fasttrack training step 4 and debayer

Stéphane CHABERT

Hi, I took images of NGC 7000 with an OSC Moravian C1x. In the FITS header the bayer pattern is RGGB but when I apply this setting in Pix with Debayer the image appears blue with unlink STF. If I select auto, the pattern is GBRG in the process console but the image appears green. Finally the best setting is BGGR. Is there a logical explanation to this ?

BlockHead

Yes, I think there is a logical explanation.

It all has to do with the starting pixel. If the image has been adjusted in anyway the bayer pattern is shifted and does not start with the correct (Red) pixel at the top left of the image. 

Some software will mirror the image. This would do it. You might also get this effect by removing (or not removing) the overscan region of the image. 

At the end of the day the most important thing is that you discover the pattern itself for your data regardless of what the header says. This is exactly why I demonstrate in FastTrack training going through each of the patterns to discover the answer. I wasn't being a jerk or didactic- I was giving you a real world way to understand how to proceed.

Now I certainly would pursue trying to understand why your first pixel in your image is not the Red pixel. 

However, in terms of processing your image... now that you know it is BGGR you can specify this in WBPP and there will not be an issue.

-the Blockhead