Image analysis – Image compression or coding – Shape – icon – or feature-based compression
Reexamination Certificate
1999-09-16
2002-12-31
Johnson, Timothy M. (Department: 2623)
Image analysis
Image compression or coding
Shape, icon, or feature-based compression
C382S240000
Reexamination Certificate
active
06501861
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to scalable coding/decoding methods and apparatus used in a still image encoder using wavelet transformation.
2. Description of the Related Art
In a conventional shape information coding method used in a still image encoder using wavelet transformation, pixel information of shapes of all layers output in a process of dividing wavelet must be encoded. In this case, when a scalable coding method is used, the number of pixels to be coded remarkably increases compared with the case where the entire shape information is directly encoded. Accordingly, the efficiency of coding decreases. Also, a system becomes more complicated as the number of pixels to be coded increases. When the size of an input image is large, this effect becomes more pronounced. Accordingly, it takes a long time to restore an overall image.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a still image scalable coding method and an apparatus for dividing a still image into blocks, classifying the divided blocks according to the possibility of using exclusive OR information of each pixel, and encoding the blocks according to classified encoding modes so that arbitrary shape information can be efficiently encoded by a wavelet-based still image encoder.
It is another object of the present invention to provide a decoding method and apparatus corresponding to the wavelet-based still image scalable coding method and apparatus.
It is still another object of the present invention to provide still image coding and decoding methods of dividing an input image having an arbitrary shape into tiles and independently restoring a part of an image desired by a user without a large amount of calculation, from compressed data.
Accordingly, to achieve the first object, there is provided a method of scalably encoding shape information on a still image using a wavelet transformation, comprising the steps of wavelet transforming and scalably encoding shape information on a luminance (Y) component, wavelet encoding texture information on the luminance (Y) component using the shape information on the wavelet transformed luminance (Y) component, padding shape information and texture information on a chrominance (UV) component using the shape information on the luminance (Y) component and texture information on the chrominance (UV) component, wavelet transforming and scalably encoding the padded shape information on the chrominance (UV) component, and wavelet encoding the texture information on the chrominance (UV) component using the shape information on the wavelet transformed chrominance (UV) component.
In a method of scalably encoding shape information on a still image using a wavelet transformation according to the present invention, the steps of scalably encoding the shape information on the luminance (Y) component and scalably encoding the padded shape information on the chrominance (UV) component each comprises the steps of obtaining respective layers by shape adaptive discrete transforming input shape information, encoding the low frequency bandwidth shape information of the lowest shape layer, scalably encoding the low frequency bandwidth shape information of each layer using the low frequency bandwidth shape information of lower layer with respect to each of the shape layers excluding the lowest shape layer, and transmitting the encoded shape information from the lowest layer to uppermost layer.
In a method of scalably encoding shape information on a still image using a wavelet transformation according to the present invention, the step of scalably encoding the low frequency bandwidth shape information of each layer comprises the steps of dividing the low frequency bandwidth shape information of the current layer and the low frequency bandwidth shape information of lower layers into blocks, bordering the respective blocks in the shape information, and determining the encoding mode, performing arithmetic coding on the determined encoding mode, and encoding the bordered block according to the determined encoding modes, with respect to each of the bordered blocks.
In a method of scalably encoding shape information on a still image using a wavelet transformation according to the present invention, when a 1×1 pixel value P
L
of a binary alpha block (BAB) f
1
(i, j) of a lower layer corresponds to 2×2 pixel values P
0
, P
1
, P
2
, and P
3
of a BAB f
2
(i, j) of the current layer, the encoding mode is determined to be an interleaved scan line (ISL) mode when all of the following conditions are satisfied with respect to all pixels in the BAB of the lower layers, and the encoding mode is determined to be a raster scan line (RSL) mode when any of the following conditions are not all satisfied.
ondition1=(
f
2
(2
i,
2
j
)
==f
1
(
i, j
))
ondition2=!(!(
f
2
(2
i,
2
j
)
⊕f
2
(2
i+
2, 2
j
)&&(
f
2
(2
i+
1, 2
j
)!=
f
2
(2
i,
2
j
))
ondition3=!(!(
f
2
(2
i,
2
j
)
⊕f
2
(2
i,
2
j+
2)&&(
f
2
(2
i,
2
j+
1)!=
f
2
(2
i,
2
j
))
ondition4=!(!(
f
2
(2
i+
1, 2
j
)
⊕f
2
(2
i+
1, 2
j+
2)&&(
f
2
(2
i+
1, 2
j+
1)!=
f
2
(2
i+
1, 2
j
)
In a method of scalably encoding shape information on a still image using a wavelet transformation according to the present invention, when the encoding mode is the ISL encoding mode, with respect to each pixel of the block, the step of encoding each bordered block comprises the steps of not encoding P
0
when the pixel value to be encoded is P
0
, calculating context information showing the arrangement of pixels of the current layer around the pixel to be encoded and a probability value for performing arithmetic coding on the pixel to be encoded only when left and right pixel values of the pixel value to be encoded are different from each other and performing the arithmetic encoding on P
1
when the pixel value to be encoded is P
1
, and calculating the context information showing the arrangement of pixels of the current layer around the pixel to be encoded and the probability value for performing the arithmetic coding on the pixel to be encoded only when the pixel values above and below the pixel value to be encoded are different from each other and performing the arithmetic coding on P
2
or P
3
when the pixel value to be encoded is P2 or P
3
.
In a method of scalably encoding shape information on a still image using a wavelet transformation according to the present invention, when the encoding mode is the RSL mode with respect to each pixel of the block, the step of encoding each bordered block comprises the steps of not encoding P
0
when the pixel value to be encoded is P
0
and the corresponding P
L
is 0, calculating the context information showing the arrangement of pixels of the current layer and lower layers around the pixel to be encoded and the probability value for performing the arithmetic coding on the pixel to be encoded and performing the arithmetic coding on P
0
when the pixel value to be encoded is P
0
and the corresponding pixel value P
L
is not 0, and calculating the context information showing the arrangement of the pixels of the current layer and the lower layers around the pixel to be encoded and the probability value for performing the arithmetic coding on the pixel to be encoded and performing the arithmetic coding on P
1
, P
2
, or P
3
when the pixel value to be encoded is P
1
, P
2
, or P
3
.
There is provided a method of scalably encoding shape information on a still image using a wavelet transformation, comprising the steps of wavelet transforming the shape information on the luminance (Y) component by an even symmetry wavelet filter and scalably encoding the shape information on the luminance (Y) component, wavelet encoding the texture information on the luminance (Y) component using the shape information on the wavelet transformed luminance (Y) component, and wavelet encoding the textu
Cho Dae-sung
Shin Jae-seob
Son Se-hoon
Burns Doane , Swecker, Mathis LLP
Johnson Timothy M.
Samsung Electronics Co,. Ltd.
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