I have a black & white image in my directory and I want to check the array of brightness of that picture, if certain pixel of that image is totally white i want to access that pixel and return the number 256(white) and if a pixel is black I want to access a index in a array and have the number 0(black). How i open that file and access to every pixel in that? I´m using Opencv to create a grey frame and i want to manipulate it with c++.