113 lines
4.7 KiB
C++
113 lines
4.7 KiB
C++
// This file is part of OpenCV project.
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// It is subject to the license terms in the LICENSE file found in the top-level directory
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// of this distribution and at http://opencv.org/license.html.
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#ifndef OPENCV_INTENSITY_TRANSFORM_H
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#define OPENCV_INTENSITY_TRANSFORM_H
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#include "opencv2/core.hpp"
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/**
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* @defgroup intensity_transform The module brings implementations of intensity transformation algorithms to adjust image contrast.
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*
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* Namespace for all functions is `cv::intensity_transform`.
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*
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* ### Supported Algorithms
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* - Autoscaling
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* - Log Transformations
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* - Power-Law (Gamma) Transformations
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* - Contrast Stretching
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* - BIMEF, A Bio-Inspired Multi-Exposure Fusion Framework for Low-light Image Enhancement @cite ying2017bio @cite ying2017new
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*
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* References from following book and websites:
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* - Digital Image Processing 4th Edition Chapter 3 [Rafael C. Gonzalez, Richard E. Woods] @cite Gonzalez2018
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* - http://www.cs.uregina.ca/Links/class-info/425/Lab3/ @cite lcs435lab
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* - https://theailearner.com/2019/01/30/contrast-stretching/ @cite theailearner
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*/
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namespace cv {
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namespace intensity_transform {
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//! @addtogroup intensity_transform
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//! @{
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/**
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* @brief Given an input bgr or grayscale image and constant c, apply log transformation to the image
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* on domain [0, 255] and return the resulting image.
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*
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* @param input input bgr or grayscale image.
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* @param output resulting image of log transformations.
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*/
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CV_EXPORTS_W void logTransform(const Mat input, Mat& output);
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/**
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* @brief Given an input bgr or grayscale image and constant gamma, apply power-law transformation,
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* a.k.a. gamma correction to the image on domain [0, 255] and return the resulting image.
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*
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* @param input input bgr or grayscale image.
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* @param output resulting image of gamma corrections.
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* @param gamma constant in c*r^gamma where r is pixel value.
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*/
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CV_EXPORTS_W void gammaCorrection(const Mat input, Mat& output, const float gamma);
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/**
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* @brief Given an input bgr or grayscale image, apply autoscaling on domain [0, 255] to increase
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* the contrast of the input image and return the resulting image.
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*
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* @param input input bgr or grayscale image.
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* @param output resulting image of autoscaling.
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*/
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CV_EXPORTS_W void autoscaling(const Mat input, Mat& output);
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/**
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* @brief Given an input bgr or grayscale image, apply linear contrast stretching on domain [0, 255]
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* and return the resulting image.
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*
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* @param input input bgr or grayscale image.
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* @param output resulting image of contrast stretching.
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* @param r1 x coordinate of first point (r1, s1) in the transformation function.
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* @param s1 y coordinate of first point (r1, s1) in the transformation function.
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* @param r2 x coordinate of second point (r2, s2) in the transformation function.
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* @param s2 y coordinate of second point (r2, s2) in the transformation function.
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*/
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CV_EXPORTS_W void contrastStretching(const Mat input, Mat& output, const int r1, const int s1, const int r2, const int s2);
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/**
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* @brief Given an input color image, enhance low-light images using the BIMEF method (@cite ying2017bio @cite ying2017new).
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*
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* @param input input color image.
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* @param output resulting image.
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* @param mu enhancement ratio.
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* @param a a-parameter in the Camera Response Function (CRF).
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* @param b b-parameter in the Camera Response Function (CRF).
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*
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* @warning This is a C++ implementation of the [original MATLAB algorithm](https://github.com/baidut/BIMEF).
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* Compared to the original code, this implementation is a little bit slower and does not provide the same results.
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* In particular, quality of the image enhancement is degraded for the bright areas in certain conditions.
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*/
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CV_EXPORTS_W void BIMEF(InputArray input, OutputArray output, float mu=0.5f, float a=-0.3293f, float b=1.1258f);
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/**
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* @brief Given an input color image, enhance low-light images using the BIMEF method (@cite ying2017bio @cite ying2017new).
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*
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* This is an overloaded function with the exposure ratio given as parameter.
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*
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* @param input input color image.
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* @param output resulting image.
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* @param k exposure ratio.
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* @param mu enhancement ratio.
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* @param a a-parameter in the Camera Response Function (CRF).
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* @param b b-parameter in the Camera Response Function (CRF).
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*
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* @warning This is a C++ implementation of the [original MATLAB algorithm](https://github.com/baidut/BIMEF).
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* Compared to the original code, this implementation is a little bit slower and does not provide the same results.
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* In particular, quality of the image enhancement is degraded for the bright areas in certain conditions.
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*/
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CV_EXPORTS_AS(BIMEF2) void BIMEF(InputArray input, OutputArray output, float k, float mu, float a, float b);
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//! @}
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}} // cv::intensity_transform::
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#endif
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