Image Contrast Enhancement Based on Linear Fusion
| Autor: | Bo-chang Chen, 陳柏璋 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Conventional histogram equalization (CHE) is a common image enhancement method, which can effectively enhance image contrast and details. However, one of fundamental problems in CHE is over enhancement. Even though, it is observed that the equalized image by CHE reveals details which are not clear in the original image while loses details in some other parts of original image. Interesting enough, the details missing in the equalized image can be found in the original image and the details not clear in the original image can be obtained from the equalized image. We call this property as detail complementary property (DCP). By the DCP, two approaches to image contrast enhancement based on linear fusion are presented in this thesis. They are DACE/LIF (detail aware contrast enhancement with linear image fusion) and APLIF (adaptive pixel-based linear image fusion). With an image and its CHE equalized image, a linear image fusion is used to obtain a fused image whose contrast and visual quality are enhanced. The linear image fusion is chosen in this thesis because the two images are of the DCP. When the fusion parameter is fixed, it is the DACE/LIF approach. When the fusion parameter is adaptively calculated, it is the APLIF approach. Both DACE/LIF and APLIF approaches are verified by several examples. The results indicate that the two approaches are able to achieve good performance of contrast enhancement. Besides, the two approaches are compared with three enhancement approaches. The results are for the proposed approaches since better contrast and visual quality are found in enhanced images. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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