From: Alan Friedman <alan@greatarrow.com>

Date: November 26, 2007 2:12:11 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Schiller

Hi Jim,

Thank you. The frames in this stream were pretty good - I looked for areas of contrast - shadows or crater features. The pixel matching was set to medium/low tolerance which worked well and allowed all selected frames to be included in the stack. I did have two regions that didn't work out - small craterlets that were off by themselves, where the seeing was iffy enough that they disappeared in some of the frames. These two stacks were only able to align 40 or so frames, so I didn't use them. The new MAP function is able to work with the image by quadrants, so this image uses data from 100 stacks total (20x4 quadrants + 20 MAPs in the center of the image). With the large chip size and average seeing, this many points offers an advantage, of course at the expense of time.

I process each of the images first in Astro IIDC. Then I choose one of the stacks to open in Photoshop as a master and open the 20 stacks for each quadrant (1 quadrant at a time) in Photoshop. Using the reference tiff image from Astro IIDC that shows the alignment points, I select the region in each image around the alignment box using the freehand marquee tool. I have an action saved in Photoshop that feathers, and copies the region and resizes it 2x for accurate nudge alignment when pasted into the master. It's time consuming, but I have a lot of cloudy nights (like 360/365!)

best,

Alan

On Nov 26, 2007, at 3:39 PM, Jim Chung wrote:

Alan,

Really outstanding as usual, not a hint of over processing at all. How do you
determine what points you will use for he multiple alignment stacking and do you
then cut and paste all the regions around that alignment point in PS?

Jim

.