opencv-矩阵的掩膜操作，增加对比度

1 按照《opencv初试》创建空项目

2 创建main.cpp 

#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;


int main()
{
	Mat src, dst;

	src = imread("E:/image/flower.bmp");
	
	if (!src.data)
	{
		printf("Could not load image");
		return -1;
	}
	namedWindow("input image", WINDOW_AUTOSIZE);
	imshow("input image", src);

	/*int cols = src.cols * src.channels();
	int offsetx = src.channels();
	int rows = src.rows;

	dst = Mat::zeros(src.size(), src.type());

	for (size_t row = 1; row < rows-1; row++)
	{
		const uchar* previous = src.ptr<uchar>(row - 1);
		const uchar* current = src.ptr<uchar>(row);
		const uchar* next = src.ptr<uchar>(row+1);

		uchar* output = dst.ptr<uchar>(row);

		for (size_t col = offsetx; col < cols; col++)
		{
			output[col] = saturate_cast<uchar>(5 * current[col] - (current[col - offsetx] + current[col + offsetx] + previous[col] + next[col]));
		}

		
	}*/

	double t = getTickCount();

	Mat kernel = (Mat_<char>(3, 3) << 0, -1, 0, -1, 5, -1, 0, -1, 0);
	filter2D(src, dst,-1, kernel);

	double timeConsume = (getTickCount() - t) / getTickFrequency();
	printf("time consume %.2f\n", timeConsume);

	namedWindow("constrast image", WINDOW_AUTOSIZE);

	imshow("constrast image", dst);
	waitKey(0);

	return 0;
}