Figure 4: Evaluation of differences in imaging sensor response characteristics across cameras of varying ages. The sensor response is characterized in terms of the digital number (y axis) produced for a given exposure (x axis, natural logarithm).
From: Tracking vegetation phenology across diverse North American biomes using PhenoCam imagery
(a-c) sensor response functions (plotted as y=a * exp (b * x), and response function parameters (inset) for 9 StarDot cameras of varying ages (whitecircles: 2008 cameras, grey circles: 2011 cameras, black symbols: 2015 cameras). Each color channel is plotted separately: (a) red channel; (b) green channel; (c) blue channel. Note that variation among cameras is minimal for DN <150. (d–f) sample images, at a constant exposure, from cameras of varying ages: (d) 2008 camera; (e) 2011 camera; (f) 2015 camera.
