A time series whole field velocity measurement was accomplished by the digital image processing. Laser light sheet illuminated the flow field synchronizing with CCD camera, and obtained images were recorded on the VTR with interval of 1/30 sec. Individual images were transferred from VTR under the control of personal computer with DSP (digital signal processor) to the image grabber, and the velocity vectors were evaluated using the cross-correlation technique. The time series analysis of the system showed good agreement with those of simultaneously applied LDV measurements. The present techniques applied to the thermally stratified shear flow in a horizontal pipe provided instantaneous and time series whole field velocities from 1400 planes (47 sec), and spatial eddy motions were revealed from the measurement which was unable to measure by point-measuring techniques.