and not to increase as far as the number of clusters does
not increase even if the classified area of MSS data
increases. The histogram table is desired to be constructed
as skilful as it has to be accessed at minimum time and it
can be effectively utilized because it is accessed as same
times as the number of pixels in the imageries.
Generation of MDH table
Indexed link structured table. We authors considered
that the indexed link structure as shown in Fig.1 is best
for realizing the shortest access time and the high
performance for memory usage. The index has 1024 entries in
the figure. Ten bits key are obtained by concatinating
lower five bits of one channel data with lower five bits of
another channel data are used for accessing the index table.
The contents in the index indicates the adress of the
histogram cell corresponding to the data pixel.
MDH table
Fig . 1
Multi-dimensional
histogram
A histogram cell contains pixel data , frequency,c1uster
number and pointer. Its length is sixteen bytes. In
general.it can be easily found there is not only one pixcel
whose data have the key of the equal value.
Access time. They are linked by the pointer which shows
the address of the other cells with the key of the same
value. Mean access time T is represented by followings;
T = To
T1 1023 j nk
# Z * Z * j * Z fki
N k = 0 j = 1 i = 1
(4 )
312