Zig-Zag Scanning Patterns
The zig-zag scanning pattern for run-length coding of the quantized DCT coefficients was established in the original MPEG standard. The same pattern is used for luminance and for chrominance. A modified (alternate) pattern more suitable for coding of some interlaced picture blocks was added in the MPEG-2 standard. A bit in the picture layer header, if set, selects the alternate scan.
The patterns are represented below, in which the upper left corner is the DC term.
zig-zag scan order:
0 1 5 6 14 15 27 28
2 4 7 13 16 26 29 42
3 8 12 17 25 30 41 43
9 11 18 24 31 40 44 53
10 19 23 32 39 45 52 54
20 22 33 38 46 51 55 60
21 34 37 47 50 56 59 61
35 36 48 49 57 58 62 63
alternate scan order:
0 4 6 20 22 36 38 52
1 5 7 21 23 37 39 53
2 8 19 24 34 40 50 54
3 9 18 25 35 41 51 55
10 17 26 30 42 46 56 60
11 16 27 31 43 47 57 61
12 15 28 32 44 48 58 62
13 14 29 33 45 49 59 63
Zig-Zag Scanning Patterns