#AARRGGBB it depends on the app and if it supports it, otherwise you are right its just 6 for the RRGGBB. The first 2 of the 8 digits are the alpha value. But I guess hex values don't matter much here since autodesk doesn't know about them in their apps.
@DarkDogma3D Maybe the polypaint's colors are different due to the alpha channel or gamma ( try other file format like BMP. TIFF and PNG afaik use gamma correction ). Or perhaps might be a bug related to the color channel order ( GGBBRR / RRGGBB / RRBBGG ). What happens if you swap the color channels in Photoshop, do you…