Have you ever wondered if you should save a picture in the PNG or JPEG format for use on your Web page? Do you know the difference between the TIFF and GIF formats? What are the MIX and BMP formats anyway? In this article, you can find answers to these questions and more as you learn when to apply which of the graphics formats commonly supported by various computer imaging programs.

Raster Formats

BMP, GIF, JPEG, MIX, PNG, and TIFF are raster image formats. A raster image is also known as a bitmap and is created from rows of small dots called pixels ("picture elements") or "bits." Because a raster format uses a fixed method of specifying an image, the image cannot always be immediately rescaled without losing definition.

Bitmap (BMP)

The Microsoft Windows® BMP format (.bmp file extension) can display millions of colors. Because it is supported by several programs, it is an extremely practical file format to use when you are providing an image to someone who may not have the program in which you created the image.

Graphics Interchange Format (GIF)

The GIF format (.gif file extension) is one of the two most common file formats for images on the World Wide Web, since it is supported by almost all Web browsers. Because this format can only display a maximum of 256 colors, it is best used for black-and-white line drawings, color clip art, and pictures with large blocks of solid colors. The GIF89a format also supports both transparency and animation.

Joint Photographic Experts Group (JPEG)

The JPEG format (.jpg or .jpeg file extension) is the other most common file format for images on the Web. It is not limited to 256 colors, so you can use it to display high-quality photographs, or pictures containing millions of colors. Because it is designed as an image storage format, it can efficiently compress large, high-quality photos into very compact files, so it is very useful when you want to send a large image via e-mail. However, the more you reduce your image's file size (or modify and re-save the image), the more image information is discarded - and quality is decreased. Moreover, this format does not support transparency or animation.

Microsoft Image Extensions (MIX)

The MIX format (.mix file extension) is the Microsoft PhotoDraw™ native file format and can display millions of colors. It maintains all the objects in the image separately, allowing you to edit the individual objects when you reopen the file. (Other file formats "flatten" all the objects into a single object.) Currently, it is only supported by PhotoDraw, but you can save to other file formats, including all of those listed in this article.

Portable Network Graphics (PNG)

The PNG format (.png file extension) can display millions of colors. Because it is such a new format, however, fewer browsers currently support it (although it is quickly gaining support). Images saved in this format will not degrade in quality, even if the file is compressed. It supports transparency, but it does not support animation, since it cannot contain multiple images.

Tagged Image File Format (TIFF)

The TIFF format (.tif or .tiff file extension) produces very high quality images and is therefore used in publishing quite often. It can display millions of colors (although grayscale images are limited to 256 colors or shades), and typically results in larger image files than the GIF or JPEG formats. If you plan to edit an image in a program other than the one in which you created it, saving it in this format is helpful, since it is widely recognized by various programs.

Comparison Table

The following table shows the best graphics format to use for various actions.

Note   If you are using PhotoDraw 2000 Version 2, you can use the Save for Use In Wizard (on the File menu) to help you decide on a format. Depending on how you answer the wizard's prompts, it determines the best image settings and file format for the image you want to save. When saving images for Web pages, the wizard also shows the estimated download times over various Internet connection speeds.