A) Qualitatively: Capacity for seeing distinctly fine details that have a very small angular separation.

b) Quantitatively: Any of a number of measures of spatial discrimination such as the reciprocal of the value of the angular separation in minutes of arc of two neighbouring objects (points or lines or other specified stimuli) which the observer can just perceive to be separate. c) In system design, the reference value for normal human visual limiting resolution is 30 cycles/degree, i.e., 60 TV lines per angular degree subtended at the viewing position. For systems of current interest, the maximum viewing distances for discrete vertical resolution of the number of lines presented are shown in the following table.

Limiting Resolution of Vertical Detail (1) TV Per Subtended Maximum Line Frame Vertical Viewing Total Active Angle Distance (1) (2) 525 485 8.08" 7.1h (3) = 5.3w (4) 625 575 9.58" 6.0h = 4.5w (4) 1125 1035 17.25" 3.3h = 1.9W (5) (1) No adjustment has been applied for possible interlace or Kell effects.

(2) Assumes a shadow mask, if present, is not limiting.

(3) h is vertical height of display.

(4) w is horizontal width of display for 4:3 aspect ratio.

(5) W is horizontal width of display for 16:9 aspect ratio.