From: Milton Aupperle <milton@outcastsoft.com>

Date: May 19, 2008 4:25:01 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Use of Histogram expand and color balance techniques

Hi doodlebun and Gail;

On 19-May-08, at 2:58 PM, doodlebun wrote:

--------Snipped for brevity-------

Thanks Milton,

  Gail is beaming now. She has been telling me that our sun, a G2V 

star, is yellow, not white. I say that everything on earth is 

illuminated with our G2V star so it only makes sense that the 

internet chatter is full of references to finding a G2V star for your 

color balance. Yet I agree with you that white is R=G=B=255. Color 

discussions can make normal people go crazy. When women consider 

themselves too pale, they put some rouge on. It makes them look 

better even though it's not the "real color". When we image planets 

we put our images through the "anti-cosmetic" treatment.

If our planetary imaging techniques with the wavelet filter Fourier 

Freakouts were applied to images of a person's face, we would 

emphasize every pimple and wrinkle that we could find to bring it out 

from the background. We would all be fired as photographers 

specializing in portrait photography. So the rule simply 

becomes "don't turn your planets into false-color clowns with details 

that arise from amplification of noise rather than real planetary 

features".

   One wonders just how dim light is on Rhea? Here on Earth the flux 

at noon is 1000 J/s/m^2. Surely you could read a newspaper through 

your space helmet? Whip out a color chart on Rhea and see how much 

saturation remains in the dimness.  Here on Earth our software 

histogram adjusters can fully illuminate a shadow scene on Pluto.

Don't forget that our "brains" are wired to see the colors of things and have a persistence on how we see color too. If you observe white paper under white light and then see it again under say reddish light, you empirically "know" that the paper is still "white". Or a white stucco ceiling when seen under sunlight and then at night when illuminated under tungsten lights, you know it's still white even if it's yellowish in absolute terms at night.

   Last night we had lost 1-2 magnitudes from the sky due to smoke. 

It's forest fire season up here too and we've had a couple of good grass / bush fires north of Edmonton. The jets stream has been carrying the smoke mainly south east so it isn't smoky here, yet.

Almost as bad as the smoke in Glacier National Park in Aug 2001 that 

resulted in Gail and I leaving for Calgary..and Banff. Photoshop 

removed the haze in my Canadian Rockies images so well I began to 

believe that all photos of ultra-clear vistas must get the Photoshop 

treatment. 

Gail is using Photoshop to fix the yellowing we got in last nites 

Saturn images.

  And before I say goodbye, do you recommend the 4.04 upgrade for us 

monochrome planetary (never lunar) imagers?

If your upgrading from version 3.x, then yes.

http://www.outcastsoft.com/UpgradingToAstroIIDC4.html

Version 4.x has several new features for people who want to more manual control for stacking, uses far less CPU cycles for video play through and is Universal so that it runs faster on x86 Macs too.

Also 4.00.04 fixes several bugs introduced by Apple, so I would recommend it if your a 4.0x user.

Milton J. Aupperle