Motion-adaptive intraframe transform coding of video signals

Spatial transform coding has been widely applied for image compression because of its high coding efficiency. However, in many intraframe systems, in which every TV frame is independently processed, coding of moving objects in the case of interlaced input signals is not addressed. In this paper, we extend intraframe transform coding techniques for interlaced video signals with limited additional complexity. After discussing key aspects of an interlaced video signal, we present a simple motion-detection scheme which is suitable for an a priori block-coding decision, thereby saving hardware complexity. The transformer is modified to obtain either intraframe or intrafield transformed blocks by performing partially different fast cosine computation algorithms. As a result, the subjective image quality of the motion-adaptive coding technique is considerably improved as compared with the nonadaptive system.