You're right. I'm remembering a different codec — I think this is how H.264 orders DC coefficients for macroblocks. JPEG uses an actual 2D DCT, not a 1D DCT of

You're right. I'm remembering a different codec — I think this is how H.264 orders DC coefficients for macroblocks. JPEG uses an actual 2D DCT, not a 1D DCT of a flattened block.