Method and device for processing video signal

An encoding apparatus for image encoding, the encoding apparatus comprising:

• a memory;
• and
• at least one processor connected to the memory, the at least one processor configured to:
• apply a transform to a transform unit corresponding to one of subblocks split from a coding unit;
• and
• encode information related to the transform,
• wherein the information related to the transform includes a sub-block transform (SBT) flag indicating whether to apply a SBT, and position information of a last significant coefficient according to a scan order within the transform unit,
• wherein the position information of the last significant coefficient includes prefix information determined by a width variable and a height variable related to an area in which a non-zero transform coefficient is present,
• wherein, based on a first condition that (i) the SBT flag equals to 1, (ii) a width of the transform unit is a first reference value, and (iii) a height of the transform unit is less than a second reference value:
• the width variable related to the area is determined as a third reference value, and
• wherein, based on a second condition that (i) the SBT flag equals to 1, (ii) the height of the transform unit is the first reference value, and (iii) the width of the transform unit is less than the second reference value:
• the height variable related to the area is determined as the third reference value.

An apparatus for transmitting data for an image, the apparatus comprising:

• at least one processor configured to obtain a bitstream for the image, wherein the bitstream is generated based on applying a transform to a transform unit corresponding to one of subblocks split from a coding unit, and encoding information related to the transform, and
• a transmitter configured to transmit the data comprising the bitstream,
• wherein the information related to the transform includes a sub-block transform (SBT) flag indicating whether to apply a SBT, and position information of a last significant coefficient according to a scan order within the transform unit,
• wherein the position information of the last significant coefficient includes prefix information determined by a width variable and a height variable related to an area in which a non-zero transform coefficient is present,
• wherein, based on a first condition that (i) the SBT flag equals to 1, (ii) a width of the transform unit is a first reference value, and (iii) a height of the transform unit is less than a second reference value:
• the width variable related to the area is determined as a third reference value, and
• wherein, based on a second condition that (i) the SBT flag equals to 1, (ii) the height of the transform unit is the first reference value, and (iii) the width of the transform unit is less than the second reference value:
• the height variable related to the area is determined as the third reference value.