[1] () https://www.fujitsu.com/downloads/JP/archive/imgjp/jmag/vol49-6/paper04.pdf
[3] () http://www.iic.ecei.tohoku.ac.jp/publication_data/211.pdf
[4] () http://www.iic.ecei.tohoku.ac.jp/publication_data/511.pdf
[5] () http://www.haralick.org/journals/extraction_characters_japan.pdf
[9] () https://www.ieice.org/publications/conference-FIT-DVDs/FIT2005/pdf/I/I_001.pdf