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

In Acrobat Pro (2020 Mac) it looks like this, see attached. Steffen

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

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

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Hi Pablo (and Hans)

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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/ 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.... https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008....]).

After manually placing /Alt in the parent dictionary of /K and both veraPDF and https://www.ngpdf.com/ 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 ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki!

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