Artifacts in Lumix G9 hi-res files in Darktable 4.2.1

[Newerth (Jan Šmucr)]

Friends,

I’ve got myself the Lumix G9 and tried out the 80 Mpx high resolution mode.

RW2 raw file (I was unable to upload it here)

DT almost got it right. Almost.

P1281992.RW2.xmp (7.8 KB)

An artifact appears on the right side of the image in both the render and the darkroom.

The GPU is Intel UHD Graphics 620. It does not matter whether I keep the OpenCL on or not.

Could you please try it out if it works for you?
Thank you.

Also: https://www.dpreview.com/forums/thread/4434494

[kmilos]

It is possible that the crop as defined in cameras.xml for the high-res mode is not 100% correct. You can adjust the crop manually by enabling the hidden and disabled option plugins/darkroom/rawprepare/allow_editing_crop=false in your darktablerc file, and then use the new crop sliders in the “raw black&white point” module after restart.

Btw, can you reproduce the same w/ the high-res G9 sample from https://raw.pixls.us/?

[Newerth (Jan Šmucr)]

The samples render the same:

Also, does this have anything to do with the issue?

[kmilos]

Yes, that shows that the image was cropped from the sensor width of 10480 to 10422, and that is not enough. You’ll see this when you enable that hidden option.

My guess is that this crop of 58px was only verified for the normal mode, not for hi-res… In cameras.xml, only this is defined for the G9:

<Crop x="0" y="0" width="-58" height="0"/>

Which works for the normal mode (5264 sensor width). Funnily, the single 20MP shot from the hi-res mode has a width of 5280?! so cropping 74 works instead. And it looks like the same 74 also works for the hi-res mode.

Even more strangely, there is this “burst mode” on G9 where the width is ok, but there are artifacts on the top and bottom.

Go figure…

Btw, it looks like there is already an open issue about this: Panasonic DC-G9 high-res RAW: insufficient crop · Issue #170 · darktable-org/rawspeed · GitHub

[Newerth (Jan Šmucr)]

There’s more I don’t understand. The EXIF info reveals more crop details:
https://raw.pixls.us/getfile.php/2584/exif/P1000475.RW2.exif.txt

Exif.PanasonicRaw.SensorWidth                 10480
Exif.PanasonicRaw.SensorHeight                7794
Exif.PanasonicRaw.SensorTopBorder             10
Exif.PanasonicRaw.SensorLeftBorder            18
Exif.PanasonicRaw.ImageHeight                 7786
Exif.PanasonicRaw.ImageWidth                  10386

Ah, I missed the GitHub issue. Thank you.

[kmilos]

RawSpeed doesn’t use metadata crop, it tries to extract maximum amount of raw data by manual inspection and tweaking for every camera.

[Newerth (Jan Šmucr)]

Okay, thank you very much, @kmilos. I had no idea it worked like this.

[bernyemm (Berny Marsden)]

I get the same magenta fringe.

[kofa (István Kovács)]

This (wrong clipping) affects more Panasonic cameras, e.g. my LX7 (not related to high-res).

Panasonic LX7 garbage pixels

[bernyemm (Berny Marsden)]

Three instances of exposure module with drawn & parametric masks gave this result.