[NTG-context] Re: Alternate text for images?

Hi Pablo, Thanks for looking into this. I am very new to the requirements, and I don’t know (yet) what defines screen readability and how this might be certified. I will investigate. So far, I have heard that all images need to have an alternate text (and I assume this can't be done automatically in order to be useful), and all equations need to be able to be read out loud by a screen reader software. There are obviously lots of issues here. So far, I have only tried Acrobat on a Mac to see whether I can add alternate texts in ConTexT that would be recognized by Acrobat. Acrobat says that the document has the accessibility flag checked, but that the image is not tagged. Letting it read the document skips the image. I have not tried what happens to formulas or other structures. I also don’t know what compliancy means in this case. I will investigate, and I’ll be more than happy to try all my documents … Thanks, Matthias

On Apr 4, 2025, at 11:34 AM, Pablo Rodriguez via ntg-context wrote:

On 4/4/25 03:37, Matthias Weber wrote:

...

Thanks Hans,

but no, I mean something like this (from the mailing list and Tagged PDF (2024)):> [...]

Hi Matthias,

your MWE mostly works, but it has an issue when validating it.

I‘m investigating it further (not clear to me whether it comes from ConTeXt or from the validator).

...

in order to provide screen readability

It isn’t clear to me how you tested this. Have you tried that Acrobat read aloud the PDF document?

If not, please describe your testing and define what “screen readability” is.

It would be great if you could provide a link to a (best when minimal) PDF document with alternative text whhat is screen--readable (as confirmed by your testing).

Sorry, but I’m only a Linux user with occasional access to a Windows machine with the current version of Acrobat Reader.

Validations are fine on Linux, but testing Acrobat is not an option here (sorry, no VM or similar things).

...

(but the above doesn’t work, the PDF doesn’t have the alternate text).

I must admit that I don’t have any idea why (or even what) doesn’t work on your side.

But the alternative text is there (uncompress the PDF document and search for "/Alt <" [https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008....]).

I will report back as soon as I have found out what may not be working here.

If you allow me a comment, testing math tagging (as described in “Tagged PDF”) would be great to confirm that it works as expected (or to know that it has to be improved).

I hope it might help (in the meantime),

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

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