Some applications extract information from images in the LUV colour space and not directly from the more commonly used RGB. Why is that?
I found this explanation at imagemagick but am not an expert on color spaces myself.
The colorspaces 'Lab' and 'Luv' are designed, such that they fully separate the greyscale intensity from the color components of an image. Unlike 'RGB' and 'sRGB' colorspaces. this makes the colorspace a lot easier to process and modify in general, once you get the hang of it.
More specifically 'Luv' was designed to be 'perceptually linear'. That is that a a small change in color in one part of the colorspace looks to be about the same, as a similar change in another part of the colorspace. This make LUV colorspace much better suited for image difference comparisions.