Picture File Formats and Sizes

Because there are many different uses for image files, Microsoft Windows XP enables you to specify which format to use when saving a picture. Different image formats can have vastly different resolution qualities or use anywhere from just a few to over 16 million colors. Different image formats might also use different methods of compression to save memory.

Image file formats can be identified by the three-letter extension at the end of a file name. The most common types of image files used in Windows have the file extensions BMP, GIF, and JPG. Other commonly used image file extensions include TIF and PNG.

Windows Bitmap files use the BMP extension, which is the default format for computers using the Windows operating system. Bitmap files use more space than other formats because they are not compressed, but they offer higher resolution and stability than other format types.

GIF files are often used on the World Wide Web. These images are highly compressed to minimize transfer time over phone lines and offer very high resolution, but they are limited to 256 colors.

JPEG files have a default JPG extension but might also use JPE or JPEG. These files use a method of compression that discards any information the human eye can’t see. In most cases, the difference between the original and the compressed version of an image is indistinguishable. Because of their high rate of compression, JPEG files are often used for Web pages or e-mail attachments.

TIFF files typically use the TIF extension. TIFF files offer a compression method that ensures no loss of data but uses more memory than other formats. TIFF files store a very large amount of information about an image and work well as an intermediary file format between scanners or paint programs and desktop publishing programs.

Files with a PNG extension typically support many colors and use a method of compression that retains a high-resolution image. Some older graphics programs might not recognize files saved in the PNG format.