Finding Out of Gamut Colors


Today’s Question: One follow up [to yesterday’s question]: How would I know what colors are actually out of gamut? What colors are in and not in gamut?

Tim’s Quick Answer: The key to determining which (or whether) colors are out of gamut for the intended print is to perform a “soft proofing” check. In Lightroom or Photoshop, for example, you can enable a soft proofing display along with an indication of which colors are out of gamut based on the printer, ink, and paper combination you intend to use to produce a print.

More Detail: In Lightroom the soft proofing feature is available in the Develop module. The reason this option is included in Develop rather than the Print module is that you have the option of applying custom adjustments to the image in an effort to compensate to the extent possible for the limitations of the intended print conditions.

After selecting the image you intend to print, you can go to the Develop module and turn on the “Soft Proofing” checkbox on the toolbar below the image preview area. This will open up a soft proofing section below the histogram display toward the top of the right panel. There you can set the appropriate printer profile for the paper you intend to print to, and also specify the desired rendering intent. I recommend turning on the “Simulate Paper & Ink” checkbox as well to get a better sense of what the overall print will look like.

At this point you are seeing a preview on your monitor of what the print will look like. To display the gamut warning, click (or hover your mouse over) the “Show Destination Gamut Warning” icon (the blank sheet of paper icon) at the top-right of the histogram display. This will present a red overlay on the image indicating any areas that contain colors the currently selected printer, ink, and paper combination is not capable of reproducing.

In Photoshop you can also enable a gamut warning display. Start by configuring the soft proofing display, which you can get started with by choosing View > Proof Setup > Custom from the menu. In the Customize Proof Condition dialog that appears, you can choose the applicable printer profile from the “Device to Simulate” popup. Then set the Rendering Intent based on your preference, and turn on the “Black Point Compensation” checkbox. I also recommend turning on the “Simulate Paper Color” and “Simulate Black Ink” checkboxes so the preview will more accurately reflect what you can expect to see in the final print.

Click OK to apply the settings for soft proofing, which will also cause the “Proof Colors” option to be enabled on the View menu. In other words, at this point you are seeing a preview of what the final print will look like. To enable the gamut warning, simply choose View > Gamut Warning from the menu. By default the overlay on the image indicating areas of the photo that are out of gamut will be gray, but you can change the color on the Transparency & Gamut page of the Preferences dialog in Photoshop.

The soft proofing display can be tremendously helpful for getting a better sense of what a given print will look like. It can also be used as part of your process for choosing which paper might make the most sense for a particular photo. The gamut warning can be helpful in advance of making a print, but it is also a useful troubleshooting tool when the print you produce doesn’t look as expected.