臺灣博碩士論文加值系統

本論文發展一套應用於單一感測器之數位照相機影像壓縮系統。文中提出一個創新的增強型JPEG壓縮演算法，此方法主要建立在傳統JPEG壓縮的基礎下，並多加入影像邊緣的特性，進而在不增加資料量的同時使得傳統JPEG照成邊緣模糊化的失真得到改善。為了得到影像中每一個像素邊緣的特性本論文引用光譜空間相關性原理(Spectral-Spatial Correlation, SSC)，光譜空間相關性的概念可以直接對色彩濾波陣列(Color Filter Array)影像作計算進而得到每一個像素的邊緣特性。實驗的結果發現無論在PSNR值的比較或直接視覺的感受下，增強型JPEG壓縮方法在邊緣的部分都有較好的壓縮品質。

目次

第一章 序論…………………………………………………………………………..1
1.1研究動機…………………………………………………………………….1
1.2問題描述…………………………………………………………………….3
1.3章節說明…………………………………………………………………….3
第二章 JPEG 壓縮原理跟方法……………………………………………………...5
2.1 JPEG概述…………………………………………………………………...5
2.2 JPEG壓縮流程…………………………………………………………...…5
2.2.1 色彩模式將RGB色彩空間轉換到YCbCr色彩空間……………7
2.2.2 取樣(down sampling)與位移……………………………………….7
2.2.3 DCT離散餘弦轉換…………………………………………………8
2.2.4 量化…………………………………………………………………9
2.2.5 Z字型係數排列 (zig-zag to sort)…………………………………10
2.2.6 Huffman 編碼……………………………………………………...11
2.2.6.1 DC值編碼………………………………………...………..12
2.2.6.2 AC值編碼……………………..………………….………..14
2.3 JPEG 解壓縮流程…………………………………………………………20
2.3.1 Huffman 解碼……………………………………………………...20
2.3.1.1 DC值解碼………………………………………………….20
2.3.1.2 AC值解碼………………………………………………….21
2.3.2 Z字型係數還原排列 (zig-zag to sort)……………………………21
2.3.3 量化反運算………………………………………………………..22
2.3.4 IDCT 離散餘弦反轉換……………………………………………23
2.3.5 取樣還原(up sampling)與位移還原………………………………23
2.3.6 色彩模式將YCbCr色彩空間轉換到RGB色彩空間……………24
2.4 JPEG的缺點……………………………………………………………….24
第三章 光譜空間的相關性(Spectral-Spatial Correlation)………………………….25
3.1 單一影像感測器之數位相機概述………………………………………..25
3.2 光譜相關性及空間相關性(Spectral and Spatial Correlation)……………26
3.3 光譜空間相關性原理(Spectral-Spatial Correlation)……………………...27
3.4 異次投影( Heterogeneity-Projection )…………………………………….28
第四章 Enhanced JPEG 壓縮原理跟方法…………………………………………31
4.1 Enhanced JPEG概述….……………………………………………………31
4.2 Enhanced JPEG壓縮流程………………………………………………….31
4.2.1 一維水平跟垂直DCT離散餘旋轉換…………………………….33
4.2.2 水平跟垂直量化…………………………………………………..35
4.2.3 水平跟垂直係數排列……………………………………………..37
4.2.4 Huffman 編碼……………………………………………………...39
4.3 Enhanced JPEG解壓縮流程……………………………………………….40
4.3.1 Huffman解碼………………………………………………………40
4.3.2水平跟垂直係數還原排列………………………………………...41
4.3.3水平跟垂直反量化………………………………………………...42
4.3.4一維水平跟垂直IDCT反離散餘旋轉換…………………………42
第五章 實驗結果跟比較……………………………………………………………43
5.1比較傳統數位相機壓縮與新形數位相機壓縮的壓縮率(Bitrate, bit/pixel)與PSNR值…………………………………………………………………44
5.2傳統數位相機壓縮跟新形數位相機壓縮在視覺上的比較……………...50
5.3實驗綜合比較說明………………………………………………………...57
第六章 結論…………………………………………………………………………58
6.1 結論………………………………………………………………………..58
6.2 後續研究…………………………………………………………………..58

參考文獻……………………………………………………………………………..59

[1] J. Adams, K Parsulski, and K. Spaulking, “Color processing in digital cameras,” IEEE Micro, pp. 20-29, Nov.-Dec. 1998.
[2] Y. L. Lee, H.C. Kim, and H. W. Park, “Blocking effect reduction of JPEG images by signal adaptive filtering,” IEEE Trans. Image Processing, vol. 7, pp. 229-234, February 1998.
[3] Y. Yang, N. Galatsanos, and A. Katsaggelos, “Projection-based spatially adaptive reconstruction of block-transform compressed images,” IEEE Trans. Image Processing, vol. 4, pp. 896-908, July 1995.
[4] Y. Yang, N. Galatsanos, and A. Katsaggelos, “Regularized reconstruction to reduce blocking artifacts of block discrete cosine transform compressed images,” IEEE Trans. Image Processing, vol. 3, pp. 421-432, Dec. 1993.
[5] Y. Kuroki, Y. Ueshige, and T. Ohta, “A new statistical model for the JPEG spatial scheme,” Proc. IEICE, vol. J-79-B-1, no. 7, pp. 509-511, July 1996.
[6] Y. Kuroki, Y. Ueshige, and T. Ohta, “New statistical models of the JPEG lossless mode subject to the super high definition images,” Proc. IEEE ICIP99, Kobe, Japan, Oct. 1999. pp. 488-452.
[7] Y. Kuroki, Y. Ueshige, and T. Ohta, “Redesigning of JPEG statistical model in the lossy mode fitting distribution of DCT coefficients,” in Proc. 7th IEEE Int. Conf. Image Proc., Kobe, Japan, 2001, pp. 825–828.
[8]M. Tadezawa, Y. Useshieg, K. Watanable, and M. Haswyama, “Quality improvement technique for JPEG images with fractal image coding,” in Proc. IEEE Int. Conf. ISCAS., Kobe, Japan, 2005, vol. 6, pp. 6320-6323.
[9] W. B. Pennebaker and J. L. Mitchell, JPEG Still Image Data Compression Standard. New York: Van Nostrand Reinhold, 1993.
[10] R. C. Gonzalez and R. E. Woods, Digital Image Processing. New Jersey: Prentice Hall, 2002.
[11] M. A. Sid-Ahmed, Image Processing, New York: McGraw-Hall, 1994.
[12] W. K. Pratt, Digital Image Processing, New York: John-Wiley, 1991.
[13] C. Y. Tsai and K. T. Song, “Demosaicing:Heterogeneity-Projection Hard-Decision Adaptive Interpolation Using Spectral-Spatial Correlation,” Proc. SPIE, vol. 699, pp. 1-10, 2006.
[14] B. Bayer, “Color imaging array”, U.S Patent 3971065, 1976.
[15] S.-C Pei and I.-K. Tan, “Effective color interpolation in CCD color filter arrays using signal correlation, ” IEEE trans. Circuits and Systems Video Technol., vol. 13, no.6, pp. 503-513, Jun. 2003.