In order to produce a calibrated hyperspectral image, each individual image must be scaled by a calibration factor. The calibration factors were determined by comparing the image data at a reference location to direct radiometric measurements (PhotoResearch PR-650) of the light coming from this location. For every illuminant setting of the BearFruitGray images, the reference location is labeled "R" in the image at right. When we acquired the BearFruitGrayB image, we also measured spectra from three additional image regions, labeled "G" (green), "P" (pink), and "B" (background). The three plots on this page compare these additional spectra to the spectra derived from the BearFruitGrayB image at the same locations. The agreement is generally good, although there are some small deviations for the background calibration check.
