Basic graphics file formats:

BMP the default bitmapped images used in the Microsoft Windows world. There is no compression. In a true color BMP with 16,000,000 colors, each pixel in the bitmap requires three bytes to store its color information. True color is also called 24-bit color, with one byte or 8 bits for the red component, 1 byte for the blue component, and 1 byte for the green component of the pixel's color. In a 256-color BMP, the color information for each pixel is stored in a single byte. That byte tells which of 256 colors on a color palette the pixel should display. All BMP graphics are rectangular. Because BMP files are Windows specific, they do not work on Web pages.

GIF (Graphics Interchange Format) bit-mapped file format maintains resolution and sharpness even when compressed. The Graphics Interchange Format compresses 256-color bitmapped graphics. Because colors in the graphic are limited to a palette of 256 hues, GIF format is best suited for clipart and diagrams. The GIF format is not effective for detailed photographs. The GIF format was developed in 1987 by CompuServe Information Service. Everyone is free to use GIF-formatted files on Web pages. The GIF89a format adds animation to GIF images by using multiple images in one file.

JPEG (Joint Photographic Experts Group) is named after the group that wrote the standard. (Either the file extention .jpg or .jpeg can be used.) Compresses images smaller than GIF using a lossy compression technique for color images. The image creator can specify image quality in trade for file size. Some amount of data is lost, lossy compression technologies attempt to eliminate redundant or unnecessary information. The smaller the file size, the more picture information is lost, and the further the JPEG image will be from the original. JPEG compression is most effective with full color photographs since it is capable of displaying 16.7 million colors.

PNG (Portable Network Graphics) pronounced ping, a new bit-mapped graphics format similar to GIF. Portable Network Graphic files resemble GIF images but do not use the patented compression algorithm employed by GIF called LZW. PNG is completely patent- and license-free. Like GIF files, a PNG file compresses the graphic without losing any data. The uncompressed file is identical to the original. PNG files can work with 256 colors or 16,000,000 colors, a distinct advantage over the GIF format. Currently PNG files cannot display animation. Because PNG is a new format, only the newest browsers can display PNG graphics. The most recent versions of Netscape Navigator and Microsoft Internet Explorer now support PNG.

TIF (Tagged Image File) files are highly supported bitmapped graphics files that can be any resolution. One of the more commonly used graphics files of the "pre-Windows" days, TIF files were widely used in the late 1980's as clip art files. Not used in today's web pages, but can be easily converted to a GIF with most graphics editors.

PCX Originally developed by ZSOFT for its PC Paintbrush program, PCX is a common bitmapped graphics file format. Another commonly used graphics files of the "pre-Windows" days, PCX files were replaced in Windows by BMP files. Also not used in today's web pages, but can be easily converted to a GIF with most graphics editors.

Windows Metafile (WMF) can hold vector graphics, bitmaps, and text. It is the preferred vector format for Windows applications. WMF files are designed for 16-bit operating systems, and EMF (Extended Metafile) files are designed for 32-bit systems. WMF and EMF formats are used to store files on the Window's clipboard. Because the files refer to the Window's built-in functions, the files are not usable on other machines and operating systems. They cannot be used on standard Web pages.

Scalable Vector Graphics (SVG) is a vector graphics format that is in development now and is expected to become the major graphic format for Web images in the future. An SVG vector graphic is described in plain text within a Web document. SVG is written in the XML formatting language that gives it the ability to draw simple or complex shapes on the screen with straightforward code. Many charts and diagrams shown on the Web were originally vector graphics that were converted to bitmapped formats like GIF or JPG. SVG is much smaller than an equivalent GIF or JPG file, so it downloads much faster. Many predefined shapes, like rectangles and ellipses, will be available. SVG will let the designer define far more complex shapes and combinations of vector and bitmapped graphics.

While the following files types can NOT be viewed directly by the browser without some type of "helper" application, you may still use them in your role as a webmaster. They are not really graphics formats, but are document formats.

PDF (Portable Document Format) captures formatting information from a variety of desktop publishing applications, making it possible to send formatted documents and have them appear on the recipient's monitor or printer as they were intended. The purpose of a PDF file is to display a document properly formatted with fonts, colors, and graphics accurately on as many computers with as many operating systems as possible.

The original document can be created using a wide variety of word processing and page layout programs and then be converted by Acrobat into a PDF file. Acrobat Reader, a free program, will read the PDF file and show the document on the screen formatted exactly as it was in the original application. Users do not need the original application that created the document in order to read it. Many companies convert manuals and training documents into PDF files and make them available for download over the Web. The users see the fully formatted manual on their screen, no matter what computer or operating system they are using, as long as it can run Acrobat Reader. The documents may run into the hundreds or thousands of pages. This is a cost effective way to send out information compared to printed materials and CD-ROMs.

RTF (Rich Text Format) created by Microsoft are actually ASCII files with special commands to allows commands such such as fonts and margins to be incorporated directly in the file. Because each word processor application has its own file format (.DOC for Microsoft Word, .WPF for Word Perfect), it is difficult to exchange files. A file saved in the Rich Text Format will not have all the formatting options possible saved with it, but it will have the basic formatting commands to let it be opened as a formatted document in a variety of word processing programs that work on a variety of operating systems.

PostScript is primarily a language for printing documents on laser printers, but it can be adapted to produce images on other types of devices. PostScript is the standard for desktop publishing because it is supported by imagesetters, the very high-resolution printers used by service bureaus to produce camera-ready copy.

EPS (Encapsulated PostScript) is the graphics side of PostScript.