Icon design is the process of designing a graphic symbol that represents a some real, fantasy or abstract motive, entity or action. In the context of software application icons oftern represent a program, function, data or collection of data on a computer system.
Icon designs can be simple with flat 2D drawing or a black silhuette, or complex presenting a combination of graphics design elements such as one or more linear and radial color gradients, projected shadows, contour shades, and 3D perspective effects.
Modern icons may have a maximum size of 512 by 512 pixels, the challenge of icon design is to create an image of that size, which can reduce down to 12 by 12 pixels, that accurately portrays what the icon represents. Common examples of this are installer icons, which usually contain images of product installation media and a computer, thus showing the rough idea of installation, or icons that involve the Internet containing a globe, now the almost universally recognized symbol for the Internet.
One of the early professional icon designers was Susan Kare, who designed many of the icons contained within the original Mac OS.
The process of icon design can be divided into two parts: defining the pictogram and creating final design or illustration.
There are three main approaches in defining pictogram. The first and the most desirable in icon design practice is using conventional images. If there is no conventional pictogram for the particular icon designer can use literal image, including image that is shared by the main concept (for example printer is shared image for printing concept), or metaphorical image. After the pictogram is defined it is necessary to check it for possible conflicts (for example the snail image is good metaphor for slow motion but if used as a road sign it will conflict with literal and partially conventional meaning "snails on the road"
Defining the pictogram can be different for the toolbar and other functional icons in the interface and for the icons representing independent software application or website which are closer to logotype or mascot design.
As computer icon can be used in different sizes icon design involves creating master artwork usually for the biggest size used and producing smaller sizes from it. It is desirable to comply with overall style of the icon set utilizing the same color palette, perspective and renderings for all icons. Special attention should be given to eliminating unnecessary details and aligning strokes and objects to pixels in small icon sizes to avoid messy and blurred images.