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Tom94 / tev

High dynamic range (HDR) image viewer for graphics people
BSD 3-Clause "New" or "Revised" License
1.02k stars 86 forks source link

Difference alpha/non-alpha images #198

Closed beltegeuse closed 1 year ago

beltegeuse commented 1 year ago

Hi Thomas,

I am not sure that the behavior is intentional, but the difference between the same OpenEXR image with and without an alpha channel does not work. Denying computing the difference between images with different numbers of channels is a very reasonable approach.

However, by default, saving an OpenEXR image from tev automatically creates an alpha channel, which can break the difference computation when the image is reopened later.

Is it possible to fix one of this behavior (saving or difference computation)? For example, I am unsure if fixing the OpenEXR saving can have a side effect.

Best, Adrien

Tom94 commented 1 year ago

Hi Adrien, yeah, tev should be able to compare images with mismatched channels — it used to be supported in a hacky way, which seems to have broken at some point in the past year.

Could you check the linked PR for whether it fixes your use case? Mismatched top-level channels should now gracefully compare.

Things will still not work if the mismatched channels are situated in mismatched layers, which I plan to address in a future PR.

beltegeuse commented 1 year ago

Hi Thomas,

Yes the changes works perfectly! Thanks for your rapid response.

Best, Adrien