Canon PowerShot G1 not decoded properly

[Thanatomanic]

Original report: https://discuss.pixls.us/t/old-canon-g1-crw-problem/19168 Related issue: https://github.com/Beep6581/RawTherapee/issues/882 Problematic image: 102-0269_CRW.zip Reference image from raw.pixls.us: https://raw.pixls.us/getfile.php/2073/nice/Canon%20-%20PowerShot%20G1%20-%20RAW%20(4:3).crw

The earliest version of RT I could test this with was 5.6 (older won't compile), and I get this when I view the sensor pattern:

The reference image looks a bit better:

But in both cases the decoding is wrong. The Bayer pattern doesn't seem to get recognized properly.

[Floessie]

I've built it down to 5.0-gtk3 and it's wrongly decoded in every version. The "CA correction supports only RGB Colour filter arrays" warnings start with 5.1.

[heckflosse]

It's an GMCY camera, not an RGB camera. We should fix the crashes with some demosaicers (VNG4, LMMSE) though...

[TJFOE]

https://discuss.pixls.us/t/for-bored-developers-canon-powershot-g1/1239

[heckflosse]

@Thanatomanic Do you plan to support this files in RT 6.0 or do you mean, the crashes with this files using LMMSE and IGV demosaicers should be fixed for RT 6.0?

[Thanatomanic]

Now that I think of it, this issue is actually not very helpful and only part of a bigger problem.

1. We should discuss and decide to support other CFA's or not (a new issue could list all currently unsupported types and corresponding camera's for future reference). This requires serious work, hence the milestone 6.0. Side note: darktable has been able to do it for a long time.
2. In the meanwhile, unsupported CFA's should be handled gracefully. This could be for 5.9. Also, best discussed in a separate issue.

Thoughts?

[heckflosse]

At least, I will try to fix the crashes with this files and some demoaicers for 5.9