VP400 Series Video Pro
Form7343A
Operation Manual
27
Ramp
Pattern Description
:
The Ramp pattern makes a smooth transition from 100% black on the left to 100% white on the
right. When electrical video signal is viewed at horizontal scan rate, it appears as linear ramp
from black level to white level.
Pattern Usage
:
The Ramp pattern is useful for visually checking
grayscale tracking performance of a display. Poor
performance is seen as a primary color tint (red,
green, or blue) at one or more light levels. It also
checks the digitizing linearity of video signal
processors. Poor performance is seen as vertical
bands which interrupt the smooth transition from
black to white.
Raster
Pattern Description
:
This is a full field raster pattern. Pattern luminance level is adjustable from 100 IRE to 0 IRE in
either 1 or 5 IRE steps. Individual colors can be gated on or off (in the Gating menu) to produce
red, green, blue, cyan, magenta, and yellow rasters (not in YPbPr or ATSC RF formats).
Pattern Usage
:
Use to check color purity and display chrominance
uniformity. Color purity problems are usually
caused by slight magnetization of some part of a
CRT display device, often metallic CRT mounting
brackets or the metallic CRT shadow mask,
located just behind the phosphor screen in a direct-
view CRT. This can usually be seen as areas of
color on a white raster, but shows up better on a
primary-color raster, especially red.
The Raster pattern may also be useful in detecting
red and blue overdrive at the sides of a projection
display, due to insufficient correction for CRT
side-to-side placement.
