Adobe 65023809 Printing Guide - Page 64

Suite workflow, the integration between Photoshop, InDesign, Illustrator, and Acrobat means that you can take advantage of the native Photoshop image format for successful output. By the same token, converting layered Photoshop files or native Illustrator files to EPS will flatten transparency, limit functionality, and may radically change the appearance and output of such files. Let's look at some of the advantages-and shortcomings-of popular image formats. Photoshop native Photoshop's native format (PSD) offers a number of significant advantages for designers: • An unlimited number of layers. • Layer masks for nondestructive masking. • Adjustment layers for nondestructive color correction and special effects. • Opacity controls. • Blending modes that allow color interaction between layers. • Special effects such as drop shadows and embossing. • Spot-color support. • Vector-drawing capabilities. • Clipping paths and vector masks for silhouetting objects. • Importing 3D content from CAD programs. • Editing and painting directly on 3D layers. Photoshop PSD files support CMYK, RGB, and Lab color spaces, as well as grayscale, multichannel, and multitone (duotone, tritone, and so on). All of these aspects of PSD files remain intact when Photoshop files are placed into Illustrator or InDesign documents, with the exception of blending modes. While opacity attributes of a Photoshop file are honored by Illustrator and InDesign, blending modes are not. See the "Photoshop Blending Mode Issue" topic in the InDesign chapter of this document for more information on the issue and how to work around it in InDesign. Current versions of InDesign and Illustrator support layered PSD files, so there is no need to flatten layers for output. Because InDesign allows overrides to Photoshop layer visibility with Object Layer Overrides, flattening an image whose appearance is managed by InDesign would result in incorrect output. If you are concerned about storing large Photoshop files, note that, pixel-for-pixel, a Photoshop file usually takes up less space on disk than an equivalent TIFF or EPS file. Certainly, a large, complex file with many layers will result in a larger file size, but consider it a fair trade-off for the flexibility such a file provides. If a customer's file contains unused, hidden layers, consult with the customer before deleting such layers to reduce file size. If the file is used in an InDesign document, determine whether those layers are rendered visible by Object Layer Options or required for alternate versions of the image on another part of the job. In some OPI (Open Prepress Interface) workflows, native Photoshop files may require special handling. In a traditional OPI environment, special low-resolution EPS files are used as placeholders; within those EPS files are OPI comments that refer to the name and location of highresolution files to be used for imaging. A server-based function performs the image swap before the RIP. Photoshop native files are not used in this type of workflow. But some modified OPI workflows don't use formal EPS-based image swaps; instead, these workflows allow all image formats and defer including high-resolution image data until the RIP. You may find that, in such a workflow, you will need to embed Photoshop files in the Illustrator or InDesign documents before generating PostScript, or you may have to include the Photoshop files in the print stream (as opposed to omitting them during print). Consult your RIP's documentation for instructions on correctly handling native Photoshop images if you use such a workflow. Now, let's look at some of the unique capabilities of native Photoshop files. Vector content in Photoshop images While most Photoshop images are composed solely of pixels, Photoshop also supports the inclusion of vector information. Vector text, vector-based Shape layers, vector masks, and Smart Objects can coexist with pixels in a Photoshop file. Such content remains editable throughout Adobe Creative Suite 4 Printing Guide 62