Abstract: A variable time integrating period to accomplish distortion free synchronization of the scanning rate to the document transport speed when the transport speed is within a predetermined tolerance with respect to it's nominal speed is disclosed. The rate levels provided by the scanner are then multiplied by an appropriate correction factor to compensate for the varied amount of light accumulated by the time integrating photo sensor array because of the varied integration time. When the document speed must be reduced to a value less than the predetermined tolerance, the system of the invention resorts to the techinque of selecting only certain scans and discarding the data from other scans. Scan selection is found to be economically accomplished by selecting those scans which were time integrating when an emitter pulse occurred.