Denoiser clamps render

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Egert_Kanep
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Denoiser clamps render

Post by Egert_Kanep » Mon May 28, 2018 9:27 pm

It seems like denoiser clamps bright parts of my images, I rendered image in 16 bit and used mostly area lights. When I used HDR image, it was working fine. Also sometimes denoiser doesn't start so I have to re render my image again.
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denoiser_problem.PNG

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Dade
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Re: Denoiser clamps render

Post by Dade » Mon May 28, 2018 10:17 pm

Egert_Kanep wrote:
Mon May 28, 2018 9:27 pm
It seems like denoiser clamps bright parts of my images, I rendered image in 16 bit and used mostly area lights. When I used HDR image, it was working fine. Also sometimes denoiser doesn't start so I have to re render my image again.
What do you mean with "rendered image in 16 bit" ? How many samples per pixel did you use ?

I don't notice any evident clamping in the attached image :?:
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Sharlybg
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Re: Denoiser clamps render

Post by Sharlybg » Mon May 28, 2018 11:30 pm

I don't notice any evident clamping in the attached image
In the image at the right you can see bright light comming beneath.

Maybe it is caused by anti spike option in denoiser ?
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B.Y.O.B.
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Re: Denoiser clamps render

Post by B.Y.O.B. » Tue May 29, 2018 7:36 am

Egert_Kanep wrote:
Mon May 28, 2018 9:27 pm
Also sometimes denoiser doesn't start so I have to re render my image again.
I have looked into this problem and I think I fixed it.
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Egert_Kanep
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Re: Denoiser clamps render

Post by Egert_Kanep » Thu Jun 14, 2018 4:49 pm

Another example of denoiser calmping render. Denoiser doesn't leave any values over 1 and therefore all information in highlights is lost, even if the values don't go over 1, its still destroys that information. It seems like denoiser outputs 8 bit image, not 16 bit float. In attached example on upper row I gained down images to see how they respond. As seen, all highlight info on denoised image is lost and bright parts appear flat, whereas info on raw render is still there. Also sometimes these rgb squares appear on denoised render, but only when using region. Just a side question, why deos denoiser kill alpha, I know I can use original image alpha, but wouldn't it be cleaner if denoised image already had correct alpha?
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denoiser_clamp.png

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Re: Denoiser clamps render

Post by B.Y.O.B. » Thu Jun 14, 2018 8:07 pm

I can reproduce this.
In my particular scene, the effect is very strong with the Tile Path CPU engine, and rather weak with Path CPU (see the images here for Path CPU results).

The scene is attached.
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smoke_backlit_denoiser_clamping_bug.bcf
(2.82 MiB) Downloaded 28 times
scrn_2018-06-14_21-59-56.png
Tile Path CPU
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Dade
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Re: Denoiser clamps render

Post by Dade » Mon Oct 01, 2018 2:36 pm

B.Y.O.B. wrote:
Thu Jun 14, 2018 8:07 pm
I can reproduce this.
Nope, the problem you are observing is expected because the BCD warmup period end before all tiles have been rendered. To fix the problem, you can decrease the TILPATH AA parameter to 1. At the moment, the end of BCD denoiser is hard coded at "<total samples count> / <total film pixel count> > 2.0". Indeed, it could be exposed as parameter so you can increase the warmup instead of reducing the AA. However, with BCD, is probably better to have AA=1 anyway in order to collect more accurate BCD statistics during the rendering.

So, to recap, I'm still unable to reproduce the problem, can someone provide a scene showing the bug ?
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Re: Denoiser clamps render

Post by B.Y.O.B. » Mon Oct 01, 2018 3:20 pm

I have pushed a commit to the addon that forces the AA samples to be set to 1 if the denoiser is enabled.
https://github.com/LuxCoreRender/BlendL ... 39b94c445e
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Re: Denoiser clamps render

Post by B.Y.O.B. » Mon Oct 01, 2018 9:13 pm

Egert_Kanep wrote:
Mon May 28, 2018 9:27 pm
It seems like denoiser clamps bright parts of my images, I rendered image in 16 bit and used mostly area lights. When I used HDR image, it was working fine. Also sometimes denoiser doesn't start so I have to re render my image again.
Egert Kanep, can you upload this scene that shows the problem? It would be a great help.
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Re: Denoiser clamps render

Post by Dez! » Tue Oct 02, 2018 4:29 am

https://mega.nz/#!sgQHCKgY!A7OcgHh7zsUW ... vHNu_rBD2M

In this scene (project), if you remove the World - there will be an error of a denoiser
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