Frequently Asked Qustions

The ICC specification available on this web site has recently undergone a major revision. The following questions and answers will help you understand why it was revised in such a major way, and what the revision is intended to achieve.

Q. Why do we need a new profile version?

Version 2 was released in 1993. With Version 4 vendors will find it easier to develop color management profiles for their products that are unambiguous, so that when used they will inter-operate more successfully with those of other vendors and also be used in a more consistent manner by different CMMs. This trouble-free inter-operability has been a prime goal of the entire ICC specification development process, and we believe Version 4 achieves this goal more fully than any previous effort. Version 4 also addresses specific operational problems revealed by a recent ICC user survey, as well as by ICC members' continuing support of their own customers.

Q. What is new in this version?

Among other provisions, Version 4 includes:

• Improved definition of the PCS for the perceptual rendering intent;
• Improved specification of Chromatic Adaptation;
• Clarification of the relationship of CIELAB and CIEXYZ to the PCS;
• A better explanation of the Profile Connection Space;
• New lookup table types, which provide a common structure for color transformations in all profiles;
• Better definition of the encoding used with monochrome profiles;
• Improved naming and other conventions;
• A set of multilingual Unicode strings for better internationalization of profiles.

Representatives from all the ICC member companies developed the specification jointly.

Q. What happens if an old application is handed a Version 4 profile?

Most applications tend to ignore profiles they don't understand. So the document is processed as Device RGB or Device CMYK. Or color management is turned off. Some applications will process Version 4 profiles as if they were Version 2 profiles, which can produce unexpected results. Some applications will crash trying to access data types that no longer exist in Version 4 profiles.

Q. Can I use Version 4 profiles with my PostScript printer?

PostScript printers don't use ICC profiles. They use Color Space Arrays and Color Rendering Dictionaries. If the application creating the PostScript file can use Version 4 profiles, then yes, you can print using Version 4 profiles. The application will convert the ICC profile to a Color Space Array.

Q. How can I check if a profile is compliant with the ICC specification?

A few tools are available. MacOS 10 includes a Version 4 profile validator as part of the ColorSync Utility. For PCs the Profile Inspector on this web site, which can be downloaded free of charge, is Version 4 compliant.

Q. Are Version 2 profiles obsolete now?

No. All products using Version 4 profiles must be able to use Version 2 profiles as well. Version 2 profiles will remain usable at least until a Version 5 specification is released. There are no concrete release plans for a Version 5. The Version 4 specification was introduced seven years after the Version 2 specification.

Q. Was there ever a Version 3? Did I miss it?

Yes and No. The version number stored in the previous version of profiles was 2.x. However, the specification for that profile format has been called 3.x, clearly out of sync with the version value in the profile itself. ICC decided to re-synchronise the file and the specification by changing both to 4.x.

Q. How can I contribute to the next generation of ICC specifications?

Start by reviewing the material on this web site. Then become a member and join a working group.