PNX1700EH/G,557 Trident Microsystems, Inc., PNX1700EH/G,557 Datasheet - Page 371

• Manufacturer Part Number: PNX1700EH/G,557
• Manufacturer: Trident Microsystems, Inc.

Specifications of PNX1700EH/G,557

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Philips Semiconductors
Volume 1 of 1
PNX17XX_SER_1
Preliminary data sheet
2.4.4 HIST (Histogram Modification) Unit
2.4.5 LSHR (Luminance/Luma Sharpening) Unit
2.4.6 Color Features (CFTR) Unit
"Panorama mode" or "Superwide mode", and it is recommended for showing 4:3 or
14:9 images on a 16:9 display. Besides a linear constant upscaling ratio, the HSRU
also supports special non-linear upscaling ratios for the panorama mode.
Remark: Layer size(final) register has to be updated to match the scaled output size
of HSRU
The Histogram modification block complements the Histogram measurement blocks
in the MBS. It modifies the Y, U & V data according to a non-linear transfer curve. The
Y transfer curve is described by the 32 values of a look up table. The color difference
signals are also coupled to this curve by a calculation derived from the original Y and
its value after the Histogram modification. The final aim is to provide a greater
contrast by increasing the range of intensities in the input signal.
The LSHR module is used to improve (increase) the sharpness impression. Inputs to
the LSHR unit are all three of the Y, U and V signals. They are 10 bit signed values (-
512 to 511 range). The LSHR unit modifies the Y component only; U and V remain
untouched. Outputs of the LSHR unit are also 10-bit signed values.
The LSHR unit has a latency of 33 cycles when it is enabled. In the bypass mode, it
has no latency. For proper operation, at least 7 dummy cycles are required between
any two lines. The unit also performs sharpness measurements on the luma signal
and the results are stored in two status register: LSHR_E_max and LSHR_E_sum.
They are updated at the end of each frame.
The Color Features block performs a sequential combination of three functions:
These features are intended to correct the errors caused by the transmission and the
phosphors used in CRT displays. The reason that skin tone, blue-stretch (alters the
white temperature) and green enhancement are chosen is that the human eye is
most sensitive to unnatural errors in these colors. In practice, they can also be used
to enhance the vividness of certain colors in the picture. Skin tone correction will be
useful to compensate for a small phase error in the demodulation of analog NTSC
(hue error). Blue stretch and green enhancement just look nice.
Remark: It may not be fully correct to state above that the color features are intended
to correct the errors caused by the transmission and the phosphors used in CRT
displays. The real cause of the tint problem may well be that people are trying to
correct for an error that no longer exists. The current practice in NTSC countries has
been for a long time to encode for phosphors that are similar to EBU. If the TV makes
no corrections for presumed original NTSC phosphors, then there will be no error.
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Skin Tone Correction
Blue Stretch
Green Enhancement
Rev. 1 — 17 March 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
PNX17xx Series
Chapter 11: QVCP
11-14