  Digital image sensors are ubiquitous in astronomical instrumentation and it
is well known that they suffer from issues that must be corrected for data to
be scientifically useful. I present discussion on errors resulting from
digitization and characterization of nonlinearity and ADC errors of the
PhotonFocus MV-D1024E cameras selected for the K-Coronagraph of the Coronal
Solar Magnetism Observatory. I derive an analytic expression for quantization
errors. The MV-D1024E camera has adequate bit depth for which quantization
error is not an issue. I show that this is not the case for all cameras,
particularly those with deep wells and low read noise. The impact of
nonlinearity and ADC errors on science observations of the K-Coronagraph is
analyzed using a simplified telescope model. Errors caused by the camera ADCs
result in systematic errors in the measurement of the polarimetric signal of
several times $10^{-9}~B_\odot$, which is about an order of magnitude above the
desired sensitivity. I demonstrate a method for post-facto data correction
using a lookup table and derive parameters from camera characterization
measurements that were made with a lab setup. Nonlinearity is traditionally
addressed with a global correction. I show through analysis of calibration data
that for the MV-D1024E this correction leaves residual systematic errors after
dark and gain correction of up to 1% of the signal. I demonstrate that a
pixel-wise correction of nonlinearity reduces the errors to below 0.1%. These
corrections are necessary for the K-Coronagraph data products to meet the
science requirements. They have been implemented in the instrument data
acquisition system and data reduction pipeline. While no other instruments
besides the K-Coronagraph or cameras besides the MV-D1024E are discussed here,
the results are illustrative for all instruments and cameras.
