Detection of targets from hyperspectral imagery

An apparatus for detecting the presence of a target substance, comprising:

• image storage configured to store at least a portion of 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;
• target spectra storage configured to store a reference spectrum of the target substance;
• a filter in communication with the image storage, the filter configured to determine 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, and to adjust a spectrum of each scene pixel in the subset through subtraction of the respective mean spectrum from the scene pixel spectrum, and to repeat the acts of determining a respective mean spectrum and adjusting each scene pixel for other subsets of scene pixels in the received hyperspectral image;
• a target scoring engine in communication with the target spectra storage and at least one of the image storage and the filter, the target scoring engine configured to determine for each scene pixel a measure of spectral match between a respective spectrum of the scene pixel and a reference spectrum of the target substance;
• a non-target scoring engine in communication with the target spectra storage and at least one of the image storage and the filter, the non-target scoring engine configured to determine for each scene pixel a quantitative measure of spectral mismatch between a respective spectrum of the scene pixel and the reference spectrum of the target substance;
• and
• a target detector in communication with the target scoring engine and the non-target scoring engine, the target detector configured to determine 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, including 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.

An apparatus for detecting the presence of the target substance, comprising

• means for 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;
• means for determining from a subset of scene pixels a respective mean spectrum;
• means for 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, 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;
• means for 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;
• means for 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;
• means for 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
• means for 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.