Chromatic discrimination by use of computer controlled set of light-emitting diodes

We propose a novel approach for measurements of two-dimensional distribution of the reflection spectra with high spatial resolution. It is based on a subspace vector model of surface reflections and includes sequential illumination of the object by basis functions preliminary calculated with principal component analysis. A simple optical system consisting of a computer controlled set of light-emitting diodes and a photo-receiver operating in integration regime is used to acquire spatial distribution of reflection spectra in compressed form. The compressed data can be directly used for accurate color classification or recognition. The system's ability to distinguish metameric samples with extremely small hue difference is experimentally demonstrated.