A method to extract spots from the image of the ELISA (Enzyme-Linked Immunosorbent Assay) Spot Assay

Abstract

ELISA (Enzyme-Linked Immunosorbent Assay) Spot Assay is a method widely used by immunologists to enumerate cytokine-producing cells within a specific cell population. The result of ELISA is presented in an image containing numerous color spots. We present a method to extract and to count the number of spots. The proposed method is based on color analysis. Since CIE L(*)u(*)v(*) space have linear perceptibility of color differences, we convert the RGB space to L(*)u(*)v(*) space. The system is trained to obtain the standard color of the spots and get the color difference image in L(*)u(*)v(*) space. According to the feature of the spots we design a special matched filters to filter out the noise and enhance the spots. Finally a binary image is obtained. In the binary images, pixels in the spots have gray scale 255 and the others are 0. Our design makes it easy to analyze the perimeter and size of the spots in addition to counting them in the binary image.