I think the reason most people want "true colour" is so the can picture themselfs standing on mars. The term true colour I agree is pointless. I work as a graphic designer and I know colour is subject to a lot of factors including lighting paper stock ink type etc etc. Even real life is not true colour. How do you know that when I look at "Red" i'am seeing the same colour as you? Unless you want NASA to pantone Mars you will just have to take their word for it.

Again, I do not think that for the most part people are asking for "true colour" other than the fact they want to make believe that they are standing on Mars. This is perfectly understandable.

On a related note I quite like stereo gram photos ( the 3D ones where you have to look at two pictures cross eyed ) Has anyone put together any mars versions of theese? I do not have 3D specs and I prefer to see them in colour.