The advantage offered by the ICC system over proprietary color management systems is its potential interoperability. This not only requires agreement on a file format but also on the way this format communicates appearance. The successful use of the format requires both cross-media and cross-environment transformations. To achieve interoperability, the ICC format places these transformations in the profile rather than in the color management engine. This paper does not attempt to summarize the ICC specification. Instead, it establishes a broader context for understanding the way the design of the ICC communicates color.