This is a V-Ray application that is common across all V-Ray installations.


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The VRImg to OpenEXR converter is both a command-line utility and a simple GUI application that can be used to convert .vrimg image files to .exr files in OpenEXR format. The .vrimg file format is a special format used by the V-Ray VFB to store the rendered image incrementally while rendering, in full floating-point format, with all available render elements. The V-Ray Image to EXR Converter converts .vrimg files to EXR format so the render elements may be loaded into compositing software, where they can be used for Back-to-Beauty compositing or for other adjustments and fine-tuning at the render element level.





Maya Installation

This tool comes with the V-Ray for Maya installation. You can start it from the shortcut in  Windows Start > All Programs > Chaos Group > V-Ray for Maya 20xx for x64 > Tools > VRImg to OpenEXR converter or manually running it from its executable in the V-Ray bin folder in the Chaos Group folder where your applications are installed:

Windows: start the vrimg2exr executable from C:\Program Files\Chaos Group\V-Ray\Maya nnnn for x64\bin\

Linux: start the vrimg2exr executable from /usr/ChaosGroup/V-Ray/Mayannnn-x64/bin/

Mac OS X: start the vrimg2exr executable from /Applications/ChaosGroup/V-Ray/Mayannnn/bin/

Note: nnnn is the Maya version.


GUI Usage

Running vrimg2exr without any parameters, or from the Start menu, will open the GUI version of the tool as seen above. The GUI allows you to convert one or a number of .vrimg files to OpenEXR files. You can also get information about the data stored in a .vrimg file.

Pixel type – Specifies whether the data in the .exr file is saved as 16-bit or 32-bit floating point numbers.

Compression type – Sets the compression type, choosing between the several available methods. If not specified, the ZIP method is used.

  • None
  • RLE - run length encoding
  • ZIPS - one scanline at a time
  • ZIP - in blocks of 16 scanlines
  • PIZ - piz-bazed wavelet compression
  • PXR24 - lossy 24-bit float compression
  • B44 - lossy 4x4 pixel compression, fixed rate
  • B44A - lossy 4x4 pixel compression
  • DWAA - lossy DCT based, blocks of 32 scanlines    
  • DWAB - lossy DCT based, blocs of 256 scanlines       

DWA compression level A floating-point value that controls the compression level when using the lossy DWA compression methods.

Buffer size (in MB) Sets the maximum allocated buffer size. By default, this value is set to 500 MB. If the image does not fit into the max buffer size, it is converted in several passes.

Data window Tries to find the valid data window from the .vrimg file. This requires that the file can be read in one pass. The non-zero pixels in the alpha channel are used to determine the data window.

Available channels Specifies which channels of the .vrimg file are written into the .exr file. Provides a list of all available channels found in the .vrimg file(s) once an input file or directory is selected.

Channels in separate files – When this option is enabled, each channel is written into a separate .exr file.

Multipart output – When this option is enabled, each channel is written into a separate OpenEXR2 'part'.

Input file mode – Selects the input file mode.

  • Single input file – Only a single file is converted. 
  • Multiple input files – Multiple files are converted at once. 

Input file – Specifies the .vrimg file when Single input file is selected as the Input file mode.

Input directory – Specifies the input files' directory when Multiple input files is selected as the Input file mode.

Output directory – Specifies the output directory for the .exr files when Multiple input files is selected as the Input file mode.

Filename – Specifies a search pattern for the input file names. Wildcards (*) can be used to define the pattern.

Subdirectories – When this option is enabled, all .vrimg files contained in subdirectories of the specified input directory are also converted.

Info – Provides information about the .vrimg file(s) once an input file or directory is selected.

Convert – Starts the conversion.


Command Line Usage

There are two methods for running the vrimg2exr converter from the command line. In both cases, the original .vrimg file is not deleted.

Converting a single .vrimg file to a single .exr file:

> vrimg2exr  <vrimg _file> <exr_file> [options]

In this case, the <vrimg_file> cannot contain wildcards. Note that the .exr extension is not added automatically to the output file name.

Converting multiple .vrimg files to multiple .exr files:

> vrimg2exr  <vrimg_wildcard>  [options]

In this case, <vrimg_wildcard> can contain the wild-card symbols '*' and '?'; the .vrimg files will automatically be converted to OpenEXR files with the .exr file extension.


Under Linux and OS X, parameters with wildcards must be placed within apostrophe symbols -'image_wildcard'. Otherwise the command line shell will automatically expand the wildcard into file list, which will force the program to terminate.



One or more of the following options may be specified:


GUI equivalent


-info Info buttonPrints information about the .vrimg file (resolution, channels present, etc.). This is only supported for .vrimg files created with V-Ray versions 1.48.xx and higher.
-half Pixel type drop-downStores the floating-point data in the .exr file as 16-bit floating point numbers. If this option is not specified, the data is stored as 32-bit floating point numbers.
-sRGB-Converts the RGB data from the .vrimg file to the sRGB color space before writing it to the .exr file. Without this option, no color conversion is performed.
-gamma <gamma_value> -Applies the specified gamma value to the RGB colors before writing the .exr file. If this option is not specified, the data is stored in linear space.
-channel <name> Available channels drop-downOnly reads the specified channel from the .vrimg file and writes it as the RGB channel in the output file. No other channels are written to the .exr file. This option can be used to extract the different channels in the .vrimg file to separate image files. Use the -info option for a list of available channels in the file.
-compression <method> Compression type drop-downSets the compression type for the resulting .exr file. If not specified, ZIP compression is used. Currently supported values for <method>are: nonezipszippizpxr24
-bufsize <buf_size> Buffer size spinnerThe maximum buffer size per channel (in megabytes) that will be used for the conversion. If the image does not fit into that buffer size, the converter will process it in several passes. Larger buffer size means faster conversion, but, obviously, requires more memory. The default is 10 MB per channel, but a larger value, f.e. 100 or more is recommended for large files. A  value of 0 removes the limit for the buffer. In that case it will try to load the image in one pass which may result in utilizing all available memory.
-dataWindow Data window checkboxAttempts to find a rectange in the image that stores non-zero data (based on the alpha channel) and only stores this data window in the OpenEXR file.
-separateFiles Channels in separate files checkboxEach render channel is written to its own OpenEXR file. If not specified, a single multichannel OpenEXR file is produced.
-multiPart Multipart output Each render channel is written to a separate "part" inside a single OpenEXR file. This allows applications to load each render element separately which may speed up the work when there are many render channels.
-longChanNames-Enable channel names with more than 31 characters. The resulting OpenEXR file might not be compatible with applications using a version of the OpenEXR library older than version 1.7
-help-Print all possible command-line parameters.