Edge strength evaluation with reaction-diffusion systems

The present paper proposes a reaction-diffusion algorithm that detects edge positions and evaluates their strength. Edge strength refers to the sharpness of spatial brightness change at an edge position in image brightness distribution. The authors previously found that a discretised system derived from the FitzHugh-Nagumo reaction-diffusion equations spontaneously organises pulses at edge positions and works as an edge detector for binary images. Although the previous system has a merit in that it can detect edges having sharp corners, it is not applicable to grey level images or edge strength evaluation. The proposed algorithm utilises multiple systems, each of which consists of two subsystems of the reaction-diffusion equations coupled with a diffusion equation. The diffusion equation modulates a parameter value of the reaction-diffusion equations and helps to evaluate a level of edge strength. In addition, there is a connection between the two subsystems in each system; the connection helps to eliminates pseudo-pulses organised in the subsystems. Integration of the outputs of the multiple systems provides edge strength distribution. Finally, we apply the proposed algorithm to test images and confirm its performance.