A differentiation system for differentiating cells includes an input device configured to receive holographic image data of a microscopic particle in suspension, holographic image data processing logic for converting the holographic image data to the frequency domain by performing a Fourier transform of the holographic image data, and a recognizer configured to determine characterization features of the holographic image data of the microscopic particle in the frequency domain for characterization of the microscopic particle, the characterization features comprising rotationally invariant features.