# OptiX Denoiser#

To denoise final renders, Clarisse provides a special image operator called Optix Denoiser which runs exclusively on NVIDIA GPUs. If you plan to render your images over a render-farm without NVIDIA GPUs, the image filter is going to fail. We recommend you instead to disable this filter and use CDenoise command line tool on the rendered EXR image sequence.

Note

It is highly recommended to set the Anti Aliasing Filter Mode attribute of the raytracer to Importance Filter otherwise, neighbor pixels noise interferes with the quality of the denoiser.

The filter can be added as an Image Filter or as an Image Node.

To add the image filter just select the layer scene you wish to denoise and using the Attribute Editor under Filters attribute, choose Add > Optix Denoiser.

To add the image node using the node based compositing, press Tab in the Build View and choose Image Node Optix Denoiser

The denoiser comes with several options to control the behavior and quality of the denoiser:

Attribute Description
Strength Control the strength of the denoiser output. It basically performs an over operation from the denoised output over the input image. When set to 100% you get the full output from the denoise image. When set to 0% you get the original input image.
Use Albedo Use the albedo AOV to guide the denoiser to improve the results. Note that sometimes this can introduce some artifacts leading to an image degradation.
Use Normal Use the camera_normal AOV to guide even further the denoiser. Note that you can only enable normals if the Raw Color is enabled.
Albedo AOV Choose the name of the image buffer you wish to use as albedo
Normal AOV Choose the name of the image buffer you wish to used as normal

By default, the albedo and the camera_normal AOVs are not automatically added to the image. You must output albedo and camera_normal from your renders using the AOV Editor. These extra AOVs generally help the denoiser to improve the quality of the denoised output.

However, in some cases, these AOVs can degrade the quality of the denoised output so uncheck them to see if the result is improved. We recommend to first uncheck Use Normals and then Use Albedo.