Coding procedure for blocks of coding images with low output - involves assessing cost of employing alternative coding modes so that use of intra=image coding is minimised

摘要

The procedure involves selecting one of three coding modes. These are simple inter-image coding (C1), inter-image coding with movement compensation (C2) and intra-image coding (C3). A preliminary stage determines the initial cost associated with each coding mode together with at least one of the following stages. Determination (I, III) of the new cost of the third mode (C3) takes into account a predetermined external parameter. Determination (II) of a new cost for the third mode taking into account transmission parameters of the coded blocks. This is followed by two supplementary stages. First, a comparison of the new cost with the costs of the first two modes (C1, C2). Secondly, forcing (V) intra-image (III) coding mode if the new cost is less than that for the first and second modes. ADVANTAGE - Ensures that intra-image coding is only employed as last resort so as to reduce the incidence of undesired effects.