Digital File Formats – When and How to Use Them

Here at Graphic Communications, we’re often asked by our customers which is the best file type to use when providing artwork for Hi-Res digital printing. The truth is, digital files can be saved in a number of different file formats, and can be moved between different imaging and page layout applications. Preparing your digital files for submission to a printer or service bureau involves many steps, but the first is understanding which digital files are suitable for each particular project.

Digital File Formats

EPS (Encapsulated Post Script) These types of files are used for placing images or graphics in documents created in word processing, page layout, or drawing programs. EPS files support both raster and vector data. An explanation of raster and vector data can be found below. An EPS file can contain any combination of text, graphics, and images. Since it is actually a PostScript file, it is the most versatile file format that is available.

GIF (Graphics Interchange Format) An 8-BIT, low memory option for posting images on the web. GIFs are used for raster or bitmap images. GIF images are limited to 256 colors, making them unsuitable for most print applications. They are well-suited for images containing large, flat areas of one color and are often used for graphics such as logos and line art.

JPEG or JPG (Joint Photographic Experts Group) JPEG files use a compression technique for images. They are used for placing imagery such as photographs in websites and online applications where high resolution files aren’t necessary. Because it is a “lossy” compression format, image quality is sacrificed to conserve disk space. JPEG images have a low resolution (72 dpi), therefore they are unsuitable for high quality print output.

PDF (Portable Document Format) PDF files are used for desktop printing or on-screen viewing. They allow documents to be viewed and printed independent of the application used to create them. Often used for transferring printed pages over the web, either for downloading existing publications, or for sending documents to service bureaus, or commercial printers for output.

TIFF (Tagged Image File Format) TIFF files are used for placing images or graphics in documents created in word processing, page layout, or drawing programs. Supports raster data and converts vectored images to bits. TIFF files can be cropped or edited. TIFFs are similar to EPS, but the smaller file size saves memory over an EPS format.

Raster Images   In computer graphics, a raster graphics image, or bitmap, is a dot matrix data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium. They cannot scale up to an arbitrary resolution without loss of apparent quality. This property contrasts with the capabilities of vector graphics, which easily scale up to the quality of the device rendering them.

Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics. Vector graphics are based on vectors (also called paths, or strokes) which lead through locations called control points. Each of these points has a definite position on the x and y axes of the work plan. Each point, as well, is a variety of database, including the location of the point in the work space and the direction of the vector (which is what defines the direction of the track). Each track can be assigned a color, a shape, a thickness and also a fill. This does not affect the size of the files in a substantial way because all information resides in the structure; it describes how to draw the vector. Vector graphics are infinitely scalable.

Source: Poppy Evans., Forms, Folds and Sizes, (Rockport Publishers, 2004)., Wikipedia.

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