Abstract: A video data decoding apparatus is configured to detect a control flag associated with at least a part of an encoded image for decoding, in which in a lossless mode of operation, a first control flag state enables sample-based angular intra-prediction but disables edge filtering of prediction samples, and a second control flag state disables sample-based angular intra prediction but enables edge filtering of prediction samples; and in a lossy mode of operation, the first control flag state enables residual differential pulse code modulation coding and enables edge filtering of prediction samples, and the second control flag state disables residual differential pulse code modulation coding but enables edge filtering of prediction samples.

Abstract: A method of coding 4:2:2 or 4:4:4 video data comprises predicting luminance and/or chrominance samples of an image from other respective reference samples derived from the same image according to a prediction mode associated with a sample to be predicted, the prediction mode being selected for each of a plurality of blocks of samples, from a set of two or more candidate prediction modes; detecting differences between the samples and the respective predicted samples; selecting a frequency-separation transform from two or more candidate frequency separation transforms according to the prediction mode associated with a current block of samples using a mapping between transform and prediction mode, the mapping between different, as between chrominance and luminance samples, for at least the 4:4:4: format; and encoding the detected differences by frequency-separating the differences, using the selected frequency-separation transform.

Abstract: A video coding or decoding method operable to generate blocks of quantized spatial frequency data by quantizing the video data according to a selected quantization step size and a matrix of data modifying the quantization step size for use at different respective block positions within an ordered block of samples, the method being operable with respect to at least two different chrominance subsampling formats.

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 selected from a set of available prediction directions, 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 derive predicted samples of the current region with respect to one or more of a group of reference samples of the same image in dependence upon a prediction direction, defined by the selected prediction operation, between a current sample to be predicted and the reference samples; in which for at least some of the candidate prediction operations: the group of reference samples comprises two or more parallel linear arrays of reference samples disposed at different respective separations from the current region, the intra-image predictor being configured to derive the predi

Abstract: A video coding or decoding method using inter-image prediction to encode input video data in which each chrominance component has 1/Mth of the horizontal resolution of the luminance component and 1/Nth of the vertical resolution of the luminance component, where M and N are integers equal to 1 or more, comprises: storing one or more images preceding a current image; interpolating a higher resolution version of prediction units of the stored images so that the luminance component of an interpolated prediction unit has a horizontal resolution P times that of the corresponding portion of the stored image and a vertical resolution Q times that of the corresponding portion of the stored image, where P and Q are integers greater than 1; detecting inter-image motion between a current image and the one or more interpolated stored images so as to generate motion vectors between a prediction unit of the current image and areas of the one or more preceding images; and generating a motion compensated prediction of the pr

Abstract: A data encoding method for encoding an array of data values as data sets and escape codes for values not encoded by the data sets, an escape code including a unary coded portion and a non-unary coded portion, the method including: setting a coding parameter defining a minimum number of bits of a non-unary coded portion; adding an offset value of 1 or more to the coding parameter to define a minimum least significant data portion size; generating one or more data sets indicative of positions, relative to the array of data values, of data values of predetermined magnitude ranges, to encode the value of at least one least significant bit of each data value; generating respective complementary most-significant data portions and least-significant data portions; encoding the data sets; encoding the most significant data portions; and encoding the least-significant portions.

Abstract: A data encoding method includes encoding an array of data values as data sets and escape codes for values not encoded by the data sets, an escape code including a prefix portion and a non-unary coded suffix portion having a length, in bits, dependent upon a value encoded by the prefix portion according to a relationship such that, for at least some values encoded by the prefix portion, the length of the non-unary coded suffix portion is greater than the length, in bits, of the prefix portion.

Abstract: A method of coding 4:2:2 or 4:4:4 video data comprises predicting luminance and/or chrominance samples of an image from other respective reference samples derived from the same image according to a prediction mode associated with a sample to be predicted, the prediction mode being selected for each of a plurality of blocks of samples, from a set of two or more candidate prediction modes; detecting differences between the samples and the respective predicted samples; selecting a frequency-separation transform from two or more candidate frequency separation transforms according to the prediction mode associated with a current block of samples using a mapping between transform and prediction mode, the mapping between different, as between chrominance and luminance samples, for at least the 4:4:4 format; and encoding the detected differences by frequency-separating the differences, using the selected frequency-separation transform.

Abstract: A method of encoding image data, including: frequency-transforming input image data to generate an array of frequency-transformed input image coefficients by a matrix-multiplication process, according to a maximum dynamic range of the transformed data and using transform matrices having a data precision; and selecting the maximum dynamic range and/or the data precision of the transform matrices according to the bit depth of the input image data.

Abstract: A data encoding method for encoding an array of data values as data sets and escape codes for values not encoded by the data sets, an escape code including a unary coded portion and a non-unary coded portion, the method including: setting a coding parameter defining a minimum number of bits of a non-unary coded portion; adding an offset value of 1 or more to the coding parameter to define a minimum least significant data portion size; generating one or more data sets indicative of positions, relative to the array of data values, of data values of predetermined magnitude ranges, to encode the value of at least one least significant bit of each data value; generating respective complementary most-significant data portions and least-significant data portions; encoding the data sets; encoding the most significant data portions; and encoding the least-significant portions.

Abstract: A video data decoding apparatus configured to decode input encoded data representing a plurality of independently decodable portions of a video image, each portion representing a spatially subsampled version of the video image so that a combination of the plurality of portions provides a representation of all of the pixels of that video image, the video data decoding apparatus: one or more decoders having a collective processing capacity which is lower than the maximum possible processing requirements for decoding the plurality of portions; a controller configured to route data of the portions to the one or more decoders so that the one or more decoders cooperate to decode the whole of at least one of the portions for that video image; and a combiner configured to combine the decoded portions to generate a representation of that video image.

Abstract: A method of encoding image data, including: frequency-transforming input image data to generate an array of frequency-transformed input image coefficients by a matrix-multiplication process, according to a maximum dynamic range of the transformed data and using transform matrices having a data precision; and selecting the maximum dynamic range and/or the data precision of the transform matrices according to the bit depth of the input image data.

Abstract: A video coding or decoding method operable to generate blocks of quantised spatial frequency data by quantising the video data according to a selected quantisation step size and a matrix of data modifying the quantisation step size for use at different respective block positions within an ordered block of samples, the method being operable with respect to at least two different chrominance subsampling formats.

Abstract: A video coding or decoding method using inter-image prediction to encode input video data in which each chrominance component has 1/Mth of the horizontal resolution of the luminance component and 1/Nth of the vertical resolution of the luminance component, where M and N are integers equal to 1 or more, comprises: storing one or more images preceding a current image; interpolating a higher resolution version of prediction units of the stored images so that the luminance component of an interpolated prediction unit has a horizontal resolution P times that of the corresponding portion of the stored image and a vertical resolution Q times that of the corresponding portion of the stored image, where P and Q are integers greater than 1; detecting inter-image motion between a current image and the one or more interpolated stored images so as to generate motion vectors between a prediction unit of the current image and areas of the one or more preceding images; and generating a motion compensated prediction of the pr

Abstract: An image data encoding and/or decoding apparatus comprises a data processor to process an image data signal comprising successive arrays of data values according to respective data value processing orders associated with the arrays of data values; and a processing order selector to select a processing order for processing a current array of data values in dependence on one or more attributes of a plurality of arrays of data values in the image data signal already processed by the data processor.

Abstract: A video data decoding apparatus is configured to detect a control flag associated with at least a part of an encoded image for decoding, in which in a lossless mode of operation, a first control flag state enables sample-based angular intra-prediction but disables edge filtering of prediction samples, and a second control flag state disables sample-based angular intra prediction but enables edge filtering of prediction samples; and in a lossy mode of operation, the first control flag state enables residual differential pulse code modulation coding and enables edge filtering of prediction samples, and the second control flag state disables residual differential pulse code modulation coding but enables edge filtering of prediction samples.

Abstract: A video coding or decoding method in which luminance and chrominance samples are predicted from other respective reference samples according to a prediction direction associated with a current sample to be predicted, the chrominance samples having a lower horizontal and/or vertical sampling rate than the luminance samples so that the ratio of luminance horizontal resolution to chrominance horizontal resolution is different than the ratio of luminance vertical resolution to chrominance vertical resolution, so that a block of luminance samples has a different aspect ratio to a corresponding block of chrominance samples, the method including: detecting a first prediction direction defined in relation to a first grid of a first aspect ratio in respect of a set of current samples to be predicted; and applying a direction mapping to the prediction direction to generate a second prediction direction defined in relation to a second grid of a different aspect ratio.

Abstract: A video data decoding apparatus is configured to detect a control flag associated with at least a part of an encoded image for decoding, in which in a lossless mode of operation, a first control flag state enables sample-based angular intra-prediction but disables edge filtering of prediction samples, and a second control flag state disables sample-based angular intra prediction but enables edge filtering of prediction samples; and in a lossy mode of operation, the first control flag state enables residual differential pulse code modulation coding and enables edge filtering of prediction samples, and the second control flag state disables residual differential pulse code modulation coding but enables edge filtering of prediction samples.

Abstract: A video coding or decoding method operable to generate blocks of quantized spatial frequency data by quantizing the video data according to a selected quantization step size and a matrix of data modifying the quantization step size for use at different respective block positions within an ordered block of samples, the method being operable with respect to at least two different chrominance subsampling formats, and includes for at least one of the chrominance subsampling formats, defining one or more quantization matrices as one or more predetermined modifications with respect to one or more reference quantization matrices defined for a reference one of the chrominance subsampling formats.

Abstract: A video coding or decoding method in which luminance and chrominance samples in a 4:4:4 format or a 4:2:2 format are predicted from other respective samples according to a prediction direction associated with blocks of samples to be predicted; comprises detecting a prediction direction in respect of a current block to be predicted; generating a predicted block of chrominance samples according to other chrominance samples defined by the prediction direction; if the detected prediction direction is substantially vertical, filtering the left column of samples in the predicted block of chrominance samples, or if the detected prediction direction is substantially horizontal, filtering the top row of samples in the predicted block of chrominance samples; and encoding a difference between the filtered predicted chrominance block and the actual chrominance block or applying a decoded difference to the filtered predicted chrominance block so as to encode or decode the block respectively.