tesseract 4.1.1
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degradeimage.h
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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 * Created: Tue Nov 19 2013
7 *
8 * (C) Copyright 2013, Google Inc.
9 * Licensed under the Apache License, Version 2.0 (the "License");
10 * you may not use this file except in compliance with the License.
11 * You may obtain a copy of the License at
12 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 **********************************************************************/
20#ifndef TESSERACT_TRAINING_DEGRADEIMAGE_H_
21#define TESSERACT_TRAINING_DEGRADEIMAGE_H_
22
23#include "allheaders.h"
24#include "genericvector.h"
25#include "helpers.h" // For TRand.
26#include "rect.h"
27
28namespace tesseract {
29
30// Degrade the pix as if by a print/copy/scan cycle with exposure > 0
31// corresponding to darkening on the copier and <0 lighter and 0 not copied.
32// If rotation is not nullptr, the clockwise rotation in radians is saved there.
33// The input pix must be 8 bit grey. (Binary with values 0 and 255 is OK.)
34// The input image is destroyed and a different image returned.
35struct Pix* DegradeImage(struct Pix* input, int exposure, TRand* randomizer,
36 float* rotation);
37
38// Creates and returns a Pix distorted by various means according to the bool
39// flags. If boxes is not nullptr, the boxes are resized/positioned according to
40// any spatial distortion and also by the integer reduction factor box_scale
41// so they will match what the network will output.
42// Returns nullptr on error. The returned Pix must be pixDestroyed.
43Pix* PrepareDistortedPix(const Pix* pix, bool perspective, bool invert,
44 bool white_noise, bool smooth_noise, bool blur,
45 int box_reduction, TRand* randomizer,
46 GenericVector<TBOX>* boxes);
47// Distorts anything that has a non-null pointer with the same pseudo-random
48// perspective distortion. Width and height only need to be set if there
49// is no pix. If there is a pix, then they will be taken from there.
50void GeneratePerspectiveDistortion(int width, int height, TRand* randomizer,
51 Pix** pix, GenericVector<TBOX>* boxes);
52// Computes the coefficients of a randomized projective transformation.
53// The image transform requires backward transformation coefficient, and the
54// box transform the forward coefficients.
55// Returns the incolor arg to pixProjective.
56int ProjectiveCoeffs(int width, int height, TRand* randomizer,
57 float** im_coeffs, float** box_coeffs);
58
59} // namespace tesseract
60
61#endif // TESSERACT_TRAINING_DEGRADEIMAGE_H_
void GeneratePerspectiveDistortion(int width, int height, TRand *randomizer, Pix **pix, GenericVector< TBOX > *boxes)
Pix * DegradeImage(Pix *input, int exposure, TRand *randomizer, float *rotation)
Pix * PrepareDistortedPix(const Pix *pix, bool perspective, bool invert, bool white_noise, bool smooth_noise, bool blur, int box_reduction, TRand *randomizer, GenericVector< TBOX > *boxes)
int ProjectiveCoeffs(int width, int height, TRand *randomizer, float **im_coeffs, float **box_coeffs)