Patent ID: 11943474
Assignee: LG ELECTRONICS INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 10:
11. An apparatus of transmitting data for an image, comprising:
at least one processor configured to obtain a bitstream for the image; and
a transmitter configured to transmit the data comprising the bitstream,
wherein the at least one processor is configured to:
determine an intra prediction mode of a current block;
determine a modified intra prediction mode from the intra prediction mode of the current block based on a width and a height of the current block and the intra prediction mode;
determine a secondary transform set index based on the modified intra prediction mode;
perform primary transform on a residual block of the current block to generate a primary-transformed block of the current block;
select a secondary transform matrix in a secondary transform set specified by the secondary transform set index;
perform secondary transform on the primary-transformed block based on the secondary transform matrix; and
generate a secondary transform index related to the secondary transform matrix,
wherein the at least one processor is configured to determine the modified intra prediction mode by adding 65 to the intra prediction mode, when (i) the width is larger than the height, (ii) the intra prediction mode is equal to or larger than 2, and (iii) the intra prediction mode is smaller than a first reference value,
wherein the at least one processor is configured to determine the modified intra prediction mode by subtracting 67 from the intra prediction mode, when (i) the height is larger than the width, (ii) the intra prediction mode is larger than a second reference value, and (iii) the intra prediction mode is equal to or smaller than 66, and
wherein the at least one processor is configured to determine the non-separable transform set index:
as 1 when the modified intra prediction mode is smaller than 0,
as 0 when the modified intra prediction mode is equal to or larger than 0 and equal to or smaller than 1,
as 1 when the modified intra prediction mode is equal to or larger than 2 and equal to or smaller than 12,
as 2 when the modified intra prediction mode is equal to or larger than 13 and equal to or smaller than 23,
as 3 when the modified intra prediction mode is equal to or larger than 24 and equal to or smaller than 44,
as 2 when the modified intra prediction mode is equal to or larger than 45 and equal to or smaller than 55, and
as 1 when the modified intra prediction mode is equal to or larger than 56 and equal to or smaller than 80.