STV3550 Datasheet, PDF (59/144 Pages) STMicroelectronics – LCD and Matrix Display TV Processor

STV3550
5.2 Gamma Correction
The Gamma correction is a completely programmable block, which is used to correct the input
pixels. The CPU supplies the gamma correction curves by writing the data into the Look Up Tables
located in this block. This block can be bypassed, in which case the flow of pixels is left unchanged.
Figure 42: Gamma Correction Block Diagram
STBus
STBus
Interface
(STI)
Red LUT
Green LUT Blue LUT
Pixel Inputs
Translation (TRA)
Pixel
outputs
5.3
Note:
Perfect Color Engine
PCE (Perfect Color Engine) dithers an input 10 bit video stream down to 4-6-8-10 output bits.The
dithering is done in space and time in such a way that the eye does not perceive objectionable
artifacts such as:
● Fixed dither patterns
● Contours
● Flickering pixels
● Phase correlated flickering, which creates wave patterns known as swimming.
The dithering efffect tends to average neighboring pixels and smooth the color tonal transition and
contours of the image. It works by spreading the quantization error over neighboring pixels (spatially
and temporally).
5.4 Digital Video Output Stage
5.4.1
Introduction
This block performs the digital video output stage. This block generates the Data Enable (DE) signal
on account of the register configuration, it also resynchronises and recalibrates the Vsync and
Hsync signals according to the register configuration. This block delivers the Data Clock (Dclk) with
a delay selected by the register and fixes the default output state of all the digital video interface.
This block also provide a reduce interface with a data valid on each edge of the clock.
The output frequency range is 22MHz up to 72MHz according to the user configuration.
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