pnx1700 NXP Semiconductors, pnx1700 Datasheet - Page 369

• Manufacturer Part Number: pnx1700
• Description: Connected Media Processor
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Volume 1 of 1
PNX17XX_SER_1
Preliminary data sheet
2.3.7 Layer and Fetch Control
The second function of the VCBM unit is to take YUV (for video) or RGB (for graphics)
inputs and produce RGB or YUV outputs. The color space conversion is effected by
multiplying a 3x1column vector (with 3 components: Y, U, V or R, G, B) in the source
color space with a 3x3 matrix (of coefficients) in order to obtain a 3x1 column vector
in the destination color space. The programmable coefficients of the 3x3 matrix can
be altered to modify contrast, saturation, and hue.
where
Thus, the main functions performed by the VCBM unit are: contrast and brightness
control and color-space conversion with white-point control; this is achieved by using
one or more operations from the following sequence:
The layer fetch control receives the global screen coordinates from the STG and
takes care of extracting the pixels from a layer when needed (i.e., when the
programmed position for the layer has reached). Another task (of the layer fetch
control unit) is to clip layers exceeding the screen coordinates.
UP
LO
MI
•
•
•
•
•
•
•
•
•
•
•
•
UP, MI, and LO = R,G,B or Y,U,V
Cij= the standard matrix coefficients multiplied by the desired contrast ratio
b = the brightness value divided by the desired contrast ratio
For YUV input b’ = 0 and for RGB input b’=b
For RGB -> RGB, there is no support for brightness control.
contrast control by multiplying the 9 matrix coefficients by the same desired
contrast ratio (where a ratio of 1 means a gain of unity).
brightness control on YUV (add offset "b", as shown above, to values at the input
of matrix, where b signifies the desired brightness offset scaled by the contrast
gain)
YUV-to-RGB matrix, also usable for YUV-to-YUV
optional saturation control via the YUV-to-RGB (etc.) matrix (by adjusting the
contribution of U and V by the same ratio, while keeping the contribution of Y as
constant, done by modifying the six matrix coefficients for U and V.
optional white-D control via the YUV-to-RGB (etc.) matrix
offset addition for making unsigned U&V
guaranteed hard-clipping to 10-bit unsigned formats
out
out
out
=
C
C
C
00
10
20
C
C
C
01
11
21
Rev. 1 — 17 March 2006
C
C
C
02
12
22
LO
MI
UP
in
in
in
+
+
+
b
b
b
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
PNX17xx Series
Chapter 11: QVCP
11-12
(10)