Sunday, September 29, 2013

Comparing DeepSkyStacker, IRIS and Regim

As I recently wrote, I've been trying to learn AstroSurf IRIS. I've been doing everything on DeepSkyStacker until this, but the result always seems too colourless. Sometimes it looks like grayscale, sometimes sepia... But rarely the colours seem real. I thought it's just my lack of skills, but seems like not necessarily. IRIS and Regim do give me colours on the same data where DSS does not.

On a side note: IRIS works quite well with Wine on Linux. The drag & drop dialog for raw conversion does not, but it's possible to convert raws using the command line. First you have to place the photos on IRIS's working directory and name them by the same theme IRIS uses in everything. This time I copied all the CR2s to /media/data/Temp/iris and renamed them andromeda#.cr2, bias#.cr2, flat#.cr2 and dark#.cr2. Then you just

> CONVERTRAW andromeda andro 31

where "andro" is the generic name for converted image and 31 is the number of pictures. Same for flats, biases and darks, of course. From there on everything seemed to work just as in Windows.


DeepSkyStacker

Procedure is quite straightforward. You load lights, darks, flats and biases, start registering and DSS recommends the best settings for stacking method and else. The process takes a while and afterwards you have a "ready" photo. Of course there's still all the postprocessing do be done, but that I did in Darktable.

Here's the photo
Andromeda with DeepSkyStacker. Same on Flickr

Regim

Procedure is even more straightforward than with DSS. You load lights, darks and flats (no biases possible) tell it to begin and after a while you have picture done. Usually the white balance is wrong but there are good automatic and manual tools for that. This time Regim's astrometrics recognized Andromeda and set the white balance correctly. Otherwise you have to set a B-V value
manually for some star in the picture. I've found these values in KStars, Stellarium or finally by googling stars name.

Regim also has an automatic gradient remover which works quite well, but as you see, I forgot to use it this time. Postprocessing was done in Darktable. I think I overdid the denoise on my first try. It looked too smudgy. Here's the second version.

Andromeda with Regim. Same on Flickr

IRIS

IRIS has the steepest learning curve. I explained the procedure shortly in a previous post. Again the postprocessing was done in Darktable. This time I was more careful with denoise.

Andromeda with IRIS. Same on Flickr

Results

An 100% zoom of the three images. You might argue that DSS gives just as much detail than the others, but I just couldn't get more than that on Darktable. I tried not to mess with colour profiles on postprocessing and show colours the stacking software gave. Of course I adjusted RGB balance in IRIS and did automatic white balance adjustment on Regim. Seems like they don't agree on this. 


I like IRIS's colours the best. Level of details is about the same on Regim and IRIS. IRIS is no doubt the most difficult to learn, but while that, it also gives user a real insight on what's really going on in the stacking