A method for analyzing a blood sample residing within an analysis chamber, which sample has one or more first and second constituents, which constituents are different from one another. The method includes the steps of: a) imaging the sample containing the first and second constituents, which sample is mixed with a colorant that causes the first and second constituents to fluoresce upon exposure to light, and which colorant is also operative to absorb light, the imaging produces image signals representative of fluorescent emissions from the sample and optical density of the sample; b) determining one or more values representative of fluorescent emission from the first and second constituents; c) determining one or more values representative of optical density for the first and second constituents; and d) distinguishing the first constituents from the second constituents using the fluorescent emission representative values and the optical density representative values.