destructive denoiser

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lacilaci
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destructive denoiser

Post by lacilaci » Mon Aug 13, 2018 4:54 pm

Is there a setting, or a way to make denoiser less destructive?
Especially in shadowy areas it completely blurs objects not respecting object edges at all.
This makes denosier useful only for very high quality output to begin with.

Even after 3h rendering and ~370 samples default denoiser settings ruins object details in jars and on the right book edge that is in the shadow. I'd gess for denoiser to not damage the image in the shadows I'd need another 3 hours, at that point I probably don't need denoiser at all.

From what I've seen in corona and I think in cycles too, even at low samples was denoising respecting objects/outlines.
At low samples in luxrender I get denoising somewhere at the level of adobe lightroom noise reduction.
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denoiser.jpg
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Sharlybg
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Re: destructive denoiser

Post by Sharlybg » Mon Aug 13, 2018 4:58 pm

Follow denoising setting tooltips to make it less agressive according to your image . just move your mouse cursor on particular setting without click and wait for the tooltips.
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B.Y.O.B.
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Re: destructive denoiser

Post by B.Y.O.B. » Mon Aug 13, 2018 5:16 pm

Which engine and sampler is this?
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lacilaci
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Re: destructive denoiser

Post by lacilaci » Mon Aug 13, 2018 5:27 pm

B.Y.O.B. wrote:
Mon Aug 13, 2018 5:16 pm
Which engine and sampler is this?
It was cpu path sobol and log power.
Metropolis and random give all very similar results once the image gets close to be "clean"

@Sharlybg yeah well. I managed to make denoiser less agressive but it kinda still looks bad and objects in shadows are a big bad blur unles the rendering progresses to near clean image, kinda defeating the purpose of using denoiser.

Even in simple cases I get details from textures and whole object boundaries lost.

lacilaci
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Re: destructive denoiser

Post by lacilaci » Tue Aug 14, 2018 5:18 am

I'm gonna do some comparisons, but first. Just to illustrate how "good denoising" can you get with simple luminance noise reduction in lightroom vs default luxcore denoiser which eats a ton of memory and can only denoise properly clean areas of the image.

BTW the only areas where denoiser did a small bit better job were the trees, which were mostly clean without denoising. I'm gonna try some tweaking on settings to see if it can be made useful and then some comparisons.
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lr_denosier.jpg

lacilaci
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Re: destructive denoiser

Post by lacilaci » Tue Aug 14, 2018 6:21 am

Alright, so here is some comparison.

First, both clearly would need more samples, but for different reasons.
In a first glance it might appear that luxcore did better job at denoising.
But it's actually worse.

Cycles has by default small denoising patches, which is good for a less noisy result, but in this case with the same amount of samples just increasing denoising radius I get pretty good result and with just a little more samples I get nice and clean output. I can do that because somehow cycles denoiser knows not to blur objects together. So without clear definition of edges and faces in rendering I still can get them clear after denoising.

On other hand, the problem with luxcore is that to not blur objects themselves I need to have enough samples in shadowy areas that the edges of objects are very clear, otherwise all the details will get lost.

So the question is, can this be fixed? Can we get the luxcore denoiser to not blur all the object details themselves?
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luxcore_cycles_denoising.jpg

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FarbigeWelt
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Re: destructive denoiser

Post by FarbigeWelt » Tue Aug 14, 2018 6:34 am

lacilaci wrote:
Tue Aug 14, 2018 5:18 am
I'm gonna do some comparisons, but first. Just to illustrate how "good denoising" can you get with simple luminance noise reduction in lightroom vs default luxcore denoiser which eats a ton of memory and can only denoise properly clean areas of the image.

BTW the only areas where denoiser did a small bit better job were the trees, which were mostly clean without denoising. I'm gonna try some tweaking on settings to see if it can be made useful and then some comparisons.
Comparison of denoiser settings might be easier if you look at the denoiser layer in blender‘s compositor. You have to enable nodes. There are also some nice filter nodes or color correction nodes available. Unfortunable the compositor processes layers after render is finished, means there is no update during rendering, what makes sense for some nodes because they take minutes to be executed.

I failed finding good settings for denoiser for my pictures. Clipping was often more appropriate and surely faster. But I was not looking much at shadows. They are difficult any way due of lacking amounts of rays they get. Random sampler could be a solution. On the other hand if you take a picture with a camera you get noise in the shadows too or the camera‘s algorithm supresses them together with details. It is a real world case your chasing. Photographer work with many lights to get better looking images. Add some lights to your scene.
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lacilaci
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Re: destructive denoiser

Post by lacilaci » Tue Aug 14, 2018 6:41 am

FarbigeWelt wrote:
Tue Aug 14, 2018 6:34 am
On the other hand if you take a picture with a camera you get noise in the shadows too or the camera‘s algorithm supresses them together with details. It is a real world case your chasing. Photographer work with many lights to get better looking images. Add some lights to your scene.
That's not a solution.
You're basicaly telling me denoiser is useless, since you found no good setting and in photography you get loss of detail anyway :D.

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B.Y.O.B.
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Re: destructive denoiser

Post by B.Y.O.B. » Tue Aug 14, 2018 9:23 am

I guess all these images have been rendered with adaptive sampling?
It might be that the adaptive sampler considered the darker parts of the image to be finished and spent less samples there.
Can you try with random sampler and adaptive amount set to 0%?
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lacilaci
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Re: destructive denoiser

Post by lacilaci » Tue Aug 14, 2018 9:52 am

B.Y.O.B. wrote:
Tue Aug 14, 2018 9:23 am
I guess all these images have been rendered with adaptive sampling?
It might be that the adaptive sampler considered the darker parts of the image to be finished and spent less samples there.
Can you try with random sampler and adaptive amount set to 0%?
Well, at least in the test case it makes no difference at all. But I wasn't talking about luxcore rendering performance anyways.

I'm talking about denoiser performance/quality where it destroys image unless it's almost clean, and if the image is almost clean then even adobe lightroom does good or even better job on denoising.
On other hand cycles for example keeps object edges and box corners in place even though there is almost no visible detail in that place.

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