The adaptive histogram equalization method [1-3] is a conventional general contrast enhancement method using local information of an image, and is effective for natural images in which local information is important. However, this method requires considerable computation time, since a mapping curve (a gray-level conversion curve using a histogram) has to be obtained for each pixel of an image. To solve this problem, this paper proposes a new contrast enhancement method for a gray-tone image. In this method, several mapping curves are prepared before an operation, and a suitable curve selected from them is applied to each region according to its mean gray-level. This produces an image with almost the same quality as that obtained by a conventional method, taking far less time. The effectiveness of the proposed method is confirmed by computer simulations using a natural image.
|Systems and Computers in Japan
|Published - 1994 11月 1
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