Hitachi, Ltd.

Takeo Tamezawa

Yoichi Takagi

Masayasu Kato

Shigeharu Jikan

Katsuji Terazono

Toshiaki Hara

Takashi Miyakita

A number of fish may be counted by emitting an ultrasonic wave or an electromagnetic wave toward a predetermined area of a body of water where fish pass (e.g., a fish farming pool, a river or the like). Reflected waves are received from the fish bodies so that the reflected waves received from a cross section of the predetermined area are periodically stored. An ultrasonic wave fish shade image is produced that shows changes of fish shades. Fish are counted by performing an image processing which discriminates the ultrasonic wave fish shade image based on a predetermined fish shade decision rule. This arrangement reduces errors occuring due to muddiness and dust in the water and allows an automatic continuous fish counting ability over a long time period.

Growing community of inventors

Kawasaki, Japan

Takeo Tamezawa