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Graphic File Formats

Two Types of 2D Graphics:

Bitmap Images are made up of individual pixels, or tiny dots of individual color that make up the image that you see. Bitmap images are resolution dependent. Resolution refers to the number of pixels in an image and is usually stated as dpi (dots per inch) or ppi (pixels per inch). When resizing a Bitmap image, software used to do this function either must throw out pixels to make the image smaller, or it must create new ones to make the image larger. Both options can sacrifice the quality of the image.

Common bitmap formats:

Popular bitmap editing programs:

Vector Graphics are made up of many individual objects. Each of these objects can be defined by mathematical statements and has individual properties assigned to it such as color, fill, and outline. Vector graphics are resolution independent because they can be output to the highest quality at any scale (Chastain, 2005).

Common vector formats:

Popular vector drawing programs:

Common Graphic File Formats

Extension Description Best for
BMP The Bitmap file format is used for bitmap graphics on the Windows platform only. Unlike other file formats the BMP format stores image data from bottom to top and pixels in blue/green/red order. Compression of BMP files is not supported, so they are usually very large (Realsoft, 2005). Windows Desktop Wallpaper
CGM The Computer Graphics Metafile is designed to be a standard vector graphics file format. It is supported by a wide variety of software, particularly word processing programs (Beal 2005). CAD software files
GIF This format is typically used for images published on the web. The Graphics Interchange Format was originally developed by CompuServe in 1987. It is most commonly used for bitmap images composed of line drawings or blocks of a few distinct colors. The GIF format supports 8 bits of color (up to 256 total colors) information or less (Realsoft, 2005). Web publishing of photographic images
JPEG, JPG This is the format used in most digital cameras and for photographs. Like GIF, the Joint Photographic Experts Group format is one of the most popular formats for Web graphics. It supports 24 bits of color information, and is most commonly used for photographs and similar continuous-tone bitmap images. The JPEG file format stores all of the color information in an RGB image. JPEG was designed so that changes made to the original image during conversion to JPEG would not be visible to the human eye. Most imaging applications let you control the amount of lossy compression performed on an image, so you can trade off image quality for smaller file size and vice versa (Realsoft, 2005). Web publishing of photographic images; saving images from a scanner or digital camera
PNG The Portable Network Graphics format will likely be the successor to the GIF file format. PNG is expected to become a mainstream format for Web images and could replace GIF entirely. It is platform independent and should be used for single images only (not animation). Compared with GIF, PNG offers greater color support and better compression, gamma correction for brightness control across platforms, better support for transparency, and a better method for displaying progressive images (Realsoft, 2005). Web publishing of photographic images
TIFF The Tag Interchange File Format is a tag-based format that was developed and maintained by Adobe. TIF, which is used for bitmap images, is compatible with a wide range of software applications and can be used across platforms such as Macintosh, Windows, and UNIX. The TIFF format is complex, so TIFF files are generally larger than GIF or JPEG files (Realsoft, 2005). High resolution printing of images
WMF Windows Metafile Format graphics file format is used to exchange graphics information between Microsoft Windows applications. WMF files can hold both vector and bit-mapped images (Beal 2005). Transfer vector images via the clipboard

References:

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Last modified: Jul 14, 2009, 15:54 EDT
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