|A Segmentation Method for Counting Microbial Cells in Microscopic Image
Hak-Kyeong Kim/Sun-Hee Lee/Myung-Suk Lee/Sang-Bong Kim
Transaction on Control Automation, and Systems Engineering, vol. 4, no. 3, pp.224-230, 2002
Abstract : In this paper, a counting algorithm hybridized with an adaptive automatic thresholding method based on Otsu's method and the algorithm that elongates markers obtained by the well-known watershed algorithm is proposed to enhance the exactness of the microcell counting in microscopic images. The proposed counting algorithm can be stated as follows. The transformed full image captured by CCD camera set up at microscope is divided into cropped images of m n blocks with an appropriate size. The thresholding value of the cropped image is obtained by Otsu's method and the image is transformed into binary image. The microbial cell images below prespecified pixels are regarded as noise and are removed in the binary image. The smoothing procedure is done by the area opening and the morphological filter. Watershed algorithm and the elongating marker algorithm are applied. By repeating the above stated procedure for blocks, the segmented images are obtained. A superposed image with the size of 640 480 pixels as same as original image is obtained from the segmented block images. By labeling the superposed image, the counting result on the image of microbial cells is achieved. To prove the effectiveness of the proposed method in counting the microbial cell on the image, we used Acinetobacter sp., a kind of ammonia-oxidizing bacteria, and compared the proposed method with the global Otsu's method, the traditional watershed algorithm based on global thresholding value and human visual method. The result counted by the proposed method shows more approximated result to the human visual counting method than the result counted by any other method.
Keyword : adaptive automatic thresholding method, otsu's method, watershed algorithm, acinetobacter sp