A small issue when processing stars with beta version 1.4 of Siril. I’m not sure I understand how clipping works.(this option was not there in previous release 1.26). Basically, I get the impression that when stretching the background, some sort of stretch is being applied (I’m definitely in linear display mode). Before, when the black point was properly aligned with the background, I had a black background. Now that’s no longer the case. I can tell it’s related to clipping, but the logic escapes me.
The clipping mode shouldn’t make any difference for background pixels, it only has any significant effect where one of the colour channels in a pixel is clipped and others are not.
I can’t see from your screenshot what colour stretch model you’re using for the background, however the default is “independent colour channels” which maybe isn’t the best choice. Try changing it to human-weighted luminance and see if that solves the issue. If you can confirm it does I’ll change the default, as we shouldn’t have a default that may introduce colour shifts.
Thanks for the response.
the colour stretched model was set to “Human weighed model”.
None of these settings have a material impact on the issue.
this is new behaviour to the 1.4 beta.
i added a screen recording (speedx2) of the issue. Again the main behaviour is that the blacks are not black even though the histogram is pushed to the left.
also note that:
- every time a parameter is changed, the recompute of the image is quite heavy ona very decent PC
- the UI is really problematic with sliders hiding etc. and the window size too small (hence need of sliders) to show all settings in one screen
further evidence of the stretch behaviour attached in the video.
When i add the starless image it seems to show a stretch of the file. then i add the starmask and the image goes back to linear? this happens also when i perform the single stretches on the starless side…