When you color match files that contain transparent objects, there can be significant changes in appearance. This is especially true for Ink Optimizing workflows.
This problem is file-specific and can be related to the transparency blending modes that were applied, the color of the objects, and the ICC DeviceLink or ICC device profile that was used to color convert the objects. The problem occurs because each graphic and image object used in the transparency group is color converted separately. Blending the objects in the destination color space after color converting changes their appearance.
Recommendation: Flatten PDF files before color matching. If your PDF files contain RGB data, it is strongly recommended that you color convert this data prior to flattening.
While any CMYK to CMYK ICC transformation can be subject to color shifts, the ink optimizing profiles are especially prone to this problem. When you are creating or processing PDF files to which you will apply Ink Optimizing GCR ICC DeviceLink profiles (from ColorFlow or another source), use one of the best practices described next. While these best practices will create more predictable PDF files, there is no substitute for strict quality control, and proofing is always highly recommended.
- Best practice when you control input file creation
- Best practice when you cannot control input file creation
Notes and References
- See the Prinergy Workflow Activity Guide for more information about working with presets and creating Press Ready PDFs.
- Useful Flattening articles: