How to create and use 3-channel master dark in SiriL

Software Siril
1

I’m sure I’m missing something basic, but I spent quite a while trying to figure it out.

I’m using the latest beta on OS X. Notably the conversion options for saving as multi- or single-channel FITS is missing.

I’m not using RGB filters, just a simple DSLR setup capturing a few full color subs as jpg and then putting the cap on the telescope to take a few darks as jpg.

Siril is able to convert these primary and dark subs to 3-channel FITS, but seemingly nothing else.

My expectations is that I would be able to independently stack the dark frames to make a master dark and then apply it to my images during the pre-processing stage. I would like to use the dark as I have in other software, to apply to the stack and also to remove hot pixels.

The problem is that when I attempt to apply cosmetic correction using the SiriL-stacked 3-channel master dark, SiriL gives a warning that it requires a single channel image to apply cosmetic corrections, which I understand to mean to remove the hot pixels.

I’m not sure if this means the dark has to be single-single channel, or if the images I’m trying to stack need to be, or both, as the message is ambiguous.

At this point if I refer to all of the online documentation, the screen captures will show an option to save as a single-channel fits, but that does not seem to be available in the current beta.

What’s the correct procedure? Surely I don’t have to use external software to create a single-channel master dark?

2

It is not possible.
Why? Because it is non sense. We must not remove biases or darks from interpolated data.

3

Going back to SiriL 0.9.12 on OS X, I can remove hot pixels if I convert jpg to three separate images - r,g,b. This option seems to be missing from latest beta, is it required in order to create darks from jpg and apply with cosmetic correction to lights from jpg?

4

No but again, it is non sens.
Even if you split your rgb image in 3 channels, you’ve already interpolated data. Dark subtraction should not be applied!!

5

This took me a while to understand what you were saying, but now that I finally understand the debayering concept, this guidance makes sense. I just can’t and shouldn’t apply dark and cosmetic correction to debayered subs, of course. My mistake was not switching my camera back to raw mode in the first place. This is a great tool along with gimp that finally brings the open imaging options up to standard!