Why is color segmentation easier on HSV?
I've heard that if you need to do a color segmentation on your software (create a binary image from a colored image by setting pixels to 1 if they meet certain threshold rules like R<100, G>100, 10< B < 123) it is better to first convert your image to HSV. Is this really true? And why?
Answer
The big reason is that it separates color information (chroma) from intensity or lighting (luma). Because value is separated, you can construct a histogram or thresholding rules using only saturation and hue. This in theory will work regardless of lighting changes in the value channel. In practice it is just a nice improvement. Even by singling out only the hue you still have a very meaningful representation of the base color that will likely work much better than RGB. The end result is a more robust color thresholding over simpler parameters.
Hue is a continuous representation of color so that 0 and 360 are the same hue which gives you more flexibility with the buckets you use in a histogram. Geometrically you can picture the HSV color space as a cone or cylinder with H being the degree, saturation being the radius, and value being the height. See the HSV wikipedia page.