raw overexposed check in lighttable

Software darktable
1

Is there a way to check raw overexposure in the lighttable?

I can see the button for focus peaking, but not toggling raw overexposed.

Using Darktable 4.9.0+1266~gb126153c3d-dirty (today’s master).

(EDIT fixed title, thanks @kofa)

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2

This would be good

3

I agree it would be useful.

But there is no way to do that currently:
Indicating raw over-exposure requires reading the raw file (no, really? :slight_smile: ).
Darktable doesn’t read raw files every time they are shown in the light table, it uses the cached thumbnails (except the first time an image is shown, or when the cache has been emptied). And to create those it can use the preview images from the raw file (much faster than handling the raw data)

Showing raw overexposure on demand would mean :

  • either re-reading the raw file every time it is shown, which would slow down the program a lot (just watch the screen after importing a series of new images).
  • or generate overlay thumbnails, and use those. But that would require adding the infrastructure to handle parallel series of thumbnails, and pick the right one/combine the two on demand (and it would increase the disk space used for the cache).

Focus peaking can be done on the thumbnails, so doesn’t have to read the raws every time.
(hint: activating focus peaking doesn’t cause any disk activity)

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4

Thanks, I thought this was a feature that I just could not enable, but not it is clear that it is missing.

BTW, where do I find the utilities modules / raw overexposure in the darkroom? I know I can toggle this feature with shift + o, but I would like to see the module. It is not in the left or right pane, and I don’t have the button either to toggle it on screen. Maybe somehow I disabled this, but I don’t know how to get it back.

5

It on the bottom panel. Ctrl + Shift + B, if memory serves me well. It cycles through a few modes, so you may have to press it several times. (That blob is supposed to be the head of an arrow…)
image

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Got it back. thanks!

7

There is an app from LibRaw, FastRawViewer, which reads raw files very quickly and allows you to check raw overexposure. I use it for culling and filtering large numbers of images. I think it costs less than 25 $.

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8

I agree this would be a nice option. The lack of it in the lighttable view means I have chosen to do my culling in the darkroom view as I do a lot of bracketed exposures and I wish to delete the images with clipped highlights.

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9

Thinking about this a bit: one could store a low-resolution bitmap for the clipped pixels, which I imagine would compress extremely well.

Parallel infrastructure could be avoided by using a container other than jpeg, that could store the low-res preview image, the compressed bitmap above, and other future extensions. As tooling for JPEG XL evolves, it may make sense to switch to that anyway.

(This is just brainstorming, I am aware that the bottleneck is developer time, not ideas :wink:)