Hyperspectral images
LENS
Any shifts in color chromaticity conferred by the SW-filtering lens may not equate to changes in color appearance, as chromatic adaptation may rebalance the color appearance to compensate for initial changes in receptor signals caused by the filter. However, the colored filter may still affect the range of color contrasts available to the observer. We were interested in predicting the effect of the filter on the available color gamut for natural scenes. Colors in RGB images have very different spectra from those in natural scenes, and correspondingly the effects of filters on RGB images will be very different from their effects on natural scenes. It is therefore not possible to fully simulate the effect of filters on the color perception of natural scenes solely from RGB images; instead, hyperspectral images are required, where full spectral information is available at each pixel. To this end, we used five sets of hyperspectral images. Three images sets were obtained from the literature (A calibrated IQ camera (Specim Spectral Imaging Oy, Ltd., Oulu, Finland) was used to gather a custom set of hyperspectral images of scenes created in the lab under controlled lighting and outdoor scenes. The custom image set consisted of 35 images featuring a mixture of manmade and colored objects, including objects where color discrimination is often critical (e.g., maps, colored markers, flowers, traffic lights, colored threads and cables, fruit). The spatial resolution of the images was 512 × 512, and the native spectral resolution was 204 wavebands between 400 and 1000 nm.These custom images were calibrated using a PR655 spectroradiometer (PhotoResearch, Chatsworth, CA), and colored stimuli were presented on a cathode-ray tube (CRT) monitor (Mitsubishi, Tokyo, Japan). By measuring a series of the same stimuli with both the PR655 and the Specim IQ, a vector of mean wavelength-specific scaling factors was calculated that allowed the camera-specific intensities of the Specim IQ to be transformed into radiance units. The wavelengths output by the Specim IQ were not calibrated, but the calibration was checked using an independent set of stimuli (Calibration of Specim IQ. Nine colored stimuli were presented on a Mitsubishi Diamond Pro CRT monitor. The spectra of the stimuli are shown measured using a PR655 spectroradiometer (red line) and using the calibrated Specim IQ hyperspectral camera (blue open circles).The two sets of publicly available hyperspectral images captured by 