This test consists in detecting captcha object images and thus defining the applicability of the test.
Human check will be then needed to determine whether the alternative is pertinent.
Pour chaque image objet (balise
type="image/…") utilisée comme CAPTCHA ou comme image-test, ayant une alternative textuelle ou un contenu alternatif, cette alternative est-elle pertinente ?
<object> tags with a
type="image" attribute, not within a link
All the elements of Set1 identified as a CAPTCHA (see Notes for details about CAPTCHA characterisation).
All the elements of Set2 with a textual alternative (see Notes for details about textual alternative detection).
For each element of Set3, raise a MessageA
MessageA : Check captcha alternative
- code : CheckCaptchaAlternative
- status: Pre-Qualified
- parameter :
"computed accessible name",
"data"attribute, tag name
- present in source : yes
The page has no
<object> tag with a
type="image" attribute with a textual alternative, identified as a captcha (Set3 is empty)
In all other cases
An element is identified as a CAPTCHA when the “captcha” occurrence is found :
- on one attribute of the element
- or within the text of the element
- or on one attribute of one parent of the element
- or within the text of one parent of the element
- or on one attribute of a sibling of the element
- or within the text of a sibling of the element
Textual alternative detection
The textual alternative can be set by the presence of any the following elements :
- Text associated via the
- Presence of an
- Presence of a
That order has to be respected to compute the textual alternative.
For instance, if an
aria-label WAI-ARIA attribute and an
title attribute are both present,
the content of the
aria-label WAI-ARIA attribute is considered as the textual alternative.
If none of these elements are present, two other conditions exist to set the textual alternative :
- A link, or a button is present just before or just after the element
- A mechanism exists to let the user replace the element by an alternative content.