If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following: (Level AA)
- Customizable: The image of text can be visually customized to the user’s requirements;
- Essential: A particular presentation of text is essential to the information being conveyed.
Note: Logotypes (text that is part of a logo or brand name) are considered essential.
People perceive the content of the web in various ways. Some use text to speech technologies called screen readers, some users increase the font size for better visibility, some users prefer loading user preferred style sheets. The screen reading technologies do not have the capability to read aloud the text on images except with some settings with latest versions of JAWS. The font size can be adjusted only if the content is real text instead of text on images. Similarly the user specified styles apply only to the content and its back-ground but not the text on images and its background. Due to all the reasons specified above certain user groups cannot perceive the content on images.
So no important content should be placed on images.
How to achieve accessible content on images
If the content author can achieve same visual appearance using CSS and provide real text the problem can be solved. If the text on images are provided due to unavoidable reasons minimum contrast (future link) should be maintained between the text and the background. If the text on images can be converted as per user needs such as increasing font size, increasing the line space between the content, change the font style etc text on images can be used.
However this success criterion have few exceptions listed below.
- Text on images which is part of logo or brand.
- Text on images which are inactive or decorative.
- Text on images provided to show a sample font style.
- Font style which the author do not have right to use on the website.
- Text on images which have less importance than the visual representation. Eg: Graphs and charts show important information than the content on the graphs.