alt text privacy issue in pptx

[resistor4u]

I am trying to specify alt text for images in a powerpoint and found IMHO a privacy concern. Here's an MRE.

---
title: "A pptx"
author: Kermit
date: 2025-10-13
header-includes:
    - \usepackage{setspace}
output:
  ioslides_presentation:
    incremental: true
---

![](https://www.worldanimalprotection.us/cdn-cgi/image/width=2304,format=auto/siteassets/images/farming/pigs/pig-in-field-getty.png "A super pig")

Process it with pandoc -t pptx mre.md -o mre.pptx and right click on the image to "View Alt Text." What I see is the expected alt text ("A super pig"), plus the source link.

People who use local images may not be expecting to reveal possibly sensitive context info like folder paths as alt text, e.g., ../../pics_from_jimmy/before_surgery/2024_10_10/image.jpg. I think defaulting to include link/path info is more of a privacy concern than a feature.

The xml field in question appears to be:

			<p:pic>
				<p:nvPicPr>
					<p:cNvPr descr="A super pig  https://www.worldanimalprotection.us/cdn-cgi/image/width=2304,format=auto/siteassets/images/farming/pigs/pig-in-field-getty.png" id="0" name="Picture 1"/>
					<p:cNvPicPr>
						<a:picLocks noGrp="1" noChangeAspect="1"/>
					</p:cNvPicPr>
					<p:nvPr/>
				</p:nvPicPr>

Commentary here suggests adding the link (or path) is necessary presumably if there's nothing else to include from the description. If there is a description (i.e., Alt Text) provided, can we omit the link/path?

[jgm]

In ![](pig.png "super pig"), "super pig" specifies the link title, not the alt text, in markdown.
The alt text is the part inside [].

[resistor4u]

In ![](pig.png "super pig"), "super pig" specifies the link title, not the alt text, in markdown. The alt text is the part inside [].

Yes, but that does even less. This

![A super pig](https://www.worldanimalprotection.us/cdn-cgi/image/width=2304,format=auto/siteassets/images/farming/pigs/pig-in-field-getty.png)

puts only the image URL in the alt text field, not even A super pig.

[jgm]

Relevant code: https://github.com/jgm/pandoc/blob/main/src/Text/Pandoc/Writers/Powerpoint/Presentation.hs#L597-L604
https://github.com/jgm/pandoc/blob/main/src/Text/Pandoc/Writers/Powerpoint/Output.hs#L1350-L1355
https://github.com/jgm/pandoc/blob/main/src/Text/Pandoc/Writers/Powerpoint/Output.hs#L1082-L1168

[jgm]

The precise place:

https://github.com/jgm/pandoc/blob/main/src/Text/Pandoc/Writers/Powerpoint/Output.hs#L1120-L1125

  -- cNvPr will contain the link information so we do that separately,
  -- and register the link if necessary.
  let description = (if T.null titleText
                      then ""
                      else titleText <> "\n\n")
                      <> T.pack (mInfoFilePath mInfo)

Obviously the author thought it was required to insert the path info. I'm not sure why, but it would be good to check the OOXML spec before modifying this.

[resistor4u]

If this helps... the spec says

Id, Name, Title and Description

An id, name, title and description for a picture can be specified with attributes on the <cNvPr> element: <cNvPr id="222" name="Rounded Rectangle 1" title="My Shape" descr="This is the description"/>. The id is an integer and specifies a unique identifier. The name is a string. The title is a string that specifies the caption. The descr is alternative text used for assistive technologies which do not display the object. Finally, note that <cNvPr> can have child elements <hlinkClick> and <hlinkhover> for links that are not covered here.

Reference: ECMA-376, 3rd Edition (June, 2011), Fundamentals and Markup Language Reference § 19.3.1.12 (presentations) and § 20.5.2.8 (spreadsheets).

So description is reserved for alt text. Maybe the author's reasoning was that in absence of deliberate alt text, that context info is better default description than none at all? Or maybe the snippet is incomplete and intention was to add the child element <hlinkClick> or <hlinkhover> as the spec notes? It sounds reasonable to have logic that, if a website is provided, include it as one of those child elements, but it seems clear that including either the URL or a local image's folder path in <p:cNvPr descr=" . . . " /> is not appropriate