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Determining Image Height Formula

The formula for determining image height based upon a certain viewing task is:

SH = D / SL

Where:

  • SH = Height of image on screen 
  • D = Distance to the farthest viewer from the screen
  • SL = Level of screen detail
    • SL = 4 for inspection viewing tasks 
    • SL = 6 for detailed viewing tasks
    • SL = 8 for general viewing tasks

 Note that the unit of measure for SH  will be the same for D, whether inches, feet, or millimeters.

The farthest viewer is 480 inches (12192 mm) away, and the viewing task is general observation.

Step one:

Determine the farthest viewer.

  • Substitute the distance, 480 inches (12192 mm), for D
  • Substitute the level of screen detail, 8, for SL

Step two:

Calculate.

SH = 480 inches / 8

SH = 60 inches (1524 mm)

The farthest viewer is 390 inches (9906 mm) away, and the viewing task is detailed viewing.

Step one:

Determine the farthest viewer.

  • Substitute the distance, 390 inches (9906 mm), for D
  • Substitute the level of screen detail, 6, for SL

Step two:

Calculate.

SH = 390 inches / 6

SH = 65 inches (1651 mm)

Here is an example of a metric-only calculation.

The farthest viewer is 12200 mm away, and the viewing task is general observation.

Step one:

Determine the farthest viewer.

  • Substitute the distance, 12200 mm, for D
  • Substitute the level of screen detail, 8, for SL

Step two:

Calculate.

SH = 12200 mm / 8

SH = 1525 mm