Author Topic: Amp Glow removal  (Read 1442 times)

Offline wboeck

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Amp Glow removal
« on: 2018 March 28 04:37:36 »
I have an amp glow from my qhy10. I reduced some of it by unchecking optimizing dark frames during calibration. I then reduced a little more by using DBE tool. However there is still some left. Is the any routine or tutorials showing how to remove it other than cropping my image. Seems like this would be a high priority with all of the new cameras having problems with amp glow.

Offline RickS

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Re: Amp Glow removal
« Reply #1 on: 2018 March 28 17:23:35 »
I would make a mask that matches the amp glow and then use HistogramTransformation or CurvesTransformation (or a mix of both) to reduce the glow.  To make the mask, take a stretched monochrome image (extract Lightness if you're working with RGB.)  Blur with Convolution or removal of layers in one of the Multiscale processes.  Black clip with HistogramTransformation to isolate the amp glow.  If there are features in the amp glow, like stars, that you want to protect then use PixelMath to subtract a bit of the original mono image (e.g. "new_mask-orig-mono*0.5" - adjust the scaling factor for best results.)  Now draw a preview around the area with the amp glow and use the SubstituteWithPreview script to copy the preview into a black image.  Clean up with CloneStamp if needed and voila!

Cheers,
Rick.

Offline wboeck

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Re: Amp Glow removal
« Reply #2 on: 2018 March 29 04:34:36 »
Thanks, I will give that a try. Wayne

Offline wimvb

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Re: Amp Glow removal
« Reply #3 on: 2018 March 30 12:35:37 »
Darks are the best way to remove amp glow. If you have a master dark that shows the amp glow, but can't completely remove it, why not use that as the mask?
Wim

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Offline wboeck

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Re: Amp Glow removal
« Reply #4 on: 2018 April 02 04:32:57 »
Yes, I do have a dark with the amp glow. Thanks for the idea

Offline STEVE333

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Re: Amp Glow removal
« Reply #5 on: 2018 April 09 11:42:23 »
I would make a mask that matches the amp glow and then use HistogramTransformation or CurvesTransformation (or a mix of both) to reduce the glow.  To make the mask, take a stretched monochrome image (extract Lightness if you're working with RGB.)  Blur with Convolution or removal of layers in one of the Multiscale processes.  Black clip with HistogramTransformation to isolate the amp glow.  If there are features in the amp glow, like stars, that you want to protect then use PixelMath to subtract a bit of the original mono image (e.g. "new_mask-orig-mono*0.5" - adjust the scaling factor for best results.)  Now draw a preview around the area with the amp glow and use the SubstituteWithPreview script to copy the preview into a black image.  Clean up with CloneStamp if needed and voila!

Cheers,
Rick.

Clever technique for creating an "isolation mask". Thanks for sharing.

Steve
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Offline gvanhau

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Re: Amp Glow removal
« Reply #6 on: 2018 April 12 11:40:50 »
Hello
Normally if darks match the lights the amp glow sould be removed during calibration.

Be aware that your flats should also be calibrated with the apropiate dark flats, else it could be that the remaining amp glow is introduced by your flats.

You can do a test calibrating the ligths without flats to see if there is still ampglow (of course, vignetting and dust dognuts will be present)

Regards
Geert

Geert Vanhauwaert