An imager having optically and electrically black reference pixels in each
row of the imager's pixel array. Since the reference pixels of each row
experience the same row-wise noise as active imaging pixels in the
associated row, the signals from the reference pixels are used to cancel
out row-wise noise from the row of imaging pixels. The reference pixels
are designed such that their photosensors are physically or effectively
removed from the row-wise noise correction, thus rendering them
electrically black or dark. As such, the reference pixels can be used to
provide row-wise noise correction without the adverse effects of warm and
hot pixels.