Thread Subject: Re: Allen's proposal for a newsection oncontent

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From: Gregg Vanderheiden
Date: Tue, Apr 03 2007 10:45 AM

Hi Barbara,



Good comments



Couple of clarifications



1) don't convey information by color alone - also applies to people
with color blindness or anomalies.




2) The pie chart has the problem that the pieces must contrast with
each other AND with the background. It turns out that that is possible
ONLY for low to moderate levels of contrast, and only for a small number of
colors. At higher levels of contrast - you fail to get the contrast either
between the pie pieces or between one of them and the background. (Unless
you only allow exploded pie charts - I which case none of the pieces are
next to each other. ) (one idea would be to just outline each pie piece
(make them light) in a very dark (black) outline. That is sort of like an
exploded pie chart but using black instead of white. )



But you get the idea. When you get things that involve more than just a
foreground and a background then you need three levels and it gets trickier
if you want high contrast.



More on this in a bit.








Gregg
-- ------------------------------
Gregg C Vanderheiden Ph.D.






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From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Lybarger,
Barbara (MOD)
Sent: Tuesday, April 03, 2007 10:35 AM
To: TEITAC Web/Software Subcommittee
Subject: Re: [teitac-websoftware] Allen's proposal for a newsection
oncontent

For clarification the two provisions in question do two very different
thing, for two very different populations.



1. The don't convey content with color only goes to folks who are blind and
really requires that things be labeled.



2. The contrast provision goes to folks with low vision or who are color
blind and requires sufficient contrast that all kinds of divisions can be
perceived, not just text to background.



Let's take Gregg's pie chart reference from earlier today. I'm a rather
practical sort. To deal with the first provision, one provides an adequate
alt tag or long description to relay the full content of the pie chart
and/or labs each section of the pie (when that is an option). For the
second, one puts dark colored pie wedges next to light colored pie wedges.



I understand there is a need for clarity on how dark is dark and how light
is light, but from the standpoint of the personnel at the federal agencies
who have to make these calls, I'm not sure making these requirements any
more technical helps.



Also, please keep in mind many folks do not use third party AT to address
the contrast issue, most particularly folks who are color blind. They have
less access to grants and government assistance to acquire AT, because color
blindness, without more, doesn't qualify as legally blind.



Barbara Lybarger




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From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of David
Poehlman
Sent: Tuesday, April 03, 2007 10:59 AM
To: TEITAC Web/Software Subcommittee
Subject: Re: [teitac-websoftware] Allen's proposal for a newsection
oncontent

One danger in this I see. If we allow direct draw, we run the risk of not
being able to take advantage of future possibilities. Also, don't you know?
Braille comes in colors.







On Apr 3, 2007, at 10:53 AM, Gregg Vanderheiden wrote:


Following up for clarification:


Peter Korn Wrote:
Gregg Vanderheiden writes:




On the first point, (i.e. color values of the forground text and

background) I still am not sure I understand the benefit. If the

content is rendered to the screen the AT can always get the color

values. But from discussions in our other group it was my

understanding that there are no AT that can deal with presenting the

millions of colors to people in a way that they can understand.


This is a bad assumption. Content rendered via DirectDraw or some other
mechanism allowing applications to communicate directly to video memory
frame buffers may not such that "AT can always get the color values".
Nor in a requirement about content should we assume a content render is
involved. If I am converting this document to Braille or DAISY or some
other format, all I have to go on is the format. If the information I
need for accessibility isn't clearly present in the format, I won't be
able (and shouldn't be required) to run a particular content rendering
application and observe what it does in order to figure out what is
going on.

<end of Peter Korn Clip>


1) even if DirectDraw is used, can't the AT sample the screen at the point
the letter is drawn and determine the color?

2) if converting the document to braille, then wouldn't the other provision
which states that 'all information presented in color is also presented in
another way' meet your needs?


I am just trying to avoid
a) requiring information that AT won't use or the user can't use if
presented to them (like one of 4 million color codes).
b) having two clauses that solve the same problem.


Thanks.






Gregg
-- ------------------------------
Gregg C Vanderheiden Ph.D.

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