SAA6721E Datasheet, PDF (20/72 Pages) NXP Semiconductors – SXGA RGB to TFT graphics engine

Philips Semiconductors
SXGA RGB to TFT graphics engine
Preliminary specification
SAA6721E
If the data transfer was a read transfer and the master was
receiver, the master must not generate an acknowledge
before the STOP condition.
7.8 De-interlacing algorithms
The SAA6721E features several de-interlacing algorithms
for processing interlaced video data. Depending on the
algorithm different memory bandwidths and field
memories are needed.
7.8.1 STATIC MESH MODE
This mode allows de-interlacing without any image
processing and filtering. A field store for 2 fields is
necessary. De-interlacing is achieved by simply putting
lines together in the right order from the odd and even
fields in the field store and generating the output frame.
7.8.2 SPATIAL FILTERING
The spatial filtering mode requires 2 field memories, but
only one memory is used at a time. For the calculation of
the whole frame from an odd field, the missing even lines
are interpolated from the odd lines before and after.
Processing of the even field is done in the same way.
7.8.3 TEMPORAL FILTERING
The filtering algorithm needs 4 field memories and will be
applied temporally to subsequent fields.
The missing even line in an odd frame will be calculated by
interpolation from the corresponding even lines in the even
fields before and after. The odd line handling is done in the
same way.
7.9 Scaling algorithm
The SAA6721E features different scaling engines for up
and downscaling, for both horizontal and vertical
processing. The horizontal scaling engines are
independent from each other. The vertical scaling engines
share the line buffer, so they cannot operate in parallel.
7.9.1 UPSCALING
The upscaling engine is used for enlarging the incoming
video frames. It can be used for zooming both RGB and
YUV video data. The magnification can be programmed
individually for horizontal and vertical scaling.
The maximum scaling factor for both directions is 64.
The implemented filter algorithm (see Fig.10) uses
interpolation with pixel enhancement, based on a free
programmable transition function. It is therefore possible
to define the transition between two calculated pixels to
obtain different sharpness characteristics. This transition
function must be defined in the 7 bits × 64 look-up table,
with a number ranging from 0 to 64. Different functions can
be programmed for horizontal and vertical scaling.
handbook, full pagewidth
intensity of
output pixel O
100% A,
0% B
A
B
(3)
MHB250
(2)
O
(1)
0% A,
100% B
100% A,
0% B
0% A,
100% B
ratio between
input pixels A, B
(1) The linear interpolation results in smoothing the sharp edges of the original picture if a pixel must be calculated.
(2) Some kind of ¹â„_x function results in sharper edges, because of the smaller transition interval.
(3) Phase correct pixel repetition can be done with this function.
Fig.10 Interpolation function definition.
1999 May 11
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