OpenCV访问图像像素值的若干种方式

image.at<uchar>(j,i)=255;//单通道时
image.at<cv::Vec3b>(j,i)[0]=255;//三通道时

cv::Mat_<uchar> im2=image;//im2 refers to image
im2(50,100)=0;//access to row 50 and column 100

//address of pixel at (j,i) that is &image.at(j,i)
data = image.data+j*image.step()+i*image.elemSize();