调整图像的亮度和对比度
简单原理:
为输出图像,为输入图像。其中用于调节对比度,增益用于调节亮度
实现代码:
#include<opencv2/opencv.hpp>
#include<iostream>
using namespace cv;
int main(int argc, char** argv)
{
Mat src, dst;
src = imread("1.jpg");
if (!src.data)
{
printf("cout not load image.../n");
return -1;
}
char input_win[] = "input image";
namedWindow(input_win, CV_WINDOW_AUTOSIZE);
imshow(input_win, src);
int height = src.rows;//高度
int width = src.cols;//宽度
//和输入图像的大小是一样的
dst = Mat::zeros(src.size(), src.type());
float alpha = 1.5;
float beta = 30;
for (int row = 0; row < height; row++)
{
for (int col = 0; col < width; col++)
{
//判断通道数,3通道,读取进到的是BGR图片
if (src.channels() == 3)
{
//图像的数据是uchar类型,所以使用的是Vec3b
//获取每隔通道的像素值
float b = src.at<Vec3b>(row, col)[0];
float g = src.at<Vec3b>(row, col)[1];
float r = src.at<Vec3b>(row, col)[2];
//然后利用已经获取到的像素值在像素位置进行操作
dst.at<Vec3b>(row, col)[0] = saturate_cast<uchar>(b*alpha + beta);
dst.at<Vec3b>(row, col)[1] = saturate_cast<uchar>(g*alpha + beta);
dst.at<Vec3b>(row, col)[2] = saturate_cast<uchar>(r*alpha + beta);
}
//判断通道数,单通道灰度图
else if (src.channels() == 1)
{
float v = src.at<uchar>(row, col);
dst.at<uchar>(row, col) = saturate_cast<uchar>(v*alpha + beta);
}
}
}
char output_title[] = "contrast and brightness change demo";
namedWindow(output_title, CV_WINDOW_AUTOSIZE);
imshow(output_title, dst);
waitKey(0);
return 0;
}
输出图像:
当然,我还可以使用src.convetTo将图片数据修改为CV_32F类型,然后读取各个通道像素值的时候就可以使用Vec3f进行读取了
#include<opencv2/opencv.hpp>
#include<iostream>
using namespace cv;
int main(int argc, char** argv)
{
Mat src, dst;
src = imread("1.jpg");
if (!src.data)
{
printf("cout not load image.../n");
return -1;
}
char input_win[] = "input image";
namedWindow(input_win, CV_WINDOW_AUTOSIZE);
imshow(input_win, src);
int height = src.rows;
int width = src.cols;
dst = Mat::zeros(src.size(), src.type());
float alpha = 1.5;
float beta = 30;
//先对图像数据进行转换
Mat m1;
src.convertTo(m1, CV_32F);
for (int row = 0; row < height; row++)
{
for (int col = 0; col < width; col++)
{
if (src.channels() == 3)
{
//此处使用的是m1的数据类型,m1是src转换后的图像数据类型
float b = m1.at<Vec3f>(row, col)[0];
float g = m1.at<Vec3f>(row, col)[1];
float r = m1.at<Vec3f>(row, col)[2];
dst.at<Vec3b>(row, col)[0] = saturate_cast<uchar>(b*alpha + beta);
dst.at<Vec3b>(row, col)[1] = saturate_cast<uchar>(g*alpha + beta);
dst.at<Vec3b>(row, col)[2] = saturate_cast<uchar>(r*alpha + beta);
}
else if (src.channels() == 1)
{
float v = src.at<uchar>(row, col);
dst.at<uchar>(row, col) = saturate_cast<uchar>(v*alpha + beta);
}
}
}
char output_title[] = "contrast and brightness change demo";
namedWindow(output_title, CV_WINDOW_AUTOSIZE);
imshow(output_title, dst);
waitKey(0);
return 0;
}
输出:同上输出.