Patent ID: 7796833
Filing Date: 2010-09-14
Classification: G01J,G01N,G06K

Abstract:
1. A method for hyper-spectral or multi-spectral data classification or target detection in diverse lighting conditions with an invariant set of detection parameters, based on decoupling target chromaticity and lighting chromaticity in a delta-logarithmic feature space and comprising the steps of: acquiring two or more multi-spectral or hyperspectral image data, each set being an image hyper-cube for a scene and the two sets having been acquired with illumination having different chromaticity; performing a logarithmic transform of the acquired image hyper-cubes; calculating chromaticity maps for all triplets or quadruplets of wavelengths, each said triplet or quadruplet comprising a “band combination”, and each element of the map corresponding to a pixel, or group of pixels treated as a single element, with the map coordinates each being the logarithm of the ratio of the pixel values at two of the different wavelengths of the triplet or quadruplet, the logarithm of the ratio of the pixel values being the spectral band subtraction in the logarithmic feature space, then determining isochrome lines for each band combination; sorting all band combinations by merit function values, the value of each band combination being calculated as a function of the value of at least one criteria that are applied to the isochromes, and the sorting being the ranking of the band combinations according to their merit function value, the greatest rank being given to the most advantageous merit function value; comparing presumed-target chromaticities in a subset of feature space that corresponds to one or more of the highest ranked band combinations with classification or detection discriminant parameters; and generating a detection mask through the denotation of the subset of pixels that have been identified or classified, as having a chromaticity that sufficiently matches the detection discriminant parameters.