Computer icons are an integral part of any graphical user interface. Icons are small pictures of standard sizes that depict objects, actions, and symbols. In window-based systems, icons are used as a faster, 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 developed in 1970 by the Xerox Research Center and widely deployed by the Apple Macintosh and Microsoft Windows systems, icons make new users feel more comfortable with operating systems, learn quicker and interact more efficiently. Icons can be employed to replace or supplement text commands. Widely used in menus, toolbars, on buttons and in new ribbon-style user interfaces, icons have come a long way from the original concept.
There are multiple image formats for storing icons. Microsoft Windows systems use Windows icons in the platform-dependent ICO format. Mac OS systems store 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 Apple platforms, while Unix users can create their icons with any graphic editor.
Generally speaking, icons are square pictograms that come in a variety of standard sizes and color resolutions. Most platforms support icons of 16×16 to 128×128 pixels, while some platforms readily accept icon images as large as 512×512 pixels. The large 512×512 pixel icons were first used in Mac OS Leopard.
Pixel dimensions of all icons are platform dependent. For example, Windows icons are defined as pictures in 16 and 256-color gammas as well as True Color pictures with alpha channel. Windows icons come in standard sizes of 16×16, 32×32, and 48×48 pixels. Windows Vista implements new standards for Windows icons, including icons in sizes of up to 256×256 pixels in True Color only. Optionally, images 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 previous versions of Windows and for lower resolution icons. Other platforms such as Windows Mobile can employ standard icons of other sizes, e.g. 24×24 pixels.
Many independent vendors 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 platforms. The company sells royalty-free icons individually and in matching sets incorporating icons drawn a common style or theme.