Preprocessing of palm image based on wavelet modulus maximum value

Authentication technology based on geometric characteristics of hand image has the advantages of high speed and easy operation. So handkey becomes another biological characteristics authentication system as fingerprint key. Palm image preprocessing is the basic of hand shape recognition system. Denoising is a necessary preprocessing before edge detection of palm image. The paper introduces a denoising method, wavelet modulus maximum value method. The wavelet transforming has the advantage of multi-resolution either in time domain or in frequency domain, so it can be used to describe the partial characteristics in the both domain. Wavelet denoising is a more successful kind of application of wavelet transforming. Because of the multi-resolution of wavelet, the non-steady characteristics of signals can be described better. The principle and processing steps of the algorithm are described in this paper in details. Experiments show that the method not only can remove noise effectively, but also keeps edge details of the hand image. The preprocessing program designed in MATLAB is listed in the paper, the original hand image and edge detect image after wavelet denoising are shown, too.