Sankur and Sezgin (2001) lists 44 binarization methods, categorized into six methods: histogram shape-based, clustering-based, entropy-based, object attribute-based, spatial, and local.
 

Glasbey, C. A. 1993. An analysis of histogram-based thresholding algorithm. Graphical Models and Image Processing, 55(6): 532-7. (11 algorithms).

Lee, S. U., S. Y. Chung, and R. H. Park. 1990. A comparative performance study of several global
 thresholding techniques for segmentation. Computer Vision, Graphics, and Image Processing 52: 171-90.

Pal, N. R., and S.K. Pal. 1993. A review on image segmentation techiniques. Pattern Recognition 26(9): 1277-94.

Sahoo, P. K., S. Soltani and A. K. C. Wang. 1988. A survey of thresholding techniques, Computer Vision, Graphics, and Image Processing 41: 233-60.
 

Sankur, B., and M. Sezgin. 2001. Image Thresholding Techniques: A Survey over Categories. Pattern
    Recognition, 2001. (under review) (44 methods)

Taxt, T., P.J. Flynn, and A.K. Jain. 1989. Segmentation of document images. IEEE Transaction on Pattern Analysis and Machine Intelligence 11(12): 1322-29.

Trier, O. D., and A. Jain. 1995. Goal-directed evaluation of binarization methods. IEEE Transactions on Pattern Analysis and Machine Intelligence17:1191-1201. (19 methods).

Trier, D., and T. Taxt. 1995. Evaluation of binarization methods for document Images, IEEE Transactions on
 Pattern Analysis and Machine Intelligence17: 312-15.

clustering (Otsu 1979)
moment-preserving method (Tsai 1984)
minimums-error method (Kittler and Illingworth 1986)
Entropy method

Otsu, N. 1979. A thresholding selection method from gray-level histogram. IEEE Transactions on Systems, Man, and Cybernetics9(1): 62-66.

Tsai, W. H. 1985. Moment-preserving thresholding: A New Approach. Computer Vision, Graphics, and Image Processing 29: 377-393.

• EXTRACTION OF BINARY CHARACTER GRAPHICS IMAGES FROM GRAYSCALE DOCUMENT IMAGES KAMEL M, ZHAO A CVGIP-GRAPHICAL MODELS AND IMAGE PROCESSING 55 (3): 203-217 MAY 1993
• An adaptive logical method for binarization of degraded document images Yang YB, Yan H PATTERN RECOGNITION 33 (5): 787-807 MAY 2000
• TextFinder: An automatic system to detect and recognize text in images Wu V, Manmatha R, Riseman EM IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 21 (11): 1224-1229 NOV 1999
• Analysis of fuzzy thresholding schemes Jawahar CV, Biswas PK, Ray AK PATTERN RECOGNITION 33 (8): 1339-1349 AUG 2000
• Integral ratio: A new class of global thresholding techniques for handwriting images Solihin Y, Leedham CG IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 21 (8): 761-768 AUG 1999
• C. A. Glasbey, "An Analysis of Histogram-Based Thresholding Algorithms," CVGIP: Graphical Models and Image Processing 55, pp. 532--537, Nov. 1993.
• L. O'Gorman, "Binarization and Multithresholding of Document Images Using Connectivity, " Computer Vision, Graphics and Image Processing 56, pp. 494--506, Nov. 1994.
• A. Rosenfeld and P. D. L. Torre, "Histogram Concavity Analysis as an Aid in Threshold Selection," IEEE Trans. Systems, Man, and Cybernetics SMC-13, pp. 231--235, 1983.
• J. S. Weszka and A. Rosenfeld, "Histogram Modification for Threshold Selection," IEEE Trans. on Systems, Man, and Cybernetics SMC-9, pp. 38--52, Jan. 1979.
• J. Kittler and J. Illingworth, "Minimum Error Thresholding," Pattern Recognition 19(1), pp. 41--47, 1986.
• Q. Z. Ye and P. E. Danielson, "On Minimum Error Thresholding and Its Implementation, " Pattern Recognition Letters 7, pp. 201--206, Apr. 1988.
• N. Otsu, "A Threshold Selection Method from Gray-Level Histogram," IEEE Trans. on Systems, Man, and Cybernetics SMC-9, pp. 62--66, Jan. 1979.
• J. N. Kapur, P. K. Sahoo, and A. K. C. Wong, "A New Method for Gray-Level Picture Thresholding Using the Entropy of the Histogram," Computer Vision, Graphics and Image Processing 29, pp. 273--285, Mar. 1985.
• T. Pun, "Entropic Thresholding: A New Approach," CVGIP: Graphical Models and Image Processing 16, pp. 210--239, July 1981.
• W. H. Tsai, "Moment-Preserving Thresholding: A New Approach," Computer Vision, Graphics, and Image Processing 29, pp. 377--393, Mar. 1985.
• Y. Liu and S. N. Srihari, "Document Image Binarization Based on Texture Features," IEEE Trans. on Pattern Analysis and Machine Intelligence 19, pp. 540--544, May 1997.
• R. G. Casey and K. Y. Wong, "Document Analysis System and Techniques," in Image Analysis Applications, R. Kasturi and M. M. Trivedi eds. Marcel Dekker, New York, N.Y. , pp. 1--36, 1990.
• M. Kamel and A. Zhao, "Extraction of Binary Character/Graphics Images from Grayscale Document Images," Computer Vision, Graphics and Image Processing 55, pp. 203--217, May. 1993.
• Ø. D. Trier and T. Taxt, "Evaluation of Binarization Methods for Document Images," IEEE Transactions on Pattern Analysis And Machine Intelligence 17, pp. 312--315, March 1995.
• V. Wu, R. Manmatha, and E. M. Riseman, "Finding Text In Images," Proc. of the 2nd intl. conf. on Digital Libraries. Philadaphia, PA , pp. 1--10, July 1997.