Document #
Revision Date
82070-243, Revision F
19 of 22
11/24/2009
Glossary
Bias (Red, Green, Blue):
Increasing the bias of a color increases the proportion of that color in the image.
The level of the selected color is varied equally for all proportions. For example:
Color Number 1 Proportions
Bias Increase New Color Proportions
Red = 20%
5%
Red = 20% + 5% = 25%
Green = 70%
0%
Green = 70%
Blue = 40%
0%
Blue = 40%
Color Number 2 Proportions
Bias Increase New Color Proportions
Red = 60%
5%
Red = 60% + 5% = 65%
Green = 40%
0%
Green = 40%
Blue = 30%
0%
Blue = 30%
Note that Red has been increased by 5% regardless of its original proportion.
Since increasing the bias will add additional proportions of the color, care must be taken to assure that
variations for very weak and very intense sections of the image do not lose their “Contrast” (ability to detect
subtle variations between colors).
Black Level:
This adjustment allows the display to be set to discriminate between small differences in dark
or near black areas of the image. The adjustment should make a black area of the image (such as a deep
shadow where all detail is lost in the image) appear black. The black level is decreased (less black) until a
change toward light or grey is perceived in this area, then the adjustment should be increased slightly to
restore the dark area to black. It is important to perform this adjustment on a truly black area in the image to
avoid making dark areas appear lighter than they actually are.
Brightness:
The intensity of light emitted from the LCD Display. This control is similar to the effect of
changing the light behind a stained glass window. As the illumination is increased the overall light output of
the image is increased. The proper adjustment takes into consideration the ambient light in the room. For a
brightly lit room, the brightness of the display may be increased to improve the visibility of the image. In a
dimly lit room, the brightness may be decreased to reduce the impact on the eye.
Clock:
This adjustment is seldom necessary, but if there is a problem with the frequency of the monitor
pixel clock that it cannot exactly match the clock signal from the camera, an adjustment may be required.
The symptom of a clock adjustment problem is the appearance of vertical bands in the image. Adjustment
of the clock will help eliminate these artifacts.
Contrast:
Contrast is the differentiation between variations of similar colors. Typically contrast is set by
adjusting for best color differentiation between light yellow and white.
Gain (Red, Green, Blue):
Increases in the gain of a color multiplies the proportion of that color in the image
by a factor. The actual amount of additional color is relative to the original level of that color in the image.
Using the two colors mentioned in the Bias description above, if we vary the Gain of the Red by 10% we add
10% of the original color to the original color proportion to get the new color.
Original Color Proportions
Gain Increase New Color Proportions
Red = 20%
10%
Red = 20% + 0.1 x 20% = 22%
Green = 70%
0%
Green = 70%
Blue = 40%
0%
Blue = 40%
Color Number 2 Proportions
Gain Increase New Color Proportions
Red = 60%
10%
Red = 60% + 0.1 x 60% = 66%
Green = 40%
0%
Green = 40%
Blue = 30%
0%
Blue = 30%
Notice that the increase in the color proportion of the Red is greater for greater original color proportions of
Red. Lighter reds are increased a lesser amount than darker reds as gain is increased.
