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Signature/Ink Compression

 
Our signature/ink compression engine compresses signatures that have been recorded using a digitizer tablet. It does not compress bitmaps.

This compression engine achieves high compression rates for individual signature files. Most other compression methods have a significant overhead that renders them unusable for small signature files.

In addition, the compression achieved far exceeds what conventional tools like zip compression utilities can achieve on this type of data.

A typical raw ink format may store each point's (x,y,penup/down) information as two 16-bit integers. Conventional zip algorithms have trouble reducing such data to half of its original size (they typically achieve 66% of original size).

Our engine will compress the same data so that it is 1/5 to 1/10 of its original size (i.e. 10-20% of original size). Some actual results on real data are given below.

Even lower compression factors are possible (1/20 for some samples). The compression ratio is related to the complexity and sampling rate for the original signature. Signatures recorded at very high sampling rates have higher redundancy and will yield higher compression rates (lower compression factor).

 
  Examples
 


976 bytes
(244 data points)
 
zip: 846 bytes (87%)

164 bytes (17%)
 
 

9,560 bytes
(2390 data points)
 
zip: 4,925 bytes (51%)

950 bytes (10%)
 
 

7,248 bytes
(1812 data points)
 
zip: 3,734 bytes (51%)

936 bytes (13%)
 
 

4,504 bytes
(1126 data points)
 
zip: 2,142 bytes (48%)

387 bytes (9%)
 
 

10,188 bytes
(2547 data points)
 
zip: 5,958 bytes (58%)

1,109 bytes (11%)
 
 

1,408 bytes
(352 data points)
 
zip: 1,016 bytes (72%)

74 bytes (5%)
 
 

1,920 bytes
(480 data points)
 
zip: 1,403 bytes (73%)

87 bytes (5%)
 
 
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Last modified: Sunday, 29-Jan-2012 09:49:22 MST
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Copyright © Salman Burkie, 1995-1998. All Rights Reserved.