FIG. 3.

The main hardware methods to increase signal specificity before camera capture are shown with (i) geometry and filter optimization, (ii) wavelength or bandwidth restrictions, or (iii) temporal signal processing with mechanical or electronic shuttering. The temporal gating approaches are illustrated in (b) as single shot pulsed, modulated relative to continuous sampling. Filtering and wavelength processing are illustrated in (c) with typical, custom and specially designed bandpass filters for detection, and (d) spectral fitting which might be implemented to remove background. The use of HDR principles (e) can allow superior detection by better background subtraction without loss of pertinent dynamic range. Finally, image texture analysis (f) might be used for improved diagnostic performance based upon the morphology of the contrast.