Patent ID: 8798338

Claim:
A method of enumerating particles in a flow wherein the flow is monitored by an imaging system including an imaging device having a focal plane that images an illuminated cross-section of the flow, the method comprising the steps of: (a) imaging one or more frames with the imaging device; (b) making a preliminary estimate of particle density, using a default counting algorithm, based upon an imaged frame; (c) determining into which of two or more predetermined categories of density the particle density of the imaged frame falls; (d) adjusting at least one of the following elements according to the determined density category— the counting algorithm; a parameter of the imaging system; and/or the flow speed; and (e) enumerating particles in the flow after making the adjustment of step (d); wherein the adjusting step adjusts the counting algorithm by selecting between counting algorithms designed to operate at different particle density categories; wherein the counting algorithms comprise a Lower Particle Density Algorithm and a High Particle Density Algorithm; and wherein the Lower Particle Density Algorithm implements the steps of— differencing two successive image frames; flagging groups of pixels above a predetermined threshold of intensity; counting flagged groups as particles; and correcting counts for spatial confusion.