DeepSkyStacker issue (or Photoshop!)

Wailin

Any DSS experts out there?! Trying to process some pics I took last night and coming across some issues I never had before between DSS and PS. Photoshop won't open the Autosave.tiff files straight from DSS so I save the stacked images as 16 bit tiff files and can open with PS. The problem is the data is clipped a lot when opened and no matter what I do to levels and curves it doesn't help.
Here is a screenshot of the stacked image on DSS:


Here is the image opened in PS showing clipping of data:


This is the first time I've had this issue (I think) so if anyone has any advice on whats the problem please let me know.

ZeRoY

You should try and select the option to align the RGB channels before stacking.

It is usually recommended to adjust very little in DSS and do most in Photoshop. I use this tutorial:

http://www.youtube.com/watch?v=vc3Gypbtiao

EDIT: Superb shot by the way, a recent capture?

Wailin

ZeRoY wrote: »

You should try and select the option to align the RGB channels before stacking.

It is usually recommended to adjust very little in DSS and do most in Photoshop. I use this tutorial:

http://www.youtube.com/watch?v=vc3Gypbtiao

EDIT: Superb shot by the way, a recent capture?

Last night Zeroy, at sugar loaf. Put the modified 450D to the test. Processing doing my head in though, didnt have this issue when using the 1100D, the image appeared in PS almost identical to the stacked image on DSS so was easy enough to get a decent finished shot. Not saying its the camera thats causing the issue, I doubt it, but something definitely not right when opening the image in PS.

ZeRoY

Wailin wrote: »

Processing doing my head in though, didnt have this issue when using the 1100D, the image appeared in PS almost identical to the stacked image on DSS so was easy enough to get a decent finished shot.

That gets me thinking.. I have to use a special version of DSS for 1100D (to open the CR2 files) maybe you are using that version also?

Still your RGB are not joined together as they should in DSS, unless you moved them apart?

Also, do you save the TIFF with the tweaks applied or not? Compressed/not?

Wailin

I never compress the image before saving, should I? I downloaded a trial version of nebulosity, seems to be much better, more difficult to get around but end result is very good. Will test it for awhile before i decide to buy or not.

ThatDrGuy

I use Nebulosity. DSS is great when you have a bunch of high quality images. You might have clipped it when you stacked them : check your settings on the stack - make sure you stack the whole images ( field rotation can be issue though but if your polar autoguiding should be fine) Nebulosity is good for not so great tracking where you desperately need every photon.

ZeRoY

DSS is free, Nebulosity isnt - just want to clear this up!

Iancar29

Droool of a shot!! , Hopefully i'll get something similar soon as i got my SW ED-80 today ! Thanks Kersh !

Very odd to see that happening opening up the file .

Wailin

Iancar29 wrote: »

Droool of a shot!! , Hopefully i'll get something similar soon as i got my SW ED-80 today ! Thanks Kersh !

Very odd to see that happening opening up the file .

Nice one! Hopefully you'll get good use with it if this weather ever picks up.

Tzetze

The data hasn't been clipped. It's just all compressed up to near the left side, with some edge artefacts from stacking appearing as the leftmost spike on the histogram.

You need to stretch out the data in Photoshop. It's best not to do any processing in DSS once stacked. Save as 16-bit compressed tiff and use photoshop from there.

Check out the 3 free full length tutorials on this page...
http://www.ip4ap.com/freetutorials.htm

Iancar29

Wailin wrote: »

Nice one! Hopefully you'll get good use with it if this weather ever picks up.

Thanks , ah there'll be a few chances over the coming nights

What was ur setup for this btw?

Wailin

Iancar29 wrote: »

Thanks , ah there'll be a few chances over the coming nights

What was ur setup for this btw?

Same scope as you with a focal reducer, NEQ6 mount and canon 450D modified. Autoguided with an ST80 scope and QHY5 camera (really only testing it all out). The 80ED is a lovely scope, nice wide FOVs, and straight forward to set up.

Wailin

Tzetze wrote: »

The data hasn't been clipped. It's just all compressed up to near the left side, with some edge artefacts from stacking appearing as the leftmost spike on the histogram.

You need to stretch out the data in Photoshop. It's best not to do any processing in DSS once stacked. Save as 16-bit compressed tiff and use photoshop from there.

Check out the 3 free full length tutorials on this page...
http://www.ip4ap.com/freetutorials.htm[/QUOTE]

So there is no loss of data, just compressed when saved as Tiff file? So I need to do a lot of stretching to get it anyway decent. But I don't understand why its so compressed, normally the data is near the centre or slightly to the left of centre when opened in pS and you have to drag the left most slider up to meet it (this is the norm for me anyway and most tutorials I've seen). Any ideas why its so compressed?

Tzetze

DSS applied a temporary stretching curve to give a preview of the stack results.
That wasn't saved in your tiff. If you check out the second vid on that page about the histogram, he explains a bit about why data is compressed to the left like that.

Wailin

Tzetze wrote: »

DSS applied a temporary stretching curve to give a preview of the stack results.
That wasn't saved in your tiff. If you check out the second vid on that page about the histogram, he explains a bit about why data is compressed to the left like that.

Ah I get you now, so if I save with settings embedded ill get the preview image shown in dss in photoshop. Great stuff i will check out those clips.

Tzetze

Curves are where the magic really happens in PS. Once you're happy with a stretch there's usually plenty more that can be done such as noise reduction, sharpening, gradient removal, etc. Star cores get blown out but their fringes still retain the true colour - this can be blended back into the stars.

There's a set of tools available to help with a lot of this stuff. Highly recommended.

The best thing you can really do for your images though is to use a set of well matched darks, flats and bias for stacking.

If you're feeling adventurous.