Quantum Data 881, User Manual

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882 Video Test Instrument User Guide (Rev A.35) 273
the maximum range available is (3760 - 256 = 3504) grayscale levels. Since PELD is set
to 32 (24 bit depth) the maximum number or grayscale levels that can be rendered by the
882 on a display with the RampDif image is 1024 (512 per ramp). So if you set the Color1
slide bar at 25% and the Color2 slide bar at 75%, the level on the left of the top ramp
would be 1132 ([3504 * 0.25] + 256 = 1132) and the level on the right end would be 2884
([3504 * 0.75] + 256 = 2884). Since the top ramp can render 512 distinct levels you would
see bands of ~2.5 pixels each (1280 / 512 = 2.5). Since the bottom ramp can render 256
distinct levels you would see bands of 5.0 pixels each (1280 / 256 = 5.0).
Checkers image
This image has two color checker or tile types arranged in a checker board pattern. It
enables you to show a contrast in the tiles at a specified color depth. You can move the
slide bars of each color such that they are close in color space. You can then view the
image and see whether distinquish between the two tile types. You need to set the pixel
depth in the 882 to 24 bit (PELD = 32) in order to access 512 grayscale or color levels for
each tile for a single image rendered on a display.
The following is a sample of the Checkers image is rendered on a display.