49 
(a)Original data (b)ABIC minimization method 
Figure 5. the comparison of histogram before and after applying ABIC minimization 
method (1991 July 21) 
5-2. Extraction of tidal front 
(1) Establishment of classification guideline 
Human judgment is necessary for establishing the threshold value from the distribution 
pattern of histogram for the single band data used for level slicing, and for extracting the 
teachers used for the classification by maximum likelihood method. In the current analysis, it 
was difficult to establish the classification standard even though the reference guideline was 
available, such as tidal front location confirmed by sea truth. Therefore, it is considered to be 
difficult to apply the human judgment for establishment of threshold values and extraction of 
teachers in constructing the practical model. 
(2) Comparison by the number of band 
The water block classification by single and multi-band clustering some times produced 
different results (Fig.6). However, the borderlines of water blocks close to the sea truth were 
extracted in both results. As far as seen from the comparisons, it was shown that increase of 
band number does not necessarily contribute to the enhancement of accuracy of water block 
classification. 
Figure 6. 
(a)Single-band 
Comparison of classification result by 
(b)Multi-band 
single and multi-band(1992 
May 25)