Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 65
LC4.5E AA
9.
The video processing is completely handled by the Hercules
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IF demodulator.
•
Chrominance decoder
•
Sync separator.
•
Horizontal & vertical drive.
•
RGB processing.
•
CVBS and SVHS source select.
It has also build in features like:
•
CTI.
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Black stretch.
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Blue stretch.
•
White stretch.
•
Slow start up.
•
Dynamic skin tone correction etc.
Further, it also incorporates sound IF traps and filters, and
requires only one crystal for all systems.
9.6.1
Histogram (YUV Picture Improvement) IC
The demodulated video-signal can be checked on pins 74, 75,
and 76 of IC7011 and is fed to pins 70, 71, and 72. In this path,
the Histogram IC TDA9171 is inserted.
This TDA9178 can control various picture improvements:
•
Histogram processing.
•
Colour transient improvement.
•
Luminance transient improvement.
•
Black and white stretch.
•
Skin tone correction.
•
Green enhancement.
•
Blue stretch.
•
Smart peaking.
•
Video dependent coring.
•
Colour dependent stretching.
Since the TDA9171 is connected to the Hercules, picture
improvement works only for signals that are routed trough the
Hercules and not for signals directly connected to the Scaler.
9.7
Video: Scaler Part (Diagram A7 and A13)
The Genesis gm1501 Scaler is a dual channel graphics and
video processing IC for LCD monitors and televisions
incorporating Picture in Picture, up to SXGA output resolutions.
The Scaler controls the display processing in an LCD TV ( in a
CRT-based TV, the deflection circuit would do this). It controls
all the view modes (e.g. like "zooming" and "shifting"). Features
like PC (VGA) or HD inputs, are also handled by this part.
