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Accessibility and Usability Forum

detecting the visually impaired
is it possible?

 9:37 pm on May 24, 2010 (gmt 0)

I'd like to make my web site accessible to the visually impaired users, is there something as a browser setting, or a pass they use when browsing, which web sites can detect to redirect them? For instance, the letters will be made bigger, and for the color blind they have a higher contrast and the images are corrected, and for the blind, the images won't display.
I don't want a small link in the corner where they can click on to go to the page corrected for them. They will probably not find it.



 10:35 pm on May 24, 2010 (gmt 0)

CSS is your friend :) [webmasterworld.com]

Instead of redirecting users to other versions based on their browsers (a.k.a. User Agents), create ONE version of your site with a variety of media-specific stylesheets to control the presentation

See w3.org/TR/CSS2/media.html#media-types [w3.org]


 12:24 am on May 25, 2010 (gmt 0)

I don't think you could detect colorblind people. Lots of color-impaired individuals probably don't even know they're colorblind.

For colorblind users, there's no real reason with minimal attention that you can't pay attention to the greyscale values and make it useful to them (us actually)


 1:12 am on May 25, 2010 (gmt 0)

I don't think you could detect colorblind people. Lots of color-impaired individuals probably don't even know they're colorblind.
Quite likely

However... all is not lost :)

colorfilter.wickline.org/ [colorfilter.wickline.org]
Colorblind Web Page Filter

I'd like to express my appreciation to pair.com for donating a dedicated server to host this utility.

Use the colorblind colorlab to select safe colors earlier in the design process.

Learn more about colorblindness in this Wikipedia entry.

This tool is still in development, but feedback is welcome while I work on it. If you only use one filter, use the grayscale filter which will not only point out potential problem areas, but will also let you see more clearly which areas the filter is unable to process.

Please indicate a resource to be viewed, and a color filter to be applied to that resource:

Type a URL:
and then
pick a color filter:


 9:58 am on May 25, 2010 (gmt 0)

Thanks a lot! That css braille media type was something I was looking for, I didn't know about it's existance. I'll try to find out in how many cases it actually works(because I heard some other media types are also not called when they should)
And about the colourblind, you may be right I should just look at the greyscale. I was thinking about when I upload an image to my site, with PHP GD it would automatically generate some versions for the colourblind, where they are corrected(the way how 'daltonize' from 'vischeck' works).
I am thinking about making accessibility codes for the colourblind, like for instace when the code for people with Anomalous trichromacy is 358, they can press those three keys at the same moment, so the site gets refreshed in a corrected version for them. And if this would be more popular, more colourblind people will know about it and more websites implement my script. Maybe I am thinking on a too large scale.. You said you are colourblind, do you think this would even be useful?
I would really like to this as I want to specialize myself into making accessible web sites.


 9:47 am on May 26, 2010 (gmt 0)

I know that in the UK the RNIB has guidance on accessibility criteria for the visually impared. No doubt other national organisations for blind and partially sighted do the same.

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