From: Alan Friedman <alan@greatarrow.com>

Date: September 6, 2005 3:50:28 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Old Aristarchus VS Stretched Aristarchus Comparion

Hi Milton -

Nice comparison of two processing values. Overall I prefer the first rather than the stretched due to the artifacts introduced in the dark regions in the stretched version (perhaps from the sharpening). It is true that curve based adjustment offers a lot more powerful control than a linear adjustment. In the same way an unsharp mask applied to the entire image is less powerful than sharpening applied using selection tools (ie in Photoshop) as some areas of the image are blown out with a sharpening level that is perfect for another area.

I've uploaded a couple of new images to the files area - an aristarchus regions at similar focal length to Milton's but at a different sun angle, an image of the crater moretus and southern highlands region at 7.5 meter focal length, and (in the DSO folder) a just completed webcam image of M57 taken this past weekend at the Black Forest Star Party. I've always wanted to try a deep sky target with my webcam and AstroIIDC - this one came out better than I thought it would.

Looking forward to meeting some of you in Chicago this week,

best,

Alan

On Sep 6, 2005, at 3:34 PM, Milton Aupperle wrote:

Hi Folks;

I was testing out the new image processing module over the weekend in

the Astro IIDC beta version for DSO's and thought it might be

interesting to see what one can do with it with lunar images,

especially along the terminator where contrast can be extreme.

Compare the original "Aristarchus_050420_MJA.jpg" to the new

streteched version "Aristarchus_050420_MJA_Stretched.jpg" in the Lunar

File section. A lot of hidden detail is now visible, especially the rills.

Using linear level adjustments to bring out the dark areas usually

wipes out the bright areas. But using the Log based curves can solve

this pretty easily.

I may have over sharpened it a little bit in Astro IIDC 2.1, but this

doesn't increase the noise level at all.

TTYL..

Milton Aupperle