B&K Precision 1253 - Manual - Manual (Page 15)

7: Raster
Description: Full field color raster patterns at 75% amplitude.
Variations: Pressing The Raster button multiple times, sequences the full-screen output through 8 colors,
at 75% amplitude: White, Yellow, Cyan, Green, Magenta, Red, Blue, and Black.
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 usually shows up better on a
primary-color raster, especially red. This 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.
Also used to check missing pixels on a TFT or LCD Monitor by switching to primary colors (Red, Green
and Blue), then observing the screen for missing (dark or "stuck") pixels, which are common on these
types of displays. Use the Red, Green and Blue Raster Patterns to test each pixel color.
Examples of Uncalibrated Displays: The following images indicate problems with a TV.
The first image shows a display which has misconvergence of the RGB guns of a CRT type monitor.
If this effect is profound, it could indicate a broken or warped shadow mask.
The second image shows "stuck" pixels on a TFT or LCD type monitor. This is normally not repairable.
RGB Misconvergence
Missing (stuck) Pixels
Non-Uniform Color