Am 09.04.2025 um 18:40 schrieb Pablo Rodriguez via ntg-context <ntg-context@ntg.nl>:

On 4/9/25 11:41, Matthias Weber wrote:

Hi Pablo (and Hans)

No, Acrobat reports an empty page when reading the text, and Preview

(on the Mac) doesn’t read anything either.
I can’t find the text when looking at the pdf in an editor.

Hi Matthias,

the attached PDF document should work now.

Unfortunately Acrobat Reader doesn’t work for me at all (reading texts
alould). But I was able to see the value of /Alt (alternative text) with
the editor from https://www.ngpdf.com/.

There were two issues here:

First, image was originally tagged as /NonStruct instead of /Figure
(which I changed with lpdf-tag-imp-testing.lmt).

Second, /Alt wasn’t properly placed. veraPDF rightly warns about no /Alt
or /ActualText (after having the image tagged as figure).

/Alt is an entry in a /StructElem dictionary (the parent of /K, where
ConTeXt places it now
[https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf#page=567]).

After manually placing /Alt in the parent dictionary of /K and both
veraPDF and https://www.ngpdf.com/ work fine now.

BTW, when adding a formula (source plus mapping below), veraPDF warns
about no /Alt or /ActualText for the formula (which is a requirement for
PDF/UA-1, no mathml in this version [at least, no mention to mathml in
the veraPDF validation rules]).

Hans, I’m afraid that this haven’t been visible due to images not tagged
as figures. Could it be fixed?

Many thanks for your help,

Pablo
<b.pdf><testing-tagging.tex><lpdf-tag-imp-testing.lmt>___________________________________________________________________________________
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
___________________________________________________________________________________