A method for processing a block of transform coefficients during intra coding includes receiving an N×M block of transform coefficients, wherein N is a row width of the block and M is a column height of the block. A first scan coding pattern is determined from a set of scan coding patterns comprising a diagonal scan coding pattern, a horizontal scan coding pattern, and a vertical scan coding pattern. The method further includes partitioning the N×M block into a plurality of sub-blocks each comprising a plurality of the transform coefficients; and processing the plurality of sub-blocks, one at a time, in a coding order along the first scan coding pattern to generate a bit sequence. The processing further comprises, for the sub-blocks containing at least one non-zero transform coefficient, coding at least the non-zero transform coefficients in a transform coefficient sequence along a second scan coding pattern.