[X] My Assistant

[DDAVIS]

http://www.donaldedavis.com/2002_addons/SSYCOLRS.html

A new set of color samples at the bottom of the page. links to other planetary color related sites as well as to my updated pages concerning Mars.
Any corrections, reactions, etc. welcome!

Don

[JRehling]

Great stuff, as always.

The upper left Mars image from Mt. Wilson pops out as just what I see through my 3" scope.

A calculation I once did, which is perhaps relevant, is that the illumination of the planets' surfaces are, in most cases, brighter than a typical monitor can imitate, and this makes any screen portrayal inherently different from "true color". The Purkinje Effect is just an extreme example of how it is impossible to have the same colors at different illumination. ("Separate but equal"?) It turns out that Uranus, Neptune, etc., are dimly-lit enough that they *can* be imitated, to within epsilon, of "true color". Eg, true illumination as well as true color. But for everything else, there's a need to compensate.

I think the Moon also makes a great example of the importance of the degree of dark-adaptation the viewer has undergone. A full Moon on a winter night can be dazzling. It just short of hurts to look at it. But I've noticed that when a day time Moon, in a place with dry air, is visually located near snow or cumulus clouds, that it's suddenly noticeable how tan it is.

[DDAVIS]

[quote name='JRehling' date='Jul 23 2008, 04:00 AM' post='121231']
>Great stuff, as always.

Thanks!

>The upper left Mars image from Mt. Wilson pops out as just what I see through my 3" scope.

It is a rather dazzling predominately yellow orange at first, then as that part of your retina gets 'saturated' something of the color range can be seen to better advantage.

>A calculation I once did, which is perhaps relevant, is that the illumination of the planets' surfaces are, in most cases, brighter than a typical monitor can imitate, and this makes any screen portrayal inherently different from "true color".

Well, yes, but it seems to me I can look at my photos made at Monument Valley and judge which ones have a more realistic color balance, etc. even though the monitor is far removed from solar illumination brightness levels. Are you saying I would need a carefully color balanced transparency, placed on a white 'light box' with enough brightness to register the same on a light meter as a white paper in daylight would, to resonably accurately show the colors of a sunlit surface? Or perhaps a projector as bright and color balanced as sunlight?

Don