Computer icons are incorporated into any graphical user interface. Icons are small pictures of standard resolutions that visually represent objects, actions, and other concepts. In graphical user interfaces, icons are used as a quicker, more intuitive way to communicate with the user. Icons depicting common elements of a user interface are better visible than text, can be recognized faster, and are certainly easier on the eyes.
Originally introduced in 1970 by the Xerox Research Center and widely deployed by the Apple Macintosh and Microsoft Windows systems, icons make computer novices feel more comfortable with operating systems, learn quicker and interact more efficiently. Icons can be used to replace or supplement text messages. Commonly used in menus, toolbars, on buttons and in the latest ribbon-type user interfaces, icons have come a long way from the original concept.
There are multiple file formats for storing icons. The Windows systems use Windows icons in the platform-dependent ICO format. Mac OS computers store Mac icons in their specific formats, while Unix-based systems employ PNG icons for most applications. As such, icon editing software is generally available for the Windows and Mac OS platforms, while Unix users can design PNG icons with any graphic editor.
As a rule of thumb, icons are square pictograms that come in a number of standard sizes and color resolutions. Most platforms support icon sizes of 16×16 to 128×128 pixels, while some platforms readily accept icon images as large as 512×512 pixels. The big 512×512 pixel icons were first used in Mac OS Leopard.
Pixel resolutions of all icons are platform dependent. For example, Windows icons are defined as images in 16 and 256-color gammas as well as True Color images with alpha channel. Windows icons are supplied in standard sizes of 16×16, 32×32, and 48×48 pixels. Windows Vista defines new standards for Windows icons, including icons in resolutions of up to 256×256 pixels in True Color only. Optionally, images of 128×128 and 512×512 pixels are supported. Interestingly, the higher resolution versions of Windows Vista icons are stored in compressed PNG format instead of Windows ICO used in older versions of Windows and for lower resolution images. Other systems such as Windows Mobile can employ standard icons of other resolutions, such as 24×24 pixels.
Many independent designers are providing custom icons. Aha-Soft offers a variety of Windows icons, Mac icons, and PNG icons in all sizes and resolutions common to those systems. The company provides royalty-free icons individually and in matching sets incorporating icons drawn a common style or theme.