Wikipedia:WikiProject Usability/Images

Images are very useful in conveying visual information. While it is important to provide a written description of a certain thing, especially for those who are unable to see it, a picture is often indespensable.

Images should be used only when... see ........

Image file size
Image file size is frequently brought up as an important consideration. The below gives a general idea of how much text is the equivalent of some images of varying compressions.

This shows the equivalent as it would be in underlying HTML, when saved to disk. By comparison, the Wikipedia main page (July 23, 2005) - without pictures, css, and javascript files - is 42103 bytes, uncompressed. Web servers may, if the browser supports it (nearly all browsers do), compress text using gzip leading to transmissions that are 4 to 6 times smaller than the original page. Images are not compressed for transmission in this form. Based on this, you may think of the main page as 8400 bytes compared to the listed image sizes below, or imagine that the 'text equivalent' is 5 times larger than it is.

These examples in no way show that any algorithm is a better than any other. Some of the pictures are very small, use limited colors, and the quality is not very important. Different compressions are good for different situations.

Also note that this applies to the HTML, and not wiki markup or displayed text. While these words appear to be 11 bytes, they are actually 18 bytes in HTML: these words.

See also: Images