Patent Document ID: 8897571
Application ID: 13077228
Patent Status: 1

Claim One:
1. A method of determining the presence of a target substance, the method comprising: receiving a hyperspectral image comprising spectra of a plurality of scene pixels indicative of light and other radiation absorbed by or emitted from, a target substance; determining from a subset of scene pixels a respective mean spectrum, wherein the mean spectrum is an n-dimensional vector of values corresponding to the subset of scene pixels, n being a number of frequency bins; adjusting a spectrum of each scene pixel in the subset through subtraction of the respective mean spectrum from the respective spectrum of the scene pixel; repeating the acts of determining a respective mean spectrum and adjusting each scene pixel for other subsets of scene pixels of the received hyperspectral image; determining for each adjusted scene pixel, a measure of spectral match between a respective spectrum of the scene pixel and a reference spectrum of the target substance; determining for each adjusted scene pixel, a quantitative measure of spectral mismatch between the respective spectrum of the scene pixel and the reference spectrum of the target substance; and detecting a presence of the target substance within the hyperspectral image in response to the determined measure of spectral match and the determined quantitative measure of spectral mismatch, wherein the detecting includes forming a ratio of the measure of spectral match based on mixture coefficients and the measure of spectral mismatch based on a residual spectrum, the ratio being indicative of presence of the target substance within the scene pixel.