Abstract: A method of determining a luma value from 4:4:4 RGB video data for encoding chroma downsampled 4:2:0 YCbCr video data into a bitstream. A location, in a colour space defined by linear luminance and non-linear 4:2:0 chroma values, is determined from the RGB video data. A region that contains the determined location is determined, the region being one region of a plurality of regions located in the colour space and having a plurality of associated coefficients. One or more of the coefficients associated with the determined region are selected, the selected coefficients being used to map the linear luminance and non-linear 4:2:0 chroma values to a luma value that compensates for a luminance shift introduced by chroma downsampling of the non-linear 4:2:0 chroma values. The method then determines the luma value for encoding into the bitstream according to a function of the selected coefficients and the determined location.

Abstract: A method of encoding a portion of a video frame into a video bitstream, in which the portion of the video frame contains samples, take account the samples representing luminance levels according to an EOTF. The method determines a luminance of the portion of the video frame, and a desired (environment) luminance step size. The desired luminance step size represents a just noticeable difference (JND) determined according to the determined luminance and a predetermined ambient luminance, the desired luminance step size being greater than a luminance (transfer function) step size from the EOTF. The method then determines a quantisation parameter from the desired luminance step size and the luminance step size from the EOTF, the quantisation parameter being used for encoding the portion of the video frame, and then encodes encoding the portion of the video frame into the video bitstream according to the determined quantisation parameter.

Abstract: A method of de-blocking video data is disclosed. The video data encoding colour channels in a 4:2:2 format is received. The video data is encoded in a quad-tree. A plurality of transform units is generated for one of the colour channels, each of the transform units including at least one transform. A distance from an edge of one of the transform units to a boundary of a transform of the transform unit is determined. An edge flag for the transform unit is determined, the edge flag indicating the determined distance. De-blocking is applied to the transform units of the video data according to the determined edge flag.

Abstract: A method of de-blocking an edge of a block of samples of video data is disclosed. A first prediction mode is decoded for a first block of two adjacent blocks of video data, each of the blocks of video data including a primary colour channel and at least one secondary colour channel. A second prediction mode is decoded for a second block of the two adjacent blocks of video data. A boundary strength value is determined for a block of samples along an edge corresponding to a boundary between said first block of video data and said second block of video data. A weak de-blocking filter is applied to the block of data along said edge if the determined boundary strength value indicates that the first prediction mode is intra prediction and the second prediction mode is intra-block copy prediction. The weak de-blocking filter is different to a filter applied to a block determined to have two, adjacently located, intra prediction mode blocks.

Abstract: A plurality of display device profiles is decoded from a bitstream containing video data. A display device profile is selected by comparing at least a portion of the device information of the display device profiles with corresponding device information of the first display device. An image modification parameter set is selected from a plurality of image modification parameter sets according to the selected display device profile, the plurality of image modification parameter sets being decoded from the bitstream and each of the plurality of image modification parameter sets providing information regarding luminance mapping to be applied to one or more portions of the video data. At least a portion of the video data is displayed on the first display device from the bitstream of video data by applying the selected image modification parameter set to the portion of video data from the bitstream of video data.

Abstract: A method of displaying images on a display. Images from a video playback are displayed on the display with a first luminance profile, the luminance profile mapping video data samples to output luminance of the display. A user initiated modification of a speed of the video playback is detected. A second luminance profile is determined for the display of the video playback, the second luminance profile being determined according to the modified speed of the video playback and a predetermined adaptation speed of a human visual system of a viewer of the video playback. Further images from the video playback are displayed on the display using the determined second luminance profile.

Abstract: A method for encoding video data into a video bitstream using a video capture device having a brightness range limited output determines capture conditions for the capture device, the capture conditions including an ambient capture light level and a measured light level of captured video data. The method adjusts a brightness adaptation model using at least the measured light level and the ambient capture light level, the brightness adaption model defining a temporally variable peak luminance for a viewer of video captured using the capture device, and then determines a tone map such that where the measured light level exceeds a determined maximum light level the tone map is modified to reduce brightness, the maximum light level is determined using the brightness adaptation model. The captured video data is then encoded into the video bitstream using the determined tone map.

Abstract: A method of displaying a calibrated image upon a display device comprises receiving an image for display. The image has at least a portion containing a calibration pattern with predetermined codeword values. The portion of the image is a non-displayed portion of the image, the predetermined codeword values encoding at least reference light levels of the image. The method generates a mapping for the image using the reference light levels and ambient viewing conditions associated with the display device. The mapping links codeword values of the image with light intensities of the display device; and outputs the image on the display device using the generated mapping.

Abstract: A method of de-blocking video data is disclosed. The video data encoding color channels in a 4:2:2 format is received. The video data is encoded in a quad-tree. A plurality of transform units is generated for one of the color channels, each of the transform units including at least one transform. A distance from an edge of one of the transform units to a boundary of a transform of the transform unit is determined. An edge flag for the transform unit is determined, the edge flag indicating the determined distance. De-blocking is applied to the transform units of the video data according to the determined edge flag.

Abstract: A method of decoding a coding unit from a video bitstream is disclosed. The coding unit references previously decoded samples. A previous block vector of a previous coding unit to said coding unit to be decoded is determined. The previous coding unit is configured to use intra-block copy. The method decodes, from the video bitstream, a block vector difference for the coding unit to be decoded. The block vector difference indicates a difference between the previous block vector and a block vector of the coding unit to be decoded. The block vector of the coding unit to be decoded is determined using the previous block vector and the block vector difference. The coding unit to be decoded is decoded based on sample values of a reference block selected using the determined block vector.

Abstract: A method of decoding a current block encoded using intra-prediction includes determining prediction modes for coding blocks neighbouring the current block. The method generates prediction values for edge samples of the decoded block from intra-prediction reference samples of the neighbouring coding blocks by applying an intra-prediction process to the intra-prediction encoded current block if a number of the neighbouring coding blocks determined to one of use intra-block copy prediction mode and palette mode is greater than or equal to a predetermined threshold. Alternatively the method generates the prediction values for the edge samples of the decoded block from intra-prediction reference samples of the neighbouring coding blocks by applying a filter, preferably an intra-boundary filter, to reference samples of the neighbouring blocks. The current block is then decoded based on the prediction values.

Abstract: A method of generating intra-predicted samples for a chroma channel of a video bitstream configured for a 4:2:2 chroma format. An intra-prediction angle is determined from an intra-prediction mode for the chroma channel, the intra-prediction mode being one of a plurality of horizontal intra-prediction modes. The intra-prediction angle due to the 4:2:2 chroma format is adjusted. A change threshold between the horizontal intra-prediction modes and vertical intra-prediction modes is modified if the adjusted angle exceeds a predetermined value, the modified change threshold being configured for converting the adjusted intra-prediction angle from one of the plurality of horizontal intra-prediction modes to a vertical intra-prediction mode. Intra-predicted samples are generated using a vertical intra-prediction mode according to the adjusted intra-prediction angle, and the change threshold.

Abstract: Disclosed is a method of decoding (712, 715, 718) sample adaptive offset type index data (242, sao_type_idx) from a received stream of encoded video data (113). The method determines an arithmetically encoded first portion (501;591) of a sample adaptive offset type index value (500, 590) from the stream of video data, and a bypass encoded second portion (502; 592) of the sample adaptive offset type index value when the first portion indicates that the second portion will be present in the stream of video data. The method decodes (7100, 7700, 7800; 7300, 7940, 7960) the sample adaptive offset type index from a combination of the decoded first and second portions of the sample adaptive offset type index values. The sample adaptive offset type index data is used to select one of a plurality of offsets in digital video decoding. Corresponding methods of encoding are also disclosed.

Abstract: A method of copying a block of samples of a video bitstream, is disclosed. A plurality of adaptation parameters is read from a local memory store. Each adaptation parameter corresponds to a component of a multi-dimensional vector in the video bitstream. Each of the components of the vector is decoded from the video bitstream using the corresponding adaptation parameter. The block of samples is copied from the video bitstream. The spatial location of the block of samples is identified using the decoded components of the vector.

Abstract: Disclosed is a method of decoding a luma transform and plurality of chroma transforms from a video bitstream. The chroma transforms contain chroma data for a single colour channel. The method determines a value of a luma transform skip flag for the luma transform indicating whether data of the luma transform is encoded in the video bitstream as a spatial domain representation. A value of a chroma transform skip flag is determined for a first chroma transform of the plurality of chroma transforms indicating whether the data of the chroma transform is encoded in the video bitstream as a spatial domain representation. The method decodes the luma transform according to the determined luma transform skip flag and the plurality of chroma transforms according to the determined chroma transform skip flag for the first chroma transform.

Abstract: A method of decoding a coding unit from a video bitstream determines reconstructed samples for a first coding unit, from the video bitstream, and decodes a dictionary store flag from the video bitstream for the first coding unit. Where the dictionary store flag indicates that reconstructed samples for the first coding unit be stored, the method (i) stores the reconstructed samples for the first coding unit into a memory buffer; (ii) determines reconstructed samples for a second coding unit, the reconstructed samples for the second coding unit being copied from reconstructed samples for the first coding unit from the memory buffer, and (iii) outputs the reconstructed samples for the second coding unit. Also disclosed is a complementary method for encoding, a decoder and an encoder.

Abstract: Disclosed is method of decoding, from a video bitstream, a transform unit containing at least one chroma residual coefficient array associated with a single chroma channel. The method determines a size of the transform unit related to a hierarchical level of the transform unit in a corresponding coding unit, and identifies a maximum number of inverse transforms according to the determined size. The method decodes from the video bitstream the at least one chroma residual coefficient array using the identified maximum number of transforms, selects an inverse transform for the decoded chroma residual coefficient arrays, the inverse transform being selected from a predetermined set of inverse transforms, and applies the selected inverse transform to each of the chroma residual coefficient arrays to decode chroma residual samples for the chroma channel of the transform unit. A similar encoding method is also disclosed.

Abstract: A method of decoding a bit-stream of encoded video data in a video decoder is disclosed. The method determines if the bit-stream of encoded video data has extended precision processing enabled and has a bit-depth greater than nine bits, when a profile of the bit-stream of the encoded video data is determined to be unsupported by the video decoder. The bit-stream of the encoded video data is decoded to determine decoded video data, using a profile supported by the video decoder, if the bit stream has extended precision processing enabled and a bit depth greater than nine (9) bits. The decoded video data has differences to the video data encoded in the bit-stream due to the unsupported profile being different to the supported profile.

Abstract: Disclosed is a method of decoding residual coefficients of a transform unit from a bitstream of video data. The method receives the transform unit (1500) from the bitstream of video data in which the transform unit has upper (1503) and lower (1502) level square layers. The upper level layer represents a square arrangement of at most four significant coefficient group flags with each of the significant coefficient group flags representing a non-overlapping region of the lower level layer. The method determines determining the significant coefficient group flags of the square upper level layer for the received transform unit, and determines values of residual coefficients of the square lower layer according to the determined significant coefficient group flags to decode the transform unit of the bitstream of video data. Corresponding encoding methods are also disclosed.

Abstract: Disclosed is a method of decoding a plurality of coding units from a bitstream of video data. The method determines a coding unit structure of the plurality of coding units from a first data block of the bitstream. The coding unit structure describes a division of a coding unit into the plurality of coding units. The method decodes, according to the determined coding unit structure, bypass encoded data for the plurality of coding units from a second data block of the bitstream. The method decodes, according to the determined coding unit structure, residual data for the plurality of coding units from a third data block of the bitstream. The method then forms the plurality of coding units from the bitstream using the residual data and the bypass encoded data. A method of encoding is also disclosed.