Computer icons are an integral part of any modern GUI. Icons are small pictures of standard sizes that visually represent objects, actions, and symbols. In graphical user interfaces, icons are used as a faster, more intuitive way to communicate with the user. Icons representing common elements of a user interface are better visible than text, can be recognized faster, and are easier for new computer users.
Originally introduced in 1970 by the Xerox Research Center and widely deployed by the Mac OS and Microsoft Windows systems, icons make new users feel more comfortable with operating systems, learn quicker and work more efficiently. Icons can be employed to replace or supplement text messages. Commonly used in menus, toolbars, on buttons and in the latest ribbon-style user interfaces, icons have come a long way from the original concept.
There are multiple graphic formats for storing icons. Microsoft Windows systems store Windows icons in the platform-dependent ICO format. Mac OS systems use Mac icons in their specific formats, while Unix-based systems employ PNG icons for most applications. As such, icon software is generally available for the Windows and Mac OS platforms, while Unix users can design their icons with any image editor.
Generally speaking, icons are square pictograms that come in a number of standard sizes and color resolutions. Most systems use icon sizes of 16×16 to 128×128 pixels, while some systems readily accept icons as large as 512×512 pixels. The big 512×512 pixel icons were first employed in Mac OS Leopard.
Pixel dimensions 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 pictures 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, icons of 128×128 and 512×512 pixels are supported. Interestingly, the high-resolution 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 sizes, e.g. 24×24 pixels.
Numerous independent designers are offering custom icons. Aha-Soft offers a variety of Windows icons, Mac icons, and PNG icons in all sizes and resolutions standard to those systems. The company provides royalty-free icons individually and in matching sets that include icons drawn a common style or theme.