Color Gamut

Anthropogenic Crisis No. 065425 copyright 2021 Douglas Stockdale

This is the second of a two part series discussing color management. In my first article, here, there is a discussion of color calibrating a photographic process flow, usually the combination of monitor and printing equipment and related printing papers.

The other aspect of color management to be aware of is the color gamut, or color space, capabilities of the photographic equipment being used. Most digital photographers quickly learn that the inherent weakness of digital photography is blowing out the highlights when taking a picture, as these cannot be recovered. That is behind the concept of the Zone System and pre-visualization for black&white photography; the eye can comprehend more contrast (tonal zones) than film can record, and film can record a larger contrast range than paper can print. I recall taking some Kodachrome slides (notorious for its very saturated colors) to a color lab to make some Cibachrome prints and the guy behind the counter pointing to one of my slides on the light-box stating that they were not going to get that green exactly right. He was correct. My first foray into the issues of color gamut.

The same is still true today, the colors you photograph and look great on your monitor may not translate very well to a print; digital sensors can not match the eye, but what it captures can exceed the capabilities of your printer and paper. Which is why color calibration is needed to map out what the monitor will show and printer-paper combinations can create. Unlike the zone system for black&white, for color photograph we may not be able to anticipate if the colors we photograph will easily correspond to a final print. So a little bit of trial and error may be necessary, but get the photograph right to begin with and then work out the subsequent color issues.

Another reason to color calibrate a monitor is to ensure it’s color space is best suited for your printer-paper combinations. Thus one of the choices you have is to select which color space you want to see your images displayed on the monitor and most (like me) select AdobeRGB that has a large color space to work within. When saving JPEGs for the web, I will change the color space to sRGB, which is a little bit smaller color space but provides consistent color rendering on most other devices (phones) and monitors. Regretfully, the AdobeRGB color space for my monitor exceeds the capabilities of my nine-color Canon printer and rag paper printing combinations. The printer has its color printing gamut and each manufacturers paper has its color gamut, thus the color calibration process determines what the resulting color gamut is for the combination of these two. For a printer the more colors it can print with usually the larger the color gamut it can handle, such as my nine-color Canon being able to leverage inks like Light Cyan, Light Magenta, Light Black, etc. versus a four-color desk top printer. Which is also a clue for those who are planning to publish a book; the book printer (just four-colors) might have some color printing issues with some of your proposed images, thus you may need to spend time during pre-press with their color management specialist and why I always ask for hard (printed) proofs.

When I print from Photoshop I keep the gamut alert toggled on, which will show on the monitor a gray area (out-of-gamut) over top the colors that the printer-paper cannot match exactly. Case in point; of my recent photographs, the image with this post above is tricky as some of the intense shades of blues are not easy to print; lots of out-of-gamut areas depending on the paper I select.

When I created the first version of this photograph the out-of-gamut areas were excessive and after selecting a paper that seemed to minimize the out-of-gamut and printing this photograph, I realized that I needed to make some changes. Big time. There are a number of ways to correct an image for out-of-gamut and with the quantity of out-of-gamut alerts with this image, making spot changes was going to take me until 2022 to complete. Thus, I made a global color change when opening the original image in Bridge/RAW implementing a series of color desaturations files (final about 10% desaturation) until I had an acceptable photograph for my largest gamut 100% rag paper. Cool!

So keep a watchful eye for those out-of-gamut alerts but don’t panic when one pops up; it just means that a little bit more of work is required, but the results should be worthwhile. Cheers!

by Douglas Stockdale

Btw, this photograph printed 22 x 28″ on a 24 x 30″ sheet is really stunning. Let me know if you would like more information about obtaining a print.

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