The filter for transformation of the monochrome image into the colored one. As the result of the work of the filter half-hue or black and white images are assigned colors. Assigning to pixels different colors is carried out as the result of quantization by brightness levels. As some areas on the monochrome image can be received by human sight as areas of constant brightness, the filter is very useful.
This filter is very convenient for working with X-ray photos as well as with monochrome images, as the human being can distinguish many color hues and a few gray hues.
Adjusting histogram and changing the Size parameter of Color, you can achieve the distinct marking of different areas of constant brightness. Quantization will have as many color levels as you point out in parameter which defines the step of grouping.
Please find more information on settings and the use of filter in the step by step instruction Tutorial on the use of Color filter.