Go TANAKA, Noriaki SUETAKE^*, and Eiji UCHINO

Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi 753-8512, Japan

(Received April 17, 2009; Accepted March 21, 2010)

In a digital still camera (DSC) system, the dynamic range is usually compressed linearly in logarithmic space. Hence, an image taken by a DSC tends to be low contrast, and gives a flat impression without liveliness in comparison with conventional silver halide photographs. In this paper, a new digital image enhancement method based on multiscale smoothing is proposed. In the proposed method, first, the difference between an input image and a smoothed one is obtained in various scales. Then, brightness conversion in the n-th scale is carried out by adding the differential image of n-th scale to an input image. Finally, by synthesizing each conversion result, high-contrast and sharpened image with liveliness is obtained. The effectiveness of the proposed method is verified by applying it to some natural images.

Key words: image enhancement, contrast improvement, image sharpening, multiscale smoothing

^*E-mail address: suetake@sci.yamaguchi-u.ac.jp