Corona for 3ds Max
Corona EXR format (CXR)
This page provides information about Corona EXR format (CXR).
Last updated 10 January 2026
This page provides information about Corona EXR format (CXR).
Overview
Images rendered in Corona Renderer can be saved into EXR files with additional metadata. This format is being referred as Corona EXR format (CXR). Files in this format can be later used to resume rendering, or they can be opened in Corona Image Editor. They are valid EXR files, but since they use some of the more advanced features, it may not be possible to correctly load them in some third party applications.
CXR files store just raw pixel data. They are not saved with applied color mapping, bloom & glare, etc. Instead of that all parameters required for these are saved in the metadata.
Metadata
Files in the CXR format store additional render elements (channels) and attributes. Both are realized by standard EXR means.
Render elements (channels)
Name | Description |
|---|
Name | Description |
|---|---|
CORONA_FB_WEIGHTS | Single channel storing weight of each pixel, roughly corresponding to the number of taken samples. It can be used to optimally merge several CXR files rendered with different random seeds to produce a single CXR file having lower amount of noise. |
VisibleDiffuse | Hidden element for Corona Denoising. |
VisibleNormals | Hidden element for the denoising. |
Hybrid | Hidden element for the denoising. |
HairIds | Hidden element for the denoising. |
OptixNormals | Hidden element for the denoising. |
Prefixed by Sqr | Hidden elements for the denoising. |
Prefixed by Denoised | In case the CXR file has been already denoised, denoised variants of all denoised render elements are stored with this prefix. |
Attributes
Names of all additional attributes always starts with 'corona' prefix.
Name | Description |
|---|
Name | Description |
|---|---|
corona.iscoronaexr | Equals to 1 when the file is saved in the CXR format. |
Prefixed by corona.cm | Parameters for tone mapping, LightMix and used LUT. |
Prefixed by corona.bg | Parameters for Bloom and Glare. |
Prefixed by corona.curves | Store used curve parameters. |
Prefixed by corona.denoise | Parameters for Corona Denoising. |
Prefixed by corona.sharp | Sharpening parameters. |
Prefixed by corona.blur | Blurring parameters. |
Prefixed by corona.vignette | Parameters required to apply vignetting. |
Prefixed by corona.renderstamp | Store text of file-save-time render stamp and other related settings. |
corona.elements | Ordered list of render element definitions. Each element definition consists of the element's name, type, and list of flags further describing the element's features and how the element should be interpreted with regard to tone mapping, bloom and glare, etc. |
corona.stats.passes | Total number of computed passes. |
corona.stats.time | Total time measured in milliseconds elapsed since render start. |
corona.stats.raysPerSecond | Average number of rays computed per second measured since render start. |
corona.stats.raysPerSample | Number of rays needed to compute one taken sample. |