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 Post subject: IRIS to the rescue!
PostPosted: Thu Aug 09, 2012 12:49 pm 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1263
Location: Bolton
Last night I was testing a different combination of webcam, computer and software, and although everything looked OK on the screen at the time, when I came to look at the files this morning I found something very strange:
File comment: all the Green & Blue fields were inverted in this entire sequence of images
colourfault.jpg [ 39.33 KiB | Viewed 2908 times ]

But a couple of hours after deleting these files, I thought of a way to recover them using IRIS.
So having restored them from the Recycle Bin I set about the rescue misson.
I loaded each file in turn, then split the Red, Green & Blue fields (as Gerald demonstrated the other evening), flipped the G & B and then re-merged them.
Using the IRIS Looper utility ( it was easy to run the following loop of instructions:
load image
split_rgb r g b
load g
save g
load b
save b
merge_rgb r g b
save image

on each of my 25 lights and 24 calibration frames - it only took a few minutes.

Then I was able to follow the usual processing work-flow to obtain this image:
File comment: M27 planetary nebula, imaged before the sky was properly dark.
25x 30-sec, plus 12 each offset & dark calibration frames.

m27_rescue.jpg [ 25.56 KiB | Viewed 2908 times ]

So the morals of the story are:
  • don't throw away "useless" images - you may eventually discover a way to rescue them!
  • it's well worth the time spent learning to use the IRIS program
  • use the not-so-dark nights to practice with your camera, computer & software, so you'll have everything sussed in time for the winter...

 Post subject: Re: IRIS to the rescue!
PostPosted: Thu Aug 09, 2012 1:00 pm 
Fantastic turnaround there Ross... A lesson for us all - never doubt the power of IRIS!

I think i'll have a dance with my 'awful M57' shots.

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