Abstract: Example methods, apparatuses, and computer program products related to analyzing fluid samples are provided. For example, an example computer-implemented method for analyzing fluid samples includes receiving digital holography image data associated with a fluid sample in a flow chamber device; extracting, from the digital holography image data, an upper reference mark image region associated with an upper reference mark and a lower reference mark image region associated with a lower reference mark; determining a maximum focal depth and a minimum focal depth associated with the digital holography image data, respectively; focusing each of a plurality of focal depth layers associated with the digital holography image data; and extracting, from the plurality of focal depth layers, one or more region of interest (ROI) portions that are associated with the fluid sample.