hardware implementation of data compression ... - INFN Bologna
hardware implementation of data compression ... - INFN Bologna
hardware implementation of data compression ... - INFN Bologna
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132<br />
Wavelet based <strong>compression</strong> algorithm<br />
s<br />
a 5<br />
d 5<br />
d 4<br />
d 3<br />
−50<br />
40<br />
20<br />
d 0<br />
2 −20<br />
−40<br />
d 1<br />
150<br />
100<br />
50<br />
0<br />
30<br />
20<br />
10<br />
10<br />
0<br />
−10<br />
20<br />
0<br />
−20<br />
50<br />
0<br />
20<br />
0<br />
−20<br />
Decomposition at level 5 : s = a5 + d5 + d4 + d3 + d2 + d1 .<br />
1 2 3 4 5 6<br />
Figure 5.1: Uni-dimensional analysis on 5 levels <strong>of</strong> the signal S<br />
– the coefficients Cth have been synthesized into the signal R, using<br />
the filters H and G.<br />
Both in the uni-dimensional and in the bi-dimensional case, the performances<br />
related to <strong>compression</strong> have been quantified using the percentage<br />
P <strong>of</strong> the number <strong>of</strong> null coefficients in Cth, while the performances<br />
related to the reconstruction error have been quantified using the root<br />
mean square error E between the original signal S and the signal R,<br />
obtained after the analysis and synthesis <strong>of</strong> Cth.<br />
In particular, since the total number <strong>of</strong> elements in Cth is 65536, in<br />
the uni-dimensional case, the parameter P can be expressed in the<br />
following way:<br />
P =<br />
100 · (number <strong>of</strong> null coefficients in Cth)<br />
65536<br />
x 10 4<br />
(5.3)<br />
Even the total number <strong>of</strong> elements in S and in R is 65536, so, if si<br />
is the i-th element <strong>of</strong> the uni-dimensional signal S and ri is the i-th