1. A method of filtering in a graphics processing unit (GPU), the method comprising: receiving, by the GPU, an instruction to filter a source pixel; retrieving, by the GPU, neighboring pixels based on the instruction; packing, by the GPU, luma values of the source pixel and the retrieved neighboring pixels in an RGBA color format data structure; and performing, by the GPU, filtering on the luma values of the source pixel and the retrieved neighboring pixels using the RGBA color format data structure, wherein four luma values are filtered for each RGBA color format data structure.