Failed to open file: Singular matrix

[LeoWelter]

In installed rawrefinery on Debian 13. CPU only

steps:
create venv, install pytorch
checkout source
pip install .
run rawrefinery
open dir with uncompressed NEFs from Nikon Z6iii
try to load a file gives : Failed to open file: Singular matrix #17

is it the NEF giving issues?

[LeoWelter]

just to confirm, it seems to be the NEFs, although they open and edit fine in Darktable. I can open my old D700 NEFs

[rymuelle]

I've replicated the results. It doesn't seem to be universal to NEF, and I also had the same issue with a CR3.

What's happening is that the color change matrix is being saved as all zeros by the dngwriter. I'm not 100% sure why that is, but it's a priority bug and hopefully has a simple fix.

Thanks for reporting.

[LeoWelter]

yes indeed. I thought to be clever and convert the files to DNG with the Adobe Raw Converter (via wine on linux), but that results in the same error

[kap5535]

As far as Nikon NEF files - this problem seems to only involve Nikon Z mount (mirrorless) cameras. Nikon F mount (DSLR) cameras do not have the problem. I have confirmed this with several different models of Nikon cameras.

[kap5535]

An update to the issue with Nikon NEF files.

The problem is not related to all Nikon Z mount cameras - only models that do not allow images to be saved as uncompressed RAW files. I have a couple of cameras that insist on using lossless compression (Z50_2 and Z6_3) that give the "Failed to open file: Singular matrix" error message. I also have a Z7_2 that does allows saving of uncompressed RAW files and they can be denoised using RawRefinery. I also noticed that exif info is now being written to the output DNG file.

Edit - Apparently the Z50_2 does have an uncompressed RAW setting - but the default camera setting is lossless compression. If that setting is changed to lossless compressiong RawRefinery should work. I not longer have that camera so am unable to check. I do have Z6_3 and can confirm that saving uncompressed files is not possible and that seems to be what is causing the problem with RawRefinery.

[LeoWelter]

Thanks for looking into it. Unfortunately I have the Z6iii indeed, it only supports lossless compressed NEF or HE NEF, with the latter using a patented mechanism.

However, Both rawspeed and libraw do support compressed NEFs.
https://github.com/darktable-org/rawspeed/blob/develop/src/librawspeed/decompressors/NikonDecompressor.cpp
https://github.com/LibRaw/

maybe borrow the implementation from them?

[kap5535]

I think there must be a way to makes things work because Z6_3 images can be processed in most (if not all) commercial and FOSS software. I believe you are correct that borrowing the implementation from either rawspeed or libraw would work.