I am using a code based typesetting program (not WYSISYG) that outputs PDFs. I am producing 100 plus pages that have multiple graphics on each page. I need to know how to format a PDF command that I can incllude in my programming that will tag my graphics with "Alternative Text".
I know that with a Microsoft product graphics can be tagged before a PDF is made. I need to know how to do this with my programming.
The Acrobat SDK might be a starting point.
From there, perhaps a plug-in (built with C+).
Perhaps with a licensed release of a PDF Library (this could be $$).
The viable and cost effective alternative is use the tried and true.
Authoring in an appropriate authoring application with appropriate tag management.
Example: Adobe InDesign; Adobe FrameMaker or MS Word with PDFMaker (comes with install of Acrobat).
This way you place "Alternative Text" when mastering content in the authoring file.
Going the route and with some look-see (research) you may find programmatic approaches to placing the alt txt in the authoring file.
Note: as discussed in the Matterhorn Protocols there is no programmatic method that provides a fully accessible PDF (specifically, that is an ISO 14289-1, PDF/UA-1 compliant PDF).
Regardless, here you have a sub-forum for discussions on Acrobat usage.
Consequently discussions on/of 3rd party software is rather out of scope eh.