Automatic discrimination between scomber japonicus and scomber australasicus by geometric and texture features

Abstract

This paper proposes a method for automatic discrimination of two mackerel species: Scomber japonicus (chub mackerel) and Scomber australasicus (blue mackerel). Because S. japonicus has a much higher market price than S. australasicus, the two species must be properly sorted before shipment, but their similar appearance makes discrimination difficult. These species can be effectively distinguished using the ratio of the base length between the dorsal fin’s first and ninth spines to the fork length. However, manual measurement of this ratio is time-consuming and reduces fish freshness. The proposed technique instead uses image processing to measure these lengths. We were able to successfully discriminate between the two species using the ratio as a geometric feature, in combination with several texture features. We then quantitatively verified the effectiveness of the proposed method and demonstrated that it is highly accurate in classifying mackerel.