Image binarization under non-uniform illumination based on gray-intensity wave equalization

A novel concept called gray-intensity wave equalization is introduced in this paper to resolve the non-uniform illumination problem in the binarization of nondestructive test images. This concept is derived from the principle that the peaks and troughs of waves in the intensity plane of image should belong to the foreground and background, respectively. This method can also be viewed as an image enhancing method and requires few parameters. Through extensive experiments, it has shown a higher performance on weakening the influence of non-uniform illumination in binarization.