Denoiser

The V-Ray Denoiser takes an existing render and applies a denoising operation to it after the image is completely rendered out via normal means. The denoising operation detects areas where noise is present and smooths them out.

Because the V-Ray Denoiser operates on other render elements rather than being part of the rendering process itself, the denoising operation does not require rerendering of the scene. The Denoiser settings can be quickly changed and tested over and over to improve the result.

Denoiser – Activates V-Ray Denoiser channel.

Engine – Allows choosing between the Default V-Ray Denoiser and the NVidia Al Denoiser.

Each offers a different denoising algorithm that comes with different benefits.

Default V-Ray denoiser - V-Ray's denoising algorithm. It can utilize the CPU or the GPU (AMD or NVIDIA GPUs) to perform the denoising. It is consistent when denoising render elements, as it applies the same denoising operator to all render channels. This means that it is recommended for denoising the render elements to be used for compositing back the beauty image.

NVIDIA AI denoiser - V-Ray's integration of NVIDIA's AI-based denoising algorithm. The NVIDIA AI denoiser requires an NVIDIA GPU to work, regardless of whether the actual rendering was performed on the CPU or GPU. This means that rendering on the CPU will still require an NVIDIA GPU for denoising with the NVIDIA AI denoiser and has some advantages and drawbacks compared to the Default V-Ray Denoiser. For example, the NVIDIA AI denoiser performs the denoising faster, but is not consistent when denoising render elements. This means that there will be differences between the original RGB image and the one reconstructed from render elements that are denoised with the NVIDIA AI denoiser.

Mode – Specifies how the results of the Denoiser will be saved.

Only generate render elements – All render elements required for denoising will be generated, but a denoised version of the image will not be computed, and the VRayDenoiser render element will not be present.
Hide denoiser result channel – The VRayDenoiser channel is not present separately in the VFB. The effectsResult channel is generated with the denoised image.
Show denoiser result channel – The VRayDenoiser and effectsResult channels are generated.

 Preset – Provides presets that automatically set strength and radius values.

Mild – Applies a more subtle level of denoising than the Default preset. 
Default – Applies default denoising. 
Strong – Applies a stronger level of denoising than the Default preset. 
Custom – Allows the strength and radius parameters to be set to custom values.

Strength – Determines how strong the denoising operation will be. This parameter is available only when Preset is set to Custom.

Radius – Specifies the area around each pixel to be denoised. A smaller radius will affect a smaller range of pixels while a larger radius will affect a larger range, which will increase the noise removal.

Use GPU – When enabled, uses the GPU version of the denoiser, if possible.

Progressive Update Rate – Specifies the regularity of updates during the progressive rendering. This value is roughly the percentage of the time denoising is allowed to take compared to total render time. A value of 0 disables updates during the progressive rendering, while larger values cause the denoiser to be updated more frequently. A value of 100 will cause updates as often as possible. Values ranging from 5 to 10 are usually sufficient.