This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
Steven, this document will be very useful to developers. One user group that I feel should be added under "Examples of scenarios where users benefit from text alternatives for images" are users with visual impairments who do not use screen readers or assistive technology. This includes users with color deficiencies and users with low vision. This is important because many users with low vision may be able to read the text and interpret most images but may need alternative text for certain images. When alt text is only displayed with the alt attribute, users of some browsers and keyboard only users in this category will not have access to this text. In addition, related to example 4.1, using the alt attribute alone would IMHO not be sufficient for WCAG 2 compliance because the alternative for those who cannot distinguish colors is provided through the alt attribute. If a person with color deficiencies with normal acuity were viewing this image with a browser such as Firefox they would not have access to the alternative text. My recommendation in this latter example is to require that any meaning conveyed in the image via color is in additionally displayed without the use of color directly in the image (hatching, lines, etc.) or as text visible on-screen. The alt attribute does not suffice in these situations. I think this note would be a great addition to the document that you are authoring. jon.avila@ssbbartgroup.com
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the tracker issue; or you may create a tracker issue yourself, if you are able to do so. For more details, see this document: http://dev.w3.org/html5/decision-policy/decision-policy.html Status: partially accepted Change Description: I will add text to the spec to warn against the siutaion you describe, I will also modify the images to ensure that there is sufficient contrast between the text abd the backgrounds in the images. Rationale: the images include text that indicates the colours. So it is not colour alone that provides the colour information.