A method for determining the area of an analysis chamber covered by a biologic fluid sample quiescently residing within the chamber, which chamber has a first panel with an interior surface, and a second panel with an interior surface, both of which panels (12, 16) are transparent, the method comprising the steps of: illuminating the sample residing within the analysis chamber at one or more wavelengths operable to highlight interfaces between the sample and air, and to highlight at least one constituent within the sample; imaging the sample along the one or more wavelengths, and producing image signals representative of the interaction of the one or more wavelengths with the sample; characterised in that said method further comprises: determining a location of at least one sample-air interface between the sample and air, using the image signals; determining a location of one or more constituents within the sample relative to the at least one sample-air interface using the image signals; determining one or more sample regions containing at least one constituent and disposed on a first side of the at least one sample-air interface, and one or more no-sample regions not containing a constituent and disposed on a second side of the at least one sample-air interface, wherein the location of the one or more constituents relative to the at least one sample-air interface is used to determine the one or more sample regions and/or the one or more no-sample regions; and determining an area of the chamber containing the sample, wherein the step of determining an area of the chamber comprises summing an area associated with each image unit located within the sample region or the no-sample region. illuminating the sample residing within the analysis chamber at one or more wavelengths operable to highlight interfaces between the sample and air, and to highlight at least one constituent within the sample; imaging the sample along the one or more wavelengths, and producing image signals representative of the interaction of the one or more wavelengths with the sample; characterised in that said method further comprises: determining a location of at least one sample-air interface between the sample and air, using the image signals; determining a location of one or more constituents within the sample relative to the at least one sample-air interface using the image signals; determining one or more sample regions containing at least one constituent and disposed on a first side of the at least one sample-air interface, and one or more no-sample regions not containing a constituent and disposed on a second side of the at least one sample-air interface, wherein the location of the one or more constituents relative to the at least one sample-air interface is used to determine the one or more sample regions and/or the one or more no-sample regions; and determining an area of the chamber containing the sample, wherein the step of determining an area of the chamber comprises summing an area associated with each image unit located within the sample region or the no-sample region. determining a location of at least one sample-air interface between the sample and air, using the image signals; determining a location of one or more constituents within the sample relative to the at least one sample-air interface using the image signals; determining one or more sample regions containing at least one constituent and disposed on a first side of the at least one sample-air interface, and one or more no-sample regions not containing a constituent and disposed on a second side of the at least one sample-air interface, wherein the location of the one or more constituents relative to the at least one sample-air interface is used to determine the one or more sample regions and/or the one or more no-sample regions; and determining an area of the chamber containing the sample, wherein the step of determining an area of the chamber comprises summing an area associated with each image unit located within the sample region or the no-sample region.