Hi Dan,
Open Color IO (OCIO) is an open source color management system that is used mostly in the CG and video workflow:
http://opencolorio.org
Photoshop and similar image editing tools that are print-centric use ICC profiles to manage color and transform image data from one device to another to insure consistent color. However, in the CG and video realm, this approach is not very useful - transforms from one color gamut and gamma to another are often achieved with LUTs or similar mathematical algorithms. For example, say live video is shot on a few different types of cameras that shoot raw video and encode it in a log gamma space to preserve the dynamic range. The video needs to have the same color and tone even though it may be from different camera makes and models- each camera has a transform (a LUT) to take the raw footage encoded in the maker-specific gamut and log gamma to a standard like REC709 for editing and grading. Same goes for CG footage that may need to be composited into live action video, etc. Most CG footage is linear, so a transform may be applied to the CG footage to display it in the same viewing environment as the REC709 video footage, for example, for purposes of matching color, etc.
OCIO is a tool to apply these types of transforms to image and video data, either for conversion or display - it is color management that you can apply explicitly to bring all of your image data into a common working form. In addition, many "look" LUTs (like film emulation) require certain input (log, REC709) to produce the required result. Applying the correct transform to your data will convert the data stream to the correct form for application of the desired look LUT. OCIO also permits the use of "config" files that organize and categorize various transforms into a set - you can make your own config files so that you can choose a single transform that may be a chain of transforms, for example.
None of this is possible with the standard ICC profiles that we often use in Photoshop. Those ICC profiles are usually for display, output referred color space or printer-paper output. What is cool about OCIO in PS is that you can create a transform (say, Log to REC709 With some film look applied) and then EXPORT that transform as an ICC profile you can load back into PS. Now, when you want to transform your log image to a film look output in PS, you simply load the log image in the proper working color space (say, REC709) and ASSIGN the newly created ICC profile that does the film look from the log input. Taa dah!
Most of this kind of thing is done in After Effects or similar tools where color management options support this workflow. Also, it helps with data formats that are not so easily managed and manipulated in PS, like log and linear 32bit data. In After Effects, the OCIO plug-in can be applied as an effect layer, which makes it non-destructive, whereas in PS it gets applied as an adjustment filter, which is destructive, unfortunately. Affinity Photo has a non-destructive OCIO adjustment layer, which is nice (it also has a non-destructive soft-proof adjustment layer!). This would be an ideal implementation of OCIO in PS, but, baby steps.
In summary, this plug-in helps adapt PS, a primarily ICC profile, output-referred, print-centric application, to the world of video and CG image processing pipelines where color management is performed explicitly via defined mathematical transforms applied as LUTs, etc. The OCIO plug-in permits one to use this technique to transform data and to export the transforms into an ICC profile for use in PS's native color management system.
kirk
