What’s the difference between all those types of graphic files?

Anyone involved with events at some point needs to deal with graphics files.  It is often required to send logo files, photos, etc. to designers for use on the web, banners or PPT presentations. But how do you know which ones to use for the best result? Here’s a brief tutorial that you may want print out and hang on your wall for reference.

Graphics file formats vary depending on how they were created, in what software program, as well as their application.  Let’s start with the two main types of graphics files, then list the various types and how they are used.

There are two main types of graphics files: Raster and Vector.

Raster File Types: 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. Raster images are stored in image files with varying formats. Think of these as lower resolution.  For a complete list of Raster file formats, click here.

Vector File Types: 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”, in this context, implies more than a straight line. These are very high resolution files that can be enlarged without forfeiting quality.  For a complete list of Vector file formats, click here.

Under each of these broad categories are the most common image file formats and which are most appropriate for printing, scanning, and Internet use.

.ai: Adobe Illustrator File. As the industry’s leader in software for creating vector graphics, Adobe Illustrator files are commonly used in the creation of logos by graphic designers all over the world. These files can also be supplied to printers for use when printing in large format or to other designers for creation of business collateral (advertisements, brochures, business cards, etc.)

.bmp: The Windows Bitmap or BMP files are image files within the Microsoft Windows operating system. These files are large and uncompressed, but the images are rich in color, high in quality, simple and compatible in all Windows OS and programs. BMP files are also called raster or paint images. When you make a BMP image larger, you are making the individual pixels larger, and thus making the shapes look fuzzy and jagged. BMP files are not great and not very popular.

.eps: Encapsulated PostScript File. .eps files are often used for signs, banners, and billboards…or anything that is to be printed in large format. Vector graphics are easily scalable and can be used at any size without loss of image quality or definition. They can also be supplied to print designers for use in their designs, guaranteeing an image that prints clear and crisp.

.gif: GIF uses only up to  256 colors from a pool of 16 million. If the image has fewer than 256 colors, GIF can render the image exactly. Otherwise, it approximates the colors as closely as possible.  Thus, GIF is “lossless” only for images with 256 colors or less. For a rich, true color image, GIF may “lose” 99.998% of the colors. GIF is still very good for web graphics (i.e., with a limited number of colors). For graphics of only a few colors, GIF can be much smaller than JPG, with more clear pure colors than JPG).

.jpg (.jpeg): JPEG is short for Joint Photographic Experts Group, and is the most popular among the image formats used on the web. JPEG files lose information from the original image when you save it in JPEG file. This is because JPEG discards most of the information to keep the image file size small, which means some degree of quality is also lost. While a .jpg will excludes some data, it is widely used and easily opened by most anyone with a computer. JPEG files are commonly used for photos but are also acceptable for logo or advertisement files.

.pdf: Portable Document Format (PDF) is an open standard for electronic document exchange.  When you convert documents, forms, graphics, and web pages to PDF, they look just like they would if printed. But unlike printed documents, PDF files can contain clickable links and buttons, form fields, video, and audio — as well as logic to help automate routine business processes. When you share a PDF file, virtually anyone can read it using free Adobe Reader® software or the Adobe Reader mobile app. (As a side note, some .pdfs can also be used as vector files so long as they were developed in Illustrator (or other vector software) and saved properly for this use.)

.psd: Adobe Photoshop Document. .psd’s are typically layered files in which designers can manipulate the text, images, shapes and format. These can be created in any size, resolution and color space.

.png: Portable Network Graphic. These are often used in web-based design and applications but can also be supplied in CMYK/300dpi if intended for print use. These are easier to use in web activities as the transparencies remain intact and are of better quality than .GIF’s.  PNG is, in all aspects, the superior version of the GIF. Just like the GIF format, the PNG is saved with 256 colors maximum but it saves the color information more efficiently.

.tif (.tiff): Tagged Image File. These files are the preferred file format for print designers as they are widely accepted by many of the design software programs and are equipped with all the file data. TIFF is a rich format and supported by many imaging programs. It is capable of recording halftone image data with different pixel intensities, and is the perfect format for graphic storage, processing and printing. This makes TIFF the superior raster image format.

Page Layout File Types

.indd: Adobe InDesign File. These are layout files with one or more pages arranged in a particular order.

.qxd: QuarkXPress File. Like .indd, these are layout files with one or more pages arranged in a particular order.

.pdf: Portable Document File : see above.


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