Matterhorn 13-001 · PDF/UA-1 UA1:7.3-1
Images not tagged as Figure
An image or vector drawing that carries meaning is not inside a Figure element. Either it is untagged, or it has been swept into a paragraph.
The condition, as the protocol states it. “Graphics objects other than text objects and artifacts are not tagged with a <Figure> tag.”
Matterhorn Protocol 1.1, checkpoint 13, index 13-001, section UA1:7.3-1. The protocol marks this as requiring human judgement.
What a screen reader actually does
The image is not announced at all, or is announced with no role and no description.
What is in the file
An image is painted by a Do operator invoking an image XObject, or by an inline image. For it to be real content it must sit inside a marked-content sequence that maps to a Figure:
/Figure <</MCID 7>> BDC
q 460 0 0 320 68 400 cm /Im0 Do Q
EMCwith a matching structure element:
21 0 obj
<< /Type /StructElem /S /Figure /P 9 0 R /Pg 3 0 R
/Alt (Quarterly revenue by region, North overtaking South in Q3.)
/K [ 7 ] >>
endobjOr, if it is decoration, inside an artifact sequence:
/Artifact BMC
q 595 0 0 60 0 782 cm /Im1 Do Q
EMCCondition 13-001 is an image that is in neither: painted, and absent from the structure tree.
Why this is worse than a missing description
There is a hierarchy of image failures, and it is worth being precise about which one you have.
A Figure with /Alt — correct.
A Figure with no /Alt — the reader announces “graphic” and stops. The user knows an image is there and knows they are not being told what it shows. That is 13-004.
An untagged image — nothing is announced. There is no cue that anything was skipped. A reader who encounters a paragraph saying “as the chart below shows” then hears the next paragraph, with no indication that a chart exists.
The third case is the one this condition covers, and it is the one that is invisible to a sighted reviewer and to Acrobat’s own alt-text tooling.
How to find it free
The reliable method is the Order panel, because it shows what is tagged rather than what has descriptions:
Accessibility → Reading Order→ Show Order Panel.- Every piece of tagged content gets a numbered box.
- Any image on the page with no box over it is untagged.
Acrobat’s Accessibility Check reports it under Figures alternate text only if the image is already a Figure; for genuinely untagged images look at Tagged content, which is 01-005 — the general case this condition is a specific instance of.
PAC reports it under clause 7.3 and shows it in the screen-reader preview as content that is simply absent.
How to fix it free, in Acrobat Pro
Accessibility → Reading Order.- Drag a marquee around the image on the page.
- Click Figure — or Background/Artifact if it is decoration.
- If you chose Figure: right-click its tag in the Tags panel → Properties → type into Alternate Text.
The decision in step 3 is the whole job. Everything else is mechanical.
Faster, if there are many: Accessibility → Set Alternate Text walks every Figure with a Decorative figure checkbox. It will not find untagged images, so run the Order panel sweep first to tag them, then use the panel to describe them.
Upstream: any image placed in Word or InDesign exports as a Figure. An image that arrives untagged usually got there by being drawn into the PDF later, or by an export with structure tagging turned off.
Where Taggart differs
Taggart counts what is painted against what is tagged, per page:
Page 3 paints 4 image(s) that are not artifacts, but the page has 1
<Figure>element(s). Meaningful graphics need a<Figure>tag; decorative ones need to be artifacts.
That comparison is the useful part — it finds the images Acrobat’s alt-text panel cannot show you, because it counts painting operators rather than walking the structure tree.
The fix wraps untagged images in <Figure> elements, and is gated behind explicit confirmation because it makes a claim: that these images are content rather than decoration. Taggart reports how many it found and what tagging them all would mean, then leaves the decision with you. Each new Figure still needs alt text or demotion to an artifact, and the change log says so.
How Taggart handles it
The protocol marks this condition as needing human judgement, so no validator can decide it outright. Taggart applies a heuristic to find the likely cases and reports them as warnings for you to confirm — it never passes them silently, and it never fails them silently either.
The fix is Tag graphics as figures. It changes what the document means, so Taggart proposes it and waits for your approval rather than applying it unattended.
Whatever Taggart changes, the page still looks identical. Fixes edit the PDF object model, not the content streams, and every remediation is re-rendered and compared against the original at structural similarity ≥ 0.999 before you get the file back. A tool that quietly reflows your document is worse than no tool.
Frequently asked questions
How is this different from a missing alt text?
A Figure with no /Alt is announced as 'graphic' with no description — the reader knows something is there. An untagged image is not announced at all. Condition 13-004 is the first case; this one is the second, and it is the more serious of the two.
Acrobat's Set Alternate Text panel does not show my image. Why?
Because that panel only walks elements already tagged as Figure. An untagged image is invisible to it, which is exactly why this condition is easy to miss — the tool you would reach for cannot see the problem.
What if the image is decorative?
Then it should be an artifact, which is also a fix for this condition. Artifacting removes it from the structure tree so the reader never encounters it. What is not acceptable is leaving it untagged: undeclared is not the same as declared-decorative.
Does this include vector drawings and charts?
Yes. The condition covers graphics objects other than text and artifacts, which includes vector paths. A chart drawn as forty separate paths needs to be one Figure, not forty — that is condition 13-006.
Where this sits in the standards
| Standard | Reference |
|---|---|
| Matterhorn Protocol 1.1 | Checkpoint 13 (Graphics), index 13-001 |
| PDF/UA-1 (ISO 14289-1) | Clause 7.3-1 |
| WCAG 2.1 | 1.1.1 Non-text Content — Level A |
| EN 301 549 / Section 508 / ADA Title II | All three point at WCAG 2.1 Level AA for non-web documents, so a Level A or AA criterion here is in scope for each of them. |
Related conditions
- 13-004 Figure tag alternative or replacement text missing A Figure element has neither /Alt nor /ActualText. Every Figure must have one or the other; if the image is decorative it should be an artifact instead of a Figure.
- 13-003 A caption is not tagged with a Caption tag "Figure 3: Quarterly revenue" is tagged as a paragraph rather than as a Caption associated with its figure or table.
- 01-005 Content is neither marked as Artifact nor tagged as real content Every text-showing, image-painting and path-painting operator on a page must sit either inside a marked-content sequence that maps to the structure tree, or inside an artifact sequence. Content that is in neither is orphaned.
- 13-006 A graphic with meaning only as part of a group is tagged on its own A chart built from dozens of separate vector paths has been tagged as dozens of Figures instead of one. Each fragment is meaningless alone.
Other conditions in checkpoint 13
Checkpoint 13 covers graphics. These are its other failure conditions; the ones without a link are in the rule set but do not have a written page yet.
- 13-002 A link with a meaningful background lacks alternative text for both An image link — a button, a logo that navigates — needs alternative text that conveys both what the graphic shows and where the link goes.
- 13-003 A caption is not tagged with a Caption tag "Figure 3: Quarterly revenue" is tagged as a paragraph rather than as a Caption associated with its figure or table.
- 13-004 Figure tag alternative or replacement text missing A Figure element has neither /Alt nor /ActualText. Every Figure must have one or the other; if the image is decorative it should be an artifact instead of a Figure.
- 13-005 ActualText used for a Figure for which alternative text is more appropriate ActualText replaces the content for text-extraction purposes; Alt describes it. A photograph needs Alt. A drop cap or a glyph-as-image needs ActualText.
- 13-006 A graphic with meaning only as part of a group is tagged on its own A chart built from dozens of separate vector paths has been tagged as dozens of Figures instead of one. Each fragment is meaningless alone.
- 13-007 A more accessible representation is not used A data table rendered as a picture, or body text set as an image, when real text and real table structure were available.
- 13-008 ActualText not present when a Figure is intended to be consumed primarily as text A drop cap, a logo that is a word, an image of a signature block — content that is text — needs ActualText so it flows into the text stream.
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