Image Processing

[orac (Charles)]

Hi,
I have a problem that I hope some one can help me with.
I have recently bought a QHY10 camera and have taken an image of NGC253 using also a 190mm Mak Newt,and an orion sky Glo filter.I took 6x5min shots and also 3x5min Darks. When I stacked them in Deep Sky Stacker and processed them in CS3 photoshop the image came up like this. see attached image.The background changes colour from top to bottom ending in a green tinge.Has this got something to do with the bayer matrix in DSS as there is none there for a QHY10 camera so I have tried to use one of the Generic types. I used GBRG with gave me the greenish colour.Has anyone come across something like this before?
Charlie

[RickS (Rick)]

Charles,

Doesn't look like a debayering problem. That would give you wrong colours, but they'd be consistent over the whole frame. What you've got there is an odd gradient. I'd take the filter off for a start and see if that's causing the problem.

There are tools for removing gradients. Gradient Xterminator is one for PS. I use one of the tools in PixInsight. Gradients are quite common and caused by light pollution, imaging with the moon up, sky brightness variations, etc. Yours is a bit more colourful than usual.

Cheers,
Rick.

[orac (Charles)]

Hi Rick,
Thanks for your help, I will try that out and see what happens.
Cheers
Charles

[cventer]

I also use a QHY10 and in DSS you need to set the camera in the fits files tab to Generic RGGB and tick the monochrome 16 bit tiff file checkbbox at the top.

Hope this helps.

[orac (Charles)]

Thanks, I tried the RGGB and it gave a purple tinge down the bottom half, but I hadn't ticked the monochrome box, so I will give that a go also.
Cheers
Charlie