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source
target
srcW=4;
tarW=8;
scale_factor=tarW/srcW;
acc_inc=srcW/tarW; % 4/8
acc=0;
for tar_col=0:tarW-1
src_col=floor(acc);
//simple example of nearest source mapping
acc=acc+acc_inc;
end
tar_col
acc
src_col
0 0 0
1 4/8 0
2 1 1
3 1 4/8 1
4 2 2
5 2 4/8 2
7 3 4/8 3
6 3 3
2
1
0
3
0
1
2
3
4
5
6
7
tarY[tar_col]=srcY[src_col];
Internal Modules
198
SPRUHI7A – December 2012 – Revised June 2016
Copyright © 2012–2016, Texas Instruments Incorporated
High-Definition Video Processing Subsystem (HDVPSS)
1.2.11.2.4.1 Half Decimation Filter
The half-decimation filter is an 11-tap filter with following coefficients – (14, 0, -29, 0, 79, 128, 79, 0, -29,
0, 14). For processing left and right edge pixels, the first and last data are repeated to pre-fill and extend
the filter data pipeline respectively.
These coefficients are hard-coded into scaler design and user cannot modify these.
1.2.11.2.4.2 Polyphase Filter
The horizontal scaling is done by stepping across the target row and interpolating target pixels based on
source pixels. Accumulator points to the source pixel that corresponds to the target pixel.
shows an up-scaling example.
Figure 1-148. Polyphase Filtering Example