[Accessibility_sig] making RTG PNG files accessible

[Moore, Michael]

Jim,

If you create the tables, people who cannot distinguish between red and
blue including some low vision or color blind individuals, they will be
able to rely on the tabular data, or use that data to determine which
line is which on the graph.

In an ideal world you would have control over the graph generation and
could chose something other than just color to differentiate between
types of data, but we usually need to create solutions that work within
real world constraints. The tabular presentation of the data will meet
the requirements of Section 508 1194.22 (a) text alternatives, and (c)
color/contrast, and also at least A level compliance with WCAG.  More
importantly, virtually all users will be able to get the information
that is presented in the graph.  

Mike

"If you don't have time to do it right, 
when will you have time to fix it?"

-----Original Message-----
From: accessibility_sig-bounces at knowbility.org
[mailto:accessibility_sig-bounces at knowbility.org] On Behalf Of Jim Lyons
Sent: Monday, June 11, 2007 5:17 PM
To: accessibility_sig at knowbility.org
Subject: Re: [Accessibility_sig] making RTG PNG files accessible

Mike,

Thanks for the response.  One other problem with these graphs, they are
color-coded.  Network flow is expressed in terms of packets in and
packets in.  One is blue, the other green.  While there is a legend, it
might not be sufficient for users who are color-blind.  There is a text
legend, saying what green and blue mean, but that's not useful if
someone has trouble distinguishing between green and blue.  But maybe
most color-blind people can distinguish blue, since the most prevelent
form of color-blindness is red-green, I think.

Jim

On Mon, 11 Jun 2007, Moore, Michael wrote:

> Jim,
>
> Since the graphs are being generated on the fly from an external 
> webservice and the statistics that are being displayed in the graph 
> are also available from the webservice I would recommend the following

> approach.
>
> The alt text for the graph should probably be quite short, providing 
> the type of graph and the type of data presented. E.g. "Bar graph of 
> site traffic over the past twelve hours by web page."
>
> Since you have the stats available, I would then autogenerate an 
> accessible tabular presentation of the data, and display the table on 
> the same page or link to it.  Displaying it on the same page would be 
> simpler programmatically.  This presentation would be helpful to all 
> of your users.
>
> Mike Moore
> Accessibility Specialist
> Department of Assistive and Rehabilitative Services (DARS)
>
> "If you don't have time to do it right, when will you have time to fix

> it?"
>
> -----Original Message-----
> From: accessibility_sig-bounces at knowbility.org
> [mailto:accessibility_sig-bounces at knowbility.org] On Behalf Of Jim 
> Lyons
> Sent: Monday, June 11, 2007 4:18 PM
> To: accessibility_sig at knowbility.org
> Subject: [Accessibility_sig] making RTG PNG files accessible
>
> This is my first post here, so hello.  My name is Jim Lyons and I work

> for the Office of Telecommunication Services at UT Austin.  I have a 
> question about generating and presenting graphs that display network 
> traffic that are accessible.
>
> In order to monitor network traffic, we use a program called RTG, a 
> third-party C program that generates graphs as PNG files.  These 
> graphs display network traffic from a variety of viewpoints.  They are

> very useful to our customers and we provide our customers a variety of

> different graphs of their network traffic, including graphs generated 
> "on the fly", displaying up-to-the-minute data.
>
> Unfortunately, these PNG files are totally inaccessible. Also, since 
> many of them are generated "on the fly" it is not possible to have 
> someone look at the graph and write an interpretive description of it.
>
> I was thinking that the best way to make these graphs accessible 
> programmatically would be to capture descriptive statistics and output

> them to files that my PHP program could read and use either as alt 
> text of longdesc files.  But I'm not sure which descriptive stats 
> would be best.
> We could modify the code for RTG (not a pretty thought but doable) or 
> access the database ourselves with the same parameters sent to RTG, 
> but that would be prohibitively long for graphs covering long periods 
> of time (like a week or more).
>
> Does anyone have any experience with this question?  I would 
> appreciate any helpyou might provide.
>
> Thank you,
>
> Jim Lyons
>
>
> -----
> Jim Lyons                     |  Operating Systems Specialist
> OTS                           |  512-471-7414
> University of Texas at Austin |  fax: 471-2449 
> jlyons at uts.cc.utexas.edu
>
> _______________________________________________
> Accessibility_sig mailing list
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> g
>

-----
Jim Lyons                     |  Operating Systems Specialist
OTS                           |  512-471-7414
University of Texas at Austin |  fax: 471-2449 jlyons at uts.cc.utexas.edu

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