From: "Tim" <tjp314@pacbell.net>

Date: November 9, 2005 5:44:53 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Camera for guiding

More on stacking:

I first stacked images to reduce noise and improve resolution ("super resolution") with 

Mars Pathfinder and Viking Lander images during the Pathfinder mission.  Interactively, 

using Photoshop.  To get to subpixel levels, I had to increase the file size 300-500 

percent, because photoshop can't "move" images by fractional pixel amounts (at least it 

couldn't then, and I doubt it can now).  

Manually stacking images to improve S/N certainly works, and super resolution probably 

works (at least up to about a factor of 2x the original image scale, but depending on the 

PSF of the imaging/ccd system - which couldn't be changed for landers on Mars!).   BUT, 

even with the Viking landers, I was working with at most a couple dozen images of a given 

scene.  And even that took many hours to produce desired results.  

I tried this technique with home videos of Jupiter and Mars back in the early 90s as well - 

with a Sony camcorder and a Video Spigot Nubus card on a Mac IIvx.  I could just about 

beat down the considerable noise of the individual frames by stacking a couple dozen 

images, but more than that I just didn't expect to live long enough to finish.  From start to 

finish, not counting sleep (because I never did the processing "right after" acquiring the 

video), took two or three hours, at least.

With Astro IIDC and the Flea camera, I can acquire a 2000-frame video, stack and process 

the result in less than 5 minutes.  I know that some imagers still prefer to choose the 

frames to stack manually, but I've tried that (with Keith's Image Stacker and Lynkeos, on 

the Mac), and I don't seem to have the patience to look at all those frames one at a time 

(or the ability to tell, more than very crudely, just which frames are enough above the 

margin to include after staring at more than about a hundred or so frames).  So, like I've 

said before, if it takes me several hours to produce a single frame worthy of posting, I'm 

afraid I won't ever produce a single frame!

Most stackers do auto aligning with a quality cutoff, but like I've also said before, I prefer 

the results I get with Astro IIDC to those I've gotten from Registax (and Virtual PC), 

Lynkeos, and Keith's.

...and by far to manually stacking them in Photoshop.  I don't think I'll ever do that again!  

;o)

-Tim.

--- In Astro_IIDC@yahoogroups.com, "Tim" <tjp314@p...> wrote:

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@o...> wrote:

David;

On 9-Nov-05, at 5:01 PM, David Illig wrote:

If that works then the only thing missing is a robust Mac  

stacking software that can handle

8 megapixel camera-RAW files.

Photoshop? But I agree -- the Mac needs a Registax, but with a  

human interface; using

Registax is a torturous process.

I take that Astro IIDC is no use to anyone for stacking then? I'd  

like to know because I'll stop all development of it if no one is  

using that aspect of it. I don 't like wasting my time on features if  

no one uses them and does not provide any constructive feedback.

Milton:

Please don't stop developing Astro IIDC!  

...okay?

-Tim.