Quote:
Originally Posted by Paul Haese
Greg, just after you normalize a stack of images, you go into data reject and sigma reject is in there. I do this just prior to final combine in CCDstack. I rarely use the option on a stacked image. I found that it can cause more damage than now.
When you use sigma reject you can vary the percentage of strength. Sometimes cosmic ray strikes will not go away without a really high setting. Odd really because they are so random.
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I'll try using Sigma Reject in data rejection and see if it helps. Are you mainly using it to get rid of satellites and cosmic rays?
Quote:
Originally Posted by multiweb
Here's my flow in CCD Stack.
1_ calibrate (flats/darks/bias)
2_ reject bad pixel map. (interpolate rejected pixels)
3_ star registration
4_ Normalisation
5_ STD Sigma reject. I aim for top image 2% or explicitly from 1.9 when it's super noisy up to 2.5 maximum factor.
6_ bit of cropping then deconv if needed 30 iterations positive constraint
7_ Save as a scaled 16bit TIFF then off to PS.
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Looks like Sigma reject is worth trying out. The other ones seem to select too much with their default settings.
Gotta watch saving as scaled as it can black clip. I save as 16bit TIFFs and use curves and levels in PS to bring up the image.
I sometimes use decon and other times not. It can make an image look harsh especially the stars but if done mildly or multiple stengths in luminance layered in PS with appropriate opacities it can be useful.
Its also useful if one colour sub stars are fatter than the others for some reason to make them match the others better.
Greg.