C++ 使用Opencv实现分通道图像滤波

目标是使用三个不同的模板对图像rgb三个通道分别进行滤波，但是opencv的filter2d函数原理是src图像的三个通道共用一个kernel，办法是将图像三个通道分别提取出来，分别进行滤波，最后再拼接成dst。

#include
#include
#include 
using namespace cv;

void cv_filter_test(String str)
{
	Mat img = imread(str);

	Mat img_b(img.size(), CV_8UC1);
	Mat img_g(img.size(), CV_8UC1);
	Mat img_r(img.size(), CV_8UC1);
	for (int i = 0; i < img.rows; i++)
	{
		unsigned char* p_src = img.ptr(i);
		unsigned char* p_b = img_b.ptr(i);
		unsigned char* p_g = img_g.ptr(i);
		unsigned char* p_r = img_r.ptr(i);
		for (int j = 0; j < img.cols; j++)
		{
			*(p_b + j) = *(p_src + j * 3);
			*(p_g + j) = *(p_src + j * 3 + 1);
			*(p_r + j) = *(p_src + j * 3 + 2);
		}
		p_src += img.step;
		p_b += img_b.step;
		p_g += img_g.step;
		p_r += img_r.step;
	}


	Mat kern_b = (Mat_(5, 5) << 
		0, 0, 0, 0, 0,
		0, 1, 2, 1, 0,
		0, 2, 4, 2, 0,
		0, 1, 2, 1, 0,
		0, 0, 0, 0, 0) / 16;

	Mat kern_g = (Mat_(5, 5) <<
		0, 0, 0, 0, 0,
		0, -1, 0, 1, 0,
		0, -2, 0, 2, 0,
		0, -1, 0, 1, 0,
		0, 0, 0, 0, 0);

	Mat kern_r = (Mat_(5, 5) <<
		1, 1, 1, 1, 1,
		1, 1, 1, 1, 1,
		1, 1, 1, 1, 1,
		1, 1, 1, 1, 1,
		1, 1, 1, 1, 1) / 25;

	Mat dst_b, dst_g, dst_r;
	filter2D(img_b, dst_b, img.depth(), kern_b, Point(-1, -1), 0.0, BORDER_DEFAULT);
	filter2D(img_g, dst_g, img.depth(), kern_g, Point(-1, -1), 0.0, BORDER_DEFAULT);
	filter2D(img_r, dst_r, img.depth(), kern_r, Point(-1, -1), 0.0, BORDER_DEFAULT);

	Mat dst(img.size(), img.type());
	for (int i = 0; i < dst.rows; i++)
	{
		unsigned char* p_dst = dst.ptr(i);
		unsigned char* p_b = dst_b.ptr(i);
		unsigned char* p_g = dst_g.ptr(i);
		unsigned char* p_r = dst_r.ptr(i);
		for (int j = 0; j < dst.cols; j++)
		{
			*(p_dst + j * 3) = *(p_b + j);
			*(p_dst + j * 3 + 1) = *(p_g + j);
			*(p_dst + j * 3 + 2) = *(p_r + j);
		}
		p_dst += dst.step;
		p_b += dst_b.step;
		p_g += dst_g.step;
		p_r += dst_r.step;
	}

	imshow("dst", dst);
	waitKey(0);
}

int main() {
	String str = "lena.jpg";
	cv_filter_test(str);

	return 0;
}