Abstract：By comparing traditional edge detection algorithm,the wavelet transform multi-scale edge detection algorithm and the optimal filtering second-order difference algorithm,it is believed in this paper that the traditional edge detection algorithm does not give the consideration for the multi-scale problem,however,because the algorithm takes the sample point as the unit,it still has the advantage in detecting small edge characteristics and can be used to easily obtain the description for edge direction.Furthermore,the multi-scale edge detection can also be implemented by applying either optimal filtering second-order difference algorithm or the wavelet transform.Each algorithm mentioned above can be regarded as the important supplement for the coherent volume technique.
