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Use directly the doxygen snippet command for the Changing the contrast and brightness of an image tutorial. Extend the tutorial with a pratical example and with a gamma correction method to adjust the brightness of an image.

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This commit is contained in:
catree
2017-01-05 16:05:53 +01:00
parent 9be630466f
commit a891caa755
9 changed files with 220 additions and 106 deletions
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samples/cpp/tutorial_code/ImgProc/BasicLinearTransforms.cpp
+42 -33
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@@ -8,51 +8,60 @@
#include "opencv2/highgui.hpp"
#include <iostream>
using namespace std;
using namespace cv;
double alpha; /**< Simple contrast control */
int beta; /**< Simple brightness control */
/**
* @function main
* @brief Main function
*/
int main( int, char** argv )
{
/// Read image given by user
Mat image = imread( argv[1] );
Mat new_image = Mat::zeros( image.size(), image.type() );
//! [basic-linear-transform-parameters]
double alpha = 1.0; /*< Simple contrast control */
int beta = 0; /*< Simple brightness control */
//! [basic-linear-transform-parameters]
/// Initialize values
std::cout<<" Basic Linear Transforms "<<std::endl;
std::cout<<"-------------------------"<<std::endl;
std::cout<<"* Enter the alpha value [1.0-3.0]: ";std::cin>>alpha;
std::cout<<"* Enter the beta value [0-100]: "; std::cin>>beta;
/// Read image given by user
//! [basic-linear-transform-load]
Mat image = imread( argv[1] );
//! [basic-linear-transform-load]
//! [basic-linear-transform-output]
Mat new_image = Mat::zeros( image.size(), image.type() );
//! [basic-linear-transform-output]
/// Initialize values
cout << " Basic Linear Transforms " << endl;
cout << "-------------------------" << endl;
cout << "* Enter the alpha value [1.0-3.0]: "; cin >> alpha;
cout << "* Enter the beta value [0-100]: "; cin >> beta;
/// Do the operation new_image(i,j) = alpha*image(i,j) + beta
/// Instead of these 'for' loops we could have used simply:
/// image.convertTo(new_image, -1, alpha, beta);
/// but we wanted to show you how to access the pixels :)
for( int y = 0; y < image.rows; y++ )
{ for( int x = 0; x < image.cols; x++ )
{ for( int c = 0; c < 3; c++ )
{
new_image.at<Vec3b>(y,x)[c] = saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
}
}
}
/// Do the operation new_image(i,j) = alpha*image(i,j) + beta
/// Instead of these 'for' loops we could have used simply:
/// image.convertTo(new_image, -1, alpha, beta);
/// but we wanted to show you how to access the pixels :)
//! [basic-linear-transform-operation]
for( int y = 0; y < image.rows; y++ ) {
for( int x = 0; x < image.cols; x++ ) {
for( int c = 0; c < 3; c++ ) {
new_image.at<Vec3b>(y,x)[c] =
saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
}
}
}
//! [basic-linear-transform-operation]
/// Create Windows
namedWindow("Original Image", 1);
namedWindow("New Image", 1);
//! [basic-linear-transform-display]
/// Create Windows
namedWindow("Original Image", WINDOW_AUTOSIZE);
namedWindow("New Image", WINDOW_AUTOSIZE);
/// Show stuff
imshow("Original Image", image);
imshow("New Image", new_image);
/// Show stuff
imshow("Original Image", image);
imshow("New Image", new_image);
/// Wait until user press some key
waitKey();
return 0;
/// Wait until user press some key
waitKey();
//! [basic-linear-transform-display]
return 0;
}
samples/cpp/tutorial_code/ImgProc/changing_contrast_brightness_image/changing_contrast_brightness_image.cpp
+91
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@@ -0,0 +1,91 @@
#include <iostream>
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
using namespace std;
using namespace cv;
namespace
{
/** Global Variables */
int alpha = 100;
int beta = 100;
int gamma_cor = 100;
Mat img_original, img_corrected, img_gamma_corrected;
void basicLinearTransform(const Mat &img, const double alpha_, const int beta_)
{
Mat res;
img.convertTo(res, -1, alpha_, beta_);
hconcat(img, res, img_corrected);
}
void gammaCorrection(const Mat &img, const double gamma_)
{
CV_Assert(gamma_ >= 0);
//![changing-contrast-brightness-gamma-correction]
Mat lookUpTable(1, 256, CV_8U);
uchar* p = lookUpTable.ptr();
for( int i = 0; i < 256; ++i)
p[i] = saturate_cast<uchar>(pow(i / 255.0, gamma_) * 255.0);
Mat res = img.clone();
LUT(img, lookUpTable, res);
//![changing-contrast-brightness-gamma-correction]
hconcat(img, res, img_gamma_corrected);
}
void on_linear_transform_alpha_trackbar(int, void *)
{
double alpha_value = alpha / 100.0;
int beta_value = beta - 100;
basicLinearTransform(img_original, alpha_value, beta_value);
}
void on_linear_transform_beta_trackbar(int, void *)
{
double alpha_value = alpha / 100.0;
int beta_value = beta - 100;
basicLinearTransform(img_original, alpha_value, beta_value);
}
void on_gamma_correction_trackbar(int, void *)
{
double gamma_value = gamma_cor / 100.0;
gammaCorrection(img_original, gamma_value);
}
}
int main( int, char** argv )
{
img_original = imread( argv[1] );
img_corrected = Mat(img_original.rows, img_original.cols*2, img_original.type());
img_gamma_corrected = Mat(img_original.rows, img_original.cols*2, img_original.type());
hconcat(img_original, img_original, img_corrected);
hconcat(img_original, img_original, img_gamma_corrected);
namedWindow("Brightness and contrast adjustments", WINDOW_AUTOSIZE);
namedWindow("Gamma correction", WINDOW_AUTOSIZE);
createTrackbar("Alpha gain (contrast)", "Brightness and contrast adjustments", &alpha, 500, on_linear_transform_alpha_trackbar);
createTrackbar("Beta bias (brightness)", "Brightness and contrast adjustments", &beta, 200, on_linear_transform_beta_trackbar);
createTrackbar("Gamma correction", "Gamma correction", &gamma_cor, 200, on_gamma_correction_trackbar);
while (true)
{
imshow("Brightness and contrast adjustments", img_corrected);
imshow("Gamma correction", img_gamma_corrected);
int c = waitKey(30);
if (c == 27)
break;
}
imwrite("linear_transform_correction.png", img_corrected);
imwrite("gamma_correction.png", img_gamma_corrected);
return 0;
}