TW9903 データシートの表示（PDF） - Unspecified
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TW9903 Datasheet PDF : 74 Pages
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TW9903
Video Format support
TW9903 supports all common video formats as shown in Table 1. The video decoder needs to be
programmed appropriately for each of the composite video input formats.
Table 1. Video Input Formats Supported by the TW9903
Format
Lines Fields
Fsc
Country
NTSC -M
525
60
3.579545 MHz U.S., many others
NTSC-Japan (1) 525
PAL-B, G, N
625
60
3.579545 MHz Japan
50
4.433619 MHz Many
PAL-D
625
50
4.433619 MHz China
PAL-H
625
50
4.433619 MHz Belgium
PAL-I
625
50
4.433619 MHz Great Britain, others
PAL-M
625
60
3.575612 MHz Brazil
PAL-CN
625
50
3.582056 MHz Argentina
SECAM
PAL-60
625
50
4.406MHz
France, Eastern Europe,
4.250MHz
Middle East, Russia
525
60
4.433619 MHz China
NTSC (4.43)
525
60
4.433619 MHz Transcoding
Notes: (1). NTSC-Japan has 0 IRE setup.
Component Processing
Luminance Processing
The TW9903 adjusts brightness by adding a programmable value (in register BRIGHTNESS) to
the Y signal. It adjusts the picture contrast by changing the gain (in register CONTRAST) of the Y
signal.
The TW9903 video decoder also performs a coring function. It can force all values below a certain
level, programmed in the Coring Control Register, to zero. This is useful because human eyes are
sensitive to variations in nearly black images. Changing levels near black to true black, can make
the image appears clearer.
Gamma
Y Gamma function is provided to compensate for different display types. Four pre-programmed
Gamma levels can be selected through registers.
Sharpness
The TW9903 also provides a sharpness control function through control registers. It provides the
control in 16 steps up to +12db. The center frequency of the enhancement curve is around 3.5Mhz.
It also provides a high frequency coring function to minimize the amplification of high frequency
noise. The coring level is adjustable through the Coring Control register. The same function can
also be used to soften the images. This can be used to provide noise reduction on noisy signal.
TECHWELL, INC.
9
REV. 0.92 ( B )
06/02/2002
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