tailieunhanh - COLOR MANAGEMENT- P6

COLOR MANAGEMENT- P6: 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. | 134 Workflows Because of the role of black in image contrast color separation used to be something of a black art requiring a high degree of operator skill both in determining the amount of black as well as the physical process film or electronic used to produce the color separation. The effort invested in producing the color separation strongly discouraged most people from changing the CMYK separations once they had been produced. In fact many print buyers would insist on color separation integrity hence the rise of half-tone proofing. In the traditional CMYK workflow color separation integrity typically came at the expense of color fidelity. Working with CMYK files in a color-managed workflow where color transformations of content can take place in multiple locations either for re-separation or more commonly for proofing can be problematic. The classic problem for such workflows is the accidental introduction of an unintended CMYK-CMYK color transformation where one was not desired destroying the structure of the CMYK file in the process. Common problems which are observed include Pure black 0-0-0-K turns into four-color C-M-Y-K color build with resulting color shift misregister and or trap implications. Also known as the black type problem. Black channel proportionality relative to CMY changes resulting in a change in apparent contrast or TAC. Also known as the shape problem. Unintentional color management of CMYK which happens silently and untraceably in a workflow with several hand-offs of data. The problems with the color-managed CMYK workflow arise because of both color transformation mathematics as well as workflow data handling issues. Workflow data handling issues revolve around the choice of when in the workflow one chooses to perform a particular color transformation. Workflow data handling is partially addressed by the PDF X-1 data interchange standard ISO 15930-1 2001 E provided the Outputintents array information is set correctly. PDF X-1a ensures .