.ai (Illustrator), .psd (Photoshop), .qxd (QuarkXpress),
.indd (InDesign), .p65 (Pagemaker), .cdr (CorelDraw), .fh10 (Freehand)
These are native file formats created by the authoring software. Only the authoring software can create or open these files. For example a Illustrator file cannot be opened by QuarkXpress or saved as a QuarkXpress file.
Postscript is a computer language optimized for printing graphics and text. The main purpose of PostScript is to provide a convenient language in which to describe pages of images, graphics and text to different print devices. When a document is printed, the information is converted to postscript and sent to the printer where the information is rendered on the page or saved as a file.
.eps (encapsulated postscript)
An EPS file is a little capsule of postscript information that can be opened or placed into various programs like Illustrator or Quark for output. EPS files can contain either vector artwork, bitmap images or a combination of both. Illustrator and Photoshop can both create EPS files. An EPS file created in any vector-based program can be opened in Illustrator (ie, a Freehand EPS or Quark EPS can be opened in Illustrator). Keep in mind, Illustrator cannot open and edit a Photoshop EPS because as mentioned, Photoshop is bitmap-based software.
.tif (tagged image file format)
TIF files are the preferred bitmap file format. They are created in Photoshop and can be placed into other software for output.
.jpg (joint photographic experts group)
JPG's are a compressed, bitmap file format created in Photoshop. When a photo is saved as a JPG it is compressed and all the nonessential data is removed in order to make the file size as small as possible. When saving a file as a JPG, the amount of compression can be chosen. As the compression increases, the image quality will decrease.
.gif, .pcx, .wmf, .bmp
These files are very low quality bitmap images and are not intended for high quality printing.
.pdf (portable document format)
A file format that preserves a digital file’s original layout, fonts and graphics as one unit for digital transfer and viewing. PDF files are referred to as a final page format because they are in most cases not meant to edited. A properly created PDF can be easily printed and viewed correctly on any computer.
.sea, .bin, .zip, sit (compressed files)
These files where created in a compression program. Compression programs take one or a group of files and compresses them to make the combined file sizes smaller while retaining the quality of the files. This is extremely helpful when
sending files over the internet.
Any vector artwork should be saved as an EPS to be placed into page layout software. Any bitmap images should be saved as a TIF. The only instances where a bitmap image must be saved as a EPS is when the image is a duotone or there is a clipping path in the image. Never resave a JPG file because each time a JPG is resaved a compression occurs which will slowly decrease the quality of the image.