In image that results from the projection of depth or orientation discontinuity in physical scene or from the effects of illumination and shading

edges are not in general ideal step edges but more typically a combination more than one type of edge primitive (e.g.

steps

pulse and ramp etc). These edge points are termed as composite edges

and composite edges detection and localization accurately is a challenge for researcher in this field. In this paper

a composite edge detector based on multi-wavelet is proposed. Take the zero systematic localization error condition as constraint

the new multi-wavelet function is constructed in spatial domain

at the same time

the scale and wavelet functions are even or odd symmetric. Theoretically

based on this approach ones have the possibility of getting arbitrary precise localization for the edges that are composed of steps and pulse with wavelet transformation. Experimental results with simulated and real gray level images demonstrated the feasibility of our edge detector

it shows that the new multi-wavelet based edge detector has a better edge detection ability than Canny edge detector and Mallat-Zhong wavelet based edge detector.