openlut

Open-source tools for practical color management.

What is it?

openlut is, at its core, a transform-focused color management library, accessible from Python 3.5+. It's built on my own color pipeline needs, which includes managing Lookup Tables, Gamma/Gamut functions/matrices, applying color transformations, etc. .

openlut is also a practical tool. Included soon will be a command line utility letting you perform complex color transformations from the comfort of your console. Included already is an OpenGL image viewer, which might grow in the future to play sequences.

I wanted it to cover this niche simply and consistently, with batteries included (a library of gamma functions and color gamut matrices). Color management doesn't have to be so difficult!

What About OpenColorIO? Why does this exist?

OpenColorIO does amazing work - but mostly in the context of large applications, not-simple config files, and self-defined color space (with the full range of int/float bit depth specifics, etc.)

openlut is all about images and the transforms on images. Everything happens in (0, 1) float space. Large emphasis is placed on managing the tools themselves as well - composing matrices, resizing LUTs, defining new gamma functions, etc. .

In many ways, OCIO is a system stringing basic operations together. I'd be perfectly plausible to write an OCIO alternative with openlut in the backend.

Installation

First: Ensure you have dependencies!!! The pip command will break without them.

Simply use pip: pip3 install openlut (pip3 denotes that you must use a Python 3 version of pip). Keep in mind, there are some external dependencies:

• Python 3.5: This is Python; you need Python.
• gcc: This is needed to compile the C++ extensions.
• pybind11: This is a library needed to link the C++ extension into Python. pip version is being difficult...
• imagemagick: For all file IO. It's not like I was gonna write that myself :) .

If it's breaking, try running pip3 install -U pip setuptools. Sometimes they are out of date. Linux: You make need to use sudo before the command. Ignore the AssertionError when building the wheel; it doesn't affect anything.

Installing Dependencies

Not Difficult, I promise!

On Debian/Ubuntu: sudo apt-get install python3-pip gcc pybind11-dev libmagickwand-dev

On Mac: brew install python3 gcc pybind11 imagemagick

• You will need Homebrew ( copy/paste a command from http://brew.sh/ to install ) and XCode Command Line Tools for gcc (it should prompt you to install this).
• If this doesn't install pip, run brew install python3; curl https://bootstrap.pypa.io/get-pip.py | python3

On Other: You need python 3.5, pip, a newer version (must support C++14) of gcc, and pybind11 in your includes.

Basic Library Usage

To represent images, use a ColMap object. This handles IO to/from all ImageMagick supported formats (including EXR and DPX), as well as storing the image data.

Use any child of the Transform class to do a color transform on a ColMap, using ColMap's apply(Transform) method.

The Transform objects themselves have plenty of features - like LUT, with open(), save(), and resize() methods, or TransMat with auto-combining input matrices, or automatic spline-based interpolation of very small 1D LUTs - to make them helpful in and of themselves!

Take a look at the test code under tests for examples.