Hi all,
I’ve stacks registered stacks for SII, Ha and OIII. On performing a simple SHO palette by the RGB composition tool the images looks after background neutralization pretty green. This comes form the strong Ha signal. In PI or Affinity Photo this can easily be corrected by the linear fit tool. As a result the colors come already close the the typical Hubble colors.
I tried to do the same in SiriL, but whatever I do, I can’t get it close to the Hubble colors. It seems that I just can’t “linear fit” the images - either manually by setting the R,G,B contribution in the RGB composition tool or int he linear match too. Actually, I thought the tool “linear match” is used for that. But even with it it’s just not working. It’s apparant from the resulting images that its result is totally different from PI or Affinity Photo 2.
Though, I think I’ missing something here. Does any know a 1 by 1 tutorial for SHO composing in SiriL or can give me some tipps what to do?
If necessar I can share the three files.
Hello and welcome,
the tutorials are on siril’s website and there is one just for that: Siril - RGB composition
It’s hard to get an image looking like the Hubble palette because it’s not a natural combination but it’s based on an artificial lookup table. But the tutorial should still help you.
Good luck
Hi, thanks for your reply. I know this tutorial. But unfortunately, this is not helpful in this case:
I know how it works, but the linear match tool doesn’t behave like anticipated. It’s not matching the channels as desired. Actually, the linear match it does goes in the wrong direction and therefore, the result is looking ugly. With PI or Affinity Photo the linear fit (how it’s called there) is working as desired and a channel balance close to the typical Hubble colors are achieved.
Maybe an issue with the stars in the image. Does it need starless images?
Some update:
It seems the linear fit module has a problem with my stars…
If I remove the stars with starnet (including the option to do some stretching, because without this option it’s not working) and do the linear match afterwards it’s working right away.
I already tried to change “reject high” in the linear match tool when I used the channel with stars, but this didn’t help. Any idea / advice is highly welcome, because it’s not optimal to eliminate the stars already at this stage.
Hi,
yes they are registered. As written above: once the stars are eliminated the linear match works with the default settings. If the stars are “in” it doesn’t work and it seems (for me) impossible to find a “reject high” value, with which it works. My understanding is, that with this value I can exclude to bright pixels for the match. Is this assumption correct?
if you still have the examples around, I’d like to see the results with and without stars to see how different they look like (zoomed out, a screen capture)