Where did all my colour go? - Woes of OSC CCD

[russp]

Having got and processed with reasonable success a few pictures with a dslr I got a while back an Atik 314L+ colour camera and still haven't managed to get anything from the data - I'd always blamed poor flats or lack of darks or something so last week I set about getting a full set of data and calibration data. I use Sequence Generator Pro for data aquisition. Got 30 Bias, 30 Flats, 11 darks and 18 lights (latter two at 1x1 bin 10minutes exposures -20degC camera temp) - (125mm refractor with 0.63 reducer if thats relevant)

Load everything up in PI batch preprocessing - I've tried all the different debayer patterns RGGB and BGGR give reasonable results that don't look much different. Other patterns seem to produce wierd background colours - the ticking or unticking of the upFIt box seems to make little difference although I suspect it should and I have no idea which option applies to my setup I'd guess it should be the amateur one.

Well I get a decent image out at the end - plenty of detail of the galaxy when STF autostretch is applied but there is no colour - nil - not in the galaxy or any of the stars, surely there should be something? I'm sure it wasn't like that when I processed the dslr pictures .. so where the hell has my colour gone. This is pretty much what happened with my previous attempts too. Getting to the point where the CCD could well end up thrown in the hedge and the dslr attached again .. Please I need help!!!

[russp]

If anyone is interested all the files are shareable from my google drive - https://drive.google.com/folderview?id=0B7-WT0lTBlOtVmV1OXM4bExsaEU&usp=sharing hopefully the folder names should be obvious enough.

[Don]

Hello russp,

The bayer matrix in the ATIK 314L+ should be RGGB from what I have read, but it is not in these images.  It looks like there is an extra row of pixels at the top, which makes the pattern GBRG.  If you use the Crop process to remove the top row of pixels, then debayer with RGGB, the images look right.  The sky background has a strong blue cast (maybe due to an LP filter?), but the color balance comes out OK when STF is applied without linking the channels after debayering with GBRG. 

I did a quick manual pre-processing (calibrate, debayer, register, integrate) followed by DynamicCrop, DBE, MLT, HistogramTransformation and CurvesTransformation with mask to increase saturation.  I used GBRG in the BatchDebayer script.  The result shows a pretty normal color balance for this object.  More data would be needed if you want to enhance the colors more, and maybe losing the LP filter if you used one.

Cheers,

Don

[msmythers]

Russp,

There is plenty of color in your image. I used GRBG for the debayer. Here is your image using 13 of the 18 light subs. I threw out some of the extremes in brightness. I also did not use any of the calibration files because I was interested only in seeing if the lights had any problems. Nothing special about the processing. ABE,BN,CC,MaskedStretch,Curves,ACDNR, ColorSaturation(StarMask and RangeMask),SCNR.



Mike

[russp]

Thank you so much for taking the time to look at this for me - along with replies on stargazers lounge I now have a lot to work with - http://stargazerslounge.com/topic/243342-where-did-all-my-colour-go-woes-of-osc-ccd/

I'd definitely read matrix should be RGGB but it appears not - from the thread above matrix should be GRBG as you surmise! No LP pollution filter on these subs, will have to look into that blue cast but at least now I can move forward with some degree of confidence - Nothing more dispiriting than not even getting the first step right and not knowing why. Will let you know how I get on (or more likely be on for more help!).

Thanks again - it really is appreciated

[pfile]

the issue with the bayer matrix could be because the fits file is being read in the opposite direction it was written.

RG
GB

when you read that from top to bottom, it's RGGB. but when read from bottom to top, it's GBRG. of course if the fits reader direction is backward your image will come out mirrored horizontally from the way it should look, so you should be able to tell if this is the problem.

rob

[russp]

Taking in all that was said I managed the following two different results with PI - not sure which I like best and I'm sure they could be a lot better but it's a start and I'm quite pleased with them