An apparatus for processing image motion compensation information for an image processing system, which can add image motion compensation information and assign the bit number suitable for a specific data size required in signal processing added data with a simple structure. The apparatus includes an adding section for adding an inputted difference data per block and a data previously stored in a frame memory, an overflow/underflow checking section for checking overflow/underflow of summed data and reducing the bit size of the added data, and an overflow/underflow executing section for output-controlling the added data according to the checked overflow/underflow.

An interframe/interfield encoding system is for coding an incoming video signal having a successive specific number of dependent frames/fields, and independent frames/fields located anterior and posterior to the dependent frames/fields on a time axis. The system has a predictor for generating prediction errors of the dependent frames/fields by the independent frames/fields and an encoder for coding the independent frames/fields and the prediction errors. The system also has a delay section delays coding the posterior independent frame/field by the specific number of dependent frames/fields on the time axis to the incoming video signal and a controller, responsive to the delaying, controls the encoder to encode the posterior independent frame/field so as to follow the coding of the prediction errors. The posterior independent frame/field, without being delayed, is employed for generation of the prediction errors.

A method of removing frame redundancy in a computer system for a sequence of moving images. The method comprises detecting a first scene change in the sequence of moving images and generating a first keyframe containing complete scene information for a first image. The first keyframe is known, in a preferred embodiment, as a "forward-facing" keyframe or intra frame, and it is normally present in CCITT compressed video data. The process then comprises generating at least one intermediate compressed frame, the at least one intermediate compressed frame containing difference information from the first image for at least one image following the first image in time in the sequence of moving images. In a preferred embodiment, this at least one frame is known as an inter frame. Finally, detecting a second scene change in the sequence of moving images and generating a second keyframe containing complete scene information for an image displayed at the time just prior to the second scene change. This is known, in the preferred embodiment, as a "backward-facing" keyframe. The first keyframe and the at least one intermediate compressed frame are linked for forward play, and the second keyframe and the intermediate compressed frames are linked in reverse for reverse play. In a preferred embodiment, the intra frame is used for generation of complete scene information when the images are played in the forward direction. When this sequence is played in reverse, the backward-facing keyframe is used for the generation of complete scene information.

Video signal transmitting system in which digital video signal are divided into groups of predetermined frames. Digital video signals of at least one frame are intraframe coded and then transmitted. Remaining digital video signals are interframe coded with reference to the intraframe coded digital video signals, and intraframe coded digital video signals of a subsequent group of frames and are then transmitted. A motion vector from a predetermined reference frame is detected. Video signals are interframe coded by the motion vector to transmit the video signals. A motion vector from a first frame which is a plurality of frames away from the reference frame is converted to a motion vector for a one frame interval between the reference frame and the first frame. The motion vector is optimized, and is then transmitted.

An efficient coding and decoding system is provided for a moving picture signal having independent and dependent frames. An interval between independent frames is varied in accordance with frame difference or amount of coded data. Predictive error signals are produced by subtracting predictive picture signals based on two of the frames, the interval therebetween thus varied, from picture signals of dependent frames. The predictive error picture signals and picture signals of the independent frames are then coded to produce a coded moving picture signal. When decoding, decoded predictive picture signals and predictive error picture signals are added to each other to reproduce the picture signals of the dependent frames. Decoded picture signals of the independent frames and the reproduced picture signals of the dependent frames are serially outputted to reproduce the original moving picture signal.