Deblocking filter for sub-partition boundaries caused by intra sub-partition coding tool

A device for use in an image encoder or an image decoder, for deblocking sub-partitions boundary within a coding block, wherein a current coding block is coded in an intra prediction mode and the current coding block is partitioned into sub-partitions comprising a first sub-partition and a second sub-partition which is adjacent to the first sub-partition;

• wherein the device comprises a de-blocking filter configured to:
• determine one or more of a first maximum filter length to be 1 for the first sub-partition or a second maximum filter length to be 1 for the second sub-partition when a width of the first sub-partition is 4 samples or a width of the second sub-partition is 4 samples, or when a height of the first sub-partition is 4 samples or a height of the second sub-partition is 4 samples;
• and
• perform one or more of:
• modifying, based at least in part upon the first maximum filter length, a value of up to one sample of the first sub-partition, wherein the up to one sample is obtained from a row or a column of the first sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition;
• or
• modifying, based at least in part upon the second maximum filter length, a value of up to one sample of the second sub-partition, wherein the up to one sample is obtained from a row or a column of the second sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition.

A non-transitory computer-readable medium carrying a program code which, when executed by a computing device, causes the computing device to perform operations for deblocking a sub-partitions boundary within an current coding block in image encoding or image decoding, wherein the current coding block is coded in an intra prediction mode and the current coding block is partitioned into sub-partitions comprising a first sub-partition and a second sub-partition which is adjacent to the first sub-partition;

• wherein the operations comprise:
• determining one or more of a first maximum filter length to be 1 for the first sub-partition or a second maximum filter length to be 1 for the second sub-partition when a width of the first sub-partition is 4 samples or a width of the second sub-partition is 4 samples, or when a height of the first sub-partition is 4 samples or a height of the second sub-partition is 4 samples;
• and
• performing one or more of:
• modifying, based at least in part upon the first maximum filter length, a value of up to one sample of the first sub-partition, wherein the up to one sample is obtained from a row or a column of the first sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition;
• or
• modifying, based at least in part upon the second maximum filter length, a value of up to one sample of the second sub-partition, wherein the up to one sample is obtained from a row or a column of the second sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition.

A device, comprising:

• one or more processors;
• and
• a non-transitory computer-readable storage medium coupled to the one or more processors and storing programming for execution by the one or more processors, wherein the programming, when executed by the processors, configures the device to carry out operations for deblocking a sub-partitions boundary within an current coding block in image encoding or image decoding, wherein the current coding block is coded in an intra prediction mode and the current coding block is partitioned into sub-partitions comprising a first sub-partition and a second sub-partition which is adjacent to the first sub-partition;
• wherein the operations comprises:
• determining one or more of a first maximum filter length to be 1 for the first sub-partition or a second maximum filter length to be 1 for the second sub-partition, when a width of the first sub-partition is 4 samples or a width of the second sub-partition is 4 samples, or when a height of the first sub-partition is 4 samples or a height of the second sub-partition is 4 samples;
• and
• performing one or more of:
• modifying, based at least in part upon the first maximum filter length, a value of up to one sample of the first sub-partition, wherein the up to one sample is obtained from a row or a column of the first sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition;
• or
• modifying, based at least in part upon the second maximum filter length, a value of up to one sample of the second sub-partition, wherein the up to one sample is obtained from a row or a column of the second sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition.