Graphics Reference
In-Depth Information
x
15 13 10 6
14 11 7 3
12
900
1
6000
3100
0000
Diagonal Scan
(same direction for all)
y
8
4
1
9
5
2
0
3
last_sig_coeff_x
0
sig_coeff_flag 1* 0 1 0 0 0 1 0 1 1
coeff_abs_level_greater1_flag 0
last_sig_coeff_y
0
1
1
1
1
coeff_abs_level_greater2_flag
0
4
7
coeff_abs_level_remaining
0
1
0
1
0
coeff_sign_flag
Regular coded bins
Bypass coded bins
3
0
1
0 1
0 0 0 1 0 1 1
0 0
1
1 1 1
0
1 0 1 0
0
4
7
*inferred
Significance map
Coefficient level and sign
Fig. 8.9
4 transform block in HEVC. Note,
however, that the corresponding bins for signaling of the “last” information (in red ) and absolute
level remaining (in yellow ) are not explicitly shown
Example of transform coefficient coding for a 4
subdivision is given for a luma CB size of 64 at RQT depth equal to 0. Table 8.7
and Fig. 8.11 illustrate an example of this configuration. Therefore, even if up to
five different RQT levels are permitted, only up to three different context models
are required for coding of split_transform_flag . Note that the signaling of
split_transform_flag at the RQT root is omitted if the quantized residual
of the corresponding CU contains no non-zero transform coefficient at all, i.e., if the
corresponding coded block flag at the RQT root (see Sect. 8.6.3 ) is equal to 0.
8.6.2
Transform Skip
For regions or blocks with many sharp edges (e.g., as typically given in screen
content coding), coding gains can be achieved by skipping the transform [ 42 , 61 ].
When the transform is skipped for a given block, the prediction error in the spatial
domain is quantized and coded in the same manner as for transform coefficient
coding (i.e., the quantized block samples of the spatial error are coded as if they
were quantized transform coefficients). The so-called transform skip mode is only
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