Opencv-图像像素读写操作

知识点

C++中的像素遍历与访问

• 数组遍历
• 指针方式遍历
  Python中的像素遍历与访问
• 数组遍历

python代码

import cv2 as cv
src = cv.imread("C:/Users/qqxd/Desktop/opencvcode/images/test1.png")
cv.namedWindow("input", cv.WINDOW_AUTOSIZE)
cv.imshow("input", src)
#图像的高，宽和通道数
h, w, ch = src.shape
print("h , w, ch", h, w, ch)
for row in range(h):
    for col in range(w):
        b, g, r = src[row, col]
        b = 255 - b
        g = 255 - g
        r = 255 - r
        src[row, col] = [b, g, r]
cv.imshow("output", src)
cv.waitKey(0)
cv.destroyAllWindows()

c++代码

#include 
#include 

using namespace cv;
using namespace std;

int main(int artc, char** argv) {
	Mat src = imread("C:/Users/qqxd/Desktop/opencvcode/images/test1.png");
	if (src.empty()) {
		printf("could not load image...\n");
		return -1;
	}
	namedWindow("input", WINDOW_AUTOSIZE);
	imshow("input", src);

	// 直接读取图像像素
	int height = src.rows;
	int width = src.cols;
	int ch = src.channels();
	for (int c = 0; c < ch; c++) {
		for (int row = 0; row < height; row++) {
			for (int col = 0; col < width; col++) {
				if (ch == 3) {
					Vec3b bgr = src.at<Vec3b>(row, col);
					bgr[0] = 255 - bgr[0];
					bgr[1] = 255 - bgr[1];
					bgr[2] = 255 - bgr[2];
					src.at<Vec3b>(row, col) = bgr;
				}
				else if (ch == 1) {
					int gray = src.at<uchar>(row, col);
					src.at<uchar>(row, col) = 255 - gray;
				}
			}
		}
	}
	imshow("output", src);

	// 指针读取
	Mat result = Mat::zeros(src.size(), src.type());
	int blue = 0, green = 0, red = 0;
	int gray;
	for (int c = 0; c < ch; c++) {
		for (int row = 0; row < height; row++) {
			uchar* curr_row = src.ptr<uchar>(row);
			uchar* result_row = result.ptr<uchar>(row);
			for (int col = 0; col < width; col++) {
				if (ch == 3) {
					blue = *curr_row++;
					green = *curr_row++;
					red = *curr_row++;

					*result_row++ = blue;
					*result_row++ = green;
					*result_row++ = red;
				}
				else if (ch == 1) {
					gray = *curr_row++;
					*result_row++ = gray;
				}
			}
		}
	}
	imshow("result", result);

	waitKey(0);
	return 0;
}

运行结果如下：