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Title: | 區域性,非區域性和全域性預測為基礎之影像壓縮和影像還原 Local, Non-local and Global Predictions based Image Compression and Image Restoration |
Authors: | Hsin-Hui Chen 陳信慧 |
Advisor: | 丁建均 |
Keyword: | 影像壓縮,霍夫曼編碼法,格倫布編碼法,可適性格倫布編碼法,鋸齒狀掃描,可適性係數掃描法,H.264/AVC,畫面內預測法,邊緣導向預測法,非區域性平均法,結構自相似性,雙向主成分分析法,影像去雜訊,影像內插, Image Compression,Golomb Coding,Adaptive Golomb Coding,Zigzag Scanning,Adaptive Coefficient Scanning,Intra Prediction,Edge-Directed Prediction,Non-local Means,Structural Self-Similarity,Bidirectional Principal Component analysis,Image Denoising,Image Interpolation, |
Publication Year : | 2014 |
Degree: | 博士 |
Abstract: | 隨著多媒體技術的進步,大量的資料如影像和視訊等資料需要加以壓縮以便於儲存和傳輸。因此,資料壓縮是一項重要的研究議題。雖然目前有許多不同的方法已經提出解決方案,我們相信其仍有改善的空間。另一方面,影像還原在電腦視覺和影像處理領域已經成為一個很熱門的研究方向。在傳統的影像濾波方法中,常利用在影像內容中分布於鄰近區域的資料來計算最佳化的權重值。不過,這些方法都忽略了高重複性的影像結構特性,因而限制了整體效果。自從非區域性平均去雜訊演算法被提出來,在近年來許多很有效的影像去雜訊、影像內插和影像去模糊方法以此為基礎陸續的發展出來。基於此非區域性原則,我們可以充分利用在影像中的非區域自相似性區塊特徵來開發影像還原演算法。
可適性預測方法在失真/無失真影像壓縮和影像還原扮演一個關鍵的角色。在影像壓縮中,我們研究目標包含移除影像中的空間冗餘性、將Z字形係數掃描法一般化,或是計算最佳參數來得出較短的編碼長度。在影像還原研究中,目標為內插出新的像素值以增加影像解析度或是去除影像中的雜訊。為了達成以上的研究目標,需要針對不同的情況來適當地設計可適性預測方法。 在本論文中,我們採取區域性,非區域性和全域性預測來改善無失真和失真影像壓縮演算法,以及在影像還原議題中影像去雜訊和影像內插的方法。本論文總共包含五個獨立的研究成果。在失真影像研究中,我們提出了兩個研究成果。其中一項為以聯合機率為基礎的可適性格倫布編碼演算法。參考欲編碼像素之鄰近區域的資訊,動態地調整格倫布參數來編碼影像,以產生較短的編碼長度。另一項成果為針對使用離散餘弦轉換為主的影像壓縮系統,提出以區域性和全域性預測為基礎的可適性係數掃描法,將Z字形掃描法一般化。參考來自之前編碼過的影像區塊,利用區域性和全域性資訊來提升整體壓縮效能。在無失真影像研究中,為了降低預測影像誤差值以及估測其精確的機率分布,我們提出了非區域性內容模型和可適性預測方法來降低位元率。此方法主要的精神為利用在影像中非區域結構的自相似性,而此特性常出現在影像空間和預測誤差空間。 針對影像去雜訊的研究,我們提出了一個強很有效的方法,稱為以雙向主成分分析為基礎的非區域性平均之影像去雜訊演算法。更進一步將其實現在一種不需迭代計算的粗略至精細演算法,無論影像受到低雜訊或高雜訊干擾的情況下,去雜訊後的影像皆能保留邊緣或紋理的完整性。而在影像內插的研究中,我們將影像結構的自相似性度量方法應用在非區域性邊緣導向的影像內插方法中,如此得到較佳的影像品質。整體而言,本論文中此五項主要的研究方法皆充分地利用區域性,非區域性或全域性資訊來提升整體的影像壓縮和影像還原效果。 With the advancement of multimedia technologies, the huge amount of data such as images and videos, etc., needs to be compressed for storage and transmission. There-fore, data compression is a very important issue. Although many different methods have been proposed, it is believed that there is still room for improvement. On the other hand, image restoration has been an active research topic in computer vision and image processing. In conventional filtering methods, the local neighboring image data is usually used for weight optimization. It limits the overall performance due to ignoring the repetitive structure patterns in images. Since the work of the non-local means (NLM) algorithm, many more powerful methods for image denoising, interpola-tion and deblurring are proposed in recent years based on the non-local principle, which exploits the non-local self-similarity between the patches in an image. Adaptive prediction is a key component in lossy/lossless image compression and image restoration. To remove the spatial redundancy in images, the adaptive prediction methods for generalizing the zigzag scanning method, obtaining the better coding pa-rameter for shorter codelength in image compression, interpolating missing pixels or filtering out noise in image restoration are developed. In this dissertation, I adopt the idea of local, non-local, and global predictions to improve lossless and lossy image compression methods and image restoration methods, such as image denoising and image interpolation. In sum, there are five individual re-search works. For lossy image coding, two research works are presented. One is the proposed joint-probability-based adaptive Golomb coding (JPBAGC) algorithm, which takes the local neighboring data into account to adaptively adjust the Golomb parameter for yielding shorter codelength. The other one is the local- and global-prediction-based adaptive scanning (LGPAS), which generalizes the zigzag scanning method. It is pro-posed to achieve a better compression performance using the local and global infor-mation from previously encoded/decoded blocks in DCT-based image coding systems. For lossless image coding, non-local context modeling and adaptive prediction (NCMAP) are proposed to reduce the image prediction errors and estimate their true probability distribution by exploiting the non-local structural self-similarity in the spatial and prediction error domain. For image denoising, a powerful and efficient scheme, called non-local means based on bidirectional principal component analysis (NLM-BDPCA), is proposed. Fur-thermore, the coarse-to-fine algorithm is also implemented. It does not perform de-noising iteratively and can well preserve the edge/texture information. For image inter-polation, the structural similarity based metric is incorporated into the framework of non-local edge-directed image interpolation (SSNLEDI) for yielding better peak-to-signal ratio (PSNR) values. Overall, these five efforts take the advantage of the rich information extracted from local, non-local, or global regions in images to achieve better performance for image compression and image restoration. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/57789 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 電信工程學研究所 |
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