An article on two-camera NDVI in intertidal mapping from PLOS One, using kites, via the KAP forums.
The authors use a color chart and a spectrometer to characterize the spectral response of consumer digital cameras. I hope we can use this technique to improve our understanding of Infragram cameras.
The spectral response functions of both cameras were determined using the procedure described in ,  to provide precise information on the spectral sensitivities of the raw imagery from the red, green and blue channels of the colour camera and the near-infrared sensitivity of the converted camera (data was taken only from the red bayer channel of the images for this camera). Images of a Macbeth colour chart were captured using the raw mode of each camera under cloudless sunlight and measurements of the spectral response of each Macbeth colour panel were taken using a handheld spectroradiometer (Ocean Optics STS-VIS with an effective range from 400–800 nm), from which the response curves were estimated. Although the panels of the Macbeth colour chart are designed for use in colour calibration in the visible spectrum, it was found that the panels exhibited variations in reflectance at wavelengths around 720 nm and above, and were therefore also effective for calibrating images captured from the near-infrared converted camera. Figure 3 (a) illustrates the estimated spectral response curves for the camera.
Figure 3. Spectral calibration data.
(a) Spectral response functions for the colour and near-infrared converted cameras: the red, green and blue channels correspond to the three channels of the colour camera whereas the near-infrared curve corresponds to the red channel of the near-infrared converted camera, which was found to have the highest response of each of the channels for this camera. (b) Reflectance spectra for key surface coverage types in the intertidal zone measured using a handheld spectroradiometer. The reflectance spectra were used in conjunction with the camera spectral response functions to validate the measured colour of objects in the kite-based imagery. doi:10.1371/journal.pone.0073550.g003