Reflectance Spectra Estimation from Digital Camera RGB Data

The patent creates a mathematical model (copy) of the spectrophotometer's measurement function that can be executed by standard digital cameras. Instead of requiring the complex physical device, the invention captures the essential measurement capability through computational algorithms that process camera RGB data to estimate reflectance spectra, thereby achieving spectrophotometer-level precision with consumer-grade equipment.

The patent replaces the mechanical/optical measurement system (spectrophotometer with moving parts, gratings, and detectors) with a computational system. The physical measurement apparatus is substituted by mathematical transformations and algorithms that process digital camera data, eliminating the need for complex mechanical components while maintaining measurement accuracy.

The patent makes standard digital cameras multi-functional by enabling them to perform both conventional photography and spectral estimation tasks. The same camera hardware that captures ordinary images is also used to estimate reflectance spectra across multiple pixels simultaneously, eliminating the need for specialized hyper-spectral imaging equipment while maintaining high productivity.

The patent creates a computational model that copies the spectral measurement capability of hyper-spectral systems into standard camera software. The algorithm processes RGB values from all pixels in an image to generate spectral estimates, effectively replicating the functionality of expensive hyper-spectral imagers using ubiquitous consumer camera technology.

The patent enables the system to self-calibrate by using the camera's own RGB sensitivity characteristics and the known properties of the scene to automatically determine the illumination spectrum. Instead of requiring external illumination measurement equipment or controlled lighting conditions, the algorithm extracts illumination information from the captured image data itself, allowing accurate spectral estimation in uncontrolled environments.

The patent introduces the camera's RGB sensor response as an intermediary that links the unknown illumination spectrum to the measurable pixel values. By using the camera's known spectral sensitivity functions as a mediator, the system can solve for both the illumination spectrum and the object reflectance simultaneously, eliminating the need for separate illumination measurements.

The patent transforms the limited three-channel RGB data into a full spectral dimension by applying mathematical transformations. Instead of trying to capture spectral information directly in the spatial domain with multiple filters, the invention uses the RGB values as a starting point and reconstructs the spectral dimension through computational algorithms, effectively adding a spectral dimension to the data without requiring spectral sensors.

The patent changes the parameter representation from discrete RGB values to continuous spectral functions. By transforming the data from three broad wavelength bands (RGB) to a continuous spectrum across the visible range, the system achieves higher spectral precision while maintaining the simplicity of conventional camera hardware. The transformation involves changing the mathematical representation rather than the physical measurement approach.