Balanced histogram thresholding: Difference between revisions

Revision as of 15:47, 6 December 2010

Revision as of 21:34, 11 December 2010

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In [[image processing]], the '''balanced histogram thresholding method''' (BHT) <ref>A. Anjos and H. Shahbazkia. Bi-Level Image Thresholding - A Fast Method. BIOSIGNALS 2008. Vol:2. P:70-76.</ref>, is a very simple method used for automatic image [[thresholding]]. Like [[Otsu's Method]] <ref>Nobuyuki Otsu (1979). "A threshold selection method from gray-level histograms". IEEE Trans. Sys., Man., Cyber. 9: 62–66.</ref> and the '''Iterative Selection Thesholding Method''' <ref>Ridler TW, Calvard S. (1978) Picture thresholding using an iterative selection method, IEEE Trans. System, Man and Cybernetics, SMC-8: 630-632.</ref>, this is a [[histogram]] based thresholding method. This approach assumes that the image is divided in two main classes: The '''background''' and the '''foreground'''. The '''BHT''' method tries to find the optimum threshold level that divides the histogram in two classes.

[[File:Lovely_spiderLovely spider.jpeg | thumb | 200px | right | Original image.]]

[[File:Lovely_spider_BHTLovely spider BHT.jpeg | thumb | 200px | right | Thresholded image.]]

This method ''weighs'' the histogram, checks which of the two sides is heavier, and removes weight from the heavier side until it becomes the lighter. It repeats the same operation until the edges of the [[weighing scale]] meet.

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[[File:BhaProgress3.gif | thumb | 200px | right | Evolution of the method.]]

This method may have problems when dealing with very noisy images, because the ''weighing scale'' may be misplaced. The problem can be minimized by ignoring the extremities of the histogram <ref>A. Anjos, R. Leite, M. L. Cancela, H. Shahbazkia. MAQ – A Bioinformatics Tool for Automatic Macroarray Analysis. International Journal of Computer Applications. 2010. Number 7 - Article 1.</ref>.

==References==

{{reflist}}

==External Linkslinks==

* [http://w3.ualg.pt/~aanjos/prototype/BHThresholding.jar ImageJ Plugin]

{{DEFAULTSORT:Balanced Histogram Thresholding}}

[[Category:Image processing]]

[[fa:آستانه گذاری هیستوگرام متقارن]]

[[pt:Limiarização por equilíbrio do histograma]]

[[ru:Алгоритм сбалансированного порогового отсечения гистограммы]]

==External Links==

[http://w3.ualg.pt/~aanjos/prototype/BHThresholding.jar ImageJ Plugin]

[[Category:Image processing]]