File Formats

Graphics files are big, and most file formats (such as BMP or TIFF) are larger than they need to be. Graphics compression techniques fall into two camps: lossless and lossy. Lossless techniques throw away redundant bits of information without affecting the quality of the image. Lossy techniques, such as JPEG, crunch files down smaller, but they throw out image quality in the process. Most of the time, however, you can't see the difference in image quality unless you try to print the graphics on a professional imagesetter.

What is a TIF?

TIFF is a tag-based image file format.

The TIFF format originated in 1986 when Aldus Corporation and leading scanner vendors worked together to create a standard file format for images used in desktop publishing.

TIFF provides a general purpose data format and is compatible with a wide range of scanners and image-processing applications. It is device independent and is used in most operating environments, including Windows, Macintosh, and UNIX.

What is a JPEG?

Joint Photographic Experts Group - This file format was developed for colour-rich images.

JPEG compresses graphics of photographic colour depth better than competing file formats like GIF, and it retains a high degree of colour fidelity. This makes JPEG files smaller and therefore quicker to download. You can choose how much to compress a JPEG file, but since it is a "lossy" format, the smaller you compress the file, the more colour information will be lost. JPEG files can be viewed by a variety of software on both the PC and Mac.

Progressive JPEG is a means of reordering the information so that, after only a small part has been downloaded, a hazy view of the entire image is presented rather than a crisp view of just a small part. It is part of the original JPEG specification, but was not implemented in Web browsers until around 1996. It is now widely supported.

There is now a new version of JPEG which offers "lossless" compression. This format is called JPEG 2000.