The Tagged PDF export for LibreOffice Impress does not contain alternative text for images
Steps to Reproduce:
- Open the attached PPT. There is a single image on the first slide.
- Right click the image. Select "Description". The image has a description of "Alternative Formats icon"
- Export as a Tagged PDF using File > Export as ... > Tagged PDF
- Open Tagged PDF in a PDF explorer such as Adobe Acrobat. The image tag does not have alternative text
The image tag does not contain an "alt" attribute
The image tag does contains an "alt" attribute of "Alternative Formats icon"
User Profile Reset: Yes
This is an accessibility concern. Users with screen readers are not able to read image descriptions in the tagged PDF export.
Created attachment 163627 [details]
The LibreOffice file containing an image
Created attachment 163628 [details]
The tagged PDF export
For bug 45636 project has implemented support for PDF/UA (ISO 14289) available with the 7.0.0rc2 release and current master/7.1.0 daily builds.
Thanks Stuart for pointing out to bug 45636. I don't understand why it says Writer only.
With PDF/UA checked (above Tagged), Impress alternative text works in 7.1+ (and probably in 7.0). We can see Title and Description of image on hovering mouse.
PDF must be open with PDF reader that reads alt text (like Adobe Reader).
So literally this bug would be NotABug (unless exact Alt Text field is required, it's not present in Impress, while it is in Writer).
But as saying goes "don't let good bug report go to waste", I see that new UA option is not documented. Help shows PDF options without it.
And it looks now as seen in https://tomazvajngerl.blogspot.com/2020/01/accessibility-checker-and-support-for.html.
So I confirm this as Documentation bug.
Seth Chaiklin committed a patch related to this issue.
It has been pushed to "master":
Resolves: tdf#127959 and tdf#135196 - updating help for PDF export - General tab
(In reply to Commit Notification from comment #5)
> Resolves: tdf#127959 and tdf#135196 - updating help for PDF export - General
As part of updating the help page for PDF Export, I have also made a separate help page for PDF / UA - based largely on Tomaz's blog (see comment 4 for link.)
It usually takes a few days before the online help gets updated from the master, but the result should appear here:
Also, there will be a link to that page from the General PDF export help:
I will close this bug as FIXED, but no doubt some improvements can be made, so all are welcome to send additional comments about that page to this ticket. I am willing to make adjustments until 7.1 is branched (around mid November).
Verified as the documentation is live, and the following version of LibreOffice has the Description saved as a "name" property when the document is exported as PDF/UA and opened in Firefox:
Version: 126.96.36.199.alpha0+ / LibreOffice Community
Build ID: 1dd4a80fa076bedb3a82821517036bad8dd79857
CPU threads: 4; OS: Linux 5.4; UI render: default; VCL: gtk3
Locale: en-AU (en_AU.UTF-8); UI: en-US
TinderBox: Linux-rpm_deb-x86_64@86-TDF, Branch:master, Time: 2021-07-26_22:41:19