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Topics - GordonH

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Bug Reports / TVGDenoise Corrupts Image
« on: 2019 January 31 12:08:38 »
TVGDenoise is corrupting my image. It worked fine in a preview, but, when I applied it to the image a part of the image turned black. I tried rebooting my PC and reloading from a project with the same result. I tried it in RGB/K mode and in CIE L*a*b* mode with the same results. See attachment

The image is a 64 bit if that matters. PixInsight is up todate Version

Gordon Hansen

Release Information / Extract Luminance
« on: 2017 August 06 12:46:50 »
The Extract Lightness icon disappeared from the Image Toolbar in the latest release. Can that be restored?


I imaged NC925 and while processing I noticed a "checker board pattern" in the background and persists into the higher signal area of the galaxy itself. The pattern runs at an angle to the row/columns of the sensor pixels. I've attached a grossly overstretched image to illustrate the conditions.

The images were taken with a Canon 6D DSLR using an AstroTech AT10RC scope. Acquisition software is TheSkyX Camera Add-in.  I've been using this combo for about the last 9 months and have not seen the pattern previously. I did go back and check some previous images.

I initially used 38 - 8 minute subs (I image from pretty badly light polluted skies and needs lots of subs!) I dithered these subs with an off-set of 10 pixels on the guide camera (translates to about 26 pixels on the image.) After seeing the pattern I inspected the individual subs, the master bias, dark, and flat and could not discern the pattern. I then stacked groups of 10 subs from the beginning and end of the run. The pattern appeared. I initially stacked using LinearFit, but, also tried WinsorizedSigma.

My next thought was some kind of relationship to the dithering pattern (TheSkyX seems to move the same number of pixels between each sub??) I re-imaged the target about 3 weeks later (I live in Michigan - you don't get many clear nights!) this time with the dither set to 5 pixels. Same result. I then stacked all the images together, tried the different rejection techniques and then started over with all the frames and used the Bayer drizzle routine in BatchPreprocessing. That's what was used for the attached image.

I also separated and inspected  the R - G - B channels from the integrated image. The pattern appear in all three channels, but, more noticeable in the red.

If the pattern were aligned with the sensor I would blame the camera. The fact that its on an angle leaves me puzzled.

Any ideas / help will be appreciated.


Bug Reports / Images Saved with STF are Permanently Altered
« on: 2016 February 11 12:45:07 »
My normal routine is to use STF to examine an image right after ImageIntegration and then save this image. In the past these images would reopen without any stretching. That no longer appears to be true.

If I save the image, close it down, and then reopen, it immediately appears stretched. Resetting in the STF will return it to its unstretched state. However, if I shut PixInsight down and then restart and open the image, it again appears stretched, but, that stretch is now permanent.

Not sure when this started. I recently upgraded to Windows 10 and the the same behavior occurs on both my desktop and laptop computers.

Gordon Hansen

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