In the July issue of The SMPTE Motion Imaging Journal, Los Angeles-based senior color scientist and image scientist Cullen Kelly takes an enlightening look at “Digital Print Stock Design: A Framework for the Post-Film Era.” Kelly notes that the craft of color grading is currently at a crossroads. Every captured image requires processing and creative adjustment before it can be reproduced. For most of cinema history, the defining factor in the post-production “look” of capture imagery was the print stock – engineered to impart preferred color characteristics while serving the technical function of transforming scene-referred imagery for display. Yet today, as the physical medium of print stock has been retired from image mastering workflows, so too has the principle of a global creative transform. Colorists and their tools continue to evolve as they look into the future of bleeding-edge image capture and reproduction.
With the ongoing proliferation of camera and display standards, unifying the imagery of content has become increasingly challenging. The industry-wide recognition of the need for world-class engineering to deliver world-class color grading has led to the development of systems addressing these technical aspects, most notably the Academy Color Encoding System (ACES). Yet there is no current initiative aimed at supporting the creative aspects of unifying motion imagery at the macro-level. In his article, Kelly outlines a proposed design of Digital Print Stocks (DSPs) within a Digital Print Stock Framework (DPSF).
These digital print stocks comprise a set of manipulations whose parameters can be intuitively modified by artists, offering a high degree of control with minimal demand for specialized knowledge of image science, and resulting in a global look that can be deployed within any imaging pipeline. Kelly proposes that the architecture of this framework should be open source, modular, lightweight, platform-agnostic, and device-independent. In addition, the framework’s manipulations should be precise, relying on per-pixel mathematical operations rather than interpolation of values, and as broad and soft as possible, relying on techniques such as tone mapping, matrix transformation, gamut mapping, and curve adjustments to sculpt a “creative color space.” Finally, the framework should offer an interface that includes visual feedback to live-preview the application of the transform, with intuitive parameters and controls, and sensible guides and constraints.
Kelly presents a list of the most common tools currently used by colorists for macro-level look design and proposes the components of a new proposed Digital Print Stock Framework.
Current tools include:
Kelly’s proposed new framework is built upon the ability to add, revise, and/or remove image transform components as needed.
Proposed core transforms should include:
Kelly considers the design and application of scene-referred creative looks to be a unique challenge, with subjective goals that can make the task more complex in many regards. Establishing a well-selected and well-implemented set of creative transforms that offer maximum aesthetic latitude and intuitive adjustment for a wide variety of artists will require the participation and collaboration of creatives and imaging scientists alike. Digital print stock design will be an ever-evolving framework as the industry continues to refine its creative practices.
Learn more about the future of Digital Print Stock Design. Read Cullen Kelly’s complete article in the July issue of The SMPTE Motion Imaging Journal.
Keywords:
Academy Color Encoding System (ACES), color grading, color management, digital cinema, film print, HDR, look development