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comparison mupdf-source/thirdparty/tesseract/src/training/degradeimage.h @ 2:b50eed0cc0ef upstream

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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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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /**********************************************************************
2 * File: degradeimage.h
3 * Description: Function to degrade an image (usually of text) as if it
4 * has been printed and then scanned.
5 * Authors: Ray Smith
6 *
7 * (C) Copyright 2013, Google Inc.
8 * Licensed under the Apache License, Version 2.0 (the "License");
9 * you may not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 *
18 **********************************************************************/
19 #ifndef TESSERACT_TRAINING_DEGRADEIMAGE_H_
20 #define TESSERACT_TRAINING_DEGRADEIMAGE_H_
21
22 #include <allheaders.h>
23 #include "helpers.h" // For TRand.
24 #include "rect.h"
25
26 namespace tesseract {
27
28 // Degrade the pix as if by a print/copy/scan cycle with exposure > 0
29 // corresponding to darkening on the copier and <0 lighter and 0 not copied.
30 // If rotation is not nullptr, the clockwise rotation in radians is saved there.
31 // The input pix must be 8 bit grey. (Binary with values 0 and 255 is OK.)
32 // The input image is destroyed and a different image returned.
33 Image DegradeImage(Image input, int exposure, TRand *randomizer, float *rotation);
34
35 // Creates and returns a Pix distorted by various means according to the bool
36 // flags. If boxes is not nullptr, the boxes are resized/positioned according to
37 // any spatial distortion and also by the integer reduction factor box_scale
38 // so they will match what the network will output.
39 // Returns nullptr on error. The returned Pix must be pixDestroyed.
40 Image PrepareDistortedPix(const Image pix, bool perspective, bool invert, bool white_noise,
41 bool smooth_noise, bool blur, int box_reduction, TRand *randomizer,
42 std::vector<TBOX> *boxes);
43 // Distorts anything that has a non-null pointer with the same pseudo-random
44 // perspective distortion. Width and height only need to be set if there
45 // is no pix. If there is a pix, then they will be taken from there.
46 void GeneratePerspectiveDistortion(int width, int height, TRand *randomizer, Image *pix,
47 std::vector<TBOX> *boxes);
48 // Computes the coefficients of a randomized projective transformation.
49 // The image transform requires backward transformation coefficient, and the
50 // box transform the forward coefficients.
51 // Returns the incolor arg to pixProjective.
52 int ProjectiveCoeffs(int width, int height, TRand *randomizer, float **im_coeffs,
53 float **box_coeffs);
54
55 } // namespace tesseract
56
57 #endif // TESSERACT_TRAINING_DEGRADEIMAGE_H_