Abstract: Image data encoding apparatus comprises an entropy encoder for selectively encoding data items representing image data to be encoded by a first, context adaptive binary arithmetic coding (CABAC), encoding system or by a second, bypass, encoding system, so as to generate encoded binarized symbols; the image data representing one or more pictures of a picture sequence, each picture comprising two or more output data units representing respective sub-sections of the picture, each sub-section being decodable and reconstructable independently of other sub-sections in that picture and picture sequence; the entropy encoder being configured to generate an output data stream subject to a constraint defining an upper limit to the number of binarized symbols that may be expressed by any individual output data unit relative to the size in bytes of that output data unit, in which the entropy encoder is configured to apply the constraint to each output data unit, and to provide padding data, for each output data unit which

Abstract: An image encoding apparatus comprises a selector configured to select, from a set of candidate prediction operations each defining at least a prediction direction, a prediction operation for prediction of samples of a current region of a current image, the current region comprising an array of two or more rows and two or more columns of samples; and an intra-image predictor configured to interpolate predicted samples of the current region with respect to one or more of a group of reference samples being samples decoded from previously encoded samples of the current image, the group of reference samples being selected in dependence upon a prediction direction, defined by the selected prediction operation, between a current sample to be predicted and a reference position amongst the reference samples, in which the intra-image predictor is configured to apply an interpolation process to the group of reference samples in order to generate each predicted sample; in which the intra-image predictor is configured to

Abstract: An image data encoding apparatus includes an entropy encoder configured to selectively encode data items representing image data by an encoding system selected from a context adaptive binary arithmetic coding (CABAC) encoding system and a bypass encoding system. The data items include (i) a first data item indicating whether a multi-direction linear model (MDLM) chroma mode applies to a current image region; and (ii) a second data item indicating a processing direction for operation of the MDLM chroma mode. The entropy encoder encodes instances of the first data item and instances of the second data item independently of the encoding of instances of the first data item.

Abstract: Apparatus comprises a data encoder configured to derive, from an array of sample values, sample range flags each indicative of whether one or more sample values of the array of sample values lie in a predetermined range of sample values, the data encoder being configured in a first encoding mode to encode the array of sample values, at least in part, by encoding the sample range flags to an output data stream; a predictor configured to predict the state of a group of the sample range flags for a given array of sample values, the group being at least a subset of the sample range flags; and a comparator configured to compare the predicted state of the group of sample range flags with the actual state of the respective sample range flags for the given array of sample values; the data encoder being configured, in response to the comparator, to encode the given array of samples values in a second encoding mode in which the encoder is configured to encode to the output data stream a predetermined number of indicato