Moving picture colour science: the maths behind Colour LUTs, ACES and film looks

One of the biggest colour-related problems for cinematographers and for the whole post-production chain, up to and including CGI artists, is preserving the same “look” for the video content and be able to consistently reproduce that, no matter either what sort of camera or computer generated it (as input), or what medium is there for the end-user to watch and enjoy the content (as output). Be it a dark digital, 35mm or IMAX theatre room, a home TV setting, a laptop with Internet streaming in a day-lit room, etc., the cinematographer needs its artistic interpretation of the light to be channelled in a devices-independent way – so the colour scientists call it. In the latest years many proprietary/commercial tools and workflow proposal emerged, each driven by a specific need (e.g. on-set grading, Digital Cinema mastering, webTVs, etc.) and by specific manufacturers. This results in the proliferation of many different formats and a few, or even almost none, standards. After reviewing two contemporary colour-management techniques for the digital imaging within the moving picture industry (Color LUTs and ACES) some mathematical methods to extract colour-correction related information by the above techniques is outlined, as valid methodology to support the analysis and synthesis of digital ‘looks’, both on-set (production) and along the Digital Intermediate (DI, post-production) phase.