Abstract: A transport system moves documents beneath a self-scanned photocell array extending substantially the entire width of a page. The output data from the photocells is scanned via a plurality of channels, amplified, multiplexed, and converted to a digital format. The digital data is then processed to compensate for fixed pattern errors characteristic of the photocell array and for scan pattern error. The corrected digital data is quantized for character thresholding and input to a recirculating memory. Line-tracking circuitry monitors the location of individual lines of character data within the recirculating memory and gates a complete line of character data into one of two storage registers. While data is input to one register, the contents of the other register is output to character recognition circuitry.