A small data file describing how a particular device or colour space reproduces colour, so software can convert colours between devices.
Defined by the International Color Consortium. A profile maps device values to a device-independent profile connection space (CIELAB or XYZ, D50), and conversions go device → connection space → device.
Embedding a profile does not change the colours; it labels what the numbers mean. Stripping it leaves software to guess.
A print shop's profile for coated stock tells design software which colours that press can reach.
Colour management across cameras, screens and printers depends on profiles being present and correct.
A profile is built by measurement. A chart of known device values is displayed or printed, each patch is read with a colorimeter or spectrophotometer, and software fits the relationship between device values and CIE colour. Display profiles are usually a matrix and three tone curves. Printer profiles are lookup tables, one per rendering intent and direction. The profile connection space that links them is CIE colour relative to D50, which is why a profile conversion includes a chromatic adaptation step.
| Colour | CIELAB L*, a*, b* (D65) | CIELAB L*, a*, b* (D50) |
|---|---|---|
| Cobalt Blue #0047ab | 32.8, 22.5, −58.4 | 31.8, 14.4, −59.9 |
| Scarlet #ff2400 | 54.6, 76.2, 67.7 | 55.6, 77.2, 70.1 |
| Sage Green #9caf88 | 69.1, −13.7, 17.9 | 69.2, −12.2, 17.8 |
Cobalt blue is 32.8, 22.5, −58.4 relative to D65 and 31.8, 14.4, −59.9 once adapted to D50, a shift of 8.1 in a* alone. Neither set is wrong. A profile's job is to say which is meant, and a Lab value copied from a print specification into a tool that assumes D65 lands on a visibly different blue.
How this was calculated: D65 values come straight from the sRGB definition; D50 values apply Bradford adaptation before the CIELAB formula, as an ICC conversion from sRGB to the profile connection space does.
Artwork is supplied as CMYK with no profile, or with one for a different paper.
The printer has to guess which printing condition the numbers were prepared for. Values separated for coated stock and printed on uncoated come out heavy and dull. Naming the intended condition, or supplying RGB with a profile and letting the printer convert, removes the guess.
A monitor is profiled once and never again.
Backlights and panels drift with age, so the profile slowly stops describing the screen and colour-managed software corrects for the wrong device.