Color Management and Photography

Free/libre software doesn't write itself, and if you use free/libre software, there are many ways to contribute:

Singling out two projects for special attention: ArgyllCMS needs monetary contributions. And GIMP needs programmers.

The philosophy behind the color management articles and tutorials

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. Most articles on the internet that discuss color management assume that you run a proprietary OS and use PhotoShop.

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.

I have no particular philosophical quarrel with proprietary editing software. But I do object to the idea that the artist's own work should be locked into a proprietary file format such as PhotoShop's PSD. Adobe's move to the cloud has made this issue of who controls access to the artist's work crucially important. The Creative Cloud license agreement itself is onerous and one-sided. Once the artist stops paying the subscription fee, she loses access to the software that unlocks the proprietary PSD format that contains her creative work.

Recent and featured articles

Recent articles

  • Default high bit depth GIMP 2.9 compared to Elle Stone's patched GIMP ("GIMP-CCE")

    My patched GIMP is targeted at users who want to edit in RGB color spaces other than sRGB and have acquired (or want to acquire) a working understanding of ICC profile color management and the basics of radiometrically correct editing. My patched GIMP also contains enhanced editing capabilities such as expanded LCH editing options, the very important Luminance blend mode, and selected additional unclamped layer blend modes, that haven't yet been incorporated into default GIMP.

    By comparison, currently default GIMP is mostly targeted at users who prefer to edit in the sRGB color space and also don't have (and perhaps don't want) a working understanding of ICC profile color management and the basics of radiometrically correct color mixing. If this describes you, then you might well prefer using default GIMP.

  • Tone mapping and shadow recovery using GIMP's 'Colors/Exposure'

    A very common editing problem is how to lighten the shadows and midtones of an image while retaining highlight details, a task sometimes referred to as "shadow recovery" and more generally speaking as "tone mapping". This step-by-step tutorial shows you how to use GIMP 2.9/2.10's floating point 'Colors/Exposure' to add one or more stops of positive exposure compensation to an image's shadows and midtones while retaining highlight details.

  • White balancing camera-saved sRGB jpegs that were shot using the wrong camera white balance

    sRGB is not the right color space for white balancing camera-saved sRGB jpegs that were shot using the wrong camera white balance setting. Better results can be obtained by editing your images in a linear gamma version of the Rec.2020 color space.

  • Autumn colors: An Introduction to High Bit Depth GIMP's New Editing Capabilities

    Early autumn foliageThe fact that GIMP 2.9/2.10 provides high bit depth image editing of course means that you can make very complex layer stacks, draw extreme gradients, and work in large color spaces without worrying about posterization and data degradation. High bit depth GIMP also offers awesome new editing capabilities that you might not have used or even heard of before. This tutorial shows you how to use GIMP's new LCH blend modes to edit separately for color and tonality.

  • How to Make a Camera Input Profile Target Shot

    When making a camera profile, the better the target chart shot, the better the resulting camera profile. This article explains how to make a good camera input profile target chart shot, including picking the right target chart, choosing the right lighting, preparing for and making a series of target shots at increasing exposure values, and picking the target shot with the best in-camera exposure.

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

    IT8 target chart shot for profiling a camera.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.

  • A tutorial on GIMP's very awesome LCH Blend Modes

    Aquarium fishThis tutorial introduces the very awesome GIMP LCH blend modes and provides examples using the LCH blend modes first to repair a color image, and then to colorize a black and white rendering of the repaired color image. Results using the LCH blend modes are compared to results using the old HSV blend modes.

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

    sRGB and ProPhotoRGB in the xyY reference color space.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.

All the color management articles and tutorials, arranged by topic

Articles & Tutorials on Color Management and Photography has links to all the color management and image editing articles on this website, arranged by topic:

  1. Tutorials on ICC Profile Color Management
  2. Calibrating and profiling your monitor
  3. Profiling your digital camera
  4. Choosing the right RGB Working Space
  5. Working in bounded and unbounded color spaces
  6. Interpolating camera raw files
  7. Digital Asset Management
  8. High bit depth GIMP

The About page has a little bit of information about why I switched to using Linux and started the Nine Degrees Below website, and the Galleries have a few of my photographs.

If you have questions or comments about any of the articles or photographs 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.