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Transkript

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US 20140198848A1
(19) United States
(12) Patent Application Publication (10) Pub. N0.: US 2014/0198848 A1
Yie et a].
(54)
(43) Pub. Date:
IMAGE ENCODING/DECODING METHOD
FOR RATE-DISTORTION OPTIMIZATION
AND DEVICE FOR PERFORMING SAME
H04N 19/122
H04N 19/61
H04N19/186
Sung Kim, Anyang (KR); J00n Seong
Park, Yongin (KR)
_
CPC
H04N19/0003 (2013.01); H04N19/00696
19/00533 (2013.01); H04N 19/00812
14/239,119
(2013.01);H04N19/00781(2013.01);H04N
_
19/00315 (2013.01); H04N19/00303
(22) PCT Flled'
seP' 3’ 2012
(86)
PCT/KR2012/007051
PCT NO;
(2013.01); H04N19/00084 (2013.01)
USPC ............................... .. 375/240.13; 375/240.16
§ 371 (c)(1),
(57)
2 4 Dt:
( )’ ( ) a e
Fb.14 2014
e
’
distortion optimization and a device for performing the same.
(KR) ...................... .. 10-2011-0089163
provided macroblock, and the residual prediction block is
transformed by applying one of a plurality of predetermined
transform matrices to the generated residual prediction block.
Accordingly, rate-distortion can be optimized, and image
quality can be enhanced.
(2006.01)
(2006.01)
(2006.01)
encoding
controller
coding
Unit
A macroblock to be encoded is provided, a prediction mac
roblock is generated by executing either inter Prediction 0r
intra prediction, a residual prediction block is generated on
the basis of the generated prediction macroblock and the
Publication Classi?cation
Int. Cl.
H04N 19/107
H04N 19/593
H04N 19/44
ABSTRACT
Disclosed are an image encoding/decoding method for rate
Foreign Application Priority Data
Sep. 2, 2011
(51)
(2006,01)
(201301); H04N19/00763 (201301); H04N
_
(21) Appl~ NO"
(30)
(2006,01)
H04N19/625
(52) us. Cl.
(73) Ass1gnee: HumaX C0., Ltd., Seongnam-sl (KR)
.
(2006.01)
(2006.01)
(2006.01)
(2006.01)
H04N 19/182
H04N19/51
(75) Inventors: Chung Ku Yie, lncheon (KR); Min
_
Jul. 17, 2014
N101
.
109
A transforming
\J.
unit
1??»
i
010000
quantizing
unit
i
111
i
113
125
predicting unit
105
100M“
motion
compensating —\
unit
l \—
intra
predicting unit
\107 119 117
\3
buffer
(J
\l21
inverse~
transforming
unit
entropy
encoding unit
115
inverse—
quantizing <—
unit
bit
stream
Patent Application Publication
Jul. 17, 2014 Sheet 1 0f4
i
US 2014/0198848 A1
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Jul. 17, 2014 Sheet 2 0f 4
US 2014/0198848 A1
FIG. 2
( START )
input coding unit
N201
inter prediction?
ll
perform motion prediction ~205
perform intra
prediction to generate ~209
prediction block
l
perform motion
compensation to
~207
generate prediction block
generate residual prediction block
l
transform residual prediction block by
using transform matrix having the best
encoding efficiency among predetermined x213
plural transform matrices for each
residual prediction block
quantization
N215
i
entropy encoding
l
END
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US 2014/0198848 A1
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Jul. 17, 2014 Sheet 4 0f4
US 2014/0198848 A1
FIG. 4
( START i
input bit stream
"\1401
perform entropy decoding (residual
prediction block, motion vector, transform
matrix, intra prediction mode)
N403
inverse—quantize entropy—decod ed
x405
residual value
perform inverse-transform using
extracted transform matrix to restore
N407
residual prediction block
motion
Yes
No
compensation?
l
perform motion
compensation to generate
prediction block
perform intra
prediction to generate
prediction block
add residual prediction block and
prediction block to restore original block N415
END
Jul. 17, 2014
US 2014/0198848 A1
[0010]
Further, another object of the present invention is to
IMAGE ENCODING/DECODING METHOD
FOR RATE-DISTORTION OPTIMIZATION
AND DEVICE FOR PERFORMING SAME
provide an image encoding apparatus and decoding apparatus
TECHNICAL FIELD
Technical Solution
[0001] The present invention relates to encoding and
decoding images, and more speci?cally, to an image encod
ing/decoding method for rate-distortion optimization and an
apparatus of performing the same.
[0011] To achieve the above-described objects of the
present invention, according to an aspect of the present inven
BACKGROUND ART
unit, generating a residual prediction block based on the
[0002] In general, an image compression method performs
encoding by separating one picture into a plurality of blocks
each having a predetermined size. Further, the inter predic
forming the generated residual prediction block by applying
of performing the above-described transform method.
tion, an image encoding method comprises receiving a coding
unit to be encoded, generating a prediction block by perform
ing one of inter prediction and intra prediction on the coding
generated prediction block and the coding unit, and trans
tion and intra prediction technology is used to remove redun
dancy of a plurality of pictures so as to raise compression
e?iciency.
[0003] A method of encoding images using inter prediction
compresses images by eliminating temporal redundancy
a plurality of predetermined transform matrices to the
residual prediction block.
[0012] To achieve the above-described objects of the
present invention, according to an aspect of the present inven
tion, an image decoding method of decoding an encoded bit
stream by applying a transform matrix having the best encod
ing ef?ciency of a plurality of predetermined transform matri
between pictures, and its representative example is the motion
ces to a residual prediction block comprises extracting at least
compensation prediction encoding method.
one information of a motion vector, a quantized residual
[0004] The motion compensation prediction encoding gen
prediction block, a motion vector, an intra prediction mode,
and a transform matrix by entropy-decoding the bit stream,
erates a motion vector (MV) by searching a region similar to
a block that is currently encoded in at least one reference
inverse-quantizing the quantized residual prediction block,
picture positioned before and/or behind a picture that is cur
rently encoded, performs DCT on a residual value between
the current block and a prediction block obtained by conduct
restoring the residual prediction block by inverse-transform
ing motion compensation using the generated motion vector,
prediction block, generating a prediction block by perform
quantizes and entropy encodes the DCTed value and trans
mits the resultant value.
[0005] In general, blocks having various sizes such as
16x16, 8x16, and 8x8 pixels are used for motion compensa
tion prediction, and a block having a size of 8x8 or 4x4 pixels
is used for transform and quantization.
[0006] The intra prediction is a method of compressing
images by eliminating spatial redundancy using a pixel cor
relation between blocks in a picture. In the intra prediction
method, a prediction value of a current block to be encoded is
generated from encoded pixels adjacent to the current block,
and the generated prediction value and the residual value of
the pixels in the current block are subjected to compression.
In the H.264/AVC standards, the size of a block used for intra
prediction is 4x4, 8x8 or 16x16 pixels. A block having a size
of 4x4 or 8x8 pixels is subject to intra prediction using nine
intra prediction modes, and a block having a size of 16x16
ing the inverse-quantized residual prediction block by apply
ing the transform matrix to the inverse-quantized residual
ing one of motion compensation and intra prediction, and
restoring an original coding unit by adding the restored
residual prediction block and the generated prediction block.
The transform matrix may use at least one transform matrix of
DST (Discrete Sine Transform) and DCT (Discrete Cosine
Transform) on a 4x4 block whose prediction mode is an intra
prediction mode with respect to a luma signal. The transform
matrix may use a DST (Discrete Sine Transform) transform
matrix on a 4x4 block whose prediction mode is an intra
prediction mode with respect to a luma signal. The transform
matrix may use at least transform matrix of DST (Discrete
Sine Transform) and DCT (Discrete Cosine Transform) on a
4x4 block whose prediction mode is an intra prediction mode
with respect to a chroma signal. The transform matrix may
use a DST (Discrete Sine Transform) transform matrix on a
4x4 block whose prediction mode is an intra prediction mode
with respect to a chroma signal.
pixels is subject to intra prediction using four intra prediction
Advantageous Effects
modes.
[0007]
As described above, the residual value generated
[0013] According to the image encoding/ decoding method
through intra prediction undergoes transform and quantiza
and apparatus of performing the same, all of a plurality of
tion.
[0008] However, conventional transform methods do not
take the characteristics of each block into consideration, thus
predetermined transform matrices, which is determined
failing to maximize transform performance in light of rate
distortion.
DISCLOSURE
according to the size of the block to be transformed upon
transform, are applied to a residual prediction block gener
ated through inter prediction or intra prediction, and a trans
form matrix having the best encoding ef?ciency is adopted to
transform the residual prediction block, thus resulting in the
ratio-distortion being optimized and the image quality being
enhanced.
image encoding and decoding method for rate-distortion opti
[0014] Further, one of DST (Discrete Sine Transform) and
DCT (Discrete Cosine Transform) is performed only on a 4x4
block whose prediction mode is an intra prediction mode with
respect to a luma signal, and thus, complexity may be reduced
mization that may maximize transform performance.
as compared with when the transform is performed on both a
Technical Problem
[0009]
An object of the present invention is to provide an
Jul. 17, 2014
US 2014/0198848 A1
4><4 block and an 8x8 block because a memory for storing
only one additional DST matrix (or DCT matrix) for the 4x4
block size is required.
[0015] Further, one of DST (Discrete Sine Transform) and
DCT (Discrete Cosine Transform) is performed only on a 4x4
block who se prediction mode is an intra prediction mode with
respect to a chroma signal, and thus, complexity may be
reduced as compared with when the transform is performed
meanings as those generally understood by one of ordinary
skill in the art. Such terms as generally de?ned in the dictio
nary should be interpreted as having meanings consistent
with those understood in the context of the related technolo
gies, and should not be construed as having excessively for
mal or ideal meanings unless clearly de?ned in the instant
application.
[0026] Hereinafter, preferred embodiments of the present
on both a 4x4 block and an 8x8 block because a memory for
invention will be described in detail with reference to the
storing only one additional DST matrix (or DCT matrix) for
the 4x4 block size is required.
entire invention, the same references are used to denote the
DESCRIPTION OF DRAWINGS
same elements throughout the drawings, and description
thereof is not repeated.
accompanying drawings. For better understanding of the
FIG. 1 is a block diagram illustrating the con?gura
[0027] A residual value generated through intra prediction
tion of an image encoding apparatus using weighted predic
goes through transform and quantization processes. In the
tion according to an example embodiment of the present
invention.
[0017] FIG. 2 is a ?owchart illustrating an image encoding
transform process, one transform matrix may be identically
applied to all the blocks, or a transform matrix predetermined
method using weighted prediction according to an example
to the blocks.
embodiment of the present invention.
[0018] FIG. 3 is a block diagram illustrating the con?gura
tional Transform) compresses energy of a prediction error
[0016]
tion of an image decoding apparatus using weighted predic
tion according to an example embodiment of the present
invention.
[0019] FIG. 4 is a ?owchart illustrating an image decoding
method using weighted prediction according to an example
embodiment of the present invention.
BEST MODE
[0020] Various modi?cations may be made to the present
invention and the present invention may have a number of
embodiments. Speci?c embodiments are described in detail
with reference to the drawings.
[0021] However, the present invention is not limited to
speci?c embodiments, and it should be understood that the
present invention includes all modi?cations, equivalents, or
replacements that are included in the spirit and technical
scope of the present invention.
[0022] The terms “?rst” and “second” may be used to
describe various components, but the components are not
limited thereto. These terms are used only to distinguish one
component from another. For example, the ?rst component
according to a selected intra prediction mode may be applied
[0028]
For example, the MDDT (Mode-Dependent Direc
block in the frequency domain using a basis vector designed
based on the KLT (Karhunen-Loeve Transform) according to
the directivity of the intra prediction method with respect to a
residual value generated after intra prediction is performed
(that is, prediction error block) in order to reduce the residual
value generated through intra prediction. The MDDT tech
nology applies transform depending on the intra prediction
mode, and thus, the characteristics of quantized transform
coef?cients generated after quantization may also have dif
ferent forms depending on the directivity, and adaptive scan
ning is adopted so as to more ef?ciently encode such coef?
cients.
[0029] In a mode-dependent transform method according
to an example embodiment of the present invention, along the
horizontal direction or vertical direction depending on the
intra prediction mode, DST (Discrete Sine Transform) and/or
DCT (Discrete Cosine Transform) can be performed on a
residual value (i.e., prediction error block) generated by per
forming intra prediction on a block having a predetermined
size (for example, a 4x4 block and/or an 8x8 block) with
respect to a luma signal.
may be also named the second component, and the second
[0030]
component may be similarly named the ?rst component. The
method according to an example embodiment of the present
term “and/or” includes a combination of a plurality of related
items as described herein or any one of the plurality of related
or DCT (Discrete Cosine Transform) on a block having a
items.
[0023] When a component is “connected” or “coupled” to
another component, the component may be directly con
nected or coupled to the other component. In contrast, when
a component is directly connected or coupled to another
component, no component intervenes.
[0024] The terms used herein are given to describe the
embodiments but not intended to limit the present invention.
A singular term includes a plural term unless otherwise
In other words, the mode-dependent transform
invention may perform DST (Discrete Sine Transform) and/
predetermined size (for example, a 4x4 block and/or an 8x8
block), whose prediction mode is an intra prediction mode,
with respect to a luma signal.
[0031] In case the size of a prediction unit is 4><4 pixels, one
of a total of 18 directions is determined as the prediction
direction, and in case the size of the prediction unit is 8x8
pixels, one of a total of 35 directions may be used as the
prediction direction. The number of prediction directions
stated. As used herein, the terms “include” or “have” are used
depending on the size of the prediction unit is not limited
thereto, and the number of prediction direction may vary
to indicate that there are features, numerals, steps, operations,
considering the spatial redundancy characteristic of images
components, parts or combinations thereof as described
so that the size of the prediction unit may be increased.
herein, but do not exclude the presence or possibility of addi
tion of one or more features, numerals, steps, operations,
components, parts or components thereof.
[0025]
Unless de?ned otherwise, all the terms including
or DCT (Discrete Cosine Transform) on a residual value (i.e.,
technical or scienti?c terms as used herein have the same
prediction error block) generated after intra prediction is per
[0032] Accordingly,
the mode-dependent transform
Jul. 17, 2014
US 2014/0198848 A1
formed on the 4x4 block along the horizontal or vertical
[0038] Alternatively, the mode-dependent transform
direction depending on 18 intra prediction modes With
respect to the luma signal.
method according to an embodiment of the present invention
[0033] For example, the mode-dependent transform
invention may perform DCT (Discrete Cosine Transform) on
a residual value (i.e., prediction error block) generated after
intra prediction is performed on the 4x4 block in case the intra
prediction mode is a vertical mode (or 0) With respect to the
luma signal along the vertical direction. Alternatively, the
mode-dependent transform method according to another
example embodiment of the present invention may perform
may perform one of DST (Discrete Sine Transform) and DCT
(Discrete Cosine Transform) only on a 4x4 block Whose
prediction mode is an intra prediction mode With respect to a
luma signal.
[0039] In the above-described mode-dependent transform
method according to example embodiments of the present
invention, transform is performed only on a 4x4 block With
respect to a luma signal. Accordingly, as compared With When
intra prediction is performed on both a 4x4 block and an 8x8
block, complexity may be reduced because a memory for
DCT along the horizontal direction on a residual value (i.e.,
storing only one additional DST matrix (or DCT matrix) With
respect to the size of the 4x4 block is required.
formed in case the intra prediction mode is the vertical mode
(or 0) on the 4x4 block With respect to the luma signal.
method according to another example embodiment of the
present invention may perform DCT along the vertical direc
tion on a residual value (i.e., prediction error block) generated
after intra prediction is performed in case the intra prediction
mode is a horizontal mode (or 1) on the 4x4 block With
[0040] The mode-dependent transform method according
to the example embodiments of the present invention has been
described With respect to the luma signal. However, the
mode-dependent transform method may be applied to a
chroma signal in the same way. This is hereinafter described
in greater detail.
to an embodiment of the present invention may perform DST
(Discrete Sine Transform) and/or DCT (Discrete Cosine
respect to the luma signal. Or, the mode-dependent transform
method according to another embodiment of the present
invention may perform DST along the horizontal direction on
intra prediction is performed in case the intra prediction mode
is the horizontal mode (or 1) on the 4x4 block With respect to
performed on a block having a predetermined sizeifor
example, a 4x4 block and/or 8x8 blOCkiWiIh respect to a
the luma signal.
according to an embodiment of the present invention may
or DCT (Discrete Cosine Transform) along the horizontal
direction or vertical direction depending on 35 intra predic
tion modes on a residual value (i.e., prediction error block)
generated after intra prediction is performed on an 8x8 block
With respect to a luma signal.
Transform) along the horizontal direction or vertical direction
depending on an intra prediction mode on a residual value
(i.e., prediction error block) generated after intra prediction is
chroma signal.
[0042]
That is, the mode-dependent transform method
perform DST (Discrete Sine Transform) and/or DCT (Dis
crete Cosine Transform) on a block having a predetermined
size (for example, a 4x4 block and/or 8x8 block) Whose
prediction mode is an intra prediction mode With respect to
the chroma signal.
to an embodiment of the present invention may perform DST
may perform DST (Discrete Sine Transform) along the ver
depending on 18 intra prediction modes on a residual value
tical direction on a residual value (i.e., prediction error block)
generated after intra prediction is performed in case the intra
prediction mode is the vertical mode (or 0) on the 8x8 block
With respect to the luma signal. Alternatively, the mode-de
pendent transform method according to another embodiment
of the present invention may perform DCT along the horizon
performed on a 4x4 block With respect to the chroma signal.
tal direction on a residual value (i.e., prediction error block)
prediction mode is the vertical mode (or 0) on a 4x4 With
With respect to the luma signal.
respect to the chroma signal. Alternatively, the mode-depen
the present invention may perform DCT along the horizontal
dent transform method according to another embodiment of
direction on a residual value (i.e., prediction error block)
invention may perform DCT along the vertical direction on a
With respect to the chroma signal.
residual value (i.e., prediction error block) generated after
the luma signal. Alternatively, the mode-dependent transform
the luma signal.
residual value (i.e., prediction error block) after intra predic
tion is performed in case the intra prediction mode is the
horizontal mode (or 1) on the 4x4 block With respect to the
chroma signal. Or the mode-dependent transform method
according to another embodiment of the present invention
Jul. 17, 2014
US 2014/0198848 A1
may perform DST along the horizontal direction on a residual
value (i.e., prediction error block) generated after intra pre
diction is perforrned in case the intra prediction mode is the
chroma signal.
or DCT (Discrete Cosine Transform) along the horizontal
direction or vertical direction depending on 35 intra predic
tion modes on a residual value (i.e., prediction error block)
generated after intra prediction is performed on the 8x8 block
?rst adder 109, a transforming unit 1 1 1, an inverse-quantizing
unit 115, an inverse-transforming unit 117, a second adder
119, a buffer 121, and an entropy encoding unit 125.
[0054]
The encoding controller 101 determines the encod
ing mode of a coding unit entered as one of an inter prediction
mode and an intra prediction mode, and based on the deter
mined encoding mode, connects one of the motion compen
sating unit 105 and the intra predicting unit 107 to the ?rst
adder 109 and the second adder 119. Further, the encoding
controller 101 provides encoding-related overhead informa
tion including a transform matrix used for transform to the
entropy encoding unit 125 and controls the operation of the
constituent elements included in the encoding apparatus.
Although in FIG. 1 the encoding controller 101 is included in
the encoding apparatus 100, the encoding controller 101 may
also be implemented not to be included in the encoding appa
ratus 100.
With respect to the chroma signal. Alternatively, the mode
dependent transform method according to another embodi
ment of the present invention may perform DCT along the
[0055] Here, the entered coding unit has a square shape,
and each coding unit (CU) may have a variable size of 2N><2N
horizontal direction on a residual value (i.e., prediction error
(unit: pixels). Inter prediction (or inter-frame prediction),
intra prediction (or intra-frame prediction), transform, quan
tization, and entropy encoding may be performed on a per
the intra prediction mode is the vertical mode (or 0) on the 8x8
block With respect to the chroma signal.
coding unit (CU) basis. The coding units (CUs) may include
a largest coding unit (LCU) and a smallest coding unit (SCU).
The size of the largest coding unit (LCU) or the smallest
coding unit (SCU) may be represented as the power of 2
Which is 8 or more. For example, the entered coding unit may
have a size of 16x16 pixels or less or may be an extended
macro block having a size of 32x32 or 64x64 pixels or more.
The extended macro block may have a size of 32x32 pixels or
more, i.e., 64x64 pixels, 128x128 pixels or more, so as to ?t
block) generated after intra prediction is performed in case
residual value (i.e., prediction error block) after intra predic
tion is performed in case the intra prediction mode is the
into a high resolution such as an HD (Ultra High De?nition)
chroma signal. Alternatively, the mode-dependent transform
or higher resolution. The extended macro block, in case it has
a high resolution such as ultra HD (High De?nition) or higher
resolution, may be limited in size to up to 64x64 pixels
the chroma signal.
may perform one of the DST (Discrete Sine Transform) and
the DCT (Discrete Cosine Transform) only on a 4x4 block
Whose prediction mode is an intra prediction mode With
respect to a chroma signal.
[0050] In the mode-dependent transform method according
to the embodiments of the present invention, intra prediction
considering the complexity of the encoder and decoder.
[0056] The coding unit (CU) may have a recursive tree
structure. The recursive tree structure may be represented
through a series of ?ags. For example, in case a coding unit
(CUk) having a level or depth of k has a ?ag value of 0, the
coding on the coding unit (CUk) is ful?lled With respect to a
current level or depth, and in case the ?ag value is l, the
coding unit (CUk) having a current level or depth of k is split
into four independent coding units (CUk+l), and the split
coding unit (CUk+l) has a level or depth of k+l, With a size
of Nk+l><Nk+l. In such case, the coding unit (CUk+l) may
be represented as a sub coding unit of the coding unit (CUk).
is performed only on a 4x4 block With respect to a chroma
The coding unit (CUk+l) may be recursively processed until
signal. Accordingly, as compared With When intra prediction
the level or depth of the coding unit (CUk+l) reaches a
is performed on both a 4x4 block and an 8x8 block, complex
ity may be reduced because a memory for storing only one
maximum permissible level or depth. In case the level or
additional DST matrix (or DCT matrix) is required With
respect to the 4x4 block size.
[0051] Hereinafter, according to an embodiment of the
present invention, the extended macro block means a block
having a size of32><32 pixels or more or a size of64><64 pixels
depth of the coding unit (CUk+ l) is the same as the maximum
permissible level or depth, no further split is allowed.
[0057]
The size of the largest coding unit (LCU) and the
size of the smallest coding unit (SCU) may be included in a
sequence parameter set (SPS). The sequence parameter set
(SPS) may include the maximum permissible level or depth
or more.
of the largest coding unit (LCU). For example, in case the
[0052] FIG. 1 is a block diagram illustrating the con?gura
tion of an image encoding apparatus according to an embodi
maximum permissible level or depth is 5, and the size of an
ment of the present invention.
types of coding unit sizes, such as 128x128 (LCU), 64x64,
32x32, 16x16, and 8x8 (SCU), may be possible. That is, ifthe
size of the largest coding unit (LCU) and the maximum per
missible level or depth are given, the permissible coding unit
[0053]
Referring to FIG. 1, the encoding apparatus 100
according to an embodiment of the present invention includes
an encoding controller 101, a motion predicting unit 103, a
motion compensating unit 105, an intra predicting unit 107, a
edge of the largest coding unit (LCU) is 128 (unit: pixels), ?ve
size may be determined.
Jul. 17, 2014
US 2014/0198848 A1
[0058] The size of the coding unit, When it comes to the
high resolution such as ultra HD (High De?nition) or higher
generating a motion vector. Here, the generated motion vector
is provided to the motion compensating unit 105 and the
resolution, may be limited to a maximum of 64x64 pixels or
entropy encoding unit 125.
[0067] The motion compensating unit 105 applies the
less considering the complexity of the encoder and decoder.
[0059] The use of the above-described recursive coding
unit structure provides the following advantages.
motion vector provided to the motion predicting unit 103 to a
is homogeneous, the largest coding unit (LCU) may display
corresponding reference picture stored in the buffer 121,
thereby generating a prediction block that has undergone
motion compensation.
[0068] The intra predicting unit 107 generates a prediction
the image region of interest With a smaller number of symbols
value of a current block from encoded pixels adjacent to the
as compared With When several small blocks are used.
entered coding unit. Here, the intra predicting unit 107 may
separate the entered coding unit into blocks each having a size
of 4x4, 8x8, or 16x16 pixels, and may generate a prediction
block from pixels adjacent to each separated block. When
performing intra prediction on blocks each having a size of
4x4 or 8x8 pixels, the intra predicting unit 107 may perform
[0060] First, a larger size than that of the existing 16x16
macro block may be provided. If an image region of interest
[0061]
Second, various sizes may be applied to the largest
coding unit (LCU) as compared With When a ?xed size of
macro block is used. Accordingly, a codec may be readily
optimized for various types of content, applications and
devices. That is, the largest coding unit (LCU) size and maxi
mum level or maximum depth may be properly chosen, so
that the hierarchical block structure may be optimized better
for a targeted application.
[0062] Third, Without being separated into the macro block,
sub-macro block, and extended macro block, a single unit,
i.e., a coding unit (LCU), is used, so that the multi-level
hierarchical structure may be represented in a very simple
manner using the largest coding unit (LCU) size, maximum
level (or maximum depth) and a series of ?ags. When used
together With a size-independent syntax representation, it
may be suf?cient to specify a syntax item having a normalized
size for the remaining coding tools, and such consistency may
simplify, e.g., the actual parsing process. The level (or maxi
mum depth) may have any maximum value, and may have a
value larger than the value permitted in the existing H.264/
AVC encoding scheme. The size-independent syntax repre
sentation may be used to specify all syntax elements in a
consistent manner independent from the size of the coding
unit (CU). The splitting process for the coding unit (CU) may
be recursively speci?ed, and other syntax elements for the
leaf coding unitilast coding unit of the levelimay be
de?ned to have the same size irrespective of the size of the
coding unit. To make a representation as described above may
be very ef?cient in reducing the parsing complexity, and in
case a large level or depth is allowed, the clarity of represen
tation may be enhanced.
[0063] If the above-described hierarchical splitting process
is complete, inter prediction or intra prediction may be per
formed on the leaf unit of the leaf coding unit layer tree With
no further split, and largest, and such leaf coding unit is used
as a prediction unit (PU) that is a basis of inter prediction or
intra prediction.
[0064] In order to perform inter prediction or intra predic
tion, partitioning is carried out on the leaf coding unit. That is,
the partitioning is ful?lled on the prediction unit (PU). Here,
the prediction unit (PU) means a basis for inter prediction or
intra prediction, and may be an existing macro block or a
sub-macro block, or may be a coding unit or an extended
macro block having a size of 32x32 pixels.
[0065] The partitioning for inter prediction or intra predic
tion may be performed by an asymmetric partitioning scheme
the intra prediction on the 4x4 or 8x8 pixel blocks using one
nine H.264/AVC intra prediction modes. The intra predicting
unit 107 may perform intra prediction on blocks each having
a size of 16x16 pixels using one of four intra prediction
modes.
[0069] Alternatively, the intra predicting unit 107 may
determine one of 18 prediction directions, When performing
intra prediction using a prediction unit having a size of 4x4
pixels, may determine one of 35 prediction directions When
performing intra prediction using a prediction unit having a
size of 8x8 pixels, may determine one of 35 prediction direc
tions When performing intra prediction on a prediction unit
having a size of 16x16 pixels, may determine one of 35
prediction directions When performing intra prediction on a
prediction unit (PU) having a size of 32x32 pixels, and may
determine one of four prediction directions When performing
intra prediction on a prediction unit (PU) having a size of
64x64 pixels. The number of prediction directions depending
on the size of the prediction unit is not limited thereto, and as
the size of the prediction unit, the number of prediction direc
tions may vary considering the spatial redundancy of the
image.
[0070] In the encoding apparatus 100 according to an
embodiment of the present invention, only one of the inter
prediction mode through the motion predicting unit 103 and
the motion compensating unit 105 and the intra prediction
mode through the intra predicting unit 107 may be carried out
under control of the encoding controller 101, and in case one
of the inter prediction mode and intra prediction mode is
selected, the encoding controller 101 sWitches a connection
path so that one of an output from the motion compensating
unit 105 and an output from the intra predicting unit 107,
Which corresponds to the selected prediction mode, may be
provided to the ?rst adder 109 and the second adder 119.
[0071] The ?rst adder 109, in case inter prediction encoding
is performed, computes the entered coding unit and the pre
diction block provided from the motion compensating unit
105 to generate a residual value (or residual predictionblock),
and in case intra prediction encoding is performed, computes
the entered coding unit and the prediction block provided
from the intra predicting unit 107 to generate a residual value.
[0072]
The transforming unit 111 performs transform
or in a geometrical partitioning scheme that provides a shape
other than a square shape, or may be done by an along-edge
using one of a plurality of predetermined transform matrices
direction partitioning scheme.
[0066] Referring back to FIG. 1, the motion predicting unit
residual prediction blocks (i.e., residual values) provided
considering the encoding ef?ciency and size of each of
103 performs inter prediction based on a plurality of refer
ence pictures that have been completely restored and are
from the ?rst adder 109, Which are to be transformed.
stored in the buffer 121 and the entered coding unit, thereby
formed and the size of a block to be transformed is 4><4 pixels
[0073]
Speci?cally, When intra prediction encoding is per
Jul. 17, 2014
US 2014/0198848 A1
or 8x8 pixels, the transforming unit 111 applies a predeter
mined number (e.g., 9) of transform matrices all to each
transform block, and then may perform encoding using a
[0081] Accordingly, the transforming unit 111 may per
form DST (Discrete Sine Transform) and/or DCT (Discrete
Cosine Transform) along the horizontal direction or vertical
transform matrix having the best encoding e?iciency. When
direction depending on 18 intra prediction modes on a
intra prediction encoding is performed, and the size of a block
to be transformed is 16x16 pixels, the transforming unit 111
applies a predetermined number (e. g., 4) of transform matri
ces all to each transform block, and then may perform encod
ing by using a transform matrix having the best encoding
e?iciency. Here, the predetermined number of transform
matrices may be transform matrices de?ned in the MDDT
(Mode Dependent Directional Transform).
intra prediction is performed on a 4x4 block With respect to a
luma signal.
[0082] For example, the transforming unit 111 may per
form DST (Discrete Sine Transform) along the vertical direc
tion on a residual value (i .e., prediction error block) generated
mode is the vertical mode (or 0) on the 4x4 block With respect
[0074] The MDDT performs transform along an intra cod
ing-speci?c directionifor example, an intra mode used for
to the luma signal. Alternatively, the transforming unit 111
encoding (or intra coding direction). For example, in case
among nine intra modes, a horizontal direction mode is used
to perform intra coding on a 4x4 block, transform may be
diction is performed in case the intra prediction mode is the
vertical mode (or 0) on the 4x4 block With respect to the luma
performed along the horizontal direction.
[0075]
The size of the block to be transformed may be a 4x4
block, an 8x8 block, a 16x16 block or a 32x32 block.
[0076]
The block used for transform may be implemented
as a transform unit (TU), and the transform unit may have a
recursive tree structure (hierarchical structure transform). For
example, the transform unit may have a two-level tree struc
ture. For example, in case a transform unit having a level or
depth of k comes With a ?ag value of 0, transform on the
transform unit is done for the current level or depth, and in
case the ?ag value is l, a coding unit (CUk) having a current
level or depth of k is split into four independent coding units
(CUk+l), and the split coding units (CUk) each may have a
may perform DCT along the horizontal direction on a residual
signal.
[0083]
Alternatively, the transforming unit 111 may per
form DCT along the vertical direction on a residual value (i.e.,
formed in case the intra prediction mode is the horizontal
mode (or 1) on the 4x4 block With respect to the luma signal.
Alternatively, the transforming unit 111 may perform DST
along the horizontal direction on a residual value (i.e., pre
diction error block) generated after intra prediction is per
[0084] Alternatively, the transforming unit 111 may per
level or depth of k+l and may have a size of Nk+l><Nk+l.
[0077]
Alternatively, even in case inter prediction encoding
is performed and the size of a block to be transformed is
32x32 pixels or more, the transforming unit 111 may apply all
of a predetermined number of transform matrices corre
sponding to the inter prediction encoding, and then may per
form encoding using a transform matrix having the best
encoding ef?ciency.
[0078] In accordance With the mode-dependent transform
method according to an embodiment of the present invention,
the transforming unit 111 may perform DST (Discrete Sine
intra prediction is performed on an 8x8 block With respect to
the luma signal.
tion on a residual value (i .e., prediction error block) generated
to the luma signal. Alternatively, the transforming unit 111
Transform) and/or DCT (Discrete Cosine Transform) along
the horizontal direction or vertical direction depending on an
intra prediction mode on a residual value (i.e., prediction
error block) generated after intra prediction is performed on a
block having a predetermined sizeifor example, a 4x4 block
and/or 8x8 blOCkiWIIh respect to a luma signal.
[0079]
signal.
[0086]
That is, in the mode-dependent transform method
according to an embodiment of the present invention, the
transforming unit 111 may perform DST (Discrete Sine
Transform) and/or DCT (Discrete Cosine Transform) on a
block Whose prediction mode is an intra prediction mode and
Which has a predetermined sizeifor example, a 4x4 block
and/ or 8x8 blOCkiWIIh respect to the luma signal.
[0080] In case the size of the prediction unit (PU) is 4><4
pixels, one of a total of l 8 prediction directions is determined,
and in case the size of the prediction unit (PU) is 8x8 pixels,
Alternatively, the transforming unit 111 may perform DST
[0087] Alternatively, in the mode-dependent transform
one of a total of 35 prediction directions may be used. The
the transforming unit 111 may perform one of DST (Discrete
number of prediction directions depending on the size of the
prediction unit is not limited thereto, and as the size of the
on a 4x4 block Whose prediction mode is an intra prediction
prediction unit (PU) increases, the number of prediction
directions may vary considering the spatial redundancy of the
image.
Sine Transform) and DCT (Discrete Cosine Transform) only
mode With respect to the luma signal.
[0088] In case the transforming unit 111 performs the trans
form on only the 4x4 block With respect to the luma signal,
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complexity may be reduced as compared With When the trans
form is performed on both the 4x4 block and the 8x8 block
because of requiring a memory for storing only one additional
to the chroma signal. Alternatively, the transforming unit 111
DST matrix (or DCT matrix) for the 4x4 block size.
vertical mode (or 0) on the 8x8 block With respect to the
chroma signal.
to the embodiments of the present invention has been
described in relation to the luma signal, but the same method
may be likeWise performed on a chroma signal. This is here
inafter described in greater detail. The transforming unit 111
may perform DST (Discrete Sine Transform) and/or DCT
(Discrete Cosine Transform) along the horizontal direction or
mode (or 1) on the 8x8 block With respect to the chroma
[0096]
vertical direction depending on an intra prediction mode on a
signal. Alternatively, the transforming unit 111 may perform
DST along the horizontal direction on a residual value (i.e.,
intra prediction is performed on a block having a predeter
mined sizeifor example, a 4x4 block and/or 8x8 blocki
With respect to a chroma signal.
[0090]
DCT (Discrete Cosine Transform) only on a 4x4 block Whose
transforming unit 111 may perform DST (Discrete Sine
Transform) and/or DCT (Discrete Cosine Transform) on a
block Whose prediction mode is an intra prediction mode and
Which has a predetermined sizeifor example, a 4x4 block
and/or 8x8 blockiWith respect to a chroma signal.
[0091]
The transforming unit 111 may perform DST (Dis
crete Sine Transform) and/or DCT (Discrete Cosine Trans
form) along the horizontal direction or vertical direction
formed on the 8x8 block With respect to the chroma signal.
prediction mode is an intra prediction mode With respect to a
chroma signal.
[0098] In the mode-dependent transform method according
to embodiments of the present invention, the transform is
performed only on a 4x4 block With respect to the chroma
signal. Accordingly, as compared With When the transform is
performed on both the 4x4 block and 8x8 block, a memory is
depending ion 18 intra prediction modes on a residual value
required for storing only one additional DST matrix (or DCT
matrix), thus reducing complexity.
performed on a 4x4 block With respect to the chroma signal.
[0099] As described above, information of a transform
matrix used for transform among a plurality of transform
matrices is provided to the entropy encoding unit 125 and is
then entropy encoded, and is then provided to the decoding
apparatus and is used for decoding.
[0100] The quantizing unit 113 quantizes the transformed
data provided from the transforming unit 111, and provides it
to the inverse-quantizing unit 115 and the entropy encoding
unit 125.
[0101] The inverse-quantizing unit 115 inverse-quantizes
the quantized data provided from the quantizing unit 113 and
then provides it to the inverse-transforming unit 117. The
inverse-transforming unit 117 inverse-transforms the inverse
quantized data using the transform matrix information used
to the chroma signal. Alternatively, the transforming unit 111
chroma signal.
[0093]
form DCT along the vertical direction on a residual value (i .e.,
signal. Alternatively, the mode-dependent transform method
according to another embodiment of the present invention
for transform in the transforming unit 111 to thereby restore
the residual prediction block and then provides it to the sec
ond adder 119.
[0102] The second adder 119 restores the coding unit by
adding the prediction block provided from the inverse-trans
forming unit 117 to the prediction block provided from the
motion compensating unit 105 or the intra predicting unit 107
and stores it in the buffer 121.
[0103] The buffer 121 may store pictures, a set of restored
chroma signal.
coding units, and the plurality of pictures stored in the buffer
[0094] Alternatively, the transforming unit 111 may per
compensation.
the chroma signal.
121 are used as reference pictures for motion prediction and
[0104] The entropy encoding unit 125 entropy encodes the
quantized residual prediction block, the motion vector infor
mation used for inter prediction, prediction mode information
used for intra prediction, and transform matrix information
used for transform, thereby generating a bit stream.
[0105] FIG. 2 is a ?owchart illustrating an image encoding
method according to an embodiment of the present invention.
[0106]
Referring to FIG. 2, if a coding unit is input to the
encoding apparatus (step 201), the encoding apparatus selects
an intra prediction mode or an inter prediction mode (step
Jul. 17, 2014
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203). The input coding unit may have a size of 16x16 pixels
inter prediction encoding and then applies a transform matrix
or less or may be an extended macro block having a size of
having the best encoding ef?ciency to perform encoding.
[0111] The encoding apparatus may perform DST (Dis
32x32 or 64x64 pixels or more. The input coding unit may
have the above-described recursive coding unit structure.
[0107] In case inter prediction is performed, motion predic
tion is performed based on the input coding unit and the
plurality of reference pictures that have been completely
restored and are stored in the buffer, thereby generating a
motion vector (step 205). The generated motion vector is used
to perform motion compensation to generate a prediction
block corresponding to a current block (step 207).
depending on an intra prediction mode on a residual value
(i .e., prediction error block) generated after intra prediction is
performed on a block having a predetermined sizeifor
example, 4><4 block and/or 8x8 blOCkiWIIh respect to a luma
signal.
[0112] That is, the encoding apparatus may perform DST
[0108] Alternatively, in case intra prediction is performed,
the prediction value of the current block is generated from
Transform) on a block having a predetermined sizeifor
encoded pixels adjacent to the input coding unit (step 209).
Here, the intra prediction may separate the input coding unit
mode is an intra prediction mode With respect to the luma
into blocks having a size of4><4, 8x8, 16x16, 32x32, or 64x64
signal.
pixels and may generate the prediction block by applying the
intra prediction mode to pixels adjacent to each separated
[0113] In case the size of the prediction unit has a size of
4x4 pixels, one of a total of 18 prediction directions may be
determined, and in case the prediction unit has a size of 8x8
pixels, one of a total of 35 prediction directions may be used.
The number of prediction directions depending on the size of
the prediction unit is not limited thereto, and as the size of the
block. In case intra prediction is performed on a block having
a size of 4x4 or 8x8 pixels, one ofthe nine H.264/AVC intra
prediction modes may be applied to perform intra prediction,
and in case intra prediction is performed on a block having a
size of 16x16 pixels, one of four intra prediction modes may
be applied to perform intra prediction. Alternatively, in case
intra prediction is performed using a prediction unit having a
size of 4x4 pixels, one of 18 prediction directions may be
determined, in case intra prediction is performed using a
prediction unit having a size of 8x8 pixels, one of a total of 35
prediction directions may be determined, in case intra predic
tion is performed using a prediction unit having a size of
16x16 pixels, one of 35 prediction directions may be deter
mined, in case intra prediction is performed using a prediction
unit having a size of 32x32 pixels, one of 35 prediction
directions may be determined, and in case intra prediction is
performed using a prediction unit having a size of 64x64
pixels, one of four prediction directions may be determined.
The number of prediction directions depending on the size of
the prediction unit is not limited thereto, and as the size of the
prediction unit increases, the number of prediction directions
may vary considering the spatial redundancy of an image.
[0109] Thereafter, the encoding apparatus generates a
residual prediction block by computing the prediction block
generated through intra prediction or inter prediction and the
input coding unit (step 211), and then, the encoding apparatus
example, 4><4 block and/or 8x8 blockiWhose prediction
prediction unit increases, the number of prediction directions
may vary considering the spatial redundancy of an image.
[0114] Accordingly, the encoding apparatus may perform
DST (Discrete Sine Transform) and/or DCT (Discrete Cosine
performed on a 4x4 block With respect to a luma signal.
[0115] For example, the encoding apparatus may perform
DST (Discrete Sine Transform) along the vertical direction
on a residual value (i.e., prediction error block) generated
to the luma signal. Alternatively, the encoding apparatus may
perform DCT along the horizontal direction on a residual
signal.
[0116] Alternatively, the encoding apparatus may perform
DCT along the vertical direction on a residual value (i.e.,
performs transform on the generated residual prediction
block using one of a predetermined number of transform
matrices considering the size of the residual prediction block
and encoding ef?ciency (step 213). That is, in case intra
prediction is performed and the size of the transformed block
is 4><4 pixels or 8x8 pixels, a predetermined number (e.g., 9)
Alternatively, the encoding apparatus may perform DST
of transform matrices are all applied to each transform block,
and then, a transform matrix having the best encoding ef?
ciency is applied to perform encoding. In case intra prediction
encoding is performed and the size of the transformed matrix
is 16x16 pixels, a predetermined number (e.g., 4) of trans
form matrices all are applied to each transform block, and
then, a transform matrix having the best encoding ef?ciency
is applied to conduct encoding. Here, the predetermined num
performed on an 8x8 block With respect to a luma signal.
ber of transform matrices may use transform matrices de?ned
in the MDDT.
[0110]
Alternatively, in case inter prediction encoding is
performed and the size of a block to be transformed is 32x32
pixels or more, the encoding apparatus applies all of a prede
termined number of transform matrices corresponding to the
mode is the vertical mode (or 0) on an 8x8 block With respect
to a luma signal.
Jul. 17, 2014
US 2014/0198848 A1
DCT along the horizontal direction on a residual value (i.e.,
chroma signal.
DCT along the vertical direction ion a residual value (i.e.,
Alternatively, the encoding apparatus may perform DCT
signal. Alternatively, the encoding apparatus may perform
signal.
Alternatively, the encoding apparatus may perform DST
performed on an 8x8 block With respect to the chroma signal.
[0129] By way of example, the encoding apparatus may
perform DST (Discrete Sine Transform) along the vertical
one of the DST (Discrete Sine Transform) and DCT (Discrete
Cosine Transform) only on a 4x4 block Whose prediction
mode is an intra prediction mode With respect to a luma
signal.
[0122] In case the mode-dependent transform method
according to embodiments of the present invention is per
formed only on a 4x4 block With respect to a luma signal, a
memory for storing one additional DST matrix (or DCT
matrix) is required With respect to the 4x4 block size is
required as compared With When the mode-dependent trans
form method is performed on both a 4x4 block and an 8x8
block, thus reducing complexity.
With respect to the chroma signal. Alternatively, the encoding
apparatus may perform DCT along the horizontal direction
to the chroma signal.
[0123] The description has focused on the luma signal, for
example. However, the same may also apply to the chroma
signal. This is hereinafter described in greater detail. The
encoding apparatus may perform DST (Discrete Sine Trans
form) and/or DCT (Discrete Cosine Transform) along the
horizontal direction or vertical direction depending on a
mined sizeifor example, 4><4 block and/or 8x8 blockiWith
signal. Alternatively, the encoding apparatus may perform
signal.
one of DST (Discrete Sine Transform) and DCT (Discrete
Cosine Transform) only on a 4x4 block Whose prediction
[0124] That is, the encoding apparatus may perform DST
mode is an intra prediction mode With respect to a chroma
signal.
mode is an intra prediction mode With respect to the chroma
[0125] The encoding apparatus may perform DST (Dis
to embodiments of the present invention is performed only on
a 4x4 block With respect to the chroma signal. Accordingly,
complexity may be reduced as compared With When trans
because a memory for storing only one additional DST matrix
signal.
form is performed on both a 4x4 block and an 8x8 block
(or DCT matrix) is required.
[0133] Thereafter, the encoding apparatus performs quan
performed on a 4x4 block With respect to a chroma signal.
tization on the transformed data (step 215), and generates a bit
to the chroma signal. Alternatively, the encoding apparatus
stream by entropy encoding the quantized data (step 217).
Here, the entropy encoded information may include quan
tized residual prediction block, motion vector information
used for inter prediction, prediction mode information used
for intra prediction, and transform matrix information used
for transform.
[0134] As described in FIGS. 1 and 2, in the encoding
Jul. 17, 2014
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all of a plurality of predetermined transform matrices are
applied to a residual prediction block generated through inter
prediction or intra prediction, according to the size of the
With respect to the luma signal. Alternatively, the inverse
transforrning unit 305 may perform DCT along the horizontal
block to be transformed upon transform, and then, a trans
form matrix having the best encoding ef?ciency is applied to
transform the residual prediction block, thus enhancing
encoding ef?ciency.
[0135]
FIG. 3 is a block diagram illustrating the con?gura
tion of a decoding apparatus according to an embodiment of
the present invention. FIG. 3 illustrates a decoding apparatus
[0144] Alternatively, the inverse-transforming unit 305
that decodes an image encoded by the encoding apparatus
may perform DCT along the vertical direction on a residual
shown in FIG. 1.
[0136]
according to an embodiment of the present invention includes
an entropy decoding unit 301, an inverse-quantizing unit 303,
an inverse-transforming unit 305, a motion compensating
Referring to FIG. 3, the decoding apparatus 300
unit 307, an intra predicting unit 309, a buffer 311, and a third
adder 313.
[0137]
The entropy decoding unit 301 entropy-decodes the
luma signal. Alternatively, the inverse-transforming unit 305
bit stream provided from the encoding apparatus and extracts
the quantized residual prediction block, motion vector used
for inter prediction, the prediction mode information used for
intra prediction, and transform matrix used for transform.
luma signal.
[0138] The inverse-quantizing unit 303 inverse-quantizes
the quantized residual prediction block provided from the
entropy decoding unit 301, and the inverse-transforming unit
vertical direction depending on 35 intra prediction modes on
305 inverse-transforms the data provided from the inverse
a luma signal.
quantizing unit 303. Here, the inverse-transforming unit 305
restores the residual prediction block by performing inverse
[0146] For example, the inverse-transforming unit 305 may
perform a DST (Discrete Sine Transform) along the vertical
transforrn based on the transform matrix information pro
vided from the entropy decoding unit 301.
With respect to the luma signal. Alternatively, the inverse
[0139]
In the mode-dependent transform method according
to an embodiment of the present invention, the inverse-trans
forming unit 305 may perform DST (Discrete Sine Trans
form) and/ or DCT (Discrete Cosine Transform) along the
horizontal direction or vertical direction depending on an
block having a predetermined sizeifor example, 4><4 block
or 8x8 blockiWith respect to a luma signal.
[0140]
value (i.e., prediction error block) in case the intra prediction
mode is the horizontal mode (or 1) on the 8x8 block With
respect to the luma signal. Alternatively, the inverse-trans
forming unit 305 may perform DST along the horizontal
inverse-transforming unit 305 may perform DST (Discrete
Sine Transform) and/ or DCT (Discrete Cosine Transform) on
a block having a predetermined sizeifor example, 4><4 block
or 8x8 blockiWhose prediction mode is an intra prediction
mode With respect to a luma signal.
[0141] In case the prediction unit has a size of 4x4 pixels,
one of a total of 18 prediction directions may be determined,
and in case the prediction unit has a size of 8x8 pixels, one of
a total of 35 prediction directions may be used. The number of
prediction directions depending on the size of the prediction
unit is not limited thereto, and as the size of the prediction unit
increases, the number of prediction directions may vary con
sidering the spatial redundancy of an image.
[0142] Accordingly, the inverse-transforming unit 305 may
crete Cosine Transform) along the horizontal direction or
prediction mode is the horizontal mode (or 1) on the 8x8
block With respect to the luma signal.
respect to the luma signal.
[0149] As described above, in case the inverse-transform
ing unit 305 performs transform only on a 4x4 block With
respect to the luma signal, a memory for storing only one
additional DST matrix (or DCT matrix) With respect to the
4x4 block is required as compared With When inverse-trans
form is performed on both a 4x4 block and an 8x8 block, thus
reducing complexity.
[0150]
luma signal.
signal, the same may also apply to the chroma signal, and an
example thereof Will be described below. The inverse-trans
[0143]
For example, the inverse-transforming unit 305 may
Although the description has focused on the luma
forming unit 305 may perform DST (Discrete Sine Trans
Jul. 17, 2014
US 2014/0198848 A1
form) and/ or DCT (Discrete Cosine Transform) along the
305 may perform DST along the horizontal direction on a
horizontal direction or vertical direction depending on an
block having a predetermined sizeifor example, 4><4 block
or 8x8 blockiWith respect to a chroma signal.
[0151] That is, the inverse-transforming unit 305 may per
Cosine Transform) on a block having a predetermined sizei
for example, 4><4 block or 8x8 blockiWhose prediction
mode is an intra prediction mode With respect to a chroma
signal.
the chroma signal.
respect to the chroma signal.
[0159] In case the inverse-transforming unit 305 performs
transform only on a 4x4 block With respect to the chroma
[0152] Accordingly, the inverse-transforming unit 305 may
signal, a memory for storing only one additional DST matrix
crete Cosine Transform) along the horizontal direction or
as compared With When transform is performed on both a 4x4
chroma signal.
[0153]
direction on a residual value (i.e., prediction error block) in
case the intra prediction mode is the vertical mode (or 0) on
the 4x4 block With respect to the chroma signal. Alternatively,
the inverse-transforming unit 305 may perform DCT along
the horizontal direction on a residual value (i.e., prediction
error block) generated after intra prediction is performed in
case the intra prediction mode is the vertical mode (or 0) on
the 4x4 block With respect to the chroma signal.
chroma signal. Alternatively, the inverse-transforming unit
305 may perform DST along the horizontal direction on a
the chroma signal.
a chroma signal.
[0156]
With respect to the chroma signal. Alternatively, the inverse
(or DCT matrix) With respect to the 4x4 block size is required
block and an 8x8 block, thus reducing complexity.
[0160] The motion compensating unit 307 generates a pre
diction block by applying the motion vector provided from
the entropy decoding unit 301 to the reference block of the
reference picture stored in the buffer 311.
[0161] The intra predicting unit 309 generates a prediction
value of a current block from pixels adjacent to the block to be
currently subject to decoding based on the intra prediction
mode provided from the entropy decoding unit 301. Here, the
intra predicting unit 309 may separate the block that is cur
rently subject to decoding into blocks having a size of 4x4,
8x8, 16x16, 32x32, or 64x64 pixels and may generate a
prediction block from pixels adjacent to each separated block
using the intra prediction mode information.
[0162] In the decoding apparatus 300 according to an
embodiment of the present invention, only one of a prediction
block generated through the motion compensating unit 307
and a prediction block generated through the intra predicting
unit 309 may be generated based on the selection information
extracted by the entropy decoding unit 301, and only one of
the motion compensating unit 307 and the intra predicting
unit 309 may be connected With the third adder 313 through
path sWitching. That is, the decoding apparatus 300 may
perform only one of the inter prediction and intra prediction
corresponding to the encoding mode that has been ful?lled in
the encoding apparatus.
[0163] The buffer 311 stores the restored image so that the
restored image may be used as a reference picture.
[0164]
The third adder 313 adds the prediction block pro
vided from the motion compensating unit 307 or the intra
predicting unit 309 and the residual prediction block provided
from the inverse-transforming unit 305, thus restoring the
original block.
[0165] FIG. 4 is a ?owchart illustrating an image decoding
method according to an embodiment of the present invention.
[0166]
Referring to FIG. 4, When receiving an encoded bit
stream from the encoding apparatus (step 401), the decoding
apparatus extracts the quantized residual prediction block,
motion vector, transform matrix, and intra prediction mode
information by performing entropy-decoding on the bit
stream (step 403). Here, the intra prediction mode may be
extracted only When the encoding apparatus has performed
intra prediction, and the entropy-decoded data may include
encoding mode information (inter prediction or intra predic
tion).
chroma signal. Alternatively, the inverse-transforming unit
[0167] Thereafter, the decoding apparatus inverse-quan
tizes the entropy-decoded residual value (step 405) and
inverse-transforms the inverse-quantized data using the
Jul. 17, 2014
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extracted transform matrix information, thereby restoring the
residual prediction block (step 407).
[0168] The inverse-transform may perform DST (Discrete
Sine Transform) and/or DCT (Discrete Cosine Transform)
signal.
along the horizontal direction or vertical direction depending
on an intra prediction mode on a residual value (i.e., predic
tion error block) generated after intra prediction is performed
on a block having a predetermined sizeifor example, 4><4
block and/or 8x8 blockiWith respect to a luma signal.
[0176] Alternatively, the inverse-transform may perform
Alternatively, the inverse-transform may perform DST along
[0169] That is, the inverse-transform may perform DST
case the intra prediction mode is the horizontal mode (or 1) on
the 8x8 block With respect to the luma signal.
[0177] The inverse-transform may use a DST (Discrete
Sine Transform) transform matrix only on a 4x4 block Whose
prediction mode is an intra prediction mode With respect to
the luma signal. As such, in case the inverse-transform is
performed only on a 4x4 block Whose prediction mode is the
intra prediction mode With respect to the luma signal, a
memory for storing only one additional DST matrix (or DCT
matrix) With respect to the 4x4 block size is required as
compared With When inverse-transform is performed on both
a 4x4 block and an 8x8 block, thus reducing complexity.
[0178] Although the description has focused on the luma
signal, the same may also apply to the chroma signal, as the
mode is an intra prediction mode With respect to the luma
signal.
[0170] In case the prediction unit has a size of 4x4 pixels,
one of a total of 18 prediction directions may be determined,
and in case the prediction unit has a size of 8x8 pixels, one of
a total of 35 prediction directions may be used. The number of
prediction directions depending on the size of the prediction
unit is not limited thereto, and as the size of the prediction unit
increases, the number of prediction directions may vary con
sidering the spatial redundancy of an image.
[0171] Accordingly, the inverse-transform may perform
(i.e., prediction error block) on a 4x4 block With respect to a
speci?c description follows below. The inverse-transform
luma signal.
vertical direction depending on an intra prediction mode on a
[0172] For example, the inverse-transform may perform
to the luma signal. Alternatively, the inverse-transform may
mined sizeifor example, 4><4 block and/or 8x8 blockiWith
[0179] That is, the inverse-transform may perform DST
mode is an intra prediction mode With respect to the chroma
signal.
[0180] The inverse-transform may perform DST (Discrete
Sine Transform) and/or DCT (Discrete Cosine Transform)
signal.
along the horizontal direction or vertical direction depending
on 18 intra prediction modes on a residual value (i.e., predic
tion error block) generated after intra prediction is performed
Alternatively, the inverse-transform may perform DST along
case the intra prediction mode is the horizontal mode (or 1) on
the 4x4 block With respect to the luma signal.
[0174] Further, the inverse-transform may perform DST
on a 4x4 block With respect to a chroma signal.
to the chroma signal. Alternatively, the inverse-transform
performed on the 8x8 block With respect to the luma signal.
chroma signal.
to the luma signal. Alternatively, the inverse-transform may
horizontal direction on a residual value (i.e., prediction error
block) generated after intra prediction is performed in case
signal. Or the inverse-transform may perform DST along the
Jul. 17, 2014
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the intra prediction mode is the horizontal mode (or 1) on the
4x4 block With respect to the chroma signal.
Description of elements
100: encoding apparatus
103: motion predicting unit
107: intra predicting unit
101:
105:
109:
113:
117:
encoding controller
motion compensating unit
?rst adder
quantizing unit
inverse—transforming unit
111: transforming unit
1 15: inverse—quantizing unit
119: second adder
121: buffer
performed on an 8x8 block With respect to a chroma signal.
125: entropy encoding unit
301: entropy decoding unit
305: inverse—transforming unit
300: decoding apparatus
303: inverse—quantizing unit
307: motion compensating unit
309: intra predicting unit
311: buffer
to the chroma signal. Alternatively, the inverse-transform
chroma signal.
signal. Alternatively, the inverse-transform may perform
313: third adder
1. An image encoding method comprising:
receiving a coding unit to be encoded;
generating a prediction block by performing one of inter
prediction and intra prediction on the coding unit;
generating a residual prediction block based on the gener
ated prediction block and the coding unit; and
transforming the generated residual prediction block by
applying a plurality of predetermined transform matri
ces to the residual prediction block.
2. The image encoding method of claim 1, Wherein trans
residual prediction block comprises transforming the residual
prediction block by applying all of nine transform matrices to
each residual prediction block and then using a transform
matrix having the best encoding ef?ciency in a case Where the
residual prediction block that is subjected to intra prediction
signal.
and transform has a size of 4x4 or 8x8 pixels.
[0186] The inverse-transform may use a DST (Discrete
Sine Transform) and/or DCT transform matrix only on a 4x4
block Who se prediction mode is an intra prediction mode With
respect to the chroma signal.
[0187] As such, in case the inverse-transform is performed
only on a 4x4 block Whose prediction mode is an intra pre
diction mode With respect to the chroma signal, a memory for
storing only one additional DST matrix (or DCT matrix) With
respect to the 4x4 block size is required as compared With
When the inverse-transform is performed on both a 4x4 block
and an 8x8 block, thus reducing complexity.
[0188] Further, the decoding apparatus determines a decod
ing mode based on the encoding mode included in the
entropy-decoded information (step 409), and in case the
decoding mode is determined as motion compensation, per
forms motion compensation using the extracted motion vec
residual prediction block comprises transforming the residual
prediction block by applying all of four transform matrices to
each residual prediction block and then using a transform
matrix having the best encoding ef?ciency in a case Where the
residual prediction block that is subjected to intra prediction
and transform has a size of 16x16 pixels.
residual prediction block comprises performing transform
using the plurality of predetermined transform matrices along
a speci?c direction of intra prediction.
tor, thereby generating a prediction block (step 411).
[0189] Alternatively, in case the decoding mode is deter
mined as intra prediction, the decoding apparatus generates a
residual prediction block comprises performing transform
using the plurality of predetermined transform matrices along
prediction block by applying an extracted intra prediction
mode to pixels adjacent to the current block to be decoded
(step 413).
[0190] Thereafter, the decoding apparatus restores an origi
nal blockithat is, the coding unitiby adding the restored
residual prediction block With the prediction block generated
a horizontal direction upon transform When intra prediction is
performed based on a horizontal direction mode among nine
intra prediction modes in a case Where the residual prediction
block has a size of 4x4 pixels.
6. The image encoding method of claim 1, Wherein the
residual prediction block used for transform is implemented
as a transform unit (TU), and Wherein the transform unit has
in step 411 or 413 (step 415).
[0191] Although embodiments of the present invention
have been described, it may be understood by those skilled in
prediction unit is an extended macro block having a size of
the art that various modi?cations and variations may be made
32x32 pixels or more.
thereto Without departing from the spirit and scope of the
8. An image decoding method of decoding an encoded bit
stream by applying one of a plurality of predetermined trans
invention de?ned in the claims.
a recursive tree structure.
7. The image encoding method of claim 1, Wherein the
Jul. 17, 2014
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14
form matrices to a residual value generated after intra predic
tion is performed, the method comprising:
extracting at least one information of a motion vector, a
quantized residual prediction block, a motion vector, an
intra prediction mode, and a transform matrix by
entropy-decoding the bit stream;
inverse-quantizing the quantized residual prediction block;
restoring the residual prediction block by inverse-trans
forming the inverse-quantized residual prediction block
by applying the transform matrix to the inverse-quan
tized residual prediction block;
transform matrix to the inverse-quantized residual prediction
block comprises performing inverse-transform using the
transform matrix along a horizontal direction upon transform
When intra prediction is performed based on a horizontal
direction mode among nine intra prediction modes in a case
Where the residual prediction block has a size of 4x4 pixels.
13. The image decoding method of claim 8, Wherein the
residual prediction block used for transform is implemented
as a transform unit (TU), and the transform unit has a recur
sive tree structure.
generating a prediction block by performing one of motion
coding unit is an extended macro block having a size of 32x32
compensation and intra prediction; and
restoring an original coding unit by adding the restored
residual prediction block and the generated prediction
pixels or more.
block.
transform matrix uses at least one transform matrix of DST
(Discrete Sine Transform) and DCT (Discrete Cosine Trans
form) on a 4x4 block Whose prediction mode is an intra
transform matrix applies all of nine transform matrices to
prediction mode With respect to a luma signal.
each residual prediction block and uses a transform matrix
having the best encoding ef?ciency in a case Where the
residual prediction block that is subjected to the intra predic
tion and transform has a size of 4x4 or 8x8 pixels.
transform matrix applies all of four transform matrices to
each residual prediction block and uses a transform matrix
having the best encoding ef?ciency in a case Where the
residual prediction block that is subjected to the intra predic
tion and transform has a size of 16x16 pixels.
11. The image decoding method of claim 8, Wherein restor
ing the residual prediction block by inverse-transforming the
inverse-quantized residual prediction block by applying the
transform matrix to the inverse-quantized residual prediction
block comprises performing inverse-transform using the
transform matrix based on the intra prediction mode.
12. The image decoding method of claim 8, Wherein restor
ing the residual prediction block by inverse-transforming the
inverse-quantized residual prediction block by applying the
transform matrix uses a DST (Discrete Sine Transform) trans
form matrix on a 4x4 block Whose prediction mode is an intra
prediction mode With respect to a luma signal.
transform matrix uses at least transform matrix of DST (Dis
crete Sine Transform) and DCT (Discrete Cosine Transform)
on a 4x4 block Whose prediction mode is an intra prediction
mode With respect to a chroma signal.
form matrix on a 4x4 block Whose prediction mode is an intra
prediction mode With respect to a chroma signal.
form matrix only on a 4x4 block Whose prediction mode is an
intra prediction mode With respect to a luma signal.
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unit l \—

Transkript

Benzer belgeler

BER Reduction for DMT-ADSL Based on DMWT

Fast and accurate algorithm for the computation of complex linear