Graphics Reference
In-Depth Information
No
≠
A
B
Yes
MPM[ 0 ] = A
MPM[ 1 ] = B
No
A
≠
INTRA_PLANAR
B
≠ INTRA_PLANAR
Yes
No
A
≠
INTRA_DC
MPM[ 2 ] = INTRA_PLANAR
B
≠ INTRA_DC
Yes
MPM[ 2 ] =
INTRA_ANGULAR[ 26 ]
MPM[ 2 ] = INTRA_DC
No
A<2(B<2)
Yes
MPM[ 0 ] = A
MPM[1]=2+((A-2-1+32)%32)
MPM[2]=2+((A-2+1)%32)
MPM[ 0 ] = INTRA_PLANAR
MPM[ 1 ] = INTRA_DC
MPM[ 2 ] = INTRA_ANGULAR[ 26 ]
Fig. 4.8
Derivation process for the three most probable modes
MPM
[0],
MPM
[1] and
MPM
[2].
A
and
B
indicate the neighboring intra modes of the left and the above PU, respectively
Tabl e 4. 4
Determination of chroma intra prediction mode according to luma intra
prediction mode
Final chroma intra mode
when derived
mode
Final chroma intra mode
when derived
mode
initial chroma
intra mode
¤
initial chroma
intra mode
D
Initial chroma intra mode
INTRA_PLANAR
INTRA_PLANAR
INTRA_ANGULAR[34]
INTRA_ANGULAR[26]
INTRA_ANGULAR[26]
INTRA_ANGULAR[34]
INTRA_ANGULAR[10]
INTRA_ANGULAR[10]
INTRA_ANGULAR[34]
INTRA_DC
INTRA_DC
INTRA_ANGULAR[34]
INTRA_DERIVED
Luma intra mode
N/A
This design is based on the finding that often structures in the chroma signal
follow those of the luma. In the case the derived mode is indicated for a chroma PU,
intra prediction is performed by using the corresponding luma PU mode. Angular
intra mode 34 is used to substitute the four chroma prediction modes with individual
identifiers when the derived mode is one of those four modes. The substitution
process is illustrated in Table
4.4
.
