本論文針對影片中的字幕提出一個創新的文字萃取方法，在本研究中利用獨立成分份分析法(Independent Component Analysis, ICA)來分離影像中的文字區及非文字區。為了符合ICA的處理程序，本研究提出了3種資料的表示方法，其中包含針對連續影像的「序列特徵表示法」，以及針對單張影像的「rgb特徵表示法」與「高次特徵表示法」。為了分析本方法的強韌性(robustness)，於研究中採用數種不同的字幕型態影片做為測試，並且進階的改變字幕的字型、顏色、尺寸以及排列方式。實驗結果顯示，本研究所提出的方法是一個強韌性佳的文字萃取方法，比一般傳統的方法更具系統性，並且不需要複雜的參數調整便能有效率且正確的將字幕從背景中分離出來。

In this thesis, a new text extraction method is proposed for digital video. The text in the video frames is extracted by means of the independent component analysis (ICA). There are three representations of the image frames are introduced to fit the need of the ICA procedure. The first is the sequence representation for a sequence of image frames. The second and the third are the rgb representation and the high order representation for a single image frame respectively. The font, color, scale, and orientation of the subtitles in the sample videos are changed to evaluate the performance of our method. The experimental results show that the method we developed in this thesis is robust and systematic. It is very effective and accurate for the text extraction in videos, without any complex adjustment of the parameters.

[1] J. C. Shim, C. Dorai, and R. Bolle, “Automatic Text Extraction from Video for Content-Based Annotation and Retrieval,” Proceedings of International Conference on Pattern Recognition, Vol. 1, pp. 618-620, 1998.
[2] M. R. Lyu, J. Song, and M. Cai, “A Comprehensive Method for Multilingual Video Text Detection, Localization, and Extraction,” IEEE transactions on circuits and systems for video technology, Vol. 15, No. 2, pp. 243-255, Feb. 2005.
[3] K. Jung, K. I. Kim, and A. K. Jain, “Text Information Extraction in Images and Video: A Survey,” Pattern Recognition, Vol. 37, No.3, pp. 977-997, 2004.
[4] M. Cai, J. Song, and M. R. Lyu, “A New Approach for Video Text Detection,” IEEE International Conference on Image Processing, pp. 117-120, 2002.
[5] Q. Ye, W. Gao, W. Wang, W. Zeng, “A Robust Text Detection Algorithm in Images and Video Frames,” Proceedings of the 2003 Joint Conference of the Fourth International Conference, Vol. 2, pp. 15-18, Dec. 2003.
[6] A. Hyvärinen and E. Oja, “Independent Component Analysis: Algorithm and Applications,” Neural Networks, Vol. 13, pp. 411-430, 2000.
[7] J. Cardoso, “Informax and Maximum Likelihood for Source Separation,” IEEE Letters on Signal Processing, Vol. 4, No. 4, pp. 112-114, Apr. 1997
[8] S. Antani, U. Gargi, D. Crandall, T. Gandhi, R. Kasturi, “Extraction of text in video,” Technical Report, Department of Computer Science and Engineering, Pennsylvania State University, CSE-99-016, August 30, 1999.
[9] K. I. Kim, K. Jung, S. H. Park, and H. J. Kim, “Support Vector Machine-Based Text Detection in Digital Video,” Pattern Recognition, Vol. 34, No.2, pp. 527-529, 2001.
[10] J. Ohya, A. Shio, and S. Akamatsu, “Recognizing Characters in Scene Images,” IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 16, No. 2, pp. 214-220, 1994.
[11] C.M. Lee, and A. Kankanhalli, “Automatic extraction of characters in complex images,” International Journal of Pattern Recognition amd Artificial Intelligence, Vol. 9, No.1, pp. 67–82, 1995.
[12] M.A. Smith, T. Kanade, “Video skimming for quick browsing based on audio and image characterization,” Technical Report CMU-CS-95-186, Carnegie Mellon University, July 1995.
[13] Y. Zhong, K. Karu, and A. K. Jain, “Locating text in complex color images”, Pattern Recognition, Vol. 28, No.10, pp. 1523–1535, 1995.
[14] Lienhart, F. Stuber, “Automatic text recognition in digital videos,” Proceedings of SPIE, pp. 180–188, 1996.
[15] B.L. Yeo, B. Liu, “Visual content highlighting via automatic extraction of embedded captions on MPEG compressed video,” IS&T/SPIE Symposium on Electronic Imaging: Digital Video Compression, pp. 142–149, 1996.
[16] T. Sato, T. Kanade, E.K. Hughes, M.A. Smith, “Video OCR for digital news archive,” Proceedings of IEEE Workshop on Content based Access of Image and Video Databases, pp. 52–60, 1998.
[17] L. Agnihotri and N. Dimitrova, “Text detection for video analysis,” Proceedings of IEEE Workshop on Content-Based Analysis of Image and Video Libraries, pp. 109-113, 1999.
[18] V. Wu, R. Manmatha, E. M. Riseman, “Text finder: An automatic system to detect and recognize text in images,” IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 21, No.11, pp.1224-1229, 1999.
[19] Y. M. Y. Hasan, L. J. Karam, “Morphological Text Extraction from Images,” IEEE Transactions on Image Processing, Vol. 9, No. 11, pp. 1978-1983, 2000.
[20] H. Li, D. Doerman, O. Kia, “Automatic Text Detection and Tracking in Digital Video,” IEEE Transactions on Image Processing, Vol. 9, No.1, pp. 147–156, 2000.
[21] Y. K. Lim, S.H. Choi, S.W. Lee, “Text Extraction in MPEG Compressed Video for Content-Based Indexing,” Proceedings of International Conference on Pattern Recognition, pp. 409–412, 2000.
[22] H. Hase, T. Shinokawa, M. Yoneda, and C. Y. Suen, “Character String Extraction from Color Documents,” Pattern Recognition, Vol.34, pp.1349-1365, 2001.
[23] K. Jung, “Neural Network-Based Text Location in Color Images,” Pattern Recognition Letter, Vol. 22, No.14, pp. 1503–1515, 2001.
[24] C. Strouthpoulos, N. Papamarkos, A. E. Atsalakis, “Text Extraction in Complex Color Document,” Pattern Recognition, Vol. 35, No.8, pp. 1743–1758, 2002.
[25] K. Wanga, J. A. Kangasb, “Character Location in Scene Images from Digital Camera,” Pattern Recognition ,Vol.36, pp.2287-2299, 2003.
[26] X. S. Hua, L. Wenyin, “An Automatic Performance Evaluation Protocol for Video Text Detection Algorithm,” IEEE transactions on circuits and systems for video technology, Vol.14, No.4, Apr. 2004.
[27] K. Jung, J. Han, “Hybrid Approach to Efficient Text Extraction in Complex Color Images,” Pattern Recognition Letters, Vol.25, pp.679-699, 2004.
[28] D. Zheng, Y. Zhao, J. Wang, “An Efficient Method of License Plate Location,” Pattern Recognition Letters, Vol.26, pp.2431-2438, 2005.
[29] B.T. Chun, Y. Bae, T. Y. Kim, “Automatic Text Extraction in Digital Videos Using FFT and Neural Network,” Proceedings of IEEE International Fuzzy Systems Conference, Seoul, South Korea,Vol. 2, pp. 1112–1115, 1999.
[30] P. Comon, “Independent Component Analysis - A New Concept,” Signal Processing, Vol. 36, No. 3, pp. 287-314, 1994.
[31] C. Jutten, “Source Separation: Form Dusk Till Dawn,” Proceedings of 2th International Workshop on Independent Component Analysis and Blind Source Separation (ICA’ 2000), pp. 15-26, Helsinki, Finland, 2000.
[32] O. Shalvi, and E. Weinstein, “New Criteria for Blind Deconvolution of Nonminimum Phase Systems,” IEEE transactions on Information Theory, Vol. 36, No. 2, pp. 312 – 321, 1990.
[33] K. Kiviluoto, and E. Oja, “Independent Component Analysis for Parallel Financial Time Series,” Proceedings of International Conference on Neural Information Processing (ICONIP’ 98), Vol. 2, pp. 895-898, Tokyo, Japan, 1998.
[34] T. Ristaniemi, and J. Joutsensalo, “On the Performance of Blind Source Separation in CDMA downlink,” Proceedings of International Workshop on Independent Component Analysis and Signal Separation (ICA’ 99), pp. 437-441, Aussois, France, 1999.
[35] A. Bell, and T. Sejnowski, “The Independent Components of natural scenes are edge filters”, Visual Research, Vol. 37, pp. 3327-3338, 1997.
[36] J. Friedman, “Exploratory projection pursuit,” Journal of the American Statistical Association, Vol.82, pp. 249-266, 1987.
[37] A. Hyvärinen, “New approximations of differential entropy for independent component analysis and projection pursuit,” In Advances in Neural Information Processing Systems, Vol.10, pp. 273-279, 1998.
[38] A. Hyvärinen and E. Oja, “A fast fixed-point algorithm for independent component analysis,” Neural Computation, Vol.9, No.7, pp.1483-1492, 1997.
[39] A. Hyvärinen, “Fast and robust fixed-point algorithms for independent component analysis,” IEEE Transactions on Neural Networks, Vol.10, No.3, pp.626-634, 1999.
[40] D. G. Luenberger, “Optimization by Vector Space Methods,” Wiley, 1969.
[41] M. Kendall, and A. Stuart, “The advanced theory of statistics,” Distribution theory, Vol. 1, 4th ed. MacMillan, New York, 1977.