What you want is the number of Samples.
A Sample refers to cycles firing a "ray" into the scene and returning information based on the color and other properties of objects it interacts with.
E.g. If a ray bounces off a red object and then hits a light source, the corresponding pixel will get a red color.
Also see Why can't cycles cast ...
You should uncheck the Progressive Refine option (Under the Performance render properties panel) in order to enable and tweak Denoising settings for high quality renders.
Following are the details for this behavior.
Denoising is a post processing pass after the render tiles and layers are finished. It tries to remove fire flies and other noise by utilizing ...
When relying heavily on the denoiser this blurred effect is inevitable, but turning the samples up a little bit from what you were previously using could help. See this 1 sample image:
vs this 6 sample image:
There is a huge difference for only adding 6 samples. What I'm saying is, even if you only added say 50 samples to the final image it could make a ...
All denoise options in Blender are based on different research efforts to speed up path tracing.
Denoising Filter for Cycles
is an implementation exclusively for Cycles by Lucas Stockner during Summer of Code 2016 combining different papers about denoising around 2015:
...this proposal is about having a denoiser right in Cycles - where all the ...
An addition to gandalf3's answer lies also with optimization of the scene's and objects settings. Given the example scene with all diffuse and emission BRDFs you could turn off or limit the bounces of some of the rays being cast. For example, there are no glossy materials then disable the glossy bounces in the Light Paths section of the Render panel. You ...
How to use the Temporal Denoiser
Step 01: Pack Denoising Data
Enable denoising data in View Layer > Passes > Denoising Data
Set file format to OpenEXR Multilayer (so Blender packs the denoising data)
Render your animation
Blender 2.8 needs to be used in the pipeline to pack the denoising data. Simply open your .blend with Blender 2.8, set up ...
When in doubt, use the Image pass.
provides unmodified render result
output also comes denoised by the Internal denoiser if it's enabled
provides a Despeckled image (useful when render has fireflies)
may cause bad shadow artifacts for low sample counts
Denoise node in Blender Manual
How to use Intel denoiser in Blender
Like Cegaton said, it uses the other tiles in the memory. Using that logic, I ran a test, and found that if you reduce the tile size (in the performance pulldown) the image renders using much less. My file was usually around 1.3GB when rendering, but as soon as the denoise kicked in, it shot to 9GB, but I reduced tile size from 512 to 256, and now, the ...
On a similar question, cegaton advised that I place my response here.
I simply stated that I prefer the denoise settings turned down a bit, to minimize it's blur effect; because yes it's useful, but it's best not to overdo it.
The denoiser is a wonderful part of the cycles render process. It runs after the tile has rendered, but during the render process. It takes information about the scene and calculations cycles makes to turn a noisy image into a remarkably smooth render.
Because it is part of the render process it works better then any filter you could throw on the image after ...
For now Intel's OpenImageDenoise is superior to all the other ones. From the release notes:
Compared to the existing denoiser, it works better with more complex materials like glass, and suffers less from splotchy artifacts. It also gives better results with very low numbers of samples, which can be used for quick previews.
It's just a post process so it's ...
Adaptive Sampling min samples is not the actual amount of samples that cycles is using to render the scene.
From the manual:
The minimum number of samples a pixel receives before adaptive
sampling is applied. When set to 0 (default), it is automatically set
to the square root of the total (max) sample count.
So, what is happening in your case, ...
The Denoiser in Blender version 2.79 can be activated per Render Layer, and as such you can mix denoised and noisy footage as you like. If you ever wondered why the Blender Devs have put that Denoiser into the Render Layers context of the Properties Panel, that's why.
All you need to do is separate your scene into Render Layers with the objects in question ...
Everything of the above, but FIRST:
As you stated in your question: you used the default settings:
This will always give you noise, no matter how many samples you render.
If you change the settings (Bounces min/max) to some equal number, render time goes slightly up (sometimes less than 1%!), depending on your scene of course, but you can get a noise free ...
Andrew Price aka. Blenderguru has written a blog post about getting rid of fireflies. There he says:
use bigger light sources.
use bigger shadow sizes
use "multiple importance sampling" if you have HDRs in your scene
use "filter glossy"
check "no caustics"
Of course, some of then will change your scene - but ...
As long as the denoiser in inserted in compositor between render layer and composite node, and "compositing" is checked in post processing tab (as default), every frame of the animation will be automatically processed.
"Optimal value" is quite a subjective measure and depends on available render time compared to desired quality - so it's not possible to generalise to one specific "optimal" value. The impact will also vary based on your particular scene and lighting conditions.
For each 'tile' rendered in the final result, Blender determines the 'noise' ...
The denoiser options are in the Properties Window > Render settings > Sampling > Denoising.
You can choose what kind of denoiser to use.
NLM is the original denoiser (native non-local denoiser), that runs on any computing device.
OpenImageDenoiser is Intel Open Image Denoiser, that runs on CPU
In this section you can enable the viewport denoising ...
Denoisers are an imperfect, but useful tool.
I have this scene where there's light coming in through a window and I've given the room a volume to catch the light. If we run a low amount of samples you can see the fireflies produced.
This is normal, the nature of a volume with lower density is that it will only affect some rays cast from the camera. The ...
There are no practical uses at the moment. It has been suggested that they will be used in compositor denoise setups, perhaps for denoising individual passes (as currently only the combined render is denoised.) However, whatever setup they are intended for has not been developed yet. It will probably happen when the denoiser is finished. So perhaps for 2.8, ...
There is banding in both your pictures. I increased the contrast so you can see clearly on any display:
You remove banding by introducing noise, the process is called dithering:
Rendered image shows visible "line strokes" artefacts
So the denoiser removed the noise making the banding more visible. If you'd save that in 16bit and view on 12bit ...
The Python tooltips are currently a bit broken for property groups, which also affects the commands displayed in the Info area.
The correct command for setting this option for the current view layer is:
bpy.context.view_layer.cycles.denoising_store_passes = True
If you want to refer to the scene and view layer by name:
The default denoise options currently offered in blender (AI, Optix and the original blender denoiser) produce jittering because they do only Spatial Denoising, meaning that they use only one frame for input, so all images are denoised separately. The main problem with this approach is that noise patterns might not be consistent or homogeneous from one frame ...