Detailed test information and WCAG references.
This test is based on the WCAG 2.0 Technique PDF4: Hiding decorative images with the Artifact tag in PDF documents
Decorative images are images that serve only an aesthetic purpose. They provide no information and have no functionality. Users of assistive technology might be confused if a screen-reader announces decorative images or if such images show up when the document reflow function is used.
Decorative image should be marked in such a way that they can be ignored by assistive technology. This prevents that presentation of unnecessary information and thus reduces the cognitive load for the user.
1.1.1 Non-text Content "“All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A)"