Create images available: graphs that cause spasms
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Warning: The original version of this document is Creating Accessible Images: Graphics That Cause Seizures . This French translation was done by Ideose as part of an agreement between WebAIM and Ideose .
Note: See page documents on web accessibility for a list of all translated documents. Other resources on web accessibility are also listed in the portal accessible digital .
Summary
- Page 1: Introduction
- Page 2: Images to enhance understanding
- Page 3: Color and contrast
- Page 4: Texts in pictures
- You are on Page 5: The graphs that cause spasms
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Page 6: Creating good text alternatives (attribute
alt) - Page 7: Long Descriptions
And flashing strobe
The main point of this page may be summarized succinctly:
Important
The visual effects may create flickering or stroboscopic effects can cause spasms in some people.
Spasms induced by flickering or strobe effects are known to cause photosensitive epilepsy. The spasms can be dangerous. Do not be responsible for creating.
How do you know if your graphics can create spasms?
There is no absolute indicator from which an animation can be dangerous and cause spasms. However, section 508 of the Rehabilitation Act prohibits US flickering effects with a frequency greater than 2 Hz and lower than 55 Hz this does not mean that everything that moves at these frequencies causes spasms otherwise all videos and animations would be prohibited. The movement is not the problem. The flashes and strobe effect are the problem.
Example
Warning
The following examples are examples of BAD: Do not click these links if you think you photosensitive epilepsy.
- An image with a flashing strobe effect
- An image with an optical illusion (the lines seem to be moving)
Most developers do not create graphics that can cause spasms but some developers of multimedia venture into this territory. Flash developers are particularly known for creating animations and produce modern flashing strobe effects. Be careful when you create your animations. Do not induce spasm.
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