1. A method of operating an input scanner having a bar including a first linear array of photosensors sensitive to a single first color and a second linear array of photosensors, parallel to the first linear array, sensitive to a single second color, comprising the steps of: moving the bar relative to an original image being scanned in a process direction perpendicular to the linear arrays; for each of a series of scan cycles as the sensor bar moves, causing integration of image signals from the photosensors of the first linear array; and for a periodically-occurring subset of the series of scan cycles as the sensor bar moves, causing integration of image signals from the photosensors of the second linear array.