Multi-scale image contrast enhancement

This paper presents a new method suitable for the contrast enhancement of digital images. The proposed algorithm employs the center-surround architecture of the human visual system (HVS) for the comparison of the central pixel with the mean intensity of its surround. These two values are inputs to a mapping function, which calculates the new intensity value of the central pixel, in a way that increases small local intensity differences while preserving the large ones. The proposed method is applied to three spatial scales by employing different surround sizes. As a result, contrast enhancement is performed in different spatial frequencies of the original image. The proposed method is tested against other similar methods and is found to exhibit better results in the enhancement of low-contrast images, such as medical, aerial or foggy scenes, revealing visual information that otherwise would not be available to the human observer.