Web Design in a Nutshell, 3rd Edition

Gamma Correction

Gamma refers to the brightness setting of a monitor (for more information on gamma, see Chapter 28). Because gamma settings vary by platform (and even by manufacturer), the graphics you create may not look the way you intend. In general, graphics created on Macs look dark on PCs and graphics created on PCs look washed out on Macs.

PNGs can be tagged with information regarding the gamma setting of the platform on which they were created. This information can then be interpreted by software on the user’s end (the browser) to make appropriate gamma compensations. When this is implemented on both the creator and end user’s side, the PNG retains its intended brightness and color intensity. Unfortunately, as of this writing, this feature is poorly supported.