Help with debayering

[Helo (Peter)]

I just received an Atik 428EX colour ccd and had my 1st cloud free night tonight and captured an image with a Hyperstar (10 x 1 sec) and C11 but the image is yellow/green? I tried other offsets in Maxim DL (this was 0/0 but 1/0 or 0/1 appear whiter but pixelated like missing colour data and 1/1 is blue!). Any tips in settings for either capturing or colour conversion would be greatly appreciated.

[mithrandir (Andrew)]

Originally Posted by Helo

I just received an Atik 428EX colour ccd and had my 1st cloud free night tonight and captured an image with a Hyperstar (10 x 1 sec) and C11 but the image is yellow/green? I tried other offsets in Maxim DL (this was 0/0 but 1/0 or 0/1 appear whiter but pixelated like missing colour data and 1/1 is blue!). Any tips in settings for either capturing or colour conversion would be greatly appreciated.

In what order were you doing your processing? Any darks/flats/bias frames must be done first, followed by debayer, before doing any stacking/rotation. Get this wrong and you'll never get the colour right.

Your colour cast is probably from light pollution, especially with yellow sodium vapour street lights.

[Gem (Grant)]

Hi Peter,

I have an ATIK 320E and had similar debayering issues. Originally I was using Artermis Capture and DSS.
I have now switched to Astroart and have great colour. ATIK states that it is supported when working with Astroart and Maxim (but nothing is said about DSS). I see you are using Maxim - so it should work... But my wife is one doing the processing, but a quick check in the settings shows that she used 0 1 RGB
I hope that helps. I spent a long time getting frustrated with debayering until recently.

As random examples:
NGC 104 done in my pre-AstroArt days and NGC 3372 (Eta carina) with astroart.

[Helo (Peter)]

Hi Andrew and Grant,

This image was no darks, flats, etc. yet as I have not been home when the sky is clear for a flat (sunny SE Qld??) and Hyperstars and this ccd are suggested no darks required for such short exposures. I do not have too many streetlights around where I am however I managed a M42 last night and some trees in the evening and the same issue with the wrong colours or a yellow/green cast. I tried 0/0, 0/1, 1/0, and 1/1 offsets in Maxim DL but the colour looks wrong in all of them. I have seen some other comments on other sites of similar debayering issues with Atik cameras which may mean a change in software (perhaps Astroart as Grant suggests?) but was hoping I can resolve it with one of the several softwares I already have. Dawn came with the Atik camera but it also did not seem to produce a correct colour rendition (lovely clear images but dodgy colour). It seems that it can be done and the results I have seen from others are very exciting, so hopefully I get it sorted soon.

Thanks

Peter

Originally Posted by mithrandir

In what order were you doing your processing? Any darks/flats/bias frames must be done first, followed by debayer, before doing any stacking/rotation. Get this wrong and you'll never get the colour right.

Your colour cast is probably from light pollution, especially with yellow sodium vapour street lights.

[Gem (Grant)]

I believe AstroArt has a demo version... maybe try the demo and see if it helps.

[Gem (Grant)]

Also, does the image look to be in colour when you are originally capturing it? On ArtemisCapture (which comes with ATIK cameras), my original images are clearly in colour - which made me think of changing software from DSS to AstroArt.

[Helo (Peter)]

Hi Grant and Andrew. Grant, if you get colour in Artemis you have to select Colour - Advanced - RAW (make sure colour is not checked). Then debayer after. Dawn is not intuitive so I watched the video on the CD and used their existing template to Debayer, Align and Stack and it worked fine. I still have a yellow/green cast on some more recent images of M42 and the Trifid nebula so I am thinking Andrew was right (sorry for not listening the 1st time Andrew - once I saw images with more colour in like M20 it was more apparent). Thank you both for your help - I am thinking a filter is now in order for the Hyperstar.