OpenExrComposer

A simple and fast tool to compose sequences of EXR files.

Usage:

To simply add two exr files and store the result in a new output.exr, do:

OpenExrComposer.exe "outputfile.exr = inputfileA.exr + inputfileB.exr"

The filenames can also contain fully qualified paths.

The righthand side of the = assignment may contain any math expression consisting of existing exr files, constants, parentheses and any number of + - * / operands. For example:

OpenExrComposer.exe "beauty_pass.exr = (diffuse.exr * (lighting_raw.exr + gi_raw.exr)) + (reflection_raw.exr * reflection_filter.exr) + (refraction_raw.exr * refraction_filter.exr) + specular.exr + sss.exr + self_illum.exr + caustics.exr + background.exr + atmospheric_effects.exr"

You can also compose sequences by using # as wildcard character. Example:

OpenExrComposer.exe "beauty_without_reflection_#.exr = beauty_#.exr - reflection#.exr - specular#.exr"

This will search the folders of the input files for all files matching the pattern (replacing # with any other string) and process all files.

When compositing sequences, it's also possible to have some input files be sequence files and others to remain the same. Example:

OpenExrComposer.exe "watermarked_output_#.exr = inputSequence#.exr + watermarkFile.exr"

You can also use constants instead of input files. Examples:

OpenExrComposer.exe "signed_normals.exr = (unsigned_normals.exr - 0.5) * 2.0"

OpenExrComposer.exe "inverted_depth_#.exr = 1.0 - depth#.exr"

By default, the ouptut will be compressed using 16-scanline zlib compression. If you'd like to use another compression, you can specify it using the -c or --compression flag. Example (pay attention not to have the flag included in the expression surrounded by ""):

OpenExrComposer.exe "output.exr = input.exr" --compression DWAB

If any of the input files contain an Alpha channel, then all input files must have Alpha channels and the output file will have an Alpha channel too.

Alpha channels of input files can be explicitly ignored by specifying the -rgb argument.

List of supported compressions:

• NO : uncompressed output
• RLE : run length encoding
• ZIP_SINGLE : zlib compression, one scan line at a time
• ZIP : zlib compression, in blocks of 16 scan lines (the default)
• PIZ : piz-based wavelet compression
• PXR24 : lossy 24-bit float compression
• B44 : lossy 4-by-4 pixel block compression, fixed compression rate
• B44A : lossy 4-by-4 pixel block compression, flat fields are compressed more
• DWAA : lossy DCT based compression, in blocks of 32 scanlines. More efficient for partial buffer access
• DWAB : lossy DCT based compression, in blocks of 256 scanlines. More efficient space wise and faster to decode full frames than DWAA. (recommended for minimal file size)

Current limitations:

• Currently only works with RGB images.
• Does not yet work with deep exr.
• When using wildcard #, all matching input files must exist.
• Outputfile will be 32bit float.

Building:

The repository bundles bazel.exe (v3.2.0) and vswhere.exe to build on Windows.

Requirements

• Have Visual Studio 2017 or newer installed
• Have MSYS2 installed

Build steps

• Run build.bat
• The output will be bazel-bin\openExrComposer.exe