Quote:
Originally Posted by Hagar
Hi Dennis. I am sorry I cannot shed light on the cause but I can give you a method to remove these holes. It does appear to be some spots on some surface of the imaging train or in a calibration file.
Using CCDStack:
1. Select "Process", "Data Reget"
2. Select "Free Hand Draw" set pixel width to 1 pixel.
3. Mark all holes with a mouse click over them. Click apply.
4. Select "Grow" from reject menu. Set width to 5 pixels and apply.
5. From reject menu, select set pixel value to missing pixel and apply.
6. From reject menu select "Interpolate missing pixels" set value to 3 and iterations to 5. and apply.
This proceedure should remove these holes and fill them with an interpolated value based on the surrounding values.
I added an image repaired with a couple on the right side not repaired.
Sorry about the quality but it is a bit hard with a JPG.
I hope this helps.
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Hi Doug
Thanks for the quick and comprehensive reply, the results do look very promising. Your re-worked example is definitely superior to the “Patch” tool that I tried to use in Photoshop.
The anomalous pixels are sometimes single pixels and sometimes small clusters and their ADU value is mostly within 10’s to 100’s of the fainter background stuff although they appear quite dark in my example as the data is Scaled with DDP applied in CCDStack.
They appear to be in the same location on all each of the L,R,G and B frames so it looks as if those particular pixels seem to be less sensitive that their neighbours, albeit by small amounts, which then get reinforced through the stacking process?
Cheers
Dennis