ILOVEUIHATEU

Is there an easy way to make a picture black and white according to the highest color value (like the following) Pixel with color 1DEA10 to EAEAEA Pixel with color 6B6B6B to 6B6B6B Pixel with color 59E8E8 to E8E8E8 Just takes the highest color value and assign that to all color values of that pixel