The invention relates to a novel image enhancement method comprising the following four steps: S1, adaptively determining the optimal value of fractional differential order according to different images, and designing a fractional differential mask for image enhancement; S2, calculating the fractional differentials and fractional differential masks in eight directions of image pixels; S3, carrying out Mallat tower wavelet decomposition and Haar wavelet decomposition on the images, and suppressing noise produced in the process; and S4, carrying out image reconstruction by combining Mallat tower wavelet decomposition and the fractional differential theory and according to the intermediate results obtained in the previous steps. The novel image enhancement method of the invention breaks through the two major traditional image enhancement methods, namely, a space-domain method and a time-domain method. Image enhancement is no longer confined to one domain, but is processed cross domains. The fractional differential theory and the wavelet decomposition method are used together in image enhancement. The excellent characteristics of various methods are single superposed. Thus, the effect of image enhancement can show the characteristics of various single methods and also produce some new characteristics, and the effect of image enhancement is better than that of a single method.