在影像處理中，直方圖均化被廣泛的運用在影像對比度增強上，其方法是基於均等直方圖來改善原圖的對比度。在此篇論文中，我們提出了一個子圖像邊緣保護方法應用到直方圖均化對比增強的演算法，進一步的去保護直方圖均化圖像的邊緣並且提高了子塊本地的對比度。在這個方法，輸入的原圖像會被劃分成不同的子圖像並且依序，使用基於直方圖均化的演算法當作轉換函數，分別在每一塊本地子圖像上運作，再者，利用每一個子塊的總梯度去權衡每一個轉換函數，產生的轉換函數提高整體圖像對比度並且保護邊緣，實驗結果顯示出在結合此演
算法與原來的轉換函數後，影像的邊緣保護率及對比增強有顯著的效果。
關鍵字：對比增強，直方圖等化，邊緣保護，直方圖建立。

Histogram equalization (HE) plays a significant role in image processing. It equalizes
the image intensity histogram to improve the image contrast. For edge preserving
image contrast enhancement, this thesis presents a block-based edge preservation method
applied to HE-based contrast enhancement algorithms to further preserve edges in the
histogram-equalized images and enhance local contrast. In this method, the input image
is partitioned into different sub-blocks and in turn, the local transform function of
each sub-block is generated respectively by applying a HE-based contrast enhancement method. Moreover, it exploits the total of gradients in each sub-block to weigh each local transform function for generating a global transform function to enhance overall image contrast while preserving edges. Experimental results show that the local contrast is significantly improved to contrast enhancement ratio. Furthermore, we also show the ability of our method through a better edge preserving rate by the proposed algorithm.
keywords: Edge preservation, contrast enhancement, histogram equalization.

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