影像對比度在對人眼區分影像品質的好壞上，佔有相當重要的地位，但是在不同情況下，由於攝影的環境不良所影響，或者其他影響影像擷取的因素影響下，經常會有擷取的影像其對比度的表現不足，導致整體影像的品質不佳的現象，為了解決此一問題，因此對比加強的演算法便應運而生。

在本文中，我們提出一個有效的區域性加強影像對比度演算法，該演算法運用直方圖等化(Histogram Equalization)技術，並利用影像內區域性的資訊設計一個參數來控制對比加強的程度，來使得輸出影像的表現能夠較符合人眼的視覺感受。為了令本演算法能適用於更多種不同的影像儲存方式，因此結合一個有效的色調再生的演算法來對高動態影像做前處理，使其能應用的更加廣泛，經由實驗可知，我們所提出的演算法架構的確能獲得不錯對比度的調整影像。

The contrast is a very important parameter in image. It is influence upon the quality of an image for human visual perception. Because of the poor photographical environment, it affects the performance of the contrast ratio to result in an unexpected image. In order to overcome this problem, contrast enhancement algorithms have been designed to adjust contrast and conform to human visual perception.

In this thesis, we addressed an effective algorithm to locally enhance the contrast of image. This algorithm use histogram equalization, and design a single parameter to control the degree of contrast enhancement with local information of an image to make contrast ratio fit in with human visual perception.

To adapt more different kind of image store technology, it combines an effective tone-mapping algorithm for high dynamic images to be pre-processing, make it can be widely used on more kinds of image formats. According to our experiments, the structure of the algorithm we bring up and can really obtain good contrast ratio of the output image.

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