Image enhancement in the fractional Fourier domain

Image enhancement in the transform domain is an indispensable technique in the image processing area. In this paper, a novel method of image enhancement with respect to the fractional Fourier transform is presented. This method filters image in the fractional Fourier domain instead of the Fourier domain which is usually applied to the classical image enhancement. The fractional Fourier transform has a rotation angle a, characters of image thus change in different transform domain. In a proper fractional Fourier domain with angle a, ideal low-pass filter makes image smoother and ideal high-pass filter loses less information of image than in the traditional Fourier domain, which provides an alternative way to enhance image with proper filter designing. The validity of this method is demonstrated via simulations.