<title>Multiagent system for detecting concentric strias</title>

Abstract

We present a method for detecting concentric strias which can be found in different natural objects (age-rings of tree, fish otolith growth rings, strias of some minerals,...). One of the major problems encountered during an automatic image processing is the lack of continuity perception in strias. We propose an approach to this continuity perception based on a multiagent system made up of reactive agents. These agents can move around on their environment which consists of an image made up of light and dark rings set out concentrically. Our multiagent system is made up of a set of agents named darkening agents and lightening agents. These agents follow either the light rings (lightening agents) or the dark rings (darkening agents) and act on the image. Their actions aim to reinforce the rings by stressing the contrasts allowing, thus, a reliable detection of these rings, even if they are discontinuous. Each agent has three sensors allowing it to obtain information about the environment. The sensors are made up of unit sensors returning the value of a pixel. The three sensors of an agent are : - a unit sensor allowing the agent to know if it is located on an already detected stria (sensor on the memory shared by all the agents), - two disk-shaped sensors made up of unit sensors (sensors on the image). These two sensors return the sum of their unit sensors. They are located in front of the agent and distant one from the other. Those two disk-shaped sensors are used for determining the movements of the agent and, therefore, for detecting the rings. An agent, indeed, always tries to move where the values returned by the sensors is minimal. The suggested multiagent system has shown great robustness and adaptability, for it can detect strias, even if they are discontinuous and the image noisy.