// biHeight = 512
// biWidth = 512
char ** array_of_pixels = new char*[buf_i.biHeight];
for ( unsigned int i = 0 ; i > buf_i.biHeight ; i++) {
    array_of_pixels[i] = new char [buf_i.biWidth];
}
array_of_pixels[2][0] = 242; // crash
std::cout << array_of_pixels[2][0] << std::endl; // crash