At the very beginning of the level, you will be given an image with the correct order of pixels. However, it is such a short amount of time to process that you will often forget the order. Fret not, all you have to do is find the correct color gradient. Just use your intuition and knowledge of colors to figure out what the smoothest possible gradient is. For example, if the first square is a dark purple color, the next square will likely be a medium purple or maybe even a medium pink.