2018-04-25 16:35:26 +08:00
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/**********************************************************************
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* File: degradeimage.h
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* Description: Function to degrade an image (usually of text) as if it
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* has been printed and then scanned.
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* Authors: Ray Smith
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* Created: Tue Nov 19 2013
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*
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* (C) Copyright 2013, Google Inc.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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**********************************************************************/
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#ifndef TESSERACT_TRAINING_DEGRADEIMAGE_H_
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#define TESSERACT_TRAINING_DEGRADEIMAGE_H_
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#include "allheaders.h"
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#include "genericvector.h"
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#include "helpers.h" // For TRand.
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#include "rect.h"
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namespace tesseract {
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// Degrade the pix as if by a print/copy/scan cycle with exposure > 0
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// corresponding to darkening on the copier and <0 lighter and 0 not copied.
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// If rotation is not nullptr, the clockwise rotation in radians is saved there.
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// The input pix must be 8 bit grey. (Binary with values 0 and 255 is OK.)
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// The input image is destroyed and a different image returned.
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struct Pix* DegradeImage(struct Pix* input, int exposure, TRand* randomizer,
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float* rotation);
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// Creates and returns a Pix distorted by various means according to the bool
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// flags. If boxes is not nullptr, the boxes are resized/positioned according to
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// any spatial distortion and also by the integer reduction factor box_scale
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// so they will match what the network will output.
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// Returns nullptr on error. The returned Pix must be pixDestroyed.
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Pix* PrepareDistortedPix(const Pix* pix, bool perspective, bool invert,
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bool white_noise, bool smooth_noise, bool blur,
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int box_reduction, TRand* randomizer,
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GenericVector<TBOX>* boxes);
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// Distorts anything that has a non-null pointer with the same pseudo-random
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// perspective distortion. Width and height only need to be set if there
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// is no pix. If there is a pix, then they will be taken from there.
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void GeneratePerspectiveDistortion(int width, int height, TRand* randomizer,
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Pix** pix, GenericVector<TBOX>* boxes);
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// Computes the coefficients of a randomized projective transformation.
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// The image transform requires backward transformation coefficient, and the
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// box transform the forward coefficients.
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// Returns the incolor arg to pixProjective.
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int ProjectiveCoeffs(int width, int height, TRand* randomizer,
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float** im_coeffs, float** box_coeffs);
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} // namespace tesseract
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#endif // TESSERACT_TRAINING_DEGRADEIMAGE_H_
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