1. An image sensor device comprising: an uncovered imaging array having M rows and N columns of pixels; a covered global reference non-imaging array comprising at least one global reference row of non-imaging pixels; imaging array sampling logic configured to sample each of the M rows of pixels of the imaging array to obtain M sets of image pixel sample values, each of the M sets of image pixel samples having N image pixel sample values; global reference non-imaging array sampling logic configured to sample a same row of said at least one global reference row non-imaging pixels to obtain a set of reference pixel sample values, and wherein said same row is sampled simultaneously with the sampling of each of the M rows of the imaging array such that M sets of reference pixel sample values are obtained; averaging circuitry configured to average each of the M sets of reference pixel sample values to obtain M average values; and difference circuitry configured to receive the selected image pixel sample values from the imaging array sample selection circuitry and the M average values from the averaging circuitry, the difference circuitry being configured to subtract each of the M average values from each of the N image pixel sample values of the associated set of image pixel sample values to obtain M sets of N output image sample values.