An image-processing system comprising: first and second 3D time-of-flight, TOF, sensors each for generating an output array of pixelwise values, the values including values indicative of distances to objects within a field of view of the sensor and an optical intensity value for each of the values indicative of distances to the objects, the fields of view of the first and second 3D TOF sensors overlapping along separate optical paths, the first and second 3D TOF sensors each configured to sequentially obtain a plurality of output arrays following a frame trigger, and wherein the first and second 3D TOF sensors are further each configured to obtain a dark frame comprising an image of the objects within the respective fields of view of the first and second 3D TOF sensors without illumination; and at least one processor configured to combine, for each 3D TOF sensor, the respective sequentially obtained plurality of output arrays into a single resulting output array, and use the respective dark frames as a measurement of ambient levels and inherent sensor noise, to correct for ambient noise and sensor offset within the obtained output arrays; first and second depth-compute engines , executable by at least one processor , for processing successive resulting output arrays originating from, respectively, the first and second 3D TOF sensors , into pixelwise arrays of depth values, the depth-compute engines operating in a pipelined fashion so as to begin processing a new resulting output array prior to completing processing of a previous resulting output array; and a comparison unit , executable by the at least one processor , for detecting pixelwise differences in depth between corresponding processed resulting output arrays originating substantially simultaneously from the first and second 3D TOF sensors ; wherein the at least one processor is further operable for generating an alert signal if the detected differences in depth aggregate to exceed a noise metric. first and second 3D time-of-flight, TOF, sensors each for generating an output array of pixelwise values, the values including values indicative of distances to objects within a field of view of the sensor and an optical intensity value for each of the values indicative of distances to the objects, the fields of view of the first and second 3D TOF sensors overlapping along separate optical paths, the first and second 3D TOF sensors each configured to sequentially obtain a plurality of output arrays following a frame trigger, and wherein the first and second 3D TOF sensors are further each configured to obtain a dark frame comprising an image of the objects within the respective fields of view of the first and second 3D TOF sensors without illumination; and at least one processor configured to combine, for each 3D TOF sensor, the respective sequentially obtained plurality of output arrays into a single resulting output array, and use the respective dark frames as a measurement of ambient levels and inherent sensor noise, to correct for ambient noise and sensor offset within the obtained output arrays; first and second depth-compute engines , executable by at least one processor , for processing successive resulting output arrays originating from, respectively, the first and second 3D TOF sensors , into pixelwise arrays of depth values, the depth-compute engines operating in a pipelined fashion so as to begin processing a new resulting output array prior to completing processing of a previous resulting output array; and a comparison unit , executable by the at least one processor , for detecting pixelwise differences in depth between corresponding processed resulting output arrays originating substantially simultaneously from the first and second 3D TOF sensors ; wherein the at least one processor is further operable for generating an alert signal if the detected differences in depth aggregate to exceed a noise metric. <EOS>