Patent ID: 7605919

Claim:
A method for analyzing particles in a sample fluid, comprising: arranging a sample fluid to form a sample fluid stream traveling in a direction of flow having a depth measuring between 20 microns and 1000 microns, and a width measuring between 25 and 10,000 microns in a direction of width; acquiring a sequence of magnified still images of the sample fluid stream, wherein the images are taken in a direction substantially perpendicular to: the direction of flow, and the direction of width of said sample fluid stream; and detecting and counting images of particles in said images of the sample fluid stream; wherein said detecting includes adjusting levels of illumination of said sample fluid stream so as to minimize a noise level present on said still images of sample fluid stream; measuring an actual level of illumination used to obtain a particular image of said sample fluid stream, for subsequent processing of such an image; subtracting a background image from said images of the sample fluid stream, forming background-corrected images, wherein said background image is substantially free of images of particles; and setting a threshold for the background-corrected images, so as to highlight images of particles present in the background-corrected images of the sample fluid stream.