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PJWU-101B 17/10/2014
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8.Image
Black level setting : brightness
White level setting : contrast
The same absolute black and white level for the three colors allows the same reference for Brightness and Contrast control of
the picture !
These two references also set the range in which the ADC will work for that particular source (this explains also why each
input balance setting is linked to a particular source and thus saved in the image file).
Adjusting the input balance
To balance the three color signals of a particular source there are conditions; in fact we must know the black and the white
level of the source i.e. :
1.
The source in question must be able to generate a white signal, ideally a 100% white (background) full screen pattern
2.
The source in question must be able to generate a black signal, ideally a 100% black (background) full screen pattern
A B
White balance : In the projector, we will set the contrast for each color until we get a 100% light output picture when
projecting a 100% white image (image A)
Black balance : In the projector, we will set the brightness for each color until we get a 0% light output picture when
projecting a 100% black image (image B).
The changeover from min to max is indicated by the apparition of bright spots also called “digital noise”
An alternative to a full screen White/black pattern is the standard gray scale pattern, the white bar will be
used for white balance and the black bar for black balance.
Offset
This refers to the control of color imbalance in the darker areas of the projected image.It is recommended that you use an
external test image with many areas of dark and gray colors (i.e. an image of 30IRE-window). If you notice minimal amount
of red, green or blue in the gray areas, adjust the offset of the corresponding color accordingly.This function will shift the
entire color spectrum for the whole image and change its brightness.
Gain
This refers to the control of color imbalance in the brighter areas of the projected image.It is recommended that you use an
external test image with many areas of white (i.e. an image of 80IRE-window). If you notice minimal amount of red, green or
blue in the gray areas, lower the gain of the corresponding color accordingly.This function is used to increase or decrease the
range of color input for the entire image.
Generally speaking, as gain increases, the contrast of the image will become lower.By increasing the offset, the image
brightness will become lower.