5.1.4: Functionality closed to text enlargement

Where any functionality of ICT is closed to the text enlargement features of platform or assistive technology, the ICT shall provide a mode of operation where the text and images of text necessary for all functionality is displayed in such a way that a non-accented capital "H" subtends an angle of at least 0,7 degrees at a viewing distance specified by the supplier.

The subtended angle, in degrees, may be calculated from:

Ψ = (180 x 60 x H) / (π x D)

Where:

  •  ψ is the subtended angle
  •  H is the height of the text
  •  D is the viewing distance.
  •  D and H are expressed in the same units

Notes

The intent is to provide a mode of operation where text is large enough to be used by most users with low vision.

Testing methods

Type of complianceInspection and measurement
Pre-conditions
  1. A functionality of the ICT is closed to enlargement features of platform or assistive technology.
  2. A viewing distance is specified by the supplier.
Procedure
  1. Measure the height of a capital letter H.
  2. Check that it subtends an angle of at least 0,7 degrees at the specified viewing distance.
Result Pass: Check 2 is true
Fail: Check 2 is false

Requirement details

Reference number: 5.1.4

Related requirements

Related functional statements

Usage with limited vision

Related technical requirements

No related technical requirements are associated with this technical requirement