Examples of Flickering Images

This page is designed to demonstrate examples of images that would cause problems for people with photosensitive epilepsy. This is intended to help rich media developers develop a sense of what images that flicker at the mentioned rate look like, in order to be able to avoid their use. You will need Macromedia's Flash player to view the demos.

From the W3C's Web Content Accessibility Guidelines:

Guideline 7.1: Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]
Note. People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights).

From the Section 508 Regulations:

§1194.21(k): Software shall not use flashing or blinking text, objects, or other elements having a flash or blink frequency greater than 2 Hz and lower than 55 Hz.
§1194.22(j): [Web] Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.

4hz.swf	7hz.swf
20hz.swf	59hz.swf