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I recently got a new OSC camera (ZWO ASI 2600 MC) and found when using a dual narrow band filter that images displayed with Debayer Preview on have a lurid pink background instead of gray/black . I don't remember this with my prior camera (ZWO ASI 071 MC), but maybe I'm not remembering correctly. Both are RGGB with the major difference being the size of pixel array and file (larger in 2600).
Images from the 2600 display with correct color balance using ASI Fits Viewer, and in PixInsight (in the latter RGB channels must be unlinked). Does SharpCap display RGB images with the channels linked? Is it possible to unlink the channels in SharpCap? Am I missing something obvious?
for 'normal' colours, Debayer Preview should be set to 'On' (there are various force options in case ON picks the wrong pattern, but those should not be necessary for ZWO cameras). Also make sure the white balance controls are set the the defaults of 50,50 .
Setting a 'flip' option other than none can affect the pattern, but SharpCap should auto-correct for that for ZWO camers. Best to try None anyway.
A good way to check the pattern is to shine a red torch onto the sensor - if it shows up as red then the pattern is correct. If it shows up as green or blue then it is set wrongly.
Probably nothing wrong - modern cameras are often more sensitive to green light than other cameras and can produce a green tinted image. Depending on the brand of camera you have, there may be white balance controls on the right hand side that you can adjust to correct this. Alternatively, many people do not try to adjust out the green while capturing, instead they do it when processing the images.
The (land based) image was captured using an Altair 183C. FITS entries are ROWORDER=TOP-DOWN and BAYERPAT=RGGB. The images show before & after processing. The 'before' (processing) show the green caste and the 'after' (processing) are an accurate representation of the colours I can see. The processing examples used:
PixInsight - Process > NoiseReduction > SCNR
Siril - Image Processing > Remove Green Noise
GIMP - Colors > Curves & select green channel
Dave
PixInsight_before-after.JPG (98.19 KiB) Viewed 6699 times
Siril-before-after.JPG (101.73 KiB) Viewed 6699 times
GIMP-remove-green-hue.JPG (80.53 KiB) Viewed 6699 times
I too am confused by the debayer preview. Viewing Jupiter last night it was displayed with a green tinge (using an Altair 290 C). I tried the various ‘force’ debayer options, but they too only displayed green or magenta, so i set it back to auto. Isn’t the preview supposed to show true colours? Am I missing something?
most modern cameras are considerably more sensitive to green light than to red and blue, so without processing the image from the camera tends to have a green hue. On a mobile phone camera, or a DSLR or compact camera, the camera will adjust for this internally in its software and you see a 'normal colour' image. For these astro cameras, you get the raw data that comes straight from the sensor - green tinge and all. My preferred option is to not worry about this - capture with the green colour cast and fix the colours in post-processing (after stacking, etc).
Thanks for the reply, Robin and happy New Year to you. I’m not worried about it exactly, it’s just that, as it said preview, I kind of expected it to show true colours. As you say, once I’ve loaded my files into other programs I can get rid of the green tinge.
. I don't remember this with my prior camera (ZWO ASI 071 MC), but maybe I'm not remembering correctly. Both are RGGB with the major difference being the size of pixel array and file (larger in 2600).
