Adjust blue, red, and green to your satisfaction. Try setting the three to equal levels, say 50 for each. Set a color to 100, and the others to 0, yields one color. Combining the colors yields more info, as each color represents a wavelength that reveal an element or molecule. Different elements, say atomic hydrogen, molecular hydrogen, oxygen, show up as different colors.
Part science, part art, each color is "false" (not what naked eye would see) but NASA scientists assigned each of three narrow band wavelength images to visualize what otherwise would be invisible. Two of three images were taken in the infrared region. Humans can't see infrared with the naked eye. It's a mosaic image of the Crab Nebula, from images taken by Hubble in October 1999, January 2000 and December 2000. The colors in the image represent different elements that were expelled during the explosion.
