Author Topic: Canon CR2 images are blue with ScreenTransferFunction  (Read 277 times)

Offline star gazer

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Canon CR2 images are blue with ScreenTransferFunction
« on: 2019 September 06 11:19:57 »
When I open my Canon 7D Raw images and then user the ScreenTransferFunction's nuclear button. The image is displayed as sky blue. I don't think this is quite right. I think there is a setting for how the bayer colour matrix is interpreted, but I may be wrong. I think there is an option to configure the RGBR sequencing when the file is processed. Can someone put my out of my misery.

Many thanks


Offline pfile

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Re: Canon CR2 images are blue with ScreenTransferFunction
« Reply #2 on: 2019 September 06 12:23:14 »
right, you can also just unlink the channels in the STF process to get a preview of how it should look after background neutralization/color calibration.

although, the images usually look green rather than blue (unless you're using a CLS filter or similar), which leaves open the possibility that the debayer settings are wrong...

rob

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Re: Canon CR2 images are blue with ScreenTransferFunction
« Reply #3 on: 2019 September 08 10:19:09 »
Hi Rob,

I am using an IDAS LPS-P2 filter in my set-up. Would that distort the colours? If I change the RGBR sequencing, do you know what I should change it to?

Thanks for your help

Tim

Offline pfile

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Re: Canon CR2 images are blue with ScreenTransferFunction
« Reply #4 on: 2019 September 08 11:10:37 »
yeah the IDAS will give you a blue cast, maybe not as turquoise as a CLS but still blue/purple.

so probably you have the right debayer settings. when using CR2 files there's really no ambiguity to the bayer pattern - it's when you are using FITS files that the capturing application may be writing the FITS file upside-down with respect to how PI is reading it. you can change the fits reader direction in PI (double click format explorer -> FITS to set it 'permanently'), pass up-bottom or bottom-up file hints to ImageCalibration to temporarily override what's in the format explorer. anyway since you are using CR2 files you should not have to worry about that.

but i think canon cameras are RGGB? there are 2 green pixels, not 2 red pixels.

rob