Articles & tutorials on color management and photography using free/libre software

What's on this website?

Most of the articles and tutorials on this website are about practical color management in the digital darkroom. Many times, articles on color management assume that all the reader really wants to know is which buttons to push. On this website the first assumption is that you want to understand enough about color management to make your own intelligent decisions.

The second assumption on this website is that you run Linux and use free/libre software. Fortunately the principles of color management are the same regardless of which operating system and which software you use. If you use a proprietary OS and you want to try any of the concrete examples provided in the articles, most free/libre imaging software also runs on Windows and Apple. The only difficulty you might encounter is with some of the command line examples, as the exact syntax does vary slightly from OS to OS.

This website also has articles on other digital darkroom topics, in particular raw processing and digital asset management, plus the occasional write-up about specific image editing software.

Links to articles and tutorials on color management and photography

All the articles and tutorials

Articles & Tutorials on Color Management and Photography has links to all the color management and photography articles on this website.

Recent and featured articles

Here are links to the most recent and and also a selection of featured articles:

Recent articles

  • Unbounded sRGB as a universal color space for image editing is a really bad idea

    Unbounded sRGB can be used to encode and display any RGB color. Nonetheless, unbounded sRGB is not suitable for use as a universal, "one size fits all" color space for image editing. Many editing operations are chromaticity dependent, giving different results in different RGB working spaces. Choosing the right working space for the task at hand is the photographer's first, and critically important, technical and artistic decision.

  • Models for image editing: Display-referred and scene-referred

    This article explains the similarities and differences between display-referred and scene-referred image editing. Even though the two models serve very different image editing goals, both models work with bounded RGB data. Display-referred RGB data is bounded by Color, which is to say by both Luminance and Chromaticity. Scene-referred RGB data is bounded only by Chromaticity.

  • How to Make a Better Custom Camera Input Profile that's also an RGB Working Space

    This article shows how to use ArgyllCMS and a target chart to make a better general purpose custom camera input profile that is color balanced and normalized. The resulting camera input profile is well behaved and so can also be used as an RGB working space for editing your interpolated raw files.

  • From sRGB color space to sRGB profile: how to calculate the ICC sRGB profile primaries from the sRGB color space specifications

    This article provides a step-by-step worked example of performing a Bradford chromatic adaptation to calculate the D50-adapted ICC sRGB profile red, green, and blue primaries from the unadapted red, green, blue, and white xyz values given in the sRGB color space specifications.

  • A Review of FLOSS Raw Processors, Part 1 (revised and updated)

    Flat and enhanced raw rendering of a dandelion. Part 1 of a review of free and open source raw processors compares seven free and open source raw processors — dcraw, darktable, the digiKam raw processor, Photivo, Rawstudio, RawTherapee, and UFRaw — "by the specs", without looking at actual interpolated output. This review only considers features relevant to radiometrically correct raw processing and not other features such as image enhancing algorithms or digital asset management.

  • What do Clipped Colors from ICC Profile Conversions really look like?

    A bright red flower with clipped colors in petal highlights. You've been told that converting an image from one color space to another can result in clipped colors. But how, why, and where does the clipping actually happen? This article shows you a real-world example of clipped colors in the image itself, in the image color gamut as seen from inside the CieLAB reference color space, and in the image's individual red, blue, and green channels.

On a personal note

The About page has a little bit of information about why I started the Nine Degrees Below website, and the Gallery has a few of my photographs.

If you have questions or comments about any of the articles on this website, I'd love to hear from you (even if you run one of those other operating systems 😉). You can reach me at ellestone (at) ninedegreesbelow (dot) com.