Computer icons are incorporated into any modern GUI. Icons are small pictograms of standard resolutions that depict objects, actions, and symbols. In graphical user interfaces, icons are used as a faster, more intuitive way to communicate with the user. Icons depicting typical 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 platforms, icons make computer novices feel more comfortable with operating systems, learn faster 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 several file formats for storing icons. Microsoft Windows systems use Windows icons in the platform-specific 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 systems, while Unix users can create PNG icons with any image editor.
Generally speaking, icons are square pictograms that come in a variety of standard sizes and color resolutions. Most platforms use icons of 16×16 to 128×128 pixels, while some platforms readily accept icons as large as 512×512 pixels. The high-resolution 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 images with alpha channel. Windows icons come in standard resolutions 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 previous versions of Windows and for lower resolution images. Other platforms such as Windows Mobile can use standard icons of other resolutions, e.g. 24×24 pixels.
Many independent vendors are offering custom icons. Aha-Soft offers a wide selection 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 incorporating icons drawn a common style or theme.