pnx1500 NXP Semiconductors, pnx1500 Datasheet - Page 366

• Manufacturer Part Number: pnx1500
• Description: Pnx15xx Series Connected Media Processor
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Volume 1 of 1
PNX15XX_SER_3
Product data sheet
2.4.1 CLUT (Color Look Up Table)
2.4.2 DCTI (Digital Chroma/Color Transient Improvement)
2.4.3 HSRU (Horizontal Sample Rate Upconverter)
2.4 Pool Resources and Functions
The following sections describe the pool elements. These elements are never needed
in all of the layers at the same time.
All of the pool units comprise three basic sub-modules (and so do the layer units):
Functional Unit: This is where the data is processed. It contains the data path and
the logic to control the flow of data.
Register File: The register file contains the registers which are used to control the
pool resource. These registers are programmed via the pbus and are read/write.
Push-Pull Interface: This unit is used to control the flow of data into and out of the
pool resource. The push pull interface allow the flow of data to be stalled by and block
in the video pipe. If a stall occurs then all processing of the inputs stops and all data is
stored. When the stall is released then the data is processed as before.
The resource pool contains one set of component-based color-look-up tables for
each color component and for the potential alpha value of a pixel. The look-up table
has a depth of 256 words, with each word being 8 bits wide.
The basic function of a CLUT is to expand indexed-color formats. An 8-bit indexed
color would be applied to all component LUTs as an address, whereby each of the
LUTs will provide on its data ports the previously-programmed data word belonging to
that address. However, since the addresses of the LUTs are not linked together,
gamma correction on a component basis is also possible.
The Digital Color Transient Improvement (DCTI) block improves the steepness of
color transients. It is a form of delay modulation: around transients the signal is time-
compressed. This is a non-linear operation, and it increases the bandwidth of the
color signal. DCTI can not increase the number of transients per line (that would
require real bandwidth in the signal path), it can only increase the steepness of
transients that are already there.
DCTI modifies the U & V data paths. Horizontal transients are detected and
enhanced (without overshoots) by shifting the color values The amount of color shift
is controlled by values generated via differentiating the original signal, taking absolute
values of the differential, and differentiating the absolute values once again. To
prevent the third harmonic distortion, the so-called over the hill protection is applied.
This prevents peak signals from being distorted.
The main purpose of HSRU is horizontal up-sampling, where the re-sampling
function obeys a third-order difference equation for the phase of the sample positions.
This creates more space in the spectrum for LTI to fill. This extra room can also be
used by other non-linear operations, like HIST and VCBM, so that they will create less
undesired aliasing. Up-sampling is good before any non-linear operation, and all
blocks behind the HSRU will run on the higher sample-rate. We can also choose to
up-sample the left and right edges of the image more than the centre. This is called
Rev. 3 — 17 March 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
PNX15xx Series
Chapter 11: QVCP
11-13