1. A an image reader for collecting image data from a target, the image reader comprising: a CMOS based image sensor array, the CMOS based image sensor array comprising a plurality of rows of pixels, each of the pixels of the CMOS based image sensor array being an active pixel comprising a pixel amplifier, a photosensitive region and an opaque shielded data storage region; a housing encapsulating said image sensor array; wherein the image reader includes a first user selectable mode of operation and a second user selectable mode of operation; an illumination module configured to illuminate the target during an illumination period; wherein the image reader is operative so that with the second user selectable mode of operation active, exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated sequentially responsively to an initiation of a decode attempt; wherein the image reader is operative so that with the second user selectable mode of operation active, exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated simultaneously responsively to an initiation of a decode attempt.