Details:
Summary:
The ICC color management system (CMS) has become a major tool for color image rendering and color matching in the printing and publishing industry. It attempts to automate color management functions, e.g., from scan to print, and from press sheet to proof, with the use of device profiles, Color Management Module (CMM), and application programming interface (API). Earlier studies on CMS performance have shown that ICC-based digital proofing does not perform better than a well calibrated film-based proofing system, in terms of delta E assessment. There are many sources of error in a digital imaging work flow. The source of errors include instability of imaging materials, device inconsistency, and the color gamut mismatch between devices. In addition, errors can come from profile generation and the performance of CMM. This paper describes a strategy for evaluating digital proofing performance under optimal testing conditions. Instead of conducting press runs, we use the ANSI CGATS TR 001-1995 - Type 1 reference printing condition as the source, and, hence, the published input ICC profile. Before we accept the Epson SC3000 as the digital proofer, we (1) tested the stability of the ink jet paper used, and (2) compared the color gamut differences between the Epson and the TR 001. The destination (proofer) profile was, then, built using the Kodak Colorflow ProfileEditor. To simulate the digital proofing effect, the IT8.7/3 basic data block, a standard TIFF (CMYK) file, was converted from source (press) to destination (proof) in Photoshop 5.0 API using ColorSync 2.6.1 and the Kodak CMM. The IT8.7/3 basic target of the ink jet proof, containing 182 patches, was measured colorimetrically (D50, 2 degree) and compared to ANSI CGATS TR 001-1995 - Type 1 Printing (SWOP) data. The average delta E between the digital proof and the CGATS TR 001 reference data set was 3.7 delta E (as opposed to 6-9 delta E reported previously.) This experiment demonstrates a significant improvement over previous research findings. The improved digital proofing performance of the ICC workflow was due to the elimination of the press variability, the use of a stable digital proofing device with a sufficiently large color gamut, and the use of improved ICC profiling and color management tools.