On the GIMP window, open the Preferences window ( Edit -> Preferences) and click Color Management on the left side. Once the ZIP file is downloaded, extract it. On the next step, accept the user license agreement and click the Proceed to Download link to download the ICC file (available in a ZIP format). On the next page, click the ICC profile download for End Users link. Select the platform you use by clicking a link on the bottom side. The file is available for Windows, Mac, and Linux. To add Adobe RGB in GIMP, you need to download the ICC file of the Adobe RGB first. You can read this Wikipedia page to learn more about why this Adobe RGB is better than sRGB.

Adobe RGB encompasses 50% of the visible colors specified by the CIELAB color space, while sRGB encompasses only 35%. If you are editing an image for a printing purpose, using Adobe RGB is highly recommended since this color space has a wider range of colors (color gamut) compared to sRGB, the default color space of GIMP. While this setting is not required, using Adobe RGB provides better color accuracy so that the colors you see on GIMP will not different from the ones you see on the paper once the image is printed. One of which, you need to set the color space to Adobe RGB.

But first, there are some settings you need to make. You can use GIMP for professional needs, including image editing to print.

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