)
+{
+l_int32    w, h, wpl, nfullwords, extra, i, j;
+l_int32    minx, miny, maxx, maxy;
+l_uint32   result, mask;
+l_uint32  *data, *line;
+BOX       *box;
+if (ppixd) *ppixd = NULL;
+if (pbox) *pbox = NULL;
+if (!ppixd && !pbox)
+return ERROR_INT("no output requested", __func__, 1);
+if (!pixs || (pixGetDepth(pixs) != 1))
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+pixGetDimensions(pixs, &w, &h, NULL);
+nfullwords = w / 32;
+extra = w & 31;
+mask = ~rmask32[32 - extra];
+wpl = pixGetWpl(pixs);
+data = pixGetData(pixs);
+result = 0;
+for (i = 0, miny = 0; i < h; i++, miny++) {
+line = data + i * wpl;
+for (j = 0; j < nfullwords; j++)
+result |= line[j];
+if (extra)
+result |= (line[j] & mask);
+if (result)
+break;
+}
+if (miny == h)  /* no ON pixels */
+return 1;
+result = 0;
+for (i = h - 1, maxy = h - 1; i >= 0; i--, maxy--) {
+line = data + i * wpl;
+for (j = 0; j < nfullwords; j++)
+result |= line[j];
+if (extra)
+result |= (line[j] & mask);
+if (result)
+break;
+}
+minx = 0;
+for (j = 0, minx = 0; j < w; j++, minx++) {
+for (i = 0; i < h; i++) {
+line = data + i * wpl;
+if (GET_DATA_BIT(line, j))
+goto minx_found;
+}
+}
+minx_found:
+for (j = w - 1, maxx = w - 1; j >= 0; j--, maxx--) {
+for (i = 0; i < h; i++) {
+line = data + i * wpl;
+if (GET_DATA_BIT(line, j))
+goto maxx_found;
+}
+}
+maxx_found:
+box = boxCreate(minx, miny, maxx - minx + 1, maxy - miny + 1);
+if (ppixd)
+*ppixd = pixClipRectangle(pixs, box, NULL);
+if (pbox)
+*pbox = box;
+else
+boxDestroy(&box);
+return 0;
+}
+/*!
+* \brief   pixTestClipToForeground()
+*
+* \param[in]    pixs      1 bpp
+* \param[out]   pcanclip  1 if fg does not extend to all four edges
+* \return  0 if OK; 1 on error
+*
+* <pre>
+* Notes:
+*      (1) This is a lightweight test to determine if a 1 bpp image
+*          can be further cropped without loss of fg pixels.
+*          If it cannot, canclip is set to 0.
+*      (2) It does not test for the existence of any fg pixels.
+*          If there are no fg pixels, it will return %canclip = 1.
+*          Check the output of the subsequent call to pixClipToForeground().
+* </pre>
+*/
+l_ok
+pixTestClipToForeground(PIX      *pixs,
+l_int32  *pcanclip)
+{
+l_int32    i, j, w, h, wpl, found;
+l_uint32  *data, *line;
+if (!pcanclip)
+return ERROR_INT("&canclip not defined", __func__, 1);
+*pcanclip = 0;
+if (!pixs || (pixGetDepth(pixs) != 1))
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+/* Check top and bottom raster lines */
+pixGetDimensions(pixs, &w, &h, NULL);
+data = pixGetData(pixs);
+wpl = pixGetWpl(pixs);
+found = FALSE;
+for (j = 0; found == FALSE && j < w; j++)
+found = GET_DATA_BIT(data, j);
+if (!found) {
+*pcanclip = 1;
+return 0;
+}
+line = data + (h - 1) * wpl;
+found = FALSE;
+for (j = 0; found == FALSE && j < w; j++)
+found = GET_DATA_BIT(data, j);
+if (!found) {
+*pcanclip = 1;
+return 0;
+}
+/* Check left and right edges */
+found = FALSE;
+for (i = 0, line = data; found == FALSE && i < h; line += wpl, i++)
+found = GET_DATA_BIT(line, 0);
+if (!found) {
+*pcanclip = 1;
+return 0;
+}
+found = FALSE;
+for (i = 0, line = data; found == FALSE && i < h; line += wpl, i++)
+found = GET_DATA_BIT(line, w - 1);
+if (!found)
+*pcanclip = 1;
+return 0;  /* fg pixels found on all edges */
+}
+/*!
+* \brief   pixClipBoxToForeground()
+*
+* \param[in]    pixs   1 bpp
+* \param[in]    boxs   [optional] use full image if null
+* \param[out]   ppixd  [optional] clipped pix returned
+* \param[out]   pboxd  [optional] bounding box
+* \return  0 if OK; 1 on error or if there are no fg pixels
+*
+* <pre>
+* Notes:
+*      (1) At least one of {&pixd, &boxd} must be specified.
+*      (2) If there are no fg pixels, the returned ptrs are null.
+*      (3) Do not use &pixs for the 3rd arg or &boxs for the 4th arg;
+*          this will leak memory.
+* </pre>
+*/
+l_ok
+pixClipBoxToForeground(PIX   *pixs,
+BOX   *boxs,
+PIX  **ppixd,
+BOX  **pboxd)
+{
+l_int32  w, h, bx, by, bw, bh, cbw, cbh, left, right, top, bottom;
+BOX     *boxt, *boxd;
+if (ppixd) *ppixd = NULL;
+if (pboxd) *pboxd = NULL;
+if (!ppixd && !pboxd)
+return ERROR_INT("no output requested", __func__, 1);
+if (!pixs || (pixGetDepth(pixs) != 1))
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (!boxs)
+return pixClipToForeground(pixs, ppixd, pboxd);
+pixGetDimensions(pixs, &w, &h, NULL);
+boxGetGeometry(boxs, &bx, &by, &bw, &bh);
+cbw = L_MIN(bw, w - bx);
+cbh = L_MIN(bh, h - by);
+if (cbw < 0 || cbh < 0)
+return ERROR_INT("box not within image", __func__, 1);
+boxt = boxCreate(bx, by, cbw, cbh);
+if (pixScanForForeground(pixs, boxt, L_FROM_LEFT, &left)) {
+boxDestroy(&boxt);
+return 1;
+}
+pixScanForForeground(pixs, boxt, L_FROM_RIGHT, &right);
+pixScanForForeground(pixs, boxt, L_FROM_TOP, &top);
+pixScanForForeground(pixs, boxt, L_FROM_BOT, &bottom);
+boxd = boxCreate(left, top, right - left + 1, bottom - top + 1);
+if (ppixd)
+*ppixd = pixClipRectangle(pixs, boxd, NULL);
+if (pboxd)
+*pboxd = boxd;
+else
+boxDestroy(&boxd);
+boxDestroy(&boxt);
+return 0;
+}
+/*!
+* \brief   pixScanForForeground()
+*
+* \param[in]    pixs      1 bpp
+* \param[in]    box       [optional] within which the search is conducted
+* \param[in]    scanflag  direction of scan; e.g., L_FROM_LEFT
+* \param[out]   ploc      location in scan direction of first black pixel
+* \return  0 if OK; 1 on error or if no fg pixels are found
+*
+* <pre>
+* Notes:
+*      (1) If there are no fg pixels, the position is set to 0.
+*          Caller must check the return value!
+*      (2) Use %box == NULL to scan from edge of pixs
+* </pre>
+*/
+l_ok
+pixScanForForeground(PIX      *pixs,
+BOX      *box,
+l_int32   scanflag,
+l_int32  *ploc)
+{
+l_int32    bx, by, bw, bh, x, xstart, xend, y, ystart, yend, wpl;
+l_uint32  *data, *line;
+BOX       *boxt;
+if (!ploc)
+return ERROR_INT("&loc not defined", __func__, 1);
+*ploc = 0;
+if (!pixs || (pixGetDepth(pixs) != 1))
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+/* Clip box to pixs if it exists */
+pixGetDimensions(pixs, &bw, &bh, NULL);
+if (box) {
+if ((boxt = boxClipToRectangle(box, bw, bh)) == NULL)
+return ERROR_INT("invalid box", __func__, 1);
+boxGetGeometry(boxt, &bx, &by, &bw, &bh);
+boxDestroy(&boxt);
+} else {
+bx = by = 0;
+}
+xstart = bx;
+ystart = by;
+xend = bx + bw - 1;
+yend = by + bh - 1;
+data = pixGetData(pixs);
+wpl = pixGetWpl(pixs);
+if (scanflag == L_FROM_LEFT) {
+for (x = xstart; x <= xend; x++) {
+for (y = ystart; y <= yend; y++) {
+line = data + y * wpl;
+if (GET_DATA_BIT(line, x)) {
+*ploc = x;
+return 0;
+}
+}
+}
+} else if (scanflag == L_FROM_RIGHT) {
+for (x = xend; x >= xstart; x--) {
+for (y = ystart; y <= yend; y++) {
+line = data + y * wpl;
+if (GET_DATA_BIT(line, x)) {
+*ploc = x;
+return 0;
+}
+}
+}
+} else if (scanflag == L_FROM_TOP) {
+for (y = ystart; y <= yend; y++) {
+line = data + y * wpl;
+for (x = xstart; x <= xend; x++) {
+if (GET_DATA_BIT(line, x)) {
+*ploc = y;
+return 0;
+}
+}
+}
+} else if (scanflag == L_FROM_BOT) {
+for (y = yend; y >= ystart; y--) {
+line = data + y * wpl;
+for (x = xstart; x <= xend; x++) {
+if (GET_DATA_BIT(line, x)) {
+*ploc = y;
+return 0;
+}
+}
+}
+} else {
+return ERROR_INT("invalid scanflag", __func__, 1);
+}
+return 1;  /* no fg found */
+}
+/*!
+* \brief   pixClipBoxToEdges()
+*
+* \param[in]    pixs        1 bpp
+* \param[in]    boxs        [optional] ; use full image if null
+* \param[in]    lowthresh   threshold to choose clipping location
+* \param[in]    highthresh  threshold required to find an edge
+* \param[in]    maxwidth    max allowed width between low and high thresh locs
+* \param[in]    factor      sampling factor along pixel counting direction
+* \param[out]   ppixd       [optional] clipped pix returned
+* \param[out]   pboxd       [optional] bounding box
+* \return  0 if OK; 1 on error or if a fg edge is not found from
+*              all four sides.
+*
+* <pre>
+* Notes:
+*      (1) At least one of {&pixd, &boxd} must be specified.
+*      (2) If there are no fg pixels, the returned ptrs are null.
+*      (3) This function attempts to locate rectangular "image" regions
+*          of high-density fg pixels, that have well-defined edges
+*          on the four sides.
+*      (4) Edges are searched for on each side, iterating in order
+*          from left, right, top and bottom.  As each new edge is
+*          found, the search box is resized to use that location.
+*          Once an edge is found, it is held.  If no more edges
+*          are found in one iteration, the search fails.
+*      (5) See pixScanForEdge() for usage of the thresholds and %maxwidth.
+*      (6) The thresholds must be at least 1, and the low threshold
+*          cannot be larger than the high threshold.
+*      (7) If the low and high thresholds are both 1, this is equivalent
+*          to pixClipBoxToForeground().
+* </pre>
+*/
+l_ok
+pixClipBoxToEdges(PIX     *pixs,
+BOX     *boxs,
+l_int32  lowthresh,
+l_int32  highthresh,
+l_int32  maxwidth,
+l_int32  factor,
+PIX    **ppixd,
+BOX    **pboxd)
+{
+l_int32  w, h, bx, by, bw, bh, cbw, cbh, left, right, top, bottom;
+l_int32  lfound, rfound, tfound, bfound, change;
+BOX     *boxt, *boxd;
+if (ppixd) *ppixd = NULL;
+if (pboxd) *pboxd = NULL;
+if (!ppixd && !pboxd)
+return ERROR_INT("no output requested", __func__, 1);
+if (!pixs || (pixGetDepth(pixs) != 1))
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (lowthresh < 1 || highthresh < 1 ||
+lowthresh > highthresh || maxwidth < 1)
+return ERROR_INT("invalid thresholds", __func__, 1);
+factor = L_MIN(1, factor);
+if (lowthresh == 1 && highthresh == 1)
+return pixClipBoxToForeground(pixs, boxs, ppixd, pboxd);
+pixGetDimensions(pixs, &w, &h, NULL);
+if (boxs) {
+boxGetGeometry(boxs, &bx, &by, &bw, &bh);
+cbw = L_MIN(bw, w - bx);
+cbh = L_MIN(bh, h - by);
+if (cbw < 0 || cbh < 0)
+return ERROR_INT("box not within image", __func__, 1);
+boxt = boxCreate(bx, by, cbw, cbh);
+} else {
+boxt = boxCreate(0, 0, w, h);
+}
+lfound = rfound = tfound = bfound = 0;
+while (!lfound || !rfound || !tfound || !bfound) {
+change = 0;
+if (!lfound) {
+if (!pixScanForEdge(pixs, boxt, lowthresh, highthresh, maxwidth,
+factor, L_FROM_LEFT, &left)) {
+lfound = 1;
+change = 1;
+boxRelocateOneSide(boxt, boxt, left, L_FROM_LEFT);
+}
+}
+if (!rfound) {
+if (!pixScanForEdge(pixs, boxt, lowthresh, highthresh, maxwidth,
+factor, L_FROM_RIGHT, &right)) {
+rfound = 1;
+change = 1;
+boxRelocateOneSide(boxt, boxt, right, L_FROM_RIGHT);
+}
+}
+if (!tfound) {
+if (!pixScanForEdge(pixs, boxt, lowthresh, highthresh, maxwidth,
+factor, L_FROM_TOP, &top)) {
+tfound = 1;
+change = 1;
+boxRelocateOneSide(boxt, boxt, top, L_FROM_TOP);
+}
+}
+if (!bfound) {
+if (!pixScanForEdge(pixs, boxt, lowthresh, highthresh, maxwidth,
+factor, L_FROM_BOT, &bottom)) {
+bfound = 1;
+change = 1;
+boxRelocateOneSide(boxt, boxt, bottom, L_FROM_BOT);
+}
+}
+#if DEBUG_EDGES
+lept_stderr("iter: %d %d %d %d\n", lfound, rfound, tfound, bfound);
+#endif  /* DEBUG_EDGES */
+if (change == 0) break;
+}
+boxDestroy(&boxt);
+if (change == 0)
+return ERROR_INT("not all edges found", __func__, 1);
+boxd = boxCreate(left, top, right - left + 1, bottom - top + 1);
+if (ppixd)
+*ppixd = pixClipRectangle(pixs, boxd, NULL);
+if (pboxd)
+*pboxd = boxd;
+else
+boxDestroy(&boxd);
+return 0;
+}
+/*!
+* \brief   pixScanForEdge()
+*
+* \param[in]    pixs        1 bpp
+* \param[in]    box         [optional] within which the search is conducted
+* \param[in]    lowthresh   threshold to choose clipping location
+* \param[in]    highthresh  threshold required to find an edge
+* \param[in]    maxwidth    max allowed width between low and high thresh locs
+* \param[in]    factor      sampling factor along pixel counting direction
+* \param[in]    scanflag    direction of scan; e.g., L_FROM_LEFT
+* \param[out]   ploc        location in scan direction of first black pixel
+* \return  0 if OK; 1 on error or if the edge is not found
+*
+* <pre>
+* Notes:
+*      (1) If there are no fg pixels, the position is set to 0.
+*          Caller must check the return value!
+*      (2) Use %box == NULL to scan from edge of pixs
+*      (3) As the scan progresses, the location where the sum of
+*          pixels equals or excees %lowthresh is noted (loc).  The
+*          scan is stopped when the sum of pixels equals or exceeds
+*          %highthresh.  If the scan distance between loc and that
+*          point does not exceed %maxwidth, an edge is found and
+*          its position is taken to be loc.  %maxwidth implicitly
+*          sets a minimum on the required gradient of the edge.
+*      (4) The thresholds must be at least 1, and the low threshold
+*          cannot be larger than the high threshold.
+* </pre>
+*/
+l_ok
+pixScanForEdge(PIX      *pixs,
+BOX      *box,
+l_int32   lowthresh,
+l_int32   highthresh,
+l_int32   maxwidth,
+l_int32   factor,
+l_int32   scanflag,
+l_int32  *ploc)
+{
+l_int32    bx, by, bw, bh, foundmin, loc, sum, wpl;
+l_int32    x, xstart, xend, y, ystart, yend;
+l_uint32  *data, *line;
+BOX       *boxt;
+if (!ploc)
+return ERROR_INT("&ploc not defined", __func__, 1);
+*ploc = 0;
+if (!pixs || (pixGetDepth(pixs) != 1))
+return ERROR_INT("pixs not defined or not 1 bpp", __func__, 1);
+if (lowthresh < 1 || highthresh < 1 ||
+lowthresh > highthresh || maxwidth < 1)
+return ERROR_INT("invalid thresholds", __func__, 1);
+factor = L_MIN(1, factor);
+/* Clip box to pixs if it exists */
+pixGetDimensions(pixs, &bw, &bh, NULL);
+if (box) {
+if ((boxt = boxClipToRectangle(box, bw, bh)) == NULL)
+return ERROR_INT("invalid box", __func__, 1);
+boxGetGeometry(boxt, &bx, &by, &bw, &bh);
+boxDestroy(&boxt);
+} else {
+bx = by = 0;
+}
+xstart = bx;
+ystart = by;
+xend = bx + bw - 1;
+yend = by + bh - 1;
+data = pixGetData(pixs);
+wpl = pixGetWpl(pixs);
+foundmin = 0;
+if (scanflag == L_FROM_LEFT) {
+for (x = xstart; x <= xend; x++) {
+sum = 0;
+for (y = ystart; y <= yend; y += factor) {
+line = data + y * wpl;
+if (GET_DATA_BIT(line, x))
+sum++;
+}
+if (!foundmin && sum < lowthresh)
+continue;
+if (!foundmin) {  /* save the loc of the beginning of the edge */
+foundmin = 1;
+loc = x;
+}
+if (sum >= highthresh) {
+#if DEBUG_EDGES
+lept_stderr("Left: x = %d, loc = %d\n", x, loc);
+#endif  /* DEBUG_EDGES */
+if (x - loc < maxwidth) {
+*ploc = loc;
+return 0;
+} else {
+return 1;
+}
+}
+}
+} else if (scanflag == L_FROM_RIGHT) {
+for (x = xend; x >= xstart; x--) {
+sum = 0;
+for (y = ystart; y <= yend; y += factor) {
+line = data + y * wpl;
+if (GET_DATA_BIT(line, x))
+sum++;
+}
+if (!foundmin && sum < lowthresh)
+continue;
+if (!foundmin) {
+foundmin = 1;
+loc = x;
+}
+if (sum >= highthresh) {
+#if DEBUG_EDGES
+lept_stderr("Right: x = %d, loc = %d\n", x, loc);
+#endif  /* DEBUG_EDGES */
+if (loc - x < maxwidth) {
+*ploc = loc;
+return 0;
+} else {
+return 1;
+}
+}
+}
+} else if (scanflag == L_FROM_TOP) {
+for (y = ystart; y <= yend; y++) {
+sum = 0;
+line = data + y * wpl;
+for (x = xstart; x <= xend; x += factor) {
+if (GET_DATA_BIT(line, x))
+sum++;
+}
+if (!foundmin && sum < lowthresh)
+continue;
+if (!foundmin) {
+foundmin = 1;
+loc = y;
+}
+if (sum >= highthresh) {
+#if DEBUG_EDGES
+lept_stderr("Top: y = %d, loc = %d\n", y, loc);
+#endif  /* DEBUG_EDGES */
+if (y - loc < maxwidth) {
+*ploc = loc;
+return 0;
+} else {
+return 1;
+}
+}
+}
+} else if (scanflag == L_FROM_BOT) {
+for (y = yend; y >= ystart; y--) {
+sum = 0;
+line = data + y * wpl;
+for (x = xstart; x <= xend; x += factor) {
+if (GET_DATA_BIT(line, x))
+sum++;
+}
+if (!foundmin && sum < lowthresh)
+continue;
+if (!foundmin) {
+foundmin = 1;
+loc = y;
+}
+if (sum >= highthresh) {
+#if DEBUG_EDGES
+lept_stderr("Bottom: y = %d, loc = %d\n", y, loc);
+#endif  /* DEBUG_EDGES */
+if (loc - y < maxwidth) {
+*ploc = loc;
+return 0;
+} else {
+return 1;
+}
+}
+}
+} else {
+return ERROR_INT("invalid scanflag", __func__, 1);
+}
+return 1;  /* edge not found */
+}
+/*---------------------------------------------------------------------*
+*           Extract pixel averages and reversals along lines          *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixExtractOnLine()
+*
+* \param[in]    pixs     1 bpp or 8 bpp; no colormap
+* \param[in]    x1, y1   one end point for line
+* \param[in]    x2, y2   another end pt for line
+* \param[in]    factor   sampling; >= 1
+* \return  na of pixel values along line, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) Input end points are clipped to the pix.
+*      (2) If the line is either horizontal, or closer to horizontal
+*          than to vertical, the points will be extracted from left
+*          to right in the pix.  Likewise, if the line is vertical,
+*          or closer to vertical than to horizontal, the points will
+*          be extracted from top to bottom.
+*      (3) Can be used with numaCountReverals(), for example, to
+*          characterize the intensity smoothness along a line.
+* </pre>
+*/
+NUMA *
+pixExtractOnLine(PIX     *pixs,
+l_int32  x1,
+l_int32  y1,
+l_int32  x2,
+l_int32  y2,
+l_int32  factor)
+{
+l_int32    i, w, h, d, xmin, ymin, xmax, ymax, npts, direction;
+l_uint32   val;
+l_float32  x, y;
+l_float64  slope;
+NUMA      *na;
+PTA       *pta;
+if (!pixs)
+return (NUMA *)ERROR_PTR("pixs not defined", __func__, NULL);
+pixGetDimensions(pixs, &w, &h, &d);
+if (d != 1 && d != 8)
+return (NUMA *)ERROR_PTR("d not 1 or 8 bpp", __func__, NULL);
+if (pixGetColormap(pixs))
+return (NUMA *)ERROR_PTR("pixs has a colormap", __func__, NULL);
+if (factor < 1) {
+L_WARNING("factor must be >= 1; setting to 1\n", __func__);
+factor = 1;
+}
+/* Clip line to the image */
+x1 = L_MAX(0, L_MIN(x1, w - 1));
+x2 = L_MAX(0, L_MIN(x2, w - 1));
+y1 = L_MAX(0, L_MIN(y1, h - 1));
+y2 = L_MAX(0, L_MIN(y2, h - 1));
+if (x1 == x2 && y1 == y2) {
+pixGetPixel(pixs, x1, y1, &val);
+na = numaCreate(1);
+numaAddNumber(na, val);
+return na;
+}
+if (y1 == y2)
+direction = L_HORIZONTAL_LINE;
+else if (x1 == x2)
+direction = L_VERTICAL_LINE;
+else
+direction = L_OBLIQUE_LINE;
+na = numaCreate(0);
+if (direction == L_HORIZONTAL_LINE) {  /* plot against x */
+xmin = L_MIN(x1, x2);
+xmax = L_MAX(x1, x2);
+numaSetParameters(na, xmin, factor);
+for (i = xmin; i <= xmax; i += factor) {
+pixGetPixel(pixs, i, y1, &val);
+numaAddNumber(na, val);
+}
+} else if (direction == L_VERTICAL_LINE) {  /* plot against y */
+ymin = L_MIN(y1, y2);
+ymax = L_MAX(y1, y2);
+numaSetParameters(na, ymin, factor);
+for (i = ymin; i <= ymax; i += factor) {
+pixGetPixel(pixs, x1, i, &val);
+numaAddNumber(na, val);
+}
+} else {  /* direction == L_OBLIQUE_LINE */
+slope = (l_float64)((y2 - y1) / (x2 - x1));
+if (L_ABS(slope) < 1.0) {  /* quasi-horizontal */
+xmin = L_MIN(x1, x2);
+xmax = L_MAX(x1, x2);
+ymin = (xmin == x1) ? y1 : y2;  /* pt that goes with xmin */
+ymax = (ymin == y1) ? y2 : y1;  /* pt that goes with xmax */
+pta = generatePtaLine(xmin, ymin, xmax, ymax);
+numaSetParameters(na, xmin, (l_float32)factor);
+} else {  /* quasi-vertical */
+ymin = L_MIN(y1, y2);
+ymax = L_MAX(y1, y2);
+xmin = (ymin == y1) ? x1 : x2;  /* pt that goes with ymin */
+xmax = (xmin == x1) ? x2 : x1;  /* pt that goes with ymax */
+pta = generatePtaLine(xmin, ymin, xmax, ymax);
+numaSetParameters(na, ymin, (l_float32)factor);
+}
+npts = ptaGetCount(pta);
+for (i = 0; i < npts; i += factor) {
+ptaGetPt(pta, i, &x, &y);
+pixGetPixel(pixs, (l_int32)x, (l_int32)y, &val);
+numaAddNumber(na, val);
+}
+#if 0  /* debugging */
+pixPlotAlongPta(pixs, pta, GPLOT_PNG, NULL);
+#endif
+ptaDestroy(&pta);
+}
+return na;
+}
+/*!
+* \brief   pixAverageOnLine()
+*
+* \param[in]    pixs     1 bpp or 8 bpp; no colormap
+* \param[in]    x1, y1   starting pt for line
+* \param[in]    x2, y2   end pt for line
+* \param[in]    factor   sampling; >= 1
+* \return  average of pixel values along line, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) The line must be either horizontal or vertical, so either
+*          y1 == y2 (horizontal) or x1 == x2 (vertical).
+*      (2) If horizontal, x1 must be <= x2.
+*          If vertical, y1 must be <= y2.
+*          characterize the intensity smoothness along a line.
+*      (3) Input end points are clipped to the pix.
+* </pre>
+*/
+l_float32
+pixAverageOnLine(PIX     *pixs,
+l_int32  x1,
+l_int32  y1,
+l_int32  x2,
+l_int32  y2,
+l_int32  factor)
+{
+l_int32    i, j, w, h, d, direction, count, wpl;
+l_uint32  *data, *line;
+l_float32  sum;
+if (!pixs)
+return ERROR_INT("pixs not defined", __func__, 1);
+pixGetDimensions(pixs, &w, &h, &d);
+if (d != 1 && d != 8)
+return ERROR_INT("d not 1 or 8 bpp", __func__, 1);
+if (pixGetColormap(pixs))
+return ERROR_INT("pixs has a colormap", __func__, 1);
+if (x1 > x2 || y1 > y2)
+return ERROR_INT("x1 > x2 or y1 > y2", __func__, 1);
+if (y1 == y2) {
+x1 = L_MAX(0, x1);
+x2 = L_MIN(w - 1, x2);
+y1 = L_MAX(0, L_MIN(y1, h - 1));
+direction = L_HORIZONTAL_LINE;
+} else if (x1 == x2) {
+y1 = L_MAX(0, y1);
+y2 = L_MIN(h - 1, y2);
+x1 = L_MAX(0, L_MIN(x1, w - 1));
+direction = L_VERTICAL_LINE;
+} else {
+return ERROR_INT("line neither horiz nor vert", __func__, 1);
+}
+if (factor < 1) {
+L_WARNING("factor must be >= 1; setting to 1\n", __func__);
+factor = 1;
+}
+data = pixGetData(pixs);
+wpl = pixGetWpl(pixs);
+sum = 0;
+count = 0;
+if (direction == L_HORIZONTAL_LINE) {
+line = data + y1 * wpl;
+for (j = x1, count = 0; j <= x2; count++, j += factor) {
+if (d == 1)
+sum += GET_DATA_BIT(line, j);
+else  /* d == 8 */
+sum += GET_DATA_BYTE(line, j);
+}
+} else if (direction == L_VERTICAL_LINE) {
+for (i = y1, count = 0; i <= y2; count++, i += factor) {
+line = data + i * wpl;
+if (d == 1)
+sum += GET_DATA_BIT(line, x1);
+else  /* d == 8 */
+sum += GET_DATA_BYTE(line, x1);
+}
+}
+return sum / (l_float32)count;
+}
+/*!
+* \brief   pixAverageIntensityProfile()
+*
+* \param[in]    pixs      any depth; colormap OK
+* \param[in]    fract     fraction of image width or height to be used
+* \param[in]    dir       averaging direction: L_HORIZONTAL_LINE or
+*                         L_VERTICAL_LINE
+* \param[in]    first,    last span of rows or columns to measure
+* \param[in]    factor1   sampling along fast scan direction; >= 1
+* \param[in]    factor2   sampling along slow scan direction; >= 1
+* \return  na of reversal profile, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) If d != 1 bpp, colormaps are removed and the result
+*          is converted to 8 bpp.
+*      (2) If %dir == L_HORIZONTAL_LINE, the intensity is averaged
+*          along each horizontal raster line (sampled by %factor1),
+*          and the profile is the array of these averages in the
+*          vertical direction between %first and %last raster lines,
+*          and sampled by %factor2.
+*      (3) If %dir == L_VERTICAL_LINE, the intensity is averaged
+*          along each vertical line (sampled by %factor1),
+*          and the profile is the array of these averages in the
+*          horizontal direction between %first and %last columns,
+*          and sampled by %factor2.
+*      (4) The averages are measured over the central %fract of the image.
+*          Use %fract == 1.0 to average across the entire width or height.
+* </pre>
+*/
+NUMA *
+pixAverageIntensityProfile(PIX       *pixs,
+l_float32  fract,
+l_int32    dir,
+l_int32    first,
+l_int32    last,
+l_int32    factor1,
+l_int32    factor2)
+{
+l_int32    i, j, w, h, d, start, end;
+l_float32  ave;
+NUMA      *nad;
+PIX       *pixr, *pixg;
+if (!pixs)
+return (NUMA *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (fract < 0.0 || fract > 1.0)
+return (NUMA *)ERROR_PTR("fract < 0.0 or > 1.0", __func__, NULL);
+if (dir != L_HORIZONTAL_LINE && dir != L_VERTICAL_LINE)
+return (NUMA *)ERROR_PTR("invalid direction", __func__, NULL);
+if (first < 0) first = 0;
+if (last < first)
+return (NUMA *)ERROR_PTR("last must be >= first", __func__, NULL);
+if (factor1 < 1) {
+L_WARNING("factor1 must be >= 1; setting to 1\n", __func__);
+factor1 = 1;
+}
+if (factor2 < 1) {
+L_WARNING("factor2 must be >= 1; setting to 1\n", __func__);
+factor2 = 1;
+}
+/* Use 1 or 8 bpp, without colormap */
+if (pixGetColormap(pixs))
+pixr = pixRemoveColormap(pixs, REMOVE_CMAP_TO_GRAYSCALE);
+else
+pixr = pixClone(pixs);
+pixGetDimensions(pixr, &w, &h, &d);
+if (d == 1)
+pixg = pixClone(pixr);
+else
+pixg = pixConvertTo8(pixr, 0);
+nad = numaCreate(0);  /* output: samples in slow scan direction */
+numaSetParameters(nad, 0, factor2);
+if (dir == L_HORIZONTAL_LINE) {
+start = (l_int32)(0.5 * (1.0 - fract) * (l_float32)w);
+end = w - start;
+if (last > h - 1) {
+L_WARNING("last > h - 1; clipping\n", __func__);
+last = h - 1;
+}
+for (i = first; i <= last; i += factor2) {
+ave = pixAverageOnLine(pixg, start, i, end, i, factor1);
+numaAddNumber(nad, ave);
+}
+} else if (dir == L_VERTICAL_LINE) {
+start = (l_int32)(0.5 * (1.0 - fract) * (l_float32)h);
+end = h - start;
+if (last > w - 1) {
+L_WARNING("last > w - 1; clipping\n", __func__);
+last = w - 1;
+}
+for (j = first; j <= last; j += factor2) {
+ave = pixAverageOnLine(pixg, j, start, j, end, factor1);
+numaAddNumber(nad, ave);
+}
+}
+pixDestroy(&pixr);
+pixDestroy(&pixg);
+return nad;
+}
+/*!
+* \brief   pixReversalProfile()
+*
+* \param[in]    pixs          any depth; colormap OK
+* \param[in]    fract         fraction of image width or height to be used
+* \param[in]    dir           profile direction: L_HORIZONTAL_LINE or
+*                             L_VERTICAL_LINE
+* \param[in]    first, last   span of rows or columns to measure
+* \param[in]    minreversal   minimum change in intensity to trigger a reversal
+* \param[in]    factor1       sampling along raster line (fast scan); >= 1
+* \param[in]    factor2       sampling of raster lines (slow scan); >= 1
+* \return  na of reversal profile, or NULL on error.
+*
+* <pre>
+* Notes:
+*      (1) If d != 1 bpp, colormaps are removed and the result
+*          is converted to 8 bpp.
+*      (2) If %dir == L_HORIZONTAL_LINE, the the reversals are counted
+*          along each horizontal raster line (sampled by %factor1),
+*          and the profile is the array of these sums in the
+*          vertical direction between %first and %last raster lines,
+*          and sampled by %factor2.
+*      (3) If %dir == L_VERTICAL_LINE, the the reversals are counted
+*          along each vertical column (sampled by %factor1),
+*          and the profile is the array of these sums in the
+*          horizontal direction between %first and %last columns,
+*          and sampled by %factor2.
+*      (4) For each row or column, the reversals are summed over the
+*          central %fract of the image.  Use %fract == 1.0 to sum
+*          across the entire width (of row) or height (of column).
+*      (5) %minreversal is the relative change in intensity that is
+*          required to resolve peaks and valleys.  A typical number for
+*          locating text in 8 bpp might be 50.  For 1 bpp, minreversal
+*          must be 1.
+*      (6) The reversal profile is simply the number of reversals
+*          in a row or column, vs the row or column index.
+* </pre>
+*/
+NUMA *
+pixReversalProfile(PIX       *pixs,
+l_float32  fract,
+l_int32    dir,
+l_int32    first,
+l_int32    last,
+l_int32    minreversal,
+l_int32    factor1,
+l_int32    factor2)
+{
+l_int32   i, j, w, h, d, start, end, nr;
+NUMA     *naline, *nad;
+PIX      *pixr, *pixg;
+if (!pixs)
+return (NUMA *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (fract < 0.0 || fract > 1.0)
+return (NUMA *)ERROR_PTR("fract < 0.0 or > 1.0", __func__, NULL);
+if (dir != L_HORIZONTAL_LINE && dir != L_VERTICAL_LINE)
+return (NUMA *)ERROR_PTR("invalid direction", __func__, NULL);
+if (first < 0) first = 0;
+if (last < first)
+return (NUMA *)ERROR_PTR("last must be >= first", __func__, NULL);
+if (factor1 < 1) {
+L_WARNING("factor1 must be >= 1; setting to 1\n", __func__);
+factor1 = 1;
+}
+if (factor2 < 1) {
+L_WARNING("factor2 must be >= 1; setting to 1\n", __func__);
+factor2 = 1;
+}
+/* Use 1 or 8 bpp, without colormap */
+if (pixGetColormap(pixs))
+pixr = pixRemoveColormap(pixs, REMOVE_CMAP_TO_GRAYSCALE);
+else
+pixr = pixClone(pixs);
+pixGetDimensions(pixr, &w, &h, &d);
+if (d == 1) {
+pixg = pixClone(pixr);
+minreversal = 1;  /* enforce this */
+} else {
+pixg = pixConvertTo8(pixr, 0);
+}
+nad = numaCreate(0);  /* output: samples in slow scan direction */
+numaSetParameters(nad, 0, factor2);
+if (dir == L_HORIZONTAL_LINE) {
+start = (l_int32)(0.5 * (1.0 - fract) * (l_float32)w);
+end = w - start;
+if (last > h - 1) {
+L_WARNING("last > h - 1; clipping\n", __func__);
+last = h - 1;
+}
+for (i = first; i <= last; i += factor2) {
+naline = pixExtractOnLine(pixg, start, i, end, i, factor1);
+numaCountReversals(naline, minreversal, &nr, NULL);
+numaAddNumber(nad, nr);
+numaDestroy(&naline);
+}
+} else if (dir == L_VERTICAL_LINE) {
+start = (l_int32)(0.5 * (1.0 - fract) * (l_float32)h);
+end = h - start;
+if (last > w - 1) {
+L_WARNING("last > w - 1; clipping\n", __func__);
+last = w - 1;
+}
+for (j = first; j <= last; j += factor2) {
+naline = pixExtractOnLine(pixg, j, start, j, end, factor1);
+numaCountReversals(naline, minreversal, &nr, NULL);
+numaAddNumber(nad, nr);
+numaDestroy(&naline);
+}
+}
+pixDestroy(&pixr);
+pixDestroy(&pixg);
+return nad;
+}
+/*---------------------------------------------------------------------*
+*                 Extract windowed variance along a line              *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixWindowedVarianceOnLine()
+*
+* \param[in]    pixs     8 bpp; no colormap
+* \param[in]    dir      L_HORIZONTAL_LINE or L_VERTICAL_LINE
+* \param[in]    loc      location of the constant coordinate for the line
+* \param[in]    c1, c2   end point coordinates for the line
+* \param[in]    size     window size; must be > 1
+* \param[out]   pnad     windowed square root of variance
+* \return  0 if OK; 1 on error
+*
+* <pre>
+* Notes:
+*      (1) The returned variance array traverses the line starting
+*          from the smallest coordinate, min(c1,c2).
+*      (2) Line end points are clipped to pixs.
+*      (3) The reference point for the variance calculation is the center of
+*          the window.  Therefore, the numa start parameter from
+*          pixExtractOnLine() is incremented by %size/2,
+*          to align the variance values with the pixel coordinate.
+*      (4) The square root of the variance is the RMS deviation from the mean.
+* </pre>
+*/
+l_ok
+pixWindowedVarianceOnLine(PIX     *pixs,
+l_int32  dir,
+l_int32  loc,
+l_int32  c1,
+l_int32  c2,
+l_int32  size,
+NUMA   **pnad)
+{
+l_int32     i, j, w, h, cmin, cmax, maxloc, n, x, y;
+l_uint32    val;
+l_float32   norm, rootvar;
+l_float32  *array;
+l_float64   sum1, sum2, ave, var;
+NUMA       *na1, *nad;
+PTA        *pta;
+if (!pnad)
+return ERROR_INT("&nad not defined", __func__, 1);
+*pnad = NULL;
+if (!pixs || pixGetDepth(pixs) != 8)
+return ERROR_INT("pixs not defined or not 8bpp", __func__, 1);
+if (size < 2)
+return ERROR_INT("window size must be > 1", __func__, 1);
+if (dir != L_HORIZONTAL_LINE && dir != L_VERTICAL_LINE)
+return ERROR_INT("invalid direction", __func__, 1);
+pixGetDimensions(pixs, &w, &h, NULL);
+maxloc = (dir == L_HORIZONTAL_LINE) ? h - 1 : w - 1;
+if (loc < 0 || loc > maxloc)
+return ERROR_INT("invalid line position", __func__, 1);
+/* Clip line to the image */
+cmin = L_MIN(c1, c2);
+cmax = L_MAX(c1, c2);
+maxloc = (dir == L_HORIZONTAL_LINE) ? w - 1 : h - 1;
+cmin = L_MAX(0, L_MIN(cmin, maxloc));
+cmax = L_MAX(0, L_MIN(cmax, maxloc));
+n = cmax - cmin + 1;
+/* Generate pta along the line */
+pta = ptaCreate(n);
+if (dir == L_HORIZONTAL_LINE) {
+for (i = cmin; i <= cmax; i++)
+ptaAddPt(pta, i, loc);
+} else {  /* vertical line */
+for (i = cmin; i <= cmax; i++)
+ptaAddPt(pta, loc, i);
+}
+/* Get numa of pixel values on the line */
+na1 = numaCreate(n);
+numaSetParameters(na1, cmin, 1);
+for (i = 0; i < n; i++) {
+ptaGetIPt(pta, i, &x, &y);
+pixGetPixel(pixs, x, y, &val);
+numaAddNumber(na1, val);
+}
+array = numaGetFArray(na1, L_NOCOPY);
+ptaDestroy(&pta);
+/* Compute root variance on overlapping windows */
+nad = numaCreate(n);
+*pnad = nad;
+numaSetParameters(nad, cmin + size / 2, 1);
+norm = 1.0f / (l_float32)size;
+for (i = 0; i < n - size; i++) {  /* along the line */
+sum1 = sum2 = 0;
+for (j = 0; j < size; j++) {  /* over the window */
+val = array[i + j];
+sum1 += val;
+sum2 += (l_float64)(val) * val;
+}
+ave = norm * sum1;
+var = norm * sum2 - ave * ave;
+if (var < 0)  /* avoid small negative values from rounding effects */
+var = 0.0;
+rootvar = (l_float32)sqrt(var);
+numaAddNumber(nad, rootvar);
+}
+numaDestroy(&na1);
+return 0;
+}
+/*---------------------------------------------------------------------*
+*              Extract min/max of pixel values near lines             *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixMinMaxNearLine()
+*
+* \param[in]    pixs        8 bpp; no colormap
+* \param[in]    x1, y1      starting pt for line
+* \param[in]    x2, y2      end pt for line
+* \param[in]    dist        distance to search from line in each direction
+* \param[in]    direction   L_SCAN_NEGATIVE, L_SCAN_POSITIVE, L_SCAN_BOTH
+* \param[out]   pnamin      [optional] minimum values
+* \param[out]   pnamax      [optional] maximum values
+* \param[out]   pminave     [optional] average of minimum values
+* \param[out]   pmaxave     [optional] average of maximum values
+* \return  0 if OK; 1 on error or if there are no sampled points
+*              within the image.
+*
+* <pre>
+* Notes:
+*      (1) If the line is more horizontal than vertical, the values
+*          are computed for [x1, x2], and the pixels are taken
+*          below and/or above the local y-value.  Otherwise, the
+*          values are computed for [y1, y2] and the pixels are taken
+*          to the left and/or right of the local x value.
+*      (2) %direction specifies which side (or both sides) of the
+*          line are scanned for min and max values.
+*      (3) There are two ways to tell if the returned values of min
+*          and max averages are valid: the returned values cannot be
+*          negative and the function must return 0.
+*      (4) All accessed pixels are clipped to the pix.
+* </pre>
+*/
+l_ok
+pixMinMaxNearLine(PIX        *pixs,
+l_int32     x1,
+l_int32     y1,
+l_int32     x2,
+l_int32     y2,
+l_int32     dist,
+l_int32     direction,
+NUMA      **pnamin,
+NUMA      **pnamax,
+l_float32  *pminave,
+l_float32  *pmaxave)
+{
+l_int32    i, j, w, h, d, x, y, n, dir, found, minval, maxval, negloc, posloc;
+l_uint32   val;
+l_float32  sum;
+NUMA      *namin, *namax;
+PTA       *pta;
+if (pnamin) *pnamin = NULL;
+if (pnamax) *pnamax = NULL;
+if (pminave) *pminave = UNDEF;
+if (pmaxave) *pmaxave = UNDEF;
+if (!pnamin && !pnamax && !pminave && !pmaxave)
+return ERROR_INT("no output requested", __func__, 1);
+if (!pixs)
+return ERROR_INT("pixs not defined", __func__, 1);
+pixGetDimensions(pixs, &w, &h, &d);
+if (d != 8 || pixGetColormap(pixs))
+return ERROR_INT("pixs not 8 bpp or has colormap", __func__, 1);
+dist = L_ABS(dist);
+if (direction != L_SCAN_NEGATIVE && direction != L_SCAN_POSITIVE &&
+direction != L_SCAN_BOTH)
+return ERROR_INT("invalid direction", __func__, 1);
+pta = generatePtaLine(x1, y1, x2, y2);
+n = ptaGetCount(pta);
+dir = (L_ABS(x1 - x2) == n - 1) ? L_HORIZ : L_VERT;
+namin = numaCreate(n);
+namax = numaCreate(n);
+negloc = -dist;
+posloc = dist;
+if (direction == L_SCAN_NEGATIVE)
+posloc = 0;
+else if (direction == L_SCAN_POSITIVE)
+negloc = 0;
+for (i = 0; i < n; i++) {
+ptaGetIPt(pta, i, &x, &y);
+minval = 255;
+maxval = 0;
+found = FALSE;
+if (dir == L_HORIZ) {
+if (x < 0 || x >= w) continue;
+for (j = negloc; j <= posloc; j++) {
+if (y + j < 0 || y + j >= h) continue;
+pixGetPixel(pixs, x, y + j, &val);
+found = TRUE;
+if (val < minval) minval = val;
+if (val > maxval) maxval = val;
+}
+} else {  /* dir == L_VERT */
+if (y < 0 || y >= h) continue;
+for (j = negloc; j <= posloc; j++) {
+if (x + j < 0 || x + j >= w) continue;
+pixGetPixel(pixs, x + j, y, &val);
+found = TRUE;
+if (val < minval) minval = val;
+if (val > maxval) maxval = val;
+}
+}
+if (found) {
+numaAddNumber(namin, minval);
+numaAddNumber(namax, maxval);
+}
+}
+n = numaGetCount(namin);
+if (n == 0) {
+numaDestroy(&namin);
+numaDestroy(&namax);
+ptaDestroy(&pta);
+return ERROR_INT("no output from this line", __func__, 1);
+}
+if (pminave) {
+numaGetSum(namin, &sum);
+*pminave = sum / n;
+}
+if (pmaxave) {
+numaGetSum(namax, &sum);
+*pmaxave = sum / n;
+}
+if (pnamin)
+*pnamin = namin;
+else
+numaDestroy(&namin);
+if (pnamax)
+*pnamax = namax;
+else
+numaDestroy(&namax);
+ptaDestroy(&pta);
+return 0;
+}
+/*---------------------------------------------------------------------*
+*                     Rank row and column transforms                  *
+*---------------------------------------------------------------------*/
+/*!
+* \brief   pixRankRowTransform()
+*
+* \param[in]    pixs   8 bpp; no colormap
+* \return  pixd with pixels sorted in each row, from
+*                    min to max value
+*
+* <pre>
+* Notes:
+*     (1) The time is O(n) in the number of pixels and runs about
+*         100 Mpixels/sec on a 3 GHz machine.
+* </pre>
+*/
+PIX *
+pixRankRowTransform(PIX  *pixs)
+{
+l_int32    i, j, k, m, w, h, wpl, val;
+l_int32    histo[256];
+l_uint32  *datas, *datad, *lines, *lined;
+PIX       *pixd;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (pixGetDepth(pixs) != 8)
+return (PIX *)ERROR_PTR("pixs not 8 bpp", __func__, NULL);
+if (pixGetColormap(pixs))
+return (PIX *)ERROR_PTR("pixs has a colormap", __func__, NULL);
+pixGetDimensions(pixs, &w, &h, NULL);
+pixd = pixCreateTemplate(pixs);
+datas = pixGetData(pixs);
+datad = pixGetData(pixd);
+wpl = pixGetWpl(pixs);
+for (i = 0; i < h; i++) {
+memset(histo, 0, 1024);
+lines = datas + i * wpl;
+lined = datad + i * wpl;
+for (j = 0; j < w; j++) {
+val = GET_DATA_BYTE(lines, j);
+histo[val]++;
+}
+for (m = 0, j = 0; m < 256; m++) {
+for (k = 0; k < histo[m]; k++, j++)
+SET_DATA_BYTE(lined, j, m);
+}
+}
+return pixd;
+}
+/*!
+* \brief   pixRankColumnTransform()
+*
+* \param[in]    pixs   8 bpp; no colormap
+* \return  pixd with pixels sorted in each column, from
+*                    min to max value
+*
+* <pre>
+* Notes:
+*     (1) The time is O(n) in the number of pixels and runs about
+*         50 Mpixels/sec on a 3 GHz machine.
+* </pre>
+*/
+PIX *
+pixRankColumnTransform(PIX  *pixs)
+{
+l_int32    i, j, k, m, w, h, val;
+l_int32    histo[256];
+void     **lines8, **lined8;
+PIX       *pixd;
+if (!pixs)
+return (PIX *)ERROR_PTR("pixs not defined", __func__, NULL);
+if (pixGetDepth(pixs) != 8)
+return (PIX *)ERROR_PTR("pixs not 8 bpp", __func__, NULL);
+if (pixGetColormap(pixs))
+return (PIX *)ERROR_PTR("pixs has a colormap", __func__, NULL);
+pixGetDimensions(pixs, &w, &h, NULL);
+pixd = pixCreateTemplate(pixs);
+lines8 = pixGetLinePtrs(pixs, NULL);
+lined8 = pixGetLinePtrs(pixd, NULL);
+for (j = 0; j < w; j++) {
+memset(histo, 0, 1024);
+for (i = 0; i < h; i++) {
+val = GET_DATA_BYTE(lines8[i], j);
+histo[val]++;
+}
+for (m = 0, i = 0; m < 256; m++) {
+for (k = 0; k < histo[m]; k++, i++)
+SET_DATA_BYTE(lined8[i], j, m);
+}
+}
+LEPT_FREE(lines8);
+LEPT_FREE(lined8);
+return pixd;
+}

Mercurial > hgrepos > Python2 > PyMuPDF

comparison mupdf-source/thirdparty/leptonica/src/pix5.c @ 2:b50eed0cc0ef upstream