tailieunhanh - COLOR MANAGEMENT- P2

COLOR MANAGEMENT- P2: ICC White Papers are one of the formal deliverables of the International Color Consortium, the other being the ICC specification itself – ISO 15076: Image technology color management – Architecture, profile format, and data structure. The White Papers undergo an exhaustive internal development process, followed by a formal technical review by the membership and a ballot for approval by the ICC Steering Committee. | 14 General medium in order to enable improved interoperability within a single vendor s products. Because PCS colorimetry may not be accurate relative to the original the CMM cannot rely on the source colorimetry as represented in the PCS and as a result v2 profiles will not support advanced CMM color rendering. There are also other issues that arise with v2 profiles because of the ambiguity of the v2 specification and incorrect interpretation of the specification in constructing profiles. The ICC v4 Solution In ICC v4 colorimetric rendering intents are measurement based. They can therefore be relied on for proofing and provide accurate colorimetry for CMM color re-rendering. Specification ambiguities are largely resolved and the text clarified to reduce the occurrence of incorrect implementations. A well-defined reference medium for the perceptual intent with an associated gamut known as the Perceptual Reference Medium Gamut PRMG ensures crossvendor interoperability. There is also greatly increased transform capability through extended look-up table LUT definitions such as the lutAtoBtype which incorporates an additional matrix and curve and provides greater mathematical flexibility and an improved definition of 16-bit CIELAB. ICC v4 Perceptual Intent Significant improvements have been made to the interoperability of the v4 perceptual path. The v4 perceptual intent color reproduction path is illustrated in Figure . With the PRMG both input and output profiles can be based on a well-defined intermediate image colorimetry appropriate for the PCS reference medium and viewing conditions. The task of the CMM is thus to connect profiles with the same or very similar PCS gamuts and minimal gamut mapping is required because the image colorimetry in the PCS is matched for the input and the output. Differences between source and output media color gamut and viewing condition are then dealt with consistently within the mapping to or from the reference medium .