Designing Accessible Icons
The GNOME desktop includes accessible themes that make the desktop and the applications running on it accessible to users with a range of visual impairments. By default, these are:
- a high contrast theme
- an inverse high contrast theme
- a large print theme
The following accessible themes are also available:
- a high contrast large print theme
- an inverse high contrast large print theme
- a low contrast theme
- a low contrast,large print theme
To be considered fully accessible, all icons in your application must be replaced by a suitable alternative when one of these themes is used.
Low contrast icon themes were deprecated in GNOME 2.22. It is no longer necessary to deliver low contrast icon equivalents.
- 9.4.1. High Contrast Icons
- 9.4.2. Low Contrast Icons
9.4.1. High Contrast Icons
High contrast icons are greatly simplified versions of an application's existing regular icons. They are drawn with two colors, black and white, and thicker borders. This style allows high contrast icons to be distinguishable when viewed by a user with a visual impairment. Below is an approximation of what well-designed high contrast icons look like when viewed by someone with a visual impairment.
| Description | High Contrast Icon | Simulated Appearance |
|---|---|---|
| Book |
 |
 |
| CD-ROM |
 |
 |
| Copy |
 |
 |
If a regular icon uses a simple, straightforward metaphor the corresponding high contrast icon can often use the same metaphor. In many cases the same metaphor will need to be drawn differently to create a simplified high contrast icon.
High contrast icons are created in a vector drawing program. Black and white shapes are layered to create a simplified icon. The process feels like layering black and white pieces of construction paper, as if you were assembling a collage.
Often shapes from existing high contrast icons can be resized and reused to more quickly build up a new icon.
It is useful to design high contrast icons over a temporary background color so you don't forget to draw the external white border.
9.4.2. Low Contrast Icons
Low contrast icon themes were deprecated in GNOME 2.22. It is no longer necessary to deliver low contrast icon equivalents.
The goal of low contrast themes is to eliminate, as much as possible, light values (e.g. a large 'V' value in HSV). To achieve this, the colors in low contrast icons are compressed toward the middle value range, i.e. dark colors are lightened and light colors are darkened.
Low contrast icons are generated from the existing regular icons by adjusting the levels in GIMP. The Input Levels are set to 100, 1.25, 200 and the Output Levels are set to 100, 160, as shown in the Levels dialog below. Large numbers of regular icons can be quickly converted to low contrast by using GIMP's scripting facilities.
