ICC Version 2 or 4?

In 2001 the International Color Consortium published a revised specification for ICC profiles. The version 4 specification addressed various issues and ambiguities with the previous spec, version 2 (I don’t know what happened to version 3). The ICC consists of highly qualified, experienced colour scientists and colour management experts who firmly believe in the advantages of the version 4 specification. However, most colour management practitioners still recommend using version 2 ICC profiles 12 years after the release of the new spec. Why?

Version 4

Version 4 tightened the specifications for various values used in the colorimetric and perceptual rendering intents that should give better and more consistent colour transformations. The ICC have many webpages extolling the virtues of the v4 spec – http://www.color.org/v4spec.xalter but the ICC only creates the specification. Companies such as X-Rite and DataColor make the profiling software and then a myriad of companies such as Adobe, Apple and Microsoft make software that can use ICC profiles in colour transformations. So while the specification of v4 is theoretically better than v2 there are problems in implementing v4 profiles in the real world.

Software Support

The first issue is that not all software supports version 4 profiles. Newer versions of Photoshop and other mainstream applications do and have done for a while but older versions may not. It took a long time for some developers to include v4 support in their applications and you may have one Adobe product, for example, that supports v4 and one that doesn’t. Or you may have software that does support v4 but perhaps displays some bugs with the implementation. Early versions of Lightroom had issues with v4 profiles, many versions of Firefox and Internet Explorer don’t support v4 profiles and early versions of Apple’s Snow Leopard operating system didn’t support them either. Sometimes if colour management isn’t a core function of the software or isn’t used by many customers it can take a very long time for developers to devote the resources to implementing the new spec. Quite often when supporting customers on the phone who are having a problem with their profiling software getting them to switch to version 2 profiles fixes the issue. But to be fair on very rare occasions switching to v4 fixes some problems as well.

Mix and not Match

The second issue is that it’s not a great idea to mix version 4 and version 2 profiles in the same workflow as the differences in the specs can lead to worse conversions than if you stuck to one or the other. This is a problem since there isn’t a version 4 copy of common working space profiles such as Adobe RGB and or printing standards such as FOGRA39, although the ICC does have a version 4 sRGB profile available for download.

Best Practice

Don’t get me wrong, if you are creating or using v4 profiles then you don’t necessarily need to switch. Most ICC profiling software, such as i1 Profiler, defaults to creating v4 profiles so unless you’ve changed the options you may well be using v4 without knowing it. But if you are getting odd results or inconsistencies between different applications then swapping to version 2 would be a very good trouble-shooting idea.

At the time of writing version 2 ICC profiles are the safer bet. I certainly make all my profiles as version 2. The theoretical advantages of version 4 profiles don’t yet correspond to real world improvements in colour reproduction for many users and due to inconsistent implementation by some software developers they can lead to problems.

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