Optical and Quantum Electronics (2005) 37:735-753 © Springer 2005The development of leukocyte counter using fluorescence imaging analysis t a i s u k e h i r o n o 1,3, * , k a t s u m i y a b u s a k i 2 a n d y u k i o y a m a d a 3Abstract. Image cytometry centrifugation (ICC) method has been developed and applied to count residual leukocytes in transfusion blood products for quality assurance testing. The standard leukocyte fluorescence image profile was established by averaging the actual fluorescence images of leukocytes. It was used for development of an optimum image analysis algorithm to avoid misinterpretation of the dust contaminated from the environment. The centrifugal concentration process of the ICC method was investigated by a computer simulation, and it was found that it caused leukocyte overlapping and limited the enumeration range. By introducing a double thresholding algorithm to the fluorescence images analysis and correcting the number of the overlapped leukocytes, we succeeded in improving the accuracy and the measurement range up to 25 [WBC/µl] of the ICC method.