A method and apparatus for determining at least one hemoglobin related parameter of a whole blood sample is provided. The method includes the steps of: a) depositing the sample into an analysis chamber adapted to quiescently hold the sample for analysis, the chamber defined by an interior surface of a first panel, and an interior surface of a second panel, and the chamber has a height extending between the interior surfaces of the panels, wherein the chamber is configured to increase the oxygenation state of the sample to a substantially oxygenated state within a predetermined amount of time after entry into the chamber; b) imaging the at least one red blood cell contacting the interior surfaces, and producing image signals; c) determining an optical density of at least a portion of the imaged red blood cell contacting both interior surfaces; and d) determining the at least one hemoglobin related parameter of the red blood cell contacting the interior surfaces, using the determined optical density and a molar extinction coefficient for oxygenated hemoglobin.