21.2.1 Which Export Format Should I Choose

The format that you choose will depend on the target application. Publishers often have strict requirements for image file formats, so be sure to get details before creating your images.

Formats common to print publishing

Extension Format Name Features

TIF

Tag Image File

Raster format, ColorSpace options, Monochrome to True Color, File compression.

TGA

Truevision Targa

Raster format, 256 color to True Color.

EPS

Encapsulated Postscript

Vector format, ColorSpace options, True Color

PDF

Portable Document Format

Vector format, ColorSpace options, True Color

Vector formats are generally preferred for their scalability. It might seem reasonable to expect that vector images should be infinitely scalable, but the information necessary to describe these images can be considerable if data sets are very large. For formats that have ColorSpace options, publishers typically prefer CYMK over RGB.

Formats common to web publishing

There are two important considerations when creating images to be used on the web. You want to:

  • Minimize file size to increase download speed.
  • Choose a format that is supported by commonly used browsers.

The two most widely supported web image formats are JPG and GIF. PNG is growing in popularity as a replacement for GIF because it does not require licensing.

Extension Format Name Features

JPG

Joint Photographic Experts Group

Raster, Grayscale or True Color, Adjustable compression (lossy).

GIF

Graphics Image Format

Raster, 256 color, Lossless compression.

PNG

Portable Network Graphics

Raster, Monochrome, 16 or 256 colors, or True Color (24 bit RGB), Lossless compression.

Note that you must balance color and detail with download speed; the lower the color density and resolution, the faster the download speed. However, there may be times when you decide to sacrifice some download speed for more color or sharpness.

Since web pages are viewed on a computer screen, export at a resolution that approximates that of a computer monitor -72 to 120 dots per inch (dpi).

Formats for use by other applications

If you intend to edit your graphic file in another application, then you should choose that application's native file format or one of its supported formats.

Extension Format Name (type) Owner Application

AI

Adobe Illustrator (vector)

Abobe Illustrator

BMP

Bitmap (raster)

Windows Paint

CGM

Computer Graphics Metafile (vector)

Wordperfect

DXF

AutoCAD Drawing Interchange (vector)

AutoCAD

EMF

Enhanced Metafile (vector)

MS Office Applications

PCX

Zsoft PC Paintbrush Bitmap (raster)

PC Paintbrush

PDF

Portable Document Format (vector)

Adobe Acrobat

PSD

Adobe Photoshop (raster)

Adobe Photoshop

WMF

Windows Metafile (vector)

MS Office Applications

These formats may be raster or vector. There are fewer vector format editors available and some of those programs will 'rasterize' a vector format when it is loaded in the editor. Consult your owner application's documentation for details.