c++ and opencv get and set pixel color to Mat

Question

I\'m trying to set a new color value to some pixel into a cv::Mat image my code is below:

    Mat image = img;
    for(int y=0;y

        

Answer 1

I would not use .at for performance reasons.

Define a struct:

//#pragma pack(push, 2) //not useful (see comments below)
struct RGB {
    uchar blue;
    uchar green;
    uchar red;  };

And then use it like this on your cv::Mat image:

RGB& rgb = image.ptr(y)[x];

image.ptr(y) gives you a pointer to the scanline y. And iterate through the pixels with loops of x and y