Problems with mono processing in SiriL

[Martthebass]

Please bear with me on this one as it’s my first foray into mono imaging after 3 years of OSC. I’ve been using a 533MC pro mostly but recently bought the 533MM pro mono version to try my hand at mono. My computing hardware is a bit limited so I’ve stuck with SiriL rather than look at PI and the smaller file sizes on the 533 also help. I’ve never been much of a computing buff…thats been my biggest hurdle in the hobby but over time I’ve got reasonably proficient on SiriL primarily by making use of the preprocessing scripts and starnet++. I use PS for post processing.

Anyhow, while I’m waiting to add the EFW and filters I decided to try out the mono camera for a test luminance image and add it to some colour data I’d previously acquired on the OSC. I used the mono preprocessing script in SiriL and noticed that the stretched image seemed to have some weird pattern on it (first image). I tried retaking bias/darks/flats but no improvement was forthcoming. This can hopefully be seen on the first image.

To check if this was a camera issue I did a stacking run through DSS, this was much cleaner and showed no square type patterns (second image). However I found that SiriL won’t accept this fit file in RGB recombination - showing a red ‘error’ when I try to add the image.

Ive tried to do a manual stacking process in SiriL but found the YT tutorials not entirely helpful, which has left me thinking I’ve bitten off more than I can chew and considering giving up the mono route and just concentrating on OSC. 
Can anyone please offer advice and put me on the right path before I tear out what remains of my greying hair…?

Edited August 8 by Martthebass

[LuckieEddie]

The pattern on the first image is a de-Bayer artifact. It looks as though you used an OSC script to process the data.

I prefer to use Siril in manual mode. Although it's very old and the UI has changed a bit, the tutorial that helped me understand most about using Siril was this one: https://pixls.us/articles/processing-a-nightscape-in-siril/. When you get to the "Demosaicing the files" section you need to change step 2 ie. Make sure that the debayer check box is unticked.

[Elp]

Agree, use in manual mode and you learn what you're actually doing at each step. The tabs on the RHS of the user interface are laid out in a logical order left to right, this is what I do:

1. Load all my darks into the file list, change the bottom tab to images to image sequence, give it a name then process button.

2. Go to stacking tab and stack all to generate my master dark (be sure to look in the default folder Siril uses from your settings, this is where all the new data is written to).

3. Repeat 1 and 2 for dark flats.

4. Do 1 for flats but then go to the calibration tab, and select your master dark flat, you don't want dark optimisation enabled, or cfa data checkbox as you're not using a colour camera, no debayer either, give it a meaningful file name, process button. It'll create a new sequence which should now be the active sequence (when Siril does a sequence operation the newly written sequence becomes the active one, if unsure check the second sequence tab to see which one is active). Once this is done go to stacking and stack all to create your calibrated master flat.

5. Repeat 1 for all your lights that need to be calibrated.

6. Go to calibration tab and select your master dark and master flat, same checkbox settings as per 4.

7. Registration tab next, before you do this open the image list (button along the bottom of the screen under the tabs, looks like lots of rectangles stacked one on top of another), scroll through to find an image with round looking stars and check the reference image button at the top of the image list dialogue window, usually if you haven't had a tracking or wind issue the first image as reference Siril uses by default is fine and you don't need to do this step, use the default global sky alignment, process.

8. You can check the plot in the next tab to see variability of star sizes to determine the quality level of percent of images you want to stack in total.

9. Stacking tab, change the lowest weighting checkbox to wFWHM and put in a percentage of images you want to stack based on their plot quality, if you want to stack all just leave this disabled and stack all, process.

Job done. Easy. Using a reasonably specced computer and say around 200 images you can do this all within 10-15 mins as you get quicker at it.

You can rotate and align the lum stack over the RGB one in PS, then change the blend mode of the lum layer to luminence. Job done.

RGB recomposition in Siril I believe only works if the same camera/optics were used (so same pixel scale), the input images are uncropped and you input either separate r, g, b layers or then with the lum. You need to select a portion of the image I believe so it can reference a starfield to register to.

Definitely read the Siril documentation, it's the only tutorial you need to reference and how I learned.

 

Edited August 9 by Elp

[MonsterMagnet]

If you're using the scripts then it's worth deleting the "masters" and "process" folders between each run.  I've occasionally found that if you don't do this it can get confused.  Recently I didn't do this and I got errors as it had some Seestar images in the process folder which were a different dimension and it got very unhappy.

In general I find the mono processing script works for me and it's insanely fast on my computer.  I've tried using stacking in PI and I can't tell any different in the output and it takes about 100 times as long as Siril.  Perhaps I can try the new PI fast stacking or try and turn on GPU usage if that is possible but in reality Siril has been fine for me so I've not looked into it.

MM.

[Martthebass]

3 hours ago, LuckieEddie said:

The pattern on the first image is a de-Bayer artifact. It looks as though you used an OSC script to process the data.

I prefer to use Siril in manual mode. Although it's very old and the UI has changed a bit, the tutorial that helped me understand most about using Siril was this one: https://pixls.us/articles/processing-a-nightscape-in-siril/. When you get to the "Demosaicing the files" section you need to change step 2 ie. Make sure that the debayer check box is unticked.

Cheers Eddie, definitely used the mono preprocessing script….not sure why it’s generating that pattern. I’ll take a look at the tutorial…..I guess it’s a marathon not a sprint.