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Figure 2: Sample illumination and camera sensitivity. Measured spectral irradiance of grape leaf disks (solid black line) as samples were illuminated by four phosphor-converted Indium Gallium Nitride (InGaN) “white” light emitting diodes. The spectral matching between the illuminant and the camera is compared to the reported spectral sensitivity of the red, green, and blue channels (dashed, dot-dashed, and dotted curves, respectively) for an RGB CMOS sensor [30] similar to that of the Nikon model D850 camera used in the present study.