Deblocking filtering

A decoder comprising a processor and a memory unit, wherein the decoder is configured to:

• select two consecutive pixels, comprising a first pixel and a second pixel, from a first block and two consecutive pixels, comprising a third pixel and a fourth pixel, from a neighboring block, the blocks being located on opposite sides of a block boundary and next to the block boundary, and the first, second, third, and fourth pixels forming a line of pixels that is perpendicular to the block boundary,
• where the first pixel is located in the first block next to the block boundary and has a first pixel value p0, the second pixel is located in the first block one pixel away from the block boundary and has a second pixel value p1, the third pixel is located in the neighboring block next to the block boundary and has a third pixel value q0, and the fourth pixel is located in the neighboring block one pixel away from the block boundary and has a fourth pixel value q1;
• calculate a first offset as a function of the first pixel value p0, the second pixel value p1, the third pixel value q0, and the fourth pixel value q1;
• and
• when an absolute value of the first offset is less than a first threshold:
• modify the first pixel value p0 by adding the first offset to the first pixel value po;
• modify the third pixel value q0 by subtracting the first offset from the third pixel value q0;
• modify the second pixel value p1 based on a second offset;
• and
• modify the fourth pixel value q1 based on a third offset.

A non-transitory computer-readable medium comprising instructions which, when executed by a processor, perform:

• selecting two consecutive pixels, comprising a first pixel and a second pixel, from a first block and two consecutive pixels, comprising a third pixel and a fourth pixel, from a neighboring block, the blocks being located on opposite sides of a block boundary and next to the block boundary, and the first, second, third, and fourth pixels forming a line of pixels that is perpendicular to the block boundary,
• where the first pixel is located in the first block next to the block boundary and has a first pixel value p0, the second pixel is located in the first block one pixel away from the block boundary and has a second pixel value p1, the third pixel is located in the neighboring block next to the block boundary and has a third pixel value q0, and the fourth pixel is located in the neighboring block one pixel away from the block boundary and has a fourth pixel value q1;
• calculating a first offset as a function of the first pixel value p0, the second pixel value p1, the third pixel value q0, and the fourth pixel value q1;
• and
• when an absolute value of the first offset is less than a first threshold:
• modifying the first pixel value p0 by adding the first offset to the first pixel value p0;
• modifying the third pixel value q0 by subtracting the first offset from the third pixel value q0;
• modifying the second pixel value p1 based on a second offset;
• and
• modifying the fourth pixel value q1 based on a third offset.