Quote:
Originally Posted by rogerg
Take it as a pinch of salt, considering how good and frequent my LRGB image processing is  ... but ....
Overall: - Reduce all files in MaximDL
- Process each filter (see below)
- CCDStack: register frames then colour combine
- PixInsight: DBE
- Photoshop: tones of processing to fix it up
For each filter: - CCDStack: de-bloom
- CCDStack: align
- CCDStack: normalise
- CCDStack: sigma reject
- CCDStack: mean combine
I'm trying to get a handle on deconvolution to fit that in the workflow, to get rid of star halo's.
Feel free to point out what I'm doing wrong  |
Sounds good Roger.
I read a post by Stan Moore and I did an experiment last night. If you do data reject and then interpolate the pixels to remove them it slightly blurs the data. Its cleaner but its also slightly blurred.
If you do data reject and don't interpolate and them stack them using say median the data is a bit sharper. Not much but you can see it slightly.
Something to know. So how you do data reject is important. Interpolating the rejected data I think must have come from a tutorial (Adam Block?).
I think also using Lanczos for the resampling after aligning makes a slight difference as well compared to bicubic sampling. Again sharper.
Which data rejection method and the final results are a little unclear to me. I settled on hot and cold pixel rejection only for a long time. Paul uses Poisson set to 2 or 3. Sigma Reject sounds good as well. I don't know that one method over another is totally superior. Open to comments about results from different data reject methods. Stan can be a bit vague about it and suggests experimentation.
Basically most of my subs are pretty clean as my cameras are very good but there can be some spot noise, shot noise, satellites etc that get cleaned up by it. Even some streaky subs can be used and the streaks get cleaned up.
As far as decon for halos- that will make them worse. Decon tends to hammer any halo area around a bright star.
I know Mike hates decon but perhaps that is a crap implementation in the software he is using. I have seen some shockers. CCDstack's decon is very good and pretty artefact free up to a certain point. A 25 iteration positive constraint with auto star selection is pretty nice and no damage. But I do agree with him a little goes a long way. You can do multiscale sharpening using various strengths of decon and layering them in Photoshop with reducing opacities as a detail enhancement tool. Marcus has done that to good effect and I have used it a few times as well and liked what I got.
It depends on the data. As Paul has pointed out 2 images are never exactly the same so your processing flow needs to be a little flexible when you get to the Photoshop/PI part of the processing flow. Some subs take decon really well and others don't. Oversampling helps decon I have read many times.
Halos are best handled ideally physically with better filters or baffling or in Photoshop. I developed a method to handle halos in photoshop. It works but like any processing getting clean data is always infinitely preferable to a Photoshop fix up.
Greg.