It's the intensity of infrared(-ish) light hitting multiple sensors with different wavelength filters. If you were to look at it in person it would be a fairly

It's the intensity of infrared(-ish) light hitting multiple sensors with different wavelength filters. If you were to look at it in person it would be a fairly smooth white patch. The colors are artificially assigned, but not by an artist. You pick a specific color for each wavelength. The Hubble palette is spelled out here: https://www.astronomymark.com/hubble_palette.htm https://www.astronomymark.com/hubble_palette.htm