[NTG-context] Alternate text for figures that includes math

[NTG-context] Alternate text for figures that includes math

[Matthias Weber]

Dear All, 

When tagging an image, it looks like the provided alternative text is used verbatim. That means no TeX commands are interpreted, nor any math is being interpreted. Is it possible to serialize the math in an alternate text (as the tracker does with the non-ALT math in the example below)? 
I can do this manually, but my figures contain quite a bit of math, and it would be nice if alternate text for math is provided consistently throughout the document.


Thanks,
Matthias

\usemodule[mathml]

\enabledirectives [backend.usetags=testing]
 \setuptagging[state=start]
 \setupstructure[state=start]
 \setupbackend
   [format=PDF/A-3a]
 \setupbackend[format=pdf/ua-1]
 \setupexternalfigures[location=default]

\setupnote[mathnote][location=page]
\enabletrackers[math.textblobs]


\starttext

\placefigure
[here]
[] % label
{}   % legend
{\externalfigure[cow][label={A cow, contemplating $e^{\pi i}+1=0$}]} % path

A human, contemplating $e^{\pi i}+1=0$.
\stoptext
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Re: Alternate text for figures that includes math

[Pablo Rodriguez via ntg-context]

On 6/15/25 18:03, Matthias Weber wrote:
> [...]
> I can do this manually, but my figures contain quite a bit of math,
> and it would be nice if alternate text for math is provided
> consistently throughout the document.

Dear Matthias,

my background is in humanities. This is why I see that tagging is
lacking language (for mixed-languages documents 😅).

I wonder whether it would make sense to replace your label with:

  {\externalfigure[cow][label={A cow, contemplating}]
  {\blank[-3st]\color[white]{$e^{\pi i}+1=0$}}} % path

Of course, full transparent text would make sense with other backgrounds
(either from the page or the image itself).

As for tagging, reading the info with https://ngpdf.com alternative text
seems fine to me (but I cannot speak for software readers).

Just in case it may help,

Pablo
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___________________________________________________________________________________

Re: Alternate text for figures that includes math

[Matthias Weber]

Thanks, Pablo (and everybody else reading this), 


I should have put my question differently. When using the math.textblobs tracker, this code:

\enabledirectives [backend.usetags=testing]
\setuptagging[state=start]
\setupstructure[state=start]
\setupbackend
  [format=PDF/A-3a]
\setupbackend[format=pdf/ua-1]
\setupexternalfigures[location=default]

\setupnote[mathnote][location=page]
\enabletrackers[math.textblobs]

\starttext

$1+1=3$

\stoptext

will put all math into what I think Hans calls “serialized math" into a footnote (please correct me if I'm wrong). Are there other ways to access that serialized math? 
One approach to making math and images accessible would be to use modes to replace all figures with their alt-texts and all math with their serialized math, so that the output of ConTeXt would be a PDF where all elements that are difficult to navigate are replaced with plain text. This is, of course, only one of many possible approaches. This would circumvent all tagging issues for the time being.

I am just trying to (in this order)

— Make my lecture notes useful for vision-impaired readers
— Achieve this as easily and cleanly as possible 
— Eventually reach some form of compliance with legal requirements

Thanks again,

Matthias



> On Jun 18, 2025, at 1:23 PM, Pablo Rodriguez via ntg-context <ntg-context@ntg.nl> wrote:
> 
> On 6/15/25 18:03, Matthias Weber wrote:
>> [...]
>> I can do this manually, but my figures contain quite a bit of math,
>> and it would be nice if alternate text for math is provided
>> consistently throughout the document.
> 
> Dear Matthias,
> 
> my background is in humanities. This is why I see that tagging is
> lacking language (for mixed-languages documents 😅).
> 
> I wonder whether it would make sense to replace your label with:
> 
>  {\externalfigure[cow][label={A cow, contemplating}]
>  {\blank[-3st]\color[white]{$e^{\pi i}+1=0$}}} % path
> 
> Of course, full transparent text would make sense with other backgrounds
> (either from the page or the image itself).
> 
> As for tagging, reading the info with https://ngpdf.com alternative text
> seems fine to me (but I cannot speak for software readers).
> 
> Just in case it may help,
> 
> Pablo
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
> 
> maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
> webpage  : https://www.pragma-ade.nl / https://context.aanhet.net (mirror)
> archive  : https://github.com/contextgarden/context
> wiki     : https://wiki.contextgarden.net
> ___________________________________________________________________________________

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
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wiki     : https://wiki.contextgarden.net
___________________________________________________________________________________

Re: Alternate text for figures that includes math

[Pablo Rodriguez via ntg-context]

On 6/19/25 17:56, Matthias Weber wrote:
> Thanks, Pablo (and everybody else reading this), 
> [...]
> \enabletrackers[math.textblobs]
> [...]
> will put all math into what I think Hans calls “serialized math"
> into a footnote (please correct me if I'm wrong). Are there other
> ways to access that serialized math?

Matthias,

no idea, I only found `math.textblobs` included in `math-ini.mkxl`.

> One approach to making math and images accessible would be to use
> modes to replace all figures with their alt-texts and all math with
> their serialized math, so that the output of ConTeXt would be a PDF
> where all elements that are difficult to navigate are replaced with
> plain text. This is, of course, only one of many possible approaches.
> This would circumvent all tagging issues for the time being.

Not sure whether I understand your approach (after all, math is all
Greek to me) and also wondering whether UA-2 could be more useful to use.

That being said, I think alternative texts should be used when just
tagging text (or formulas) is not an option.

Pablo
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
webpage  : https://www.pragma-ade.nl / https://context.aanhet.net (mirror)
archive  : https://github.com/contextgarden/context
wiki     : https://wiki.contextgarden.net
___________________________________________________________________________________