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-- by James Alan Miller and Deborah K. Wong
Maximum resolution is a basic spec that monitor manufacturers supply. But you can use other numbers to determine a monitor's true maximum resolution.
First, you need to know three numbers: dot pitch (dot- trio pitch for shadow-mask monitors, or stripe or horizontal pitch for Trinitron monitors), and the actual viewing area's horizontal and vertical measurements in millimeters. You can get the horizontal and vertical measurements from the manufacturer or the manual, or you can take the measurements yourself. If you're going to do the measuring, make sure the screen's image is maximized, and take the horizontal and vertical measurements close to the screen's center.
Plug these numbers into one of the following formulas.
For dot-trio monitors: To find the maximum horizontal resolution, divide the horizontal measurement by the dot pitch times 0.866 (the sine of 60 degrees)
Horizontal Measurement/(.866 x dot pitch) = Maximum Pixels Horizontally (MPH)
To find the maximum number of pixels vertically (MPV), replace the horizontal measurement with the vertical dimension.
So, for a 17-inch dot-trio monitor with an actual viewing area of 320mm x 240mm (HxV) and a 0.25mm dot pitch, the following equations yield a real physical maximum resolution of 1478x1109:
320/(0.866 x 0.25) = 1478 MPH
240/(0.866 x 0.25) = 1109 MPV
For Trinitron monitors: Divide the horizontal or vertical measurement by the horizontal or vertical stripe pitch.
Horizontal Measurement/Horizontal Stripe Pitch = MPH
Vertical Measurement /Vertical Stripe Pitch = MPV
For a 17-inch Trinitron monitor with an actual viewing area of 320mm x 240mm (HxV), a .25mm horizontal stripe pitch and a .40mm vertical stripe pitch, the equations indicate a maximum resolution of 1280x600.
320/.25= 1280 MPH
240/.40= 600 MPV