[Accessibility_sig] making RTG PNG files accessible

[Jim Lyons]

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
> Accessibility_sig at knowbility.org
> http://knowbility.org/mailman/listinfo/accessibility_sig_knowbility.org
>

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