How can a photograph keep a similar appearance on different devices?

The same photograph can look different on two screens, even when the file contains identical red, green and blue numbers. Those numbers specify values within a color system; they are not a complete description of the light every device will produce. Screens have different primaries and responses, while a printer uses ink and paper to modify illuminating light.

A color profile supplies the missing interpretation. For a device profile, measured color patches can connect device values with a shared color reference. The profile describes a relationship between numerical settings and color behavior. An embedded source profile tells compatible software how the image's stored values are intended to be interpreted.

A color-management system uses that source interpretation and a destination profile to choose suitable output values. The shared reference serves as a bridge. Without it, every possible pair of devices would need its own separately specified translation; with it, source and destination descriptions can be combined. Keeping appearance similar may therefore require changing the numbers sent to the second device.

Some matches remain physically impossible. A device's reproducible range is its gamut, and a brilliant screen color may lie outside the range a particular ink-and-paper combination can reproduce. Gamut mapping must choose a substitute or adjust relationships among colors. No profile can make a printer emit light like a screen or manufacture an unavailable ink color.

Calibration establishes a device's operating condition; profiling describes its behavior under relevant conditions. Changes to that condition can weaken the match, and paper, illumination and viewing surroundings affect appearance too. Color management is therefore a coordinated interpretation-and-reproduction process, not a promise of identical light everywhere. It makes differences between devices explicit so an image can travel with a more consistent intended appearance.