--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/libjpeg/jdcolor.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,769 @@
+/*
+ * jdcolor.c
+ *
+ * Copyright (C) 1991-1997, Thomas G. Lane.
+ * Modified 2011-2023 by Guido Vollbeding.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains output colorspace conversion routines.
+ */
+
+#define JPEG_INTERNALS
+#include "jinclude.h"
+#include "jpeglib.h"
+
+
+#if RANGE_BITS < 2
+  /* Deliberate syntax err */
+  Sorry, this code requires 2 or more range extension bits.
+#endif
+
+
+/* Private subobject */
+
+typedef struct {
+  struct jpeg_color_deconverter pub; /* public fields */
+
+  /* Private state for YCbCr->RGB and BG_YCC->RGB conversion */
+  int * Cr_r_tab;		/* => table for Cr to R conversion */
+  int * Cb_b_tab;		/* => table for Cb to B conversion */
+  INT32 * Cr_g_tab;		/* => table for Cr to G conversion */
+  INT32 * Cb_g_tab;		/* => table for Cb to G conversion */
+
+  /* Private state for RGB->Y conversion */
+  INT32 * R_y_tab;		/* => table for R to Y conversion */
+  INT32 * G_y_tab;		/* => table for G to Y conversion */
+  INT32 * B_y_tab;		/* => table for B to Y conversion */
+} my_color_deconverter;
+
+typedef my_color_deconverter * my_cconvert_ptr;
+
+
+/***************  YCbCr -> RGB conversion: most common case **************/
+/*************** BG_YCC -> RGB conversion: less common case **************/
+/***************    RGB -> Y   conversion: less common case **************/
+
+/*
+ * YCbCr is defined per Recommendation ITU-R BT.601-7 (03/2011),
+ * previously known as Recommendation CCIR 601-1, except that Cb and Cr
+ * are normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
+ * sRGB (standard RGB color space) is defined per IEC 61966-2-1:1999.
+ * sYCC (standard luma-chroma-chroma color space with extended gamut)
+ * is defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex F.
+ * bg-sRGB and bg-sYCC (big gamut standard color spaces)
+ * are defined per IEC 61966-2-1:1999 Amendment A1:2003 Annex G.
+ * Note that the derived conversion coefficients given in some of these
+ * documents are imprecise.  The general conversion equations are
+ *
+ *	R = Y + K * (1 - Kr) * Cr
+ *	G = Y - K * (Kb * (1 - Kb) * Cb + Kr * (1 - Kr) * Cr) / (1 - Kr - Kb)
+ *	B = Y + K * (1 - Kb) * Cb
+ *
+ *	Y = Kr * R + (1 - Kr - Kb) * G + Kb * B
+ *
+ * With Kr = 0.299 and Kb = 0.114 (derived according to SMPTE RP 177-1993
+ * from the 1953 FCC NTSC primaries and CIE Illuminant C), K = 2 for sYCC,
+ * the conversion equations to be implemented are therefore
+ *
+ *	R = Y + 1.402 * Cr
+ *	G = Y - 0.344136286 * Cb - 0.714136286 * Cr
+ *	B = Y + 1.772 * Cb
+ *
+ *	Y = 0.299 * R + 0.587 * G + 0.114 * B
+ *
+ * where Cb and Cr represent the incoming values less CENTERJSAMPLE.
+ * For bg-sYCC, with K = 4, the equations are
+ *
+ *	R = Y + 2.804 * Cr
+ *	G = Y - 0.688272572 * Cb - 1.428272572 * Cr
+ *	B = Y + 3.544 * Cb
+ *
+ * To avoid floating-point arithmetic, we represent the fractional constants
+ * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
+ * the products by 2^16, with appropriate rounding, to get the correct answer.
+ * Notice that Y, being an integral input, does not contribute any fraction
+ * so it need not participate in the rounding.
+ *
+ * For even more speed, we avoid doing any multiplications in the inner loop
+ * by precalculating the constants times Cb and Cr for all possible values.
+ * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
+ * for 9-bit to 12-bit samples it is still acceptable.  It's not very
+ * reasonable for 16-bit samples, but if you want lossless storage
+ * you shouldn't be changing colorspace anyway.
+ * The Cr=>R and Cb=>B values can be rounded to integers in advance;
+ * the values for the G calculation are left scaled up,
+ * since we must add them together before rounding.
+ */
+
+#define SCALEBITS	16	/* speediest right-shift on some machines */
+#define ONE_HALF	((INT32) 1 << (SCALEBITS-1))
+#define FIX(x)		((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
+
+
+/*
+ * Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.
+ */
+
+LOCAL(void)
+build_ycc_rgb_table (j_decompress_ptr cinfo)
+/* Normal case, sYCC */
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  int i;
+  INT32 x;
+  SHIFT_TEMPS
+
+  cconvert->Cr_r_tab = (int *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
+  cconvert->Cb_b_tab = (int *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
+  cconvert->Cr_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+  cconvert->Cb_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+
+  for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
+    /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
+    /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
+    /* Cr=>R value is nearest int to 1.402 * x */
+    cconvert->Cr_r_tab[i] = (int) DESCALE(FIX(1.402) * x, SCALEBITS);
+    /* Cb=>B value is nearest int to 1.772 * x */
+    cconvert->Cb_b_tab[i] = (int) DESCALE(FIX(1.772) * x, SCALEBITS);
+    /* Cr=>G value is scaled-up -0.714136286 * x */
+    cconvert->Cr_g_tab[i] = (- FIX(0.714136286)) * x;
+    /* Cb=>G value is scaled-up -0.344136286 * x */
+    /* We also add in ONE_HALF so that need not do it in inner loop */
+    cconvert->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;
+  }
+}
+
+
+LOCAL(void)
+build_bg_ycc_rgb_table (j_decompress_ptr cinfo)
+/* Wide gamut case, bg-sYCC */
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  int i;
+  INT32 x;
+  SHIFT_TEMPS
+
+  cconvert->Cr_r_tab = (int *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
+  cconvert->Cb_b_tab = (int *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));
+  cconvert->Cr_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+  cconvert->Cb_g_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+
+  for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
+    /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
+    /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
+    /* Cr=>R value is nearest int to 2.804 * x */
+    cconvert->Cr_r_tab[i] = (int) DESCALE(FIX(2.804) * x, SCALEBITS);
+    /* Cb=>B value is nearest int to 3.544 * x */
+    cconvert->Cb_b_tab[i] = (int) DESCALE(FIX(3.544) * x, SCALEBITS);
+    /* Cr=>G value is scaled-up -1.428272572 * x */
+    cconvert->Cr_g_tab[i] = (- FIX(1.428272572)) * x;
+    /* Cb=>G value is scaled-up -0.688272572 * x */
+    /* We also add in ONE_HALF so that need not do it in inner loop */
+    cconvert->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
+  }
+}
+
+
+/*
+ * Convert some rows of samples to the output colorspace.
+ *
+ * Note that we change from noninterleaved, one-plane-per-component format
+ * to interleaved-pixel format.  The output buffer is therefore three times
+ * as wide as the input buffer.
+ *
+ * A starting row offset is provided only for the input buffer.  The caller
+ * can easily adjust the passed output_buf value to accommodate any row
+ * offset required on that side.
+ */
+
+METHODDEF(void)
+ycc_rgb_convert (j_decompress_ptr cinfo,
+		 JSAMPIMAGE input_buf, JDIMENSION input_row,
+		 JSAMPARRAY output_buf, int num_rows)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register int y, cb, cr;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+  /* copy these pointers into registers if possible */
+  register JSAMPLE * range_limit = cinfo->sample_range_limit;
+  register int * Crrtab = cconvert->Cr_r_tab;
+  register int * Cbbtab = cconvert->Cb_b_tab;
+  register INT32 * Crgtab = cconvert->Cr_g_tab;
+  register INT32 * Cbgtab = cconvert->Cb_g_tab;
+  SHIFT_TEMPS
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      y  = GETJSAMPLE(inptr0[col]);
+      cb = GETJSAMPLE(inptr1[col]);
+      cr = GETJSAMPLE(inptr2[col]);
+      /* Range-limiting is essential due to noise introduced by DCT losses,
+       * for extended gamut (sYCC) and wide gamut (bg-sYCC) encodings.
+       */
+      outptr[RGB_RED]   = range_limit[y + Crrtab[cr]];
+      outptr[RGB_GREEN] = range_limit[y +
+			      ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
+						 SCALEBITS))];
+      outptr[RGB_BLUE]  = range_limit[y + Cbbtab[cb]];
+      outptr += RGB_PIXELSIZE;
+    }
+  }
+}
+
+
+/**************** Cases other than YCC -> RGB ****************/
+
+
+/*
+ * Initialize for RGB->grayscale colorspace conversion.
+ */
+
+LOCAL(void)
+build_rgb_y_table (j_decompress_ptr cinfo)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  INT32 i;
+
+  cconvert->R_y_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+  cconvert->G_y_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+  cconvert->B_y_tab = (INT32 *) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));
+
+  for (i = 0; i <= MAXJSAMPLE; i++) {
+    cconvert->R_y_tab[i] = FIX(0.299) * i;
+    cconvert->G_y_tab[i] = FIX(0.587) * i;
+    cconvert->B_y_tab[i] = FIX(0.114) * i + ONE_HALF;
+  }
+}
+
+
+/*
+ * Convert RGB to grayscale.
+ */
+
+METHODDEF(void)
+rgb_gray_convert (j_decompress_ptr cinfo,
+		  JSAMPIMAGE input_buf, JDIMENSION input_row,
+		  JSAMPARRAY output_buf, int num_rows)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register INT32 y;
+  register INT32 * Rytab = cconvert->R_y_tab;
+  register INT32 * Gytab = cconvert->G_y_tab;
+  register INT32 * Bytab = cconvert->B_y_tab;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      y  = Rytab[GETJSAMPLE(inptr0[col])];
+      y += Gytab[GETJSAMPLE(inptr1[col])];
+      y += Bytab[GETJSAMPLE(inptr2[col])];
+      outptr[col] = (JSAMPLE) (y >> SCALEBITS);
+    }
+  }
+}
+
+
+/*
+ * Convert some rows of samples to the output colorspace.
+ * [R-G,G,B-G] to [R,G,B] conversion with modulo calculation
+ * (inverse color transform).
+ * This can be seen as an adaption of the general YCbCr->RGB
+ * conversion equation with Kr = Kb = 0, while replacing the
+ * normalization by modulo calculation.
+ */
+
+METHODDEF(void)
+rgb1_rgb_convert (j_decompress_ptr cinfo,
+		  JSAMPIMAGE input_buf, JDIMENSION input_row,
+		  JSAMPARRAY output_buf, int num_rows)
+{
+  register int r, g, b;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      r = GETJSAMPLE(inptr0[col]);
+      g = GETJSAMPLE(inptr1[col]);
+      b = GETJSAMPLE(inptr2[col]);
+      /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
+       * (modulo) operator is equivalent to the bitmask operator AND.
+       */
+      outptr[RGB_RED]   = (JSAMPLE) ((r + g - CENTERJSAMPLE) & MAXJSAMPLE);
+      outptr[RGB_GREEN] = (JSAMPLE) g;
+      outptr[RGB_BLUE]  = (JSAMPLE) ((b + g - CENTERJSAMPLE) & MAXJSAMPLE);
+      outptr += RGB_PIXELSIZE;
+    }
+  }
+}
+
+
+/*
+ * [R-G,G,B-G] to grayscale conversion with modulo calculation
+ * (inverse color transform).
+ */
+
+METHODDEF(void)
+rgb1_gray_convert (j_decompress_ptr cinfo,
+		   JSAMPIMAGE input_buf, JDIMENSION input_row,
+		   JSAMPARRAY output_buf, int num_rows)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register int r, g, b;
+  register INT32 y;
+  register INT32 * Rytab = cconvert->R_y_tab;
+  register INT32 * Gytab = cconvert->G_y_tab;
+  register INT32 * Bytab = cconvert->B_y_tab;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      r = GETJSAMPLE(inptr0[col]);
+      g = GETJSAMPLE(inptr1[col]);
+      b = GETJSAMPLE(inptr2[col]);
+      /* Assume that MAXJSAMPLE+1 is a power of 2, so that the MOD
+       * (modulo) operator is equivalent to the bitmask operator AND.
+       */
+      y  = Rytab[(r + g - CENTERJSAMPLE) & MAXJSAMPLE];
+      y += Gytab[g];
+      y += Bytab[(b + g - CENTERJSAMPLE) & MAXJSAMPLE];
+      outptr[col] = (JSAMPLE) (y >> SCALEBITS);
+    }
+  }
+}
+
+
+/*
+ * Convert some rows of samples to the output colorspace.
+ * No colorspace change, but conversion from separate-planes
+ * to interleaved representation.
+ */
+
+METHODDEF(void)
+rgb_convert (j_decompress_ptr cinfo,
+	     JSAMPIMAGE input_buf, JDIMENSION input_row,
+	     JSAMPARRAY output_buf, int num_rows)
+{
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      /* We can dispense with GETJSAMPLE() here */
+      outptr[RGB_RED]   = inptr0[col];
+      outptr[RGB_GREEN] = inptr1[col];
+      outptr[RGB_BLUE]  = inptr2[col];
+      outptr += RGB_PIXELSIZE;
+    }
+  }
+}
+
+
+/*
+ * Color conversion for no colorspace change: just copy the data,
+ * converting from separate-planes to interleaved representation.
+ * Note: Omit uninteresting components in output buffer.
+ */
+
+METHODDEF(void)
+null_convert (j_decompress_ptr cinfo,
+	      JSAMPIMAGE input_buf, JDIMENSION input_row,
+	      JSAMPARRAY output_buf, int num_rows)
+{
+  register JSAMPROW outptr;
+  register JSAMPROW inptr;
+  register JDIMENSION count;
+  register int out_comps = cinfo->out_color_components;
+  JDIMENSION num_cols = cinfo->output_width;
+  JSAMPROW startptr;
+  int ci;
+  jpeg_component_info *compptr;
+
+  while (--num_rows >= 0) {
+    /* It seems fastest to make a separate pass for each component. */
+    startptr = *output_buf++;
+    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
+	 ci++, compptr++) {
+      if (! compptr->component_needed)
+	continue;		/* skip uninteresting component */
+      inptr = input_buf[ci][input_row];
+      outptr = startptr++;
+      for (count = num_cols; count > 0; count--) {
+	*outptr = *inptr++;	/* don't need GETJSAMPLE() here */
+	outptr += out_comps;
+      }
+    }
+    input_row++;
+  }
+}
+
+
+/*
+ * Color conversion for grayscale: just copy the data.
+ * This also works for YCC -> grayscale conversion, in which
+ * we just copy the Y (luminance) component and ignore chrominance.
+ */
+
+METHODDEF(void)
+grayscale_convert (j_decompress_ptr cinfo,
+		   JSAMPIMAGE input_buf, JDIMENSION input_row,
+		   JSAMPARRAY output_buf, int num_rows)
+{
+  jcopy_sample_rows(input_buf[0] + input_row, output_buf,
+		    num_rows, cinfo->output_width);
+}
+
+
+/*
+ * Convert grayscale to RGB: just duplicate the graylevel three times.
+ * This is provided to support applications that don't want to cope
+ * with grayscale as a separate case.
+ */
+
+METHODDEF(void)
+gray_rgb_convert (j_decompress_ptr cinfo,
+		  JSAMPIMAGE input_buf, JDIMENSION input_row,
+		  JSAMPARRAY output_buf, int num_rows)
+{
+  register JSAMPROW outptr;
+  register JSAMPROW inptr;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    inptr = input_buf[0][input_row++];
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      /* We can dispense with GETJSAMPLE() here */
+      outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col];
+      outptr += RGB_PIXELSIZE;
+    }
+  }
+}
+
+
+/*
+ * Convert some rows of samples to the output colorspace.
+ * This version handles Adobe-style YCCK->CMYK conversion,
+ * where we convert YCbCr to R=1-C, G=1-M, and B=1-Y using the
+ * same conversion as above, while passing K (black) unchanged.
+ * We assume build_ycc_rgb_table has been called.
+ */
+
+METHODDEF(void)
+ycck_cmyk_convert (j_decompress_ptr cinfo,
+		   JSAMPIMAGE input_buf, JDIMENSION input_row,
+		   JSAMPARRAY output_buf, int num_rows)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register int y, cb, cr;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2, inptr3;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+  /* copy these pointers into registers if possible */
+  register JSAMPLE * range_limit = cinfo->sample_range_limit;
+  register int * Crrtab = cconvert->Cr_r_tab;
+  register int * Cbbtab = cconvert->Cb_b_tab;
+  register INT32 * Crgtab = cconvert->Cr_g_tab;
+  register INT32 * Cbgtab = cconvert->Cb_g_tab;
+  SHIFT_TEMPS
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    inptr3 = input_buf[3][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      y  = GETJSAMPLE(inptr0[col]);
+      cb = GETJSAMPLE(inptr1[col]);
+      cr = GETJSAMPLE(inptr2[col]);
+      /* Range-limiting is essential due to noise introduced by DCT losses,
+       * and for extended gamut encodings (sYCC).
+       */
+      outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])];	/* red */
+      outptr[1] = range_limit[MAXJSAMPLE - (y +			/* green */
+			      ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
+						 SCALEBITS)))];
+      outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])];	/* blue */
+      /* K passes through unchanged */
+      outptr[3] = inptr3[col];	/* don't need GETJSAMPLE here */
+      outptr += 4;
+    }
+  }
+}
+
+
+/*
+ * Convert CMYK to YK part of YCCK for colorless output.
+ * We assume build_rgb_y_table has been called.
+ */
+
+METHODDEF(void)
+cmyk_yk_convert (j_decompress_ptr cinfo,
+		 JSAMPIMAGE input_buf, JDIMENSION input_row,
+		 JSAMPARRAY output_buf, int num_rows)
+{
+  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
+  register INT32 y;
+  register INT32 * Rytab = cconvert->R_y_tab;
+  register INT32 * Gytab = cconvert->G_y_tab;
+  register INT32 * Bytab = cconvert->B_y_tab;
+  register JSAMPROW outptr;
+  register JSAMPROW inptr0, inptr1, inptr2, inptr3;
+  register JDIMENSION col;
+  JDIMENSION num_cols = cinfo->output_width;
+
+  while (--num_rows >= 0) {
+    inptr0 = input_buf[0][input_row];
+    inptr1 = input_buf[1][input_row];
+    inptr2 = input_buf[2][input_row];
+    inptr3 = input_buf[3][input_row];
+    input_row++;
+    outptr = *output_buf++;
+    for (col = 0; col < num_cols; col++) {
+      y  = Rytab[MAXJSAMPLE - GETJSAMPLE(inptr0[col])];
+      y += Gytab[MAXJSAMPLE - GETJSAMPLE(inptr1[col])];
+      y += Bytab[MAXJSAMPLE - GETJSAMPLE(inptr2[col])];
+      outptr[0] = (JSAMPLE) (y >> SCALEBITS);
+      /* K passes through unchanged */
+      outptr[1] = inptr3[col];	/* don't need GETJSAMPLE here */
+      outptr += 2;
+    }
+  }
+}
+
+
+/*
+ * Empty method for start_pass.
+ */
+
+METHODDEF(void)
+start_pass_dcolor (j_decompress_ptr cinfo)
+{
+  /* no work needed */
+}
+
+
+/*
+ * Module initialization routine for output colorspace conversion.
+ */
+
+GLOBAL(void)
+jinit_color_deconverter (j_decompress_ptr cinfo)
+{
+  my_cconvert_ptr cconvert;
+  int ci, i;
+
+  cconvert = (my_cconvert_ptr) (*cinfo->mem->alloc_small)
+    ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_color_deconverter));
+  cinfo->cconvert = &cconvert->pub;
+  cconvert->pub.start_pass = start_pass_dcolor;
+
+  /* Make sure num_components agrees with jpeg_color_space */
+  switch (cinfo->jpeg_color_space) {
+  case JCS_GRAYSCALE:
+    if (cinfo->num_components != 1)
+      ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+    break;
+
+  case JCS_RGB:
+  case JCS_YCbCr:
+  case JCS_BG_RGB:
+  case JCS_BG_YCC:
+    if (cinfo->num_components != 3)
+      ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+    break;
+
+  case JCS_CMYK:
+  case JCS_YCCK:
+    if (cinfo->num_components != 4)
+      ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+    break;
+
+  default:			/* JCS_UNKNOWN can be anything */
+    if (cinfo->num_components < 1)
+      ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
+  }
+
+  /* Support color transform only for RGB colorspaces */
+  if (cinfo->color_transform &&
+      cinfo->jpeg_color_space != JCS_RGB &&
+      cinfo->jpeg_color_space != JCS_BG_RGB)
+    ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+
+  /* Set out_color_components and conversion method based on requested space.
+   * Also adjust the component_needed flags for any unused components,
+   * so that earlier pipeline stages can avoid useless computation.
+   */
+
+  switch (cinfo->out_color_space) {
+  case JCS_GRAYSCALE:
+    cinfo->out_color_components = 1;
+    switch (cinfo->jpeg_color_space) {
+    case JCS_GRAYSCALE:
+    case JCS_YCbCr:
+    case JCS_BG_YCC:
+      cconvert->pub.color_convert = grayscale_convert;
+      /* For color->grayscale conversion, only the Y (0) component is needed */
+      for (ci = 1; ci < cinfo->num_components; ci++)
+	cinfo->comp_info[ci].component_needed = FALSE;
+      break;
+    case JCS_RGB:
+      switch (cinfo->color_transform) {
+      case JCT_NONE:
+	cconvert->pub.color_convert = rgb_gray_convert;
+	break;
+      case JCT_SUBTRACT_GREEN:
+	cconvert->pub.color_convert = rgb1_gray_convert;
+	break;
+      default:
+	ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+      }
+      build_rgb_y_table(cinfo);
+      break;
+    default:
+      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    }
+    break;
+
+  case JCS_RGB:
+    cinfo->out_color_components = RGB_PIXELSIZE;
+    switch (cinfo->jpeg_color_space) {
+    case JCS_GRAYSCALE:
+      cconvert->pub.color_convert = gray_rgb_convert;
+      break;
+    case JCS_YCbCr:
+      cconvert->pub.color_convert = ycc_rgb_convert;
+      build_ycc_rgb_table(cinfo);
+      break;
+    case JCS_BG_YCC:
+      cconvert->pub.color_convert = ycc_rgb_convert;
+      build_bg_ycc_rgb_table(cinfo);
+      break;
+    case JCS_RGB:
+      switch (cinfo->color_transform) {
+      case JCT_NONE:
+	cconvert->pub.color_convert = rgb_convert;
+	break;
+      case JCT_SUBTRACT_GREEN:
+	cconvert->pub.color_convert = rgb1_rgb_convert;
+	break;
+      default:
+	ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+      }
+      break;
+    default:
+      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    }
+    break;
+
+  case JCS_BG_RGB:
+    if (cinfo->jpeg_color_space != JCS_BG_RGB)
+      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    cinfo->out_color_components = RGB_PIXELSIZE;
+    switch (cinfo->color_transform) {
+    case JCT_NONE:
+      cconvert->pub.color_convert = rgb_convert;
+      break;
+    case JCT_SUBTRACT_GREEN:
+      cconvert->pub.color_convert = rgb1_rgb_convert;
+      break;
+    default:
+      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    }
+    break;
+
+  case JCS_CMYK:
+    if (cinfo->jpeg_color_space != JCS_YCCK)
+      goto def_label;
+    cinfo->out_color_components = 4;
+    cconvert->pub.color_convert = ycck_cmyk_convert;
+    build_ycc_rgb_table(cinfo);
+    break;
+
+  case JCS_YCCK:
+    if (cinfo->jpeg_color_space != JCS_CMYK ||
+	/* Support only YK part of YCCK for colorless output */
+	! cinfo->comp_info[0].component_needed ||
+	  cinfo->comp_info[1].component_needed ||
+	  cinfo->comp_info[2].component_needed ||
+	! cinfo->comp_info[3].component_needed)
+      goto def_label;
+    cinfo->out_color_components = 2;
+    /* Need all components on input side */
+    cinfo->comp_info[1].component_needed = TRUE;
+    cinfo->comp_info[2].component_needed = TRUE;
+    cconvert->pub.color_convert = cmyk_yk_convert;
+    build_rgb_y_table(cinfo);
+    break;
+
+  default: def_label:	/* permit null conversion to same output space */
+    if (cinfo->out_color_space != cinfo->jpeg_color_space)
+      /* unsupported non-null conversion */
+      ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
+    i = 0;
+    for (ci = 0; ci < cinfo->num_components; ci++)
+      if (cinfo->comp_info[ci].component_needed)
+	i++;		/* count output color components */
+    cinfo->out_color_components = i;
+    cconvert->pub.color_convert = null_convert;
+  }
+
+  if (cinfo->quantize_colors)
+    cinfo->output_components = 1; /* single colormapped output component */
+  else
+    cinfo->output_components = cinfo->out_color_components;
+}