Extended reference intra-picture prediction

A video decoding apparatus comprising:

• a processor;
• and
• a memory storing instructions that, when executed by the processor, cause the processor to:
• decode, by block based intra-picture predictive decoding, pictures coded in coding data to generate a video;
• generate a plurality of reference samples for a prediction block of a picture, using a plurality of nearest reference samples of the picture directly neighboring the prediction block and a plurality of extended reference samples, with each extended reference sample of the plurality of extended reference samples separated from the prediction block at least by one nearest reference sample of the plurality of nearest reference samples;
• and
• boundary filtering in a mode where no extended samples are used, wherein boundary filtering is not used in a mode where extended samples are used;
• decode, by block based intra-picture predictive decoding, pictures coded in coding data to generate a video, wherein the block based intra-picture predictive decoding of the prediction block uses the extended samples and the boundary-filtered nearest reference samples.

A method of video decoding comprising:

• generating a plurality of extended reference samples for a prediction block of a picture, with each extended reference sample of the plurality of extended reference samples separated from the prediction block at least by one nearest reference sample directly neighboring the prediction block by:
• sequentially determining an availability or unavailability of each of the plurality of extended reference samples;
• and
• substituting a substitute sample for an extended reference sample determined as unavailable;
• generating one or more extended reference samples in a reference area, wherein a position of each of the one or more extended reference samples in the reference area exceeds positions of extended reference samples from the plurality of extended reference samples along a first image direction or a second image direction, by copying a closest extended reference sample of the plurality of extended reference samples;
• and
• decoding, by block based intra-picture predictive decoding, pictures coded in coding data to generate a video, wherein the block based intra-picture predictive decoding of the prediction block uses the plurality of extended reference samples and the one or more extended reference samples in the reference area.

A non-transitory processor-readable medium storing a program, which when executed by a computer causes the computer to execute an image processing method, the method comprising:

• generating a plurality of extended reference samples for a prediction block of a picture, with each extended reference sample of the plurality of extended reference samples separated from the prediction block at least by one nearest reference sample directly neighboring the prediction block by:
• sequentially determining an availability or unavailability of each of the plurality of extended reference samples;
• and
• substituting a substitute sample for an extended reference sample determined as unavailable;
• generating one or more extended reference samples in a reference area, wherein a position of each of the one or more extended reference samples in the reference area exceeds positions of extended reference samples from the plurality of extended reference samples along a first image direction or a second image direction, by copying a closest extended reference sample;
• and
• decoding, by block based intra-picture predictive decoding, pictures coded in coding data to generate a video, wherein the block based intra-picture predictive decoding of the prediction block uses the plurality of extended reference samples and the one or more extended reference samples in the reference area.

A video decoding apparatus comprising:

• a processor;
• and
• a memory storing instructions that, when executed by the processor, cause the processor to:
• generate a plurality of extended reference samples for a prediction block of a picture, with each extended reference sample of the plurality of extended reference samples separated from the prediction block at least by one nearest reference sample directly neighboring the prediction block;
• sequentially determine an availability or unavailability of each of the plurality of extended reference samples according to a sequence;
• determine a substitution sample for an extended reference sample determined as unavailable based on a combination of:
• a copy of a last extended reference sample determined as available in the sequence, wherein the last extended reference sample is arranged in the sequence prior to the reference sample determined as unavailable;
• and
• a copy of a next extended reference sample determined as available in the sequence, wherein the next extended reference sample is arranged in the sequence after the reference sample determined as unavailable;
• substitute the substitute sample for the extended reference sample determined as unavailable;
• and
• decode, by block based intra-picture predictive decoding, pictures coded in coding data to generate a video, wherein the block based intra-picture predictive decoding of the prediction block uses the substitute sample.

A method of video decoding comprising:

• generating a plurality of extended reference samples for a prediction block of a picture, with each extended reference sample of the plurality of extended reference samples separated from the prediction block at least by one nearest reference sample directly neighboring the prediction block;
• sequentially determining an availability or unavailability of each of the plurality of extended reference samples according to a sequence;
• substituting a substitute sample for an extended reference sample determined as unavailable;
• determining a substitution sample for an extended reference sample determined as unavailable based on a combination of:
• a copy of a last extended reference sample determined as available in the sequence, wherein the last extended reference sample is arranged in the sequence prior to the reference sample determined as unavailable;
• and
• a copy of a next extended reference sample determined as available in the sequence, wherein the next extended reference sample is arranged in the sequence after the reference sample determined as unavailable;
• and
• decoding, by block based intra-picture predictive decoding, pictures coded in coding data to generate a video, wherein the block based intra-picture predictive decoding of the prediction block uses the substitute sample.