While some RenderMan plugins integrate the Denoise feature, RenderMan does ship with a tool for processing images after rendering. Keep in mind that the appropriate AOVs must be included for the Denoise filter to work.
Denoise can attempt to use GPU acceleration. You can activate this mode by adding
--override gpuIndex 0 to the command line, where the number indicates which GPU to use. In a single-GPU system, this will always be 0. If no compatible hardware is found it will failover to CPUs. Using the GPU requires CUDA 7.0 (compute capability 2.0 or later) and a capable graphics card with support.
Enabling GPU Denoise
Globally you can enable the GPU features by changing the .json file here: $RMANTREE/lib/denoise/default.filter.json
-o name Outputs to shotCam_name.exr instead of shotCam_filtered.exr -n Output basename is based on variance image rather than to-be-filtered image --outdir dir Outputs to this directory instead of the input file's directory --filtervariance If a mix of variance and non-variance files are specified, output includes filtered version of variance's color channels too --crossframe Cross-frame sequence mode: filters across frames --skipfirst, -F Doesn't output an image for the first frame --skiplast, -L Doesn't output an image for the last frame --layers Filter only render output layers matching these names. Supports wildcards ?, *, [...]. E.g., --layers 'diffuse, specular,emission' -v name Uses motion vectors with crossframe mode. Motion vectors are located based on the variance filename, changing "/variance/" to "/<name>/", "variance." after "." or "_" to "<name>." Note that "-v variance" will use the motion vectors from the variance file itself -f configFiles Filter definition file and/or overrides. Separate multiple files with '+' or use multiple -f's. Use -H to list available files. The default baseFile.filter.json is $RMANTREE/lib/denoise/default. filter.json -H Lists all available filter config files --override key val Override a value from filter definition file. Can use multiple times. If last flag, follow with -- before input file names. Examples: --override strength 0.5 --override 'kernels.params.sigma_albedo' 0.05 --override debugPixel '[336, 209]' -t nthreads Number of threads; default is number of cores on machine -h, --help Help --version Version information
The Denoise tool comes with three filter presets: