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Topics - akulapanam

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I have been noticing recently that all the time I put in initially with PCC or traditional color calibration is sometimes lost after I use the LRGBCombination process.  Not completely sure what is going on here besides the Lum highlighting different areas of the image that are a bit more bias in one color? 

What is the best way to fix the problem?  You can manually use HistrogramTransformation to fix the problem or in some cases export to photoshop and then use autotone or autocolor.  However, it seems like there should be a better solution.

Bug Reports / ImageSolver Problem
« on: 2018 December 04 23:53:52 »
I'm trying to use my image with Aladin but when I plate solve with ImageSolver the star coordinates appear ever so slightly off so Aladin draws boxes in the wrong position.  When I plate solve using TSX it works perfectly.  All images were captured with TSX.  Interestingly the annotateimage script in Pixinsight annotates the ImageSolver image correctly

I haven't used PixInsight in awhile to do stacking but I had a particularly bad framing issue occur that CCDStack couldn't register.  In any case I've run into an issue where imagecalibration would take my master flat (already calibrated with flat darks) and overcorrect my light frames.  The light frames now have white dust moles and a dark center but are bright towards the edges.  Using the same master flat frame in CCDStack and Nebulosity calibrates the light frame correctly.  I did make sure PixInsight had calibrate unchecked on the master flat.

General / ImageIntegration on Two Images
« on: 2017 October 23 21:28:53 »
I was curious why ImageIntegration doesn't allow you to do a noise weighted integration of only two images.  I have a situation where I'm shooting SH2 187 and I want to use some ha frames I took to enhance Lum because neither stands on its own.  I could use PixelMath but I would like to use a noise evaluation based weight but unfortunately it appears that the imageintegration process requires at least 3 images.

General / ASinH stretch?
« on: 2017 January 19 13:01:24 »
I came across a thread on another forum showing the power that ASinH stretching has to preserve star color and I was curious how to write a pixel math expression to mimic the that type of stretch.

General / What ever happened to maximum entropy deconvolution
« on: 2017 January 08 16:05:36 »
I remember it was listed as a priority several years ago but I don't think it was ever released?

I'm getting a bizarre area of red noise when using the LRGBCombination tool vs. using CCDStack or Nebulosity to create the LRGB.  My general process has been as follows:

Use PixelMath or ChannelCombination to create RGB image
Apply DBE (sometimes even reapplying DBE)
Apply BackgroundNeutralization
Apply Color Correction
Use SFT to stretch

Use DBE on L
Use SFT to stretch L

Use LRGBCombination to apply L on to the stretched RGB image.  I have tried every possible approach including applying DBE to each channel individually.  Before the L application the RGB stretch looks flat and using display shows the R, G, and B individually looking fine.

Now if I use CCDStack or Nebulosity 4 to create the LRGB image and then process it as if it is combined I get a very different result...

Any ideas why?

General / Lanczos Resampling Issue
« on: 2015 July 28 19:55:47 »
In order to register my osc ha frames to my rgb frames I have been using the Lanczos resampling method. Unfortunately last night I realized that this was causing extensive ringing and in general noise. I tried changing the clamp with out effect and then tried a couple other methods. The good news is the other methods resolved the issue but the bad news is the overall brightness and contrast of the image decreased dramatically. Any ideas on how to get the best of both.

I'm curious about the differences between how the three different methods of combining narrowband data work, specifically with an interest in HA + OSC RGB, and if anyone had some good work flows to use.  In particular do you use the tools to combine with linear or non linear data?  I noticed it looks like the SHO author prefers non linear but I could be mistaken.

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