At first it may seem alien to think about negative brightness but it really is necessary when dealing with different color spaces. The area inside the "RGB" co

At first it may seem alien to think about negative brightness but it really is necessary when dealing with different color spaces. The area inside the "RGB" color triangle is represented by positive (non-negative) values. The sRGB color triangle only covers some part of the colors that physically can exist. If you have colors outside the sRGB color triangle at least one component will turn negative. Not all colors you could represent by RGB-values do actually exist. You can even define a bigger color triangle covering all colors that exist with positive values but also some colors that don't exist. It doesn't physically make sense but it is a very useful tool when doing calculations. By using floating point of sufficient precision you have to worry less about how you calculate your things. It's not needed but useful. If you know your calculations well you probably don't need float. Here is an image of some color triangles and what area they cover: https://en.wikipedia.org/wiki/Color_space#/media/File:CIE1931xy_gamut_comparison.svg https://en.wikipedia.org/wiki/Color_space#/media/File:CIE193...