1. An image sensor comprising: an array of pixels arranged in rows and columns, the columns being separated into groups each comprising a plurality of the columns and sharing a common output; sampling and readout circuitry comprising, for each group of columns in the pixel array, a corresponding plurality of column circuits, the sampling and readout circuitry being configured to sample the common output for each group of columns independently into one of the plurality of column circuits associated with said group, and to read out the common output for each group of columns as previously sampled into another of the plurality of column circuits associated with said group; and a sparse color filter array pattern disposed over the array of pixels, wherein the sparse color filter array pattern includes a minimal repeating unit including sixteen pixels arranged in four four-pixel cells as follows: Z P Y P P Z P Y Y P X P P Y P X wherein P represents panchromatic pixels and X, Y and Z represent respective color pixels.