Georgia Tech Research Institute
 
Issues

Labeling: Issue 1 of 6

Issue: Small icons and text are difficult for users with low vision to perceive.

A numeric keypad on a kiosk is shown.  The text labels and icons on the various number keys and function keys are very small, filling very little of the available space.

Text and icons used in labels on kiosks may be difficult for users with low vision to read if the characters or graphics are too small.

Populations Impacted: Users with low vision.

Potential Solutions:
  • Ensure that the font size of the text is sufficiently large. For 20/20 vision, the Human Factors Design Standard (HFDS) recommends that the height of characters occupy a visual angle of 16 to 24 minutes of arc. To compute the character height, use the following formula

    h = 2dTan(x/2)


    where h is the character height, d is the viewing distance, and x is the desired angle in radians. (One radian equals 3437.747 arc minutes, or 57.296 arc degrees.)

    1194.31(b) of Section 508 states that a mode that does not require visual acuity greater than 20/70 must be provided. Multiplying the character height (h) calculated for 20/20 vision by 3.5 (70/20) yields the recommended character height for 20/70 vision for the specified viewing distance.

    While this font size may not be possible for all instances of text on a device, making the text as large as possible will increase the chance that users with low vision will able to read the labels.

  • A numeric keypad on a kiosk is shown.  The text labels and icons on the various number keys and function keys are large, filling most of the available space.
  • Ensure that icons are large enough for low vision users to see. The largest dimension (height or width) of icons should be at least as large as the character height calculated above. Icons should be made as large as possible, given the space available. Often, a control is fairly large, but the icon on the control is only a small fraction of the total size of the control. If a control will accommodate the same icon in a larger size, the larger size should be used to enhance visibility for those with low vision.

Applicable Guidelines:
Section 508 - 1194.31(b)
Section 255 - 1193.43(b)
HFDS - 8.2.5.6.5, 8.2.5.6.6, 8.2.5.6.9
EITAAC - 5.2.1.2.1