Dynamic CCD line length timing for color scanners

A line clocking arrangement is used in a scanner for synchronizing the line readout of a clocked imaging device with the motion of an object being scanned. The line clocking arrangement includes an encoder for sensing movement of the object being scanned and generating a sync signal in correspondence with a movement of the object, and a timing generation circuit for generating clock signals for controlling the clocked imaging device. The clock signals include a drain clock signal for controlling the dumping of charge into an overflow drain and an output clock signal for clocking image charge through an horizontal output register. The timing generation circuit receives the sync signal and times the duration of the drain clock signal and the beginning of the output clock signal to the occurrence of the sync signal, whereby the line readout time is dynamically adjusted to changes in velocity of the scanned object during a period when charge is being dumped into the overflow drain.