Although colorimetric assays have been demonstrated, some key problems have remained—questions regarding the accuracy and precision of the spectroscopic data and what processing is done by these devices before we can get hold of the data. In general, the cameras’ hardware properties are not disclosed by the smartphone manufacturers, and it is left to those performing "teardowns" to uncover this information. This paper gets to the fundamentals and presents a standardized methodology and database for spectral and radiometric calibrations of consumer cameras. The authors did find linearity in the RAW, but not JPEG, format data, although limited to 8-bits, but also found that results in general varied widely among cameras. In addition, the spectral response varied among the cameras, especially in the long wavelength cut-off of the R filter in the RGB Bayer set.
This is a thorough piece of work and is highly recommended for all those seeking to use smartphones, and other consumer cameras, for spectroscopy.
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