Given the maximum distance from an image and the viewer task, calculate image height.

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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 image height formula reveals that tasks requiring more detail require bigger images. These tasks have been grouped into three selections called "levels of detail."

  • Use 8 when the viewers will generally view content. This could be for any type of motion picture viewing where details are not critical. This task is known as general viewing.
  • Use 6 when the viewers will read content with clues. This could be for reviewing web pages, spreadsheets or simple presentations. Words offer "clues" to the meaning of the surrounding images for easier interpretation. This task is known as reading with clues.
  • Use 4 when the viewers will inspect content without clues. This could be for carefully analyzing engineering drawings or medical images, without words to help interpret the image's meaning. This task is known as inspection.
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Watch the Video: Calculating Image Height by Task

View video lecture (2 mins) to learn how to calculate image height by task.

"11132 Projection Screens", SpecGUIDE Draft .February 14, 1991, CSI.