Method and device for processing video signal

A method for encoding a video signal, the method comprising:

• applying a transform to a transform unit corresponding to one of subblocks split from a coding unit;
• and
• encoding 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.

A non-transitory computer-readable medium storing picture information generated by performing the steps of:

• applying a transform to a transform unit corresponding to one of subblocks split from a coding unit;
• and
• encoding 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.