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If you’re new, or even not so new to the Mac, you may find the variety of cryptically - named graphics file formats -- TIFF, GIF, PICT, etc., confusing.

For Web work you will encounter JPEG, GIF, and more recently PNG files. The Mac’s default screen capture or screenshot formats are PICT for the legacy Mac OS, and TIFF with OS X.

PICT is an Apple proprietary format used for the user - interface icons in the Classic Mac OS, and also as the native file format for Mac object-oriented drawing programs, although bitmap graphics (“painting”) programs also support it. The Classic Mac clipboard also uses PICT as its graphics support format, and the SimpleText utility can open PICTs. While PICT files have served the Mac community well, they are not portable across platforms, and are less precise in rendering than some other formats, and with the advent of OS X, PICTs are on their way out.

TIFF files (TIFF stands for Tagged Image File Format) are very high density bitmap images that involve no compression, and they tend to be much larger than PICT files. Most scanners produce TIFF images. TIFF is a standard format in publishing and an excellent choice for quality digital images.

JPEG (or .jpg) files are the most popular graphics format for compressed photographic images for use on Web pages or sending photos via email. JPEG is an acronym for the Joint Photographic Experts Group, which developed JPEG as a file protocol for bringing digital photos down to manageable file sizes. For example, a 1.2 MB TIFF file might be reduced to only 100k as a JPEG.

The reason for this is that JPEG is a “lossy” format -- during the compression process, a great deal of the color information that TIFF files fussily record is discarded, but for low-resolution reproduction, such as on a computer screen in a Web browser, the loss is not apparent.

GIF or Graphics Interchange Format is the other traditionally popular Web graphics format. Originally developed by CompuServe, GIF is still a proprietary format, now owned by Unisys, which has decided to become a copyright bully and demand royalties for use of the GIF format, which has seen GIF eliminated as a save format from some newer graphics programs, and its popularity diminish substantially.

GIFs are, or were, a convenient format, readable by any Web browser on any platform, but they are technically unsophisticated, supporting a maximum of only 256 colors, making GIF a poor format for photographic reproduction. Their main virtue is compatibility and relatively small file sizes, but they are being superseded by the PNG format. However GIF supports animations, which PNG does not.

PNG (Portable Network Graphics) is a relatively new graphics file format developed by the World Wide Web consortium as a replacement for dog-in-the-manger Unisys’ GIF. Unlike GIF, PNG files can support more than 256 colors, and unlike JPEG, they don’t lose quality when compressed, however JPEG is still the preferred file format for Web photos.

PDF is Adobe’s ubiquitous Portable Digital File format which works across platforms and also of forms the basis for the OS X Quartz graphics subsystem. PDF files were originally supported only by Adobe’s Acrobat and Acrobat Reader applications, but PDF support is being included in many more applications these days, and the OS X Text Edit word-processor, for example, can save files as PDFs. PDF files retain very high reproduction quality, and are becoming the file format of choice for image transfers, especially across platforms.

Photoshop (.psd) files are the Adobe Photoshop proprietary graphics format, useful mainly when working in Photoshop, or transferring files to another Photoshop user. OS X however can open (and OS X Preview can export) Photoshop files, which is a convenience.

EPS or Encapsulated PostScript is a graphics file format developed by Adobe for graphics support with PostScript printers. They are both large and complex, and somewhat difficult to work with, but support high quality printed images,