Camera Calibration for Device-Independent Colorimetric Sensing

The patent creates a mathematical model (characteristic equation) that copies the spectral measurement functionality of an expensive spectrometer using a conventional digital camera. By capturing images at multiple exposure times and applying calibration-derived transformations, the system reproduces spectral color values without requiring actual spectral instrumentation, thus achieving spectrometer-level precision with camera-level simplicity

The patent replaces the mechanical/optical system of a spectrometer with a computational approach using a conventional digital camera. Instead of using a spectrometer's diffraction grating and detector array to physically separate wavelengths, the system uses the camera's existing sensor combined with multi-exposure imaging and mathematical transformations to derive spectral information, substituting physical spectral separation with computational spectral reconstruction

The patent changes the parameters of the image capture process by taking multiple images at different exposure times rather than relying on a single exposure. This multi-exposure approach, combined with camera-specific calibration parameters, allows the system to adapt to different camera sensors while maintaining consistent spectral color measurements across various camera types

The patent performs preliminary calibration for each camera type by capturing images of reference samples at multiple exposure times before actual measurement. This pre-calibration establishes camera-specific fit parameters and characteristic equations that compensate for sensor variations, ensuring that subsequent measurements maintain precision across different camera models

The patent performs the time-consuming multi-exposure calibration process as a preliminary action during device setup or initialization rather than during routine measurements. The calibration data is stored and reused for subsequent measurements, so the time penalty is incurred only once per camera or infrequently, while all subsequent measurements benefit from the precision enabled by the multi-exposure calibration

The patent creates a reusable mathematical model (characteristic equation) during the initial multi-exposure calibration process. This model copies the essential calibration information into a compact form that can be applied to future measurements without requiring repeated multi-exposure captures, thus preserving measurement precision while minimizing time loss in ongoing operations