25. The video coding device of claim 15 , wherein the retained coefficient block comprises a rectangular area, wherein the processor is configured to: when a width of the rectangular area is less than or equal to a height of the rectangular area, apply a row transform to the first transform unit having the first size before applying a column transform to the first transform unit; and when the width of the rectangular area is greater than the height of the rectangular area, apply a column transform to the first transform unit having the first size before applying a row transform to the first transform unit.
26. The video coding device of claim 25 , wherein the processor is configured to select the rectangular area of the retained coefficient block within the first transform unit having the first size based on at least one of an intra-coding mode, a scan pattern, and a position of the last significant coefficient for the retained coefficient block.