H-compress Performance


Following is a table of LASCO H-Compress statistics that I
compiled last week.  I have also indicated movies
with the results of the tests if you would like to
see the images.  Since July 25 we have roughly been 
running C2 and C3 alternating Rice and H-Compress.
For C2 we have been using H-Compress 5 (compression
factor 7.6) and for C3 H-Compress 3 (compression
factor 6.2).

General Impressions:

1. H-Compress works great for C1-C2-C3 (no EIT testing done yet).
   The images look good at significant compression factors and
   the algorithm itself is fast.

2. For lossless compression Rice provides a better compression
   factor and is faster than lossless H-compress.
   [Ed Note. Ground testing showed lossless H-compress to be 
    faster than Rice but not as good at compression. ]
    
3. With the same H-Compress Scale Factors C1 compresses better
   than C3 which compresses better than C2.

4. With H-compress as you raise the compression factor the
   compression time gets considerably faster so it is 
   possible to reach an equilibrium between processing time
   and image downlink time.


Compression Statistics using H-Compress (July 24-25 '97)

------------------------------
C3 - 1024x1024 full-resolution	see $MVIS/hcompress_c3.mvi
------------------------------

H-Compress   Scale    Compression  time to        compressed   time to downlink
IP Step      Factor   Factor       process (sec)  size (bits)  (@ 7.9 kbps)
----------   ------   -----------  -------------  -----------  ----------------
Rice                      2.4        275           5,774,304     731
 0              0         2.3        378           6,381,392     808
 1              8         3.5        274           4,324,448     547
 2             16         4.5        243           3,375,904     427
 3             32         6.2        212           2,440,256     309
 4             48         7.8        193           1,924,704     244
 5             64         9.6        182           1,566,192     198


------------------------------
C2 - 1024x1024 full-resolution	see $MVIS/hcompress_c2.mvi
------------------------------

H-Compress   Scale    Compression  time to        compressed   time to downlink
IP Step      Factor   Factor       process (sec)  size (bits)  (@ 7.9 kbps)
----------   ------   -----------  -------------  -----------  ----------------
Rice                      2.3        290           6,726,880     851
 0              0         2.2        308           7,165,632     907
 1              8         3.1        303           5,040,624     638
 2             16         3.9        267           4,044,992     512
 3             32         5.2        234           3,048,896     386
 4             48         6.4        215           2,444,704     310
 5             64         7.6        204           2,060,112     261
 6             96        10.2                      1,538,688     195
 7            128        13.6        173           1,159,360     147
 8            192        21.5        162             730,560      93
 9            256        28.3        155             555,648      70


------------------------------
C1 - 768x640 full-resolution	see $MVIS/hcompress_c1.mvi
------------------------------

H-Compress   Scale    Compression  time to        compressed   time to downlink
IP Step      Factor   Factor       process (sec)  size (bits)  (@ 7.9 kbps)
----------   ------   -----------  -------------  -----------  ----------------
Rice                      2.3        122           2,065,008     261
 0              0         2.2        140           2,391,088     303
 1              8         4.6        110           1,428,720     180
 2             16         6.4         96           1,028,784     130
 3             32        10.1         84             657,472      83
 4             48        12.9         79             512,160      65
 5             64        15.6         75             424,912      54


------------------------------
C1 - 768x640 2x2 LEB-Binned 
------------------------------

H-Compress   Scale    Compression  time to        compressed   time to downlink
IP Step      Factor   Factor       process (sec)  size (bits)  (@ 7.9 kbps)
----------   ------   -----------  -------------  -----------  ----------------
Rice                      2.3         44             756,128      96
 1              8         2.8         49             615,408      78
 2             16         3.4         45             504,384      64
 3             32         4.4         42             396,192      50
 4             48         5.2         40             332,224      42
 5             64         5.9         39             293,664      37