View Full Version here: : Post processing help
10-04-2012, 11:18 AM
Was wanting a little bit of help with post processing. I took 20x30sec tracked images of M42 and put it through DSS and had a play around with curves and levels in photoshop and wasn't happy with it at all. http://farm8.staticflickr.com/7253/6907370080_97939f3db2_c.jpg (http://www.flickr.com/photos/63655425@N05/6907370080/)
Oriontest2 (http://www.flickr.com/photos/63655425@N05/6907370080/) by doddso99 (http://www.flickr.com/people/63655425@N05/)
I then attempted to edit just a single shot of M42 and the results were much better in my opinion than the stacked images.
_MG_8137 (http://www.flickr.com/photos/63655425@N05/6903547496/) by doddso99 (http://www.flickr.com/people/63655425@N05/)
any advice on what I'm doing wrong in DSS+Photoshop to not get results?
10-04-2012, 03:13 PM
just starting on this massive learning curve myself too, i got a similar result to your stacked one there, but the more i mucked about with it the smoother it went
it just looks too noisy but i wouldnt say for sure that that is the problem
one thing is for sure though, it is going to keep me busy for the rest of my life!
10-04-2012, 08:42 PM
Welcome to IIS, a couple of questions to help try and understand a few things.
1) What camera are you using? DSLR I suspect?
2) Are you capturing in JPG or FITS or RAW (CR2)?
3) Any darks or flats or bias frames added to the stack?
I have had a similar frustration recently with QHY8 fits and Canon Raw files and DSS, so as much info on your set up and capture type will hopefully allow me (and others) to offer you tips on what settings to use in DSS.
10-04-2012, 09:32 PM
I am using a Canon 600D shooting in RAW, I have tried adding in the dark frames but found that it didn't help much and the image in question hasn't got any dark frames. Also my understanding of flats and bias frames is a bit low so havent even attempted any of that yet!
thanks in advance!
10-04-2012, 09:57 PM
I found Nebulosity 3 very good in stacking images, darks and flats.
10-04-2012, 10:47 PM
OK, lets forget dark, flat and bias frames for the moment and simply work on the light frames to see if you can get an improvement. We will be working from the top down in the left menu bar for simplicity.
1) Load up the files by clicking on "open picture files".
2) Select all the CR2 files you have (or for testing, only use say 3-6 to make things run faster)
3) Click on Check all.
4) Click on your first image in the list and wait for the red banner at the top to go blue, this means the program has loaded the RAW file into the preview window using the settings already set in the program. It may look dark to you.
5) Slide the MIDDLE arrow on the greyscale type slider next to the blue "window" looking icon at the top right of the screen so the slider moves to the left. Set it to about 30% from the left side and watch the preview window. Your image should get brighter and show more details hopefully in the centre. This slider is simply a screen "stretch" so you can visually adjust what your images look like on the screen, no changes occur.
6) Skip to the bottom left and select "settings" under the option heading.
7) Select the register settings link and slide the star detection slider to say 40%. Dont worry about the median filter check box, press OK.
8) Click on Settings, but this time click on the stacking settings link. A new window pops up.
9) On the Result tab select standard mode. On the light tab select Kappa-Sigma clipping and set the Kappa to 1.0 with 5 iterations. Forget dark, flat and bias tabs as you arent using these yet. Normally I set all these to median anyway. As there arent many stars in your image, select Bilinear alignment on the alignment tab. On the cosmetic tab, select the hot and cold pixel removal option and the sliders should already be on 1 px and 50%, leave them there. Click OK.
10) As you are using RAW CR2 files, you need to set the RAW/FITS DDP settings, click on this. Set the RAW files tab to AHD Interpolation. Uncheck the white balance boxes. On the FITS tab, select the check box on, and pick the Canon 400D from the drop down list. This is the same as your 500D for bayer matrix. Select AHD again and click OK.
11) Click on Register checked pictures and set the best % to 100% so you keep all the files in the stack. Check the register already registered pictures box, make sure all three tick boxes are ticked. Click OK.
12) The stacking steps window will come up and show you what you have set. Leave this for now as you have set everything already and click OK.
13) Wait for everything to finish and then watch the final stack appear like a magic reveal at the end. You can play with the sliders on each colour to make the black S shaped line intersect near where the colour humps go from horizontal through to vertical (e.g base of the hill) by sliding the middle arrow left or right, watch the screen to see the result while you play around here.
14) Most people just dump the stack result straight into PS, however, I often play with the sliders to see if I can tweak what it looks like further here and sometimes even boost the saturation by say 15% to bring out the colour.
Give this a go, I am by no means an expert, but I have spent close to a week processing my DSLR RAWS from my 1000D and have done this over and over so many times, I think these settings should show you something better than a single RAW file that is opened in DPP.
Hope this helps. If the settings give you good results, click on Save and save the settings to a file on your desktop with an easy name to remember like M42 stacking settings and then you can call this file up with all those buttons and settings set to where you want them, next time you load these files in. Likewise, you can save the file list and simply call that up, which loads all the lights, darks, flats and bias etc in one go rather than having to select them each time.
Have a play with these and see if anything shows better results. I may have some of the theory wrong, but I have found you should get a better result than looking at a single file using these options. Feel free to play around with them but only use say 3 files, so it is quicker to see if those options make any difference.
(whew) long post, hope it is of benefit. I am sure someone more versed in DSS will correct me if I have made any glaringly bad errors in advice.
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