Adobe 13102498 User Guide - Page 471

PHOTOSHOP CS3 464 User Guide PCX PCX format is commonly used by IBM PC-compatible computers. Most PC software supports version 5 of PCX format. A standard VGA color palette is used with version 3 files, which do not support custom color palettes. PCX format supports Bitmap, Grayscale, Indexed Color, and RGB color modes, and does not support alpha channels. PCX supports the RLE compression method. Images can have a bit depth of 1, 4, 8, or 24. PDF Portable Document Format (PDF) is a flexible, cross-platform, cross-application file format. Based on the PostScript imaging model, PDF files accurately display and preserve fonts, page layouts, and both vector and bitmap graphics. In addition, PDF files can contain electronic document search and navigation features such as electronic links. PDF supports 16-bits-per-channel images. Adobe Acrobat also has a Touch Up Object tool for minor editing of images in a PDF. For more information about working with images in PDFs, see Acrobat Help. Note: The Touch Up Object tool is mainly for last-minute revisions to images and objects. It's best to do image editing in Photoshop before saving as PDF. Photoshop recognizes two types of PDF files: Photoshop PDF files and generic PDF files. You can open both types of PDF files. When you save PDF files, Photoshop saves them as Photoshop PDF files by default. Deselect Preserve Photoshop Editing Capabilities in the General section of the Save PDF dialog box to save a generic PDF file. Photoshop PDF files Created using the Photoshop Save As command with Preserve Photoshop Editing Capabilities selected in the General section of the Save PDF dialog box. Photoshop PDF files can contain only a single image. Photoshop PDF format supports all of the color modes (except Multichannel mode) and features that are supported in standard Photoshop format. Photoshop PDF also supports JPEG and ZIP compression, except for Bitmap-mode images, which use CCITT Group 4 compression. Generic PDF files Created using the Photoshop Save As command, with Preserve Photoshop Editing Capabilities deselected in the General section of the Save PDF dialog box, by creating a PDF presentation in Photoshop, or by using applications other than Photoshop, such as Adobe Acrobat and Adobe Illustrator. They can contain multiple pages and images. When you open a generic PDF file, Photoshop rasterizes the image. PICT File PICT format is used in Mac OS graphics and page-layout applications as an intermediary file format for transferring images between applications. PICT format supports RGB images with a single alpha channel and Indexed Color, Grayscale, and Bitmap mode images without alpha channels. PICT format is especially effective for compressing images with large areas of solid color. This compression can be substantial for alpha channels with their large areas of white and black. When saving an RGB image in PICT format, you can choose either a 16-bit or 32-bit pixel resolution. For bitmap and grayscale images, you can choose from 2, 4, or 8 bits per pixel. In Mac OS with QuickTime™ installed, four JPEG compression options are available. PICT Resource (Mac OS) A PICT resource is a PICT file but takes a name and resource ID number. The PICT Resource format supports RGB images with a single alpha channel, and Indexed Color, Grayscale, and Bitmap mode images without alpha channels.