February 22, 2006
Common file Types in Commercial Printing & Design
There are quite a few file formats that you will encounter when designing your brochure, newsletter, business card, catalog, letterhead, or other print project. I have listed some of the most common you will deal with in commercial printing and design.
TIFF
TIFF stands for Tagged Image File Format and has been adopted by the American National Standards Institute (ANSI) and International Organization of Standards (IS0). TIFF files form high-resÂolution raster images of digital pages by converting vectored images to bits. TIFF files are large but are easily compressed.
There are at least six possible variÂeties of TIFF files. Some contain informaÂtion that gets sent to a RIP (raster image processor), which in turn gets processed into spots. Some TIFF files, including TIFF/IT, have already been converted to bitmaps. Some advertisers like TIFF files because they print the same regardless of the imagesetter or platesetter used, and they are easy to archive. An ad sent to ten publications in TIFF should look the same in every publication.
EPS
Encapsulated PostScript files are a subset of PostScript files that supports both raster and vector data. This means that you can crop and scale EPS images without destroying the integrity of the file created in the original application. For example, you could edit an image in PhoÂtoshop, crop it and place it on a page in WordPerfect, then output the WordPerÂfect file to a PostScript device.
EPS files also support embedding halftones and transfer curves, functions normally performed during raster image processing. Halftone embedding allows an application to set the frequency and shape of a halftone dot. Setting the halftone in the application overrides simÂilar functions in a RIP. Embedding of a transfer function allows you to make the image look lighter or darker when printing without affecting the original values in the image itself. If the transfer function is removed, the image will print with the original values
JPEG
Joint Photographic Expert Group files are compressed to save storage space and increase transmission speeds. JPEG files usually begin as EPS files.
Compression results in loss of image quality. JPEG offers many compression ratios. The highest ratio results in a small file but with the most lost data. The lowÂest compression ratio results in a less comÂpressed file with less loss to image fidelity.
PostScript
PostScript is a language that converts images and keystrokes from application files to coordinates that the RIPs of laser printers and imagesetters and platesetters can easily convert into spots. Because it works with pages and docuÂments created using application software, it's called a page description language.
The value of PostScript comes from its flexibility. Any output device using PostScript can print any document conÂverted to PostScript, meaning that files are printer and resolution independent.
The flexibility to create documents using various machines or applications and then print them using any output device is referred to as an open systems approach. Device independence makes PostScript one of the cornerstones of desktop publishing.
PDF
Portable Document Format files are best created after application files have been exported to PostScript.
PDF files allow users to view and print documents independently of the appliÂcations used to create them. Viewing is especially important: Alternative formats such as PostScript do not allow on-screen preview.
Adobe Distiller, the utility that creÂates the PDF file, interprets PostScript code and creates a display list. With these functions done, any device that creates halftone dots can display or image the dots from the PDF file. Resolutions are not determined until output on a RIP. ResÂolution independence means that you can repurpose PDF files for media other than print. For example, PDF images can appear on CDs and web pages.
PDF files have the additional advanÂtages of being searchable and relatively small. They also help avoid errors caused when a RIP cannot interpret PostScript. Correctly made PDF files minimize the need for preflighting and other prepress work. To ensure this benefit, consult with your printer to make sure you set DisÂtiller's preferences properly.
Miscellaneous formats.
These are just some of the common files you will come across on your day to day design and print jobs. There obviously are others out there such and PSD and GIF files, but this just gives a flavor of what is out there.
