PixInsight Forum (historical)

PixInsight => General => Off-topic => Topic started by: tsaban on 2011 August 28 14:04:35

Title: Artifacts after DSLR Workflow
Post by: tsaban on 2011 August 28 14:04:35

Hi,

I managed to process my recent DSLR subs exactly (I hope so) according to the guidelines found in

http://pixinsight.com/forum/index.php?topic=2570.0 (http://pixinsight.com/forum/index.php?topic=2570.0) and the video tutorials (normalization: additive+scaling, rejection1: Linear fit clipping,... as in the example). The stars seem to be stacked quite nicely but I see some artifacts when auto stretch the image with the screen transfer function in low s/n areas as can be seen below:

(http://members.aon.at/tsaban/artifacts.jpg)

Interestingly I don't get these (in PixInsight with the screen transfer function) when I use ImagesPlus fro the calibration and stacking.

One fact: The subs are far from being perfect, they show quite a variation in background brightness.

Does anyone have a hint what I did wrong?

Thanks!

Tahir Saban

Title: Re: Artifacts after DSLR Workflow
Post by: pfile on 2011 August 28 15:17:52

these are hot pixels that were not rejected by your stacking algorithm. what algorithm did you use?

since they are streaking like that they should be relatively easy to reject.

Title: Re: Artifacts after DSLR Workflow
Post by: tsaban on 2011 August 29 13:01:53

Thanks pfile. I have solved the problem by now.
I had used the linear fit algorithm suggested in the example.

Thanks
Tahir

Title: Re: Artifacts after DSLR Workflow
Post by: astropixel on 2011 September 03 05:14:19

I had the same problem and used Windsorised clipping, which was better, but proper dithering eliminates these trailing artifacts, or so I have found.