An image sensor is provided that includes a pixel array divided into a plurality of pixel groups. Each pixel group is clocked by a respective plurality of horizontal-register clocks. Clock signals for the image sensor are adjusted. Adjusting the clock signals includes phase-shifting each plurality of horizontal-register clocks by a respective phase delay of a plurality of phase delays. The phase delays are evenly spaced and are spaced symmetrically about zero. With the clock signals adjusted, a target is imaged using the image sensor.