File Formats



File Formats

File formats refer to the different formats in which image files can be saved.

How you intend to use a format will determine the format you should use.

To save a file choose File+Save, File+Save As, or File+Save a Copy As.

In the dialog box, you will see a drop-down menu that offers you these options.

• Photoshop (.psd): This is, of course, the native Photoshop format. This is the optimum file to use while you are still working in Photoshop. It enables layers

• Bitmap (.bmp): This is a Windows compatible file format. It is lossless, meaning that no file information is discarded whatsoever when you save.

• EPS (.eps): This is an Encapsulated Postscript file, a great option for line art and for when you want to import line art into page layout programs.

• GIF (.gif): The Graphics Interchange Format is an excellent choice for the web. Use the File+Export Gif89a to create transparent GIFs. See Day 14, "Photoshop for the Web," for more information on this format.

• JPG (.jpg): This the Joint Photographic Group Experts file format. This is a lossy format. Depending on how you save the file, image information, for the sake of conserving file size, is discarded. You can adjust these settings as you save. This is a great option for the World Wide Web (see Day 14 for more information).

• PDF (.pdf): This stands for Portable Document Format. It works in conjunction with Adobe's Acrobat product, which is another option for web publishing.

• PNG (.png): This format is an alternative to the GIF file format. It is great for web publishing and is growing in popularity. It enables you to save your files such that they download progressively over the World Wide Web.

• TIFF (.tif): A very common format, the Tagged-Image File Format works cross-platform and uses lossless LZW compression (meaning that no image data is discarded from an image as it is compressed.

AI - is Adobe® Illustrator's metafile format, a type of Encapsulated Postscript format.

BMP -  is the standard Microsoft® Windows® bitmap format for images up to 24 bit (16,777,216 different colors). BMP is the native bitmap format for Windows®.

DWG - the AutoCAD® Drawing is the standard file format for saving vector graphics created in AutoCAD.

DXF - the AutoCAD® Interchange File is a drawing interchange format for exporting AutoCAD drawings to or importing drawings from other applications. The DXF format is a tagged data representation of all the information contained in an AutoCAD drawing file.

EPS - the EPS file format is used to transfer PostScript language artwork between applications and is supported by most illustration and page-layout programs. Typically, EPS files represent single illustrations or tables that are placed onto a host page, but an EPS file can also represent a complete page. Because EPS files are based on the PostScript language, they can contain both vector and bitmap graphics.

In addition to the PostScript language representation of the graphics to be placed, many EPS files contain a bitmap preview of the graphic that the application can display. EPS files intended to be used by Macintosh applications, for example, can contain PICT or TIFF images for screen preview; those intended for use by Windows applications contain either TIFF or Windows Metafile bitmap images.

GIF - the Graphics Interchange Format (pronounced "JIF") is the file format commonly used to display indexed-color graphics and images over the World Wide Web. GIF animations are popular on the Internet because they are compatible with all browsers. GIF images are limited to 256 different colors. GIF is an LZW-compressed format designed to minimize file size and electronic transfer time.

There are two distinct types of GIFs:

• The GIF87 format is used for bitmaps only.

• The GIF89a format adds transparency and animation.

The GIF89a format supports binary transparency by allowing one of the indexed colors to be fully transparent, but does not support partial opacity as found in an alpha channel.

JPEG - the Joint Photographic Experts Group File Interchange Format is commonly used to display photographs and other continuous-tone images over the World Wide Web. JPEG format does not support transparency.

A JPEG image can be compressed using "lossy compression". JPEG compresses file size by selectively discarding data. Because of this, JPEG compression is referred to as lossy. 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.

PDF - the format used by Adobe Acrobat, Adobe's electronic publishing software for Mac OS, Windows, and UNIX. PDF can represent both vector and bitmap graphics and can also contain electronic document search and navigation features. PDF files, for example, can contain hypertext links and an electronic table of contents.

You can view PDF files using Acrobat Reader software available from Adobe for free.

PNG - The Portable Network Graphics format (pronounced "ping") offers 1-bit thru 48-bit images. Developed as a patent-free alternative to GIF, Portable Network Graphics (PNG) format is used for lossless compression and for display of images on the World Wide Web. Unlike GIF, PNG supports 24-bit images and produces background transparency without jagged edges; however, some Web browsers do not support PNG images.

PSD - is Adobe® Photoshop's native format for layer and image data.

SWF - the Macromedia® Flash format is a version of the Macromedia® Flash Player vector-based graphics format for interactive, animated Web graphics. You can create artwork to the Macromedia Flash format for use in Web design, and view the artwork in any browser equipped with the Macromedia Flash Player.

TIF - the TIFF ( Tag Image File Format) is used to exchange files between applications and computer platforms. TIFF is a flexible bitmap image format that is supported by virtually all paint, image-editing, and page-layout applications. Also, virtually all desktop scanners can produce TIFF images.

TIFF files are relatively large 24-bit color images used by most professional graphics software and many pre-press firms to create publications.

TIFF supports RGB, CMYK, and grayscale color models. It also supports LZW compression, a lossless compression method that does not discard detail from the image.[pic][pic][pic][pic][pic][pic]

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download