Text needs sufficient contrast against its background

PDF/UA check COLOR_CONTRAST · Page content · severity High · PDF/UA WCAG 2.x 1.4.3 Contrast (Minimum)

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Why it matters#

Low contrast text is hard to read for people with low vision or color blindness. Adequate contrast ensures text remains readable in various lighting conditions and for users with visual impairments. Note: this is a WCAG requirement, not directly mandated by PDF/UA-2.

What you will see#

Text on the flagged pages falls below the 4.5:1 contrast ratio against its background.

How to fix#

Increase the contrast between the text color and its background to at least 4.5:1, or 3:1 for large text (18pt, or 14pt bold). Darken the text fill color or lighten the background in the source document and re-export the PDF.

Step-by-step guide#

1. Identify the flagged text from the EQChecker report - failed pages and, when image capture is enabled, the preview crops showing the exact low-contrast runs.
2. Fix in the source document wherever possible: darken the text fill or lighten the background until the contrast ratio is at least 4.5:1, then re-export the PDF. WCAG allows 3:1 for large text (at least 18 pt, or 14 pt bold), but EQChecker applies the flat 4.5:1 threshold to all text - aim for 4.5:1 to clear this check. Pick compliant pairs with any WCAG contrast ratio calculator.
3. For small touch-ups directly in the PDF, use Acrobat Edit a PDF: select the text and change its fill color in the format properties to a compliant value.
4. For text placed over photographs or gradients, measure against the least contrasting region behind the text; if the background varies too much, add a solid or semi-opaque backing plate behind the text in the source layout.
5. Recheck any text in charts, stamps, and headers/footers - exported graphics are a frequent source of low-contrast labels.

Verify: Re-run the EQChecker scan and confirm COLOR_CONTRAST reports zero failed objects. Acrobat's automated checks do not measure contrast (it is listed as a manual step), so spot-check the fixed pages with a contrast analyzer or the report preview images.

Note: This is WCAG 2.x SC 1.4.3, not a PDF/UA-2 requirement. WCAG exemptions apply: large text needs only 3:1, and incidental text (pure decoration, inactive UI, text in inactive parts of images) and text in logotypes have no contrast requirement. EQChecker does not implement the large-text or incidental-text carve-outs - it measures every rendered text run against 4.5:1 - so treat flags on exempt text as candidates for manual review rather than mandatory fixes.

WCAG success criteria#

1.4.3 Contrast (Minimum) — Level AA#

Text needs a contrast ratio of at least 4.5:1 (3:1 for large text) against its background.

Understanding 1.4.3

Standards#

This check contributes to the following standards:

PDF/UA WCAG AA EN 301 549

References#

• W3C — Understanding SC 1.4.3 Contrast (Minimum)