Adobe Photoshop CC 2014 v.14.xx - Manual (Page 848)

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Photoshop PDF files
Joint Photographic Experts Group (JPEG) format is commonly used to display photographs and other continuous-tone images in hypertext markup
language (HTML) documents over the World Wide Web and other online services. JPEG format supports CMYK, RGB, and Grayscale color
modes, and does not support transparency. Unlike GIF format, JPEG retains all color information in an RGB image but compresses file size by
selectively discarding data.
A JPEG image is automatically decompressed when opened. A higher level of compression results in lower image quality, and a lower level of
compression results in better image quality. In most cases, the Maximum quality option produces a result indistinguishable from the original.
Large Document Format (PSB)
The Large Document Format (PSB) supports documents up to 300,000 pixels in any dimension. All Photoshop features, such as layers, effects,
and filters, are supported. (With documents larger than 30,000 pixels in width or height, some plug-in filters are unavailable.)
You can save high dynamic range, 32-bits-per-channel images as PSB files. Currently, if you save a document in PSB format, it can be opened
only in Photoshop CS or later. Other applications and earlier versions of Photoshop cannot open documents saved in PSB format.
Most other applications and older versions of Photoshop cannot support documents with file sizes larger than 2 GB.
OpenEXR format
OpenEXR (EXR) is a file format used by the visual effects industry for high dynamic range images. The film format has high color fidelity and a
dynamic range suitable for use in motion picture production. Developed by Industrial Light and Magic, OpenEXR supports multiple lossless or
lossy compression methods. An OpenEXR file supports transparency and only works with 32 bits/channel images; the file format stores the values
as 16 bits/channel floating point.
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.
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:
Created when Preserve Photoshop Editing Capabilities is selected in the Save Adobe PDF dialog box. Photoshop PDF files
can contain only a single image.
Photoshop PDF format supports all color modes (except Multichannel) 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.
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