ProPhoto RGB

ProPhoto RGB
Fred the Oyster · Public domain · source
Name	ProPhoto RGB
Created	1998
Creator	Kodak
Gamma	1.8 (approx.)
Primaries	Wide gamut
Whitepoint	D50
Bit depth	8–16 bit recommended

ProPhoto RGB ProPhoto RGB is a wide-gamut RGB color encoding developed to preserve color information for photographic and prepress workflows. It was introduced by Kodak to capture and retain colors beyond the range of conventional spaces used by Adobe Systems and Microsoft software, intended for high-bit-depth editing in applications such as Adobe Photoshop, Capture One, and Lightroom Classic. The space is often employed in professional workflows involving devices and institutions like Nikon Corporation, Canon Inc., and imaging laboratories such as MPI Media Development and Technologies.

Overview

ProPhoto RGB was designed to encompass a very large portion of the colors producible by typical digital capture devices and archival media used by Eastman Kodak Company research, FujiFilm, and scanning houses serving museums and galleries such as the Museum of Modern Art and Getty Research Institute. Its primary aim was to minimize clipping when converting from camera raw formats produced by vendors including Sony Corporation, Olympus Corporation, and Panasonic Corporation. The encoding has been implemented in popular tools from Adobe Systems, adopted by studios collaborating with institutions like National Geographic Society, and referenced in specifications by bodies such as International Color Consortium stakeholders.

Technical specifications

ProPhoto RGB uses primaries defined to provide an exceptionally large gamut based on measurements and theoretical extrapolations applied by engineers at Kodak Research Laboratories and contributors from imaging groups affiliated with Rochester Institute of Technology and MIT Media Lab. The working space uses a D50 white point consistent with standards promulgated by International Commission on Illumination and color management practices used within World Wide Web Consortium-adjacent workflows. Typical implementations recommend 16-bit per channel integer or floating-point processing to avoid quantization artifacts when performing color transforms between profiles provided by ICC profile tools and software from Apple Inc. and Microsoft Corporation.

Color gamut and performance

ProPhoto RGB’s primaries extend beyond the gamut of media-referred spaces used by companies like Apple Inc. (sRGB) and Adobe Systems (Adobe RGB), aiming to encompass a substantial portion of the theoretical surface defined by models employed at research centers such as Bell Labs and National Institute of Standards and Technology. This results in the ability to represent colors outside the reproducible range of printers from Epson Corporation and Xerox Corporation and displays from Samsung Electronics and LG Electronics. Color scientists at institutions like Rensselaer Polytechnic Institute and University of Rochester have analyzed its gamut relative to devices characterized in studies from Inter-Society Color Council and found it advantageous for archival capture but challenging for final output mapping to Pantone or Fogra process profiles.

Usage and workflows

Professional photographers and post-production facilities working with camera systems from Canon Inc., Nikon Corporation, Sony Corporation, and raw converters such as Adobe Camera Raw commonly select ProPhoto RGB during intermediate editing stages to preserve chromatic data prior to conversion to output spaces intended for printers like Hewlett-Packard and proofing presses standardized by ISO. Museums, archives, and scientific imaging groups at Smithsonian Institution and Library of Congress use wide-gamut spaces in digitization pipelines alongside color targets by X-Rite and GretagMacbeth for reference. Education programs at Royal College of Art and Parsons School of Design teach workflows incorporating high-bit-depth processing chains using software from Adobe Systems and color management modules from LittleCMS.

Compatibility and support

Major image-editing applications from Adobe Systems (Photoshop, Lightroom) and raw-processing tools from Phase One and Capture One include profiles allowing editing in ProPhoto-style wide-gamut spaces; printers and RIPs from EFI and Harlequin require careful rendering intent selection and device link profiles to map to FOGRA and GRACoL press standards. Operating systems by Apple Inc. and Microsoft Corporation provide color management APIs that can carry ICC profile transforms involving wide-gamut spaces, while hardware vendors such as Dell Technologies, BenQ Corporation, and Eizo Corporation offer monitors with wider gamut coverage and calibration tools from Datacolor and X-Rite to better approximate ProPhoto-range colors.

Criticisms and limitations

Critics from academic labs such as Stanford University and University College London have noted that the primaries of ProPhoto RGB extend into imaginary colors when plotted on the CIE chromaticity diagram, necessitating non-linear handling and careful colorimetric conversions described in literature from Society for Imaging Science and Technology and standards discussed at International Color Consortium. Using 8-bit representations in this space leads to posterization and banding as highlighted by practitioners at National Media Museum; hence, experts recommend 16-bit editing workflows, which can increase storage and processing demands for systems from Intel Corporation and AMD. Conversion to output-referred spaces for printers from Canon Inc. or displays from Samsung Electronics requires perceptual rendering and soft-proofing strategies taught in programs at Rochester Institute of Technology and workshops held by Professional Photographers of America.

Category:Color spaces