An apparatus and a method for identifying at least one type of white blood cell (WBC) within a whole blood sample is provided. The method includes: adding at least one colorant to the sample; providing at least one fluorescent excitation light and at least one transmission light; receiving both light fluorescing from and transmitted through the sample and producing signals representative thereof; creating at least one image of the sample using the signals; identifying WBCs within the sample image; quantitatively analyzing at least some of the identified WBCs within the image, including determining one or more quantitative values; and identifying at least one type of WBC from the identified WBCs using the quantitative values.