I want to load an SDL_Surface into an OpenGL texture with padding (so that NPOT-POT) and apply a color key on the surface afterwards. I either end up colorkeying all pixels, regardless of their color, or not colorkey anything at all. I have tried a lot of different things, but none of them seem to work. Here's the working snippet of my code. I use a custom color class for the colorkey (range [0-1]): // Create an empty surface with the same settings as the original image SDL_Surface* paddedImage = SDL_CreateRGBSurface(image->flags, width, height, image->format->BitsPerPixel, #if SDL_BYTEORDER == SDL_BIG_ENDIAN 0xff000000, 0x00ff0000, 0x0000ff00, 0x000000ff #else 0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000 #endif ); // Map RGBA color to pixel format value Uint32 colorKeyPixelFormat = SDL_MapRGBA(paddedImage->format, static_cast<Uint8>(colorKey.R * 255), static_cast<Uint8>(colorKey.G * 255), static_cast<Uint8>(colorKey.B * 255), static_cast<Uint8>(colorKey.A * 255)); SDL_FillRect(paddedImage, NULL, colorKeyPixelFormat); // Blit the image onto the padded image SDL_BlitSurface(image, NULL, paddedImage, NULL); SDL_SetColorKey(paddedImage, SDL_SRCCOLORKEY, colorKeyPixelFormat); Afterwards, I generate an OpenGL texture from paddedImage using similar code to the SDL+OpenGL texture loading code found online (I'll post if necessary). This code works if I just want the texture with or without padding, and is likely not the problem. I realize that I set all pixels in paddedImage to have alpha zero which causes the first problem I mentioned, but I can't seem to figure out how to do this. Should I just loop over the pixels and set the appropriate colors to have alpha zero?