20.10.20264 min

Corona noise: Denoising and CXR workflow

Use a compatible AI Denoiser for quick Corona previews, then compare it with Corona Denoiser for the final still. Check fine details: denoising can soften fabric, wood grain and narrow edges. Save a CXR with denoising data if you need to revisit the settings after rendering.

Choose a mode for the job

In Render Setup, open Scene → General Settings → Denoising → Mode. The lesson shows NVIDIA GPU AI, Intel CPU/GPU AI, Corona High Quality and Gather data for later. Recent versions call Corona High Quality simply Corona Denoiser; check the settings in your installed version.

Only firefly removal targets individual bright pixels. Use it when those pixels are the problem; it does not replace full denoising for general grain. One scene is not enough to judge how useful the mode is.

Enable AI Denoising for previews

NVIDIA GPU AI needs a supported NVIDIA graphics card and is useful for fast previews. Interactive rendering has a separate setting: Performance → Interactive Rendering → Denoising during rendering. Selecting a production denoiser does not automatically establish the interactive setting.

Intel CPU/GPU AI can denoise production renders on the CPU, including AMD processors. Interactive use requires a supported NVIDIA GPU; an arbitrary graphics card does not guarantee compatibility. Check the requirements for your Corona version and driver.

Selecting NVIDIA GPU AI in Render Setup. 00:01:58

Let the source image gather enough detail

A denoiser cannot reliably recover detail from an extremely noisy image. If patches appear or a surface looks plastic, render longer and compare the same area again. There is no single noise target that suits every scene.

Use Stop to finish rendering and apply denoising. Cancel may discard the denoising step. Compare the raw and processed images at the same zoom level, paying attention to textures and lighting boundaries.

Adjust Amount and Radius separately

Denoise amount blends the original image with the denoised result. Reduce it when the texture loses detail; increase it only while those details remain visible. Corona Denoiser's Radius controls the filter radius, and a larger radius can blur the image more strongly.

Corona Denoiser does not require the High Quality image filter. AI modes have separate compatibility restrictions with that filter. Distinguish the denoiser from the image filter and read Corona's warnings.

Save a CXR for later denoising

Choose Gather data for later before rendering when you want to calculate denoising afterward. Stop the render, use Save CXR, open the file in Corona Image Editor and run Denoise. A regular image export does not replace a CXR containing the additional data.

The gathered data in this workflow is for Corona Denoiser. Switching between NVIDIA and Intel AI requires a corresponding AI mode during the original render and a saved CXR. Keep the working CXR separate from the final client image.

Gather data for later in the scene settings. 00:05:54

Review the result before exporting

In Corona Image Editor, compare different Amount and Radius settings on the same image. Run Denoise again after changing Radius, then check whether reducing it restores texture detail. Toggle between the original and denoised result to assess the difference.

This workflow is intended for still images. Denoising can cause flickering in animation, so one good frame does not validate an entire sequence. Performance and quality also depend on the scene and hardware.

Adjusting Radius in Corona Image Editor. 00:06:53

Technical documentation: Chaos: Denoising · Chaos: hardware requirements · Chaos: Corona Image Editor