This is a special variant of ICC profiles that maps a color conversion directly from the source to the target in ONE profile. Each color of the source color space is hence directly mapped to a specific color of the target color space. Thereby, source and target color space can vary or be the same depending on the purpose of a DeviceLink profile. Unlike in ICC profiles that can be combined freely as source and target profiles, a special DeviceLink profile is calculated for each specific task. DeviceLink profiles are specified by the International Color Consortium (ICC).
DeviceLink profiles complement the use of standard ICC profiles to bypass the weak points of an ICC profile based color conversion for specific tasks. These are available primarily during conversion from CMYK to CMYK and in a custom-made conversion or optimization for specific purposes - e.g. preservation of a font in an image built in pure black.
Another advantage of the DeviceLink technology is that color data can be changed only when it is effectively necessary. If no change is necessary, the separation is also not changed - a fact that is rather impossible during the ICC profile based conversion!
For a conversion of already “separated” CMYK print data, a pure ICC profile based approach is not optimum, because some architecture-specific features of the CMYK original data are lost. This is substantiated by the fact that a conversion from CMYK (4-channel) to CMYK (4-channel) via ICC profiles is always via the device-independent color space Lab (3-channel) and hence necessarily leads to a complete reseparation of the already separated data - with partially unforeseen and typographically unwanted results.
DeviceLink profiles are particularly suitable wherever complete print data (e.g. as PDF) must be converted from CMYK to CMYK, because here a specific control of the color structure is possible, e.g. to get specific colors or color combinations.
Most prominent example is the black generation that can be acquired through conversion using a DeviceLink profile. Therefore, you can be sure that a text built in pure black or a technical tone consists of only pure black even after the conversion. Similarly, uncolored tones (CMK, MYK, CYK) or combinations from primary or secondary colors can be retained.
From: PDF Document “DeviceLink_FAQ”, Impressed Computertechnologie Vertriebs GmbH