Hervé Troadec, Abdesslam Benzinou, Vincent Rodin and Jean Le Bihan.
Use of deformable template for two-dimensional growth ring detection of otoliths by digital image processing: Application to plaice (pleuronectes platessa) otoliths.
Fisheries Research, Elsevier, 46(1-3):155-163, May 2000.
Abstract:
Today, most computer-assisted age reading software is limited to one-dimensional processing. Automated two-dimensional growth ring detection is closely linked to the ability of image processing algorithms to perceive structure continuity. By using deformable models, based on closed B-splines, it is possible to fit a shape to the image features using maximum or minimum criteria according to the nature of translucent or opaque zones. Otolith edge contours were used as templates that were inflated from the core toward the edge in order to detect the growth zones. Template step sizes were modulated by an a priori growth pattern in order to take into account the decrease in ring size.
A reference test image set (n=102) of plaice otoliths, previously aged by one reader, was processed. For the first age groups, there was a total agreement with reader estimates. Mean agreement with reader estimates for age groups 1-5 averaged 80% but decreased for age groups 6-8. Overall, age was significantly underestimated by an average of -0.89 year.
Keywords: Fish, Age, Otolith, Computer-assisted, Image, Deformable template, Pleuronectes platessa.
[doi:10.1016/S0165-7836(00)00142-9] [Troadec00a.pdf]

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