KR20110011499A - Method and apparatus for encoding/decoding mode information - Google Patents

Abstract

PURPOSE: A method and an apparatus for encoding/decoding mode information are provided to encode/decode an image using a skip mode, a natural mode, and a graphic mode, thereby guaranteeing low complexity and a proper compression rate. CONSTITUTION: An image encoding apparatus determines whether to encode a current block by a skip mode(1010). When an encoding mode of the current block is not the skip mode, the image encoding apparatus determines the encoding mode of the current block(1020). The image encoding apparatus encodes the current block according to a graphic mode(1030). The image encoding apparatus encodes the current block according to a natural mode(1040). The image encoding apparatus encodes information about the used encoding mode(1050).

Description

Method and apparatus for encoding and decoding mode information {Method and apparatus for encoding / decoding mode information}

The present invention relates to a method and apparatus for encoding and decoding mode information, and more particularly, to a method and apparatus for encoding and decoding mode information of an image encoded according to a plurality of modes.

As wireless network technology advances, interconnections between devices over wireless networks become an issue. Many companies are working to secure interconnect technology between devices over wireless networks. Recently, standardization of WiHD (Wireless HD), an uncompressed HD interconnect technology that replaces high definition multimedia interface (HDMI), is being progressed. According to WiHD, TVs, home theaters, DVD players, Blu-ray players, camcorders, and many other devices are interconnected via wireless networks.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method and apparatus for encoding and decoding mode information of an image encoded according to a plurality of modes, wherein the computer-readable recording medium has recorded thereon a program for executing the method. To provide.

According to an embodiment of the present invention for solving the above technical problem, whether a current block is encoded according to the same encoding mode as a plurality of consecutive previous blocks based on information on the number of repetitions of a predetermined encoding mode. Determining; Determining that the decoding mode of the current block is the same as the decoding mode of the plurality of blocks when it is determined that the same is the same; And if it is determined that it is not the same, parsing first information indicating whether the current block is encoded according to a first mode and second information indicating which mode of the current block is encoded according to the other modes. Determining a decoding mode of a current block, wherein the first mode includes information indicating that the first block is encoded according to the first mode by being identical to a previously encoded second block adjacent to the first block. And a mode of encoding instead of the pixel value of the first block.

According to another embodiment of the present invention, parsing the first information and the second information to determine a mode to be used for decoding the current block comprises: parsing the first information; Parsing the first information, if it is determined that the current block is not encoded according to a first mode, parsing second information indicating which of the second and third modes the current block is encoded; ; And determining a decoding mode of the current block based on a decoding result of at least one of the first information and the second information.

According to another embodiment of the present invention, the second mode performs a discrete cosine transform of pixel values of the first block, and a plurality of bit planes from the most significant bit to the least significant bit of coefficients resulting from the discrete cosine It is characterized in that the mode is divided into and is encoded in a bit plane unit.

According to another embodiment of the present invention, the third mode is a mode for encoding the pixel values of the first block into bit plane units by dividing the pixel values of the most significant bit into the plurality of bit planes.

According to another embodiment of the present invention, if the same encoding mode is repeated for two consecutive blocks, the information about the number of repetitions of the predetermined encoding mode is repeated for the third and subsequent blocks having the same encoding mode. Information and information parsed in place of the second information.

According to another embodiment of the present invention, the information on the number of repetitions of the predetermined encoding mode includes at least one of the information on the number of repetitions for each of the plurality of encoding modes that can be used for encoding the current block.

According to an aspect of the present invention, there is provided a method of decoding mode information, the method comprising: determining an encoding mode of a current block; Determining whether the determined encoding mode of the current block is the same as the encoding mode of a plurality of consecutive previous blocks; If it is determined that it is the same, encoding information on the number of repetitions of the same encoding mode instead of information about the encoding mode of the current block; And if it is determined that it is not the same, encoding first information indicating whether the current block is encoded according to a first mode and second information indicating which mode of the current block is encoded according to another mode. Wherein the first mode includes information indicating that the first block is encoded according to the first mode by being identical to a previously encoded second block adjacent to the first block, instead of pixel values of the first block. It is characterized by the mode of encoding.

According to an aspect of the present invention, there is provided an apparatus for decoding mode information according to the same encoding mode as a plurality of previous blocks in which a current block is continuous based on information on the number of repetitions of a predetermined encoding mode. A run determining unit determining whether the code is encoded; And if the determination result is the same, the decoding mode of the current block is determined in the same manner as the decoding mode of the plurality of blocks. If the determination result is not the same, the current block is determined according to the first mode. And a mode determiner configured to determine a decoding mode of the current block based on first information indicating whether the current block is encoded and second information indicating which mode the current block is encoded according to among other modes. And a mode in which information indicating that one block is encoded according to the first mode is the same as a previously encoded second block adjacent to the first block, instead of the pixel value of the first block.

According to an aspect of the present invention, there is provided an apparatus for encoding mode information, comprising: a run determining unit determining whether an encoding mode of a determined current block is the same as an encoding mode of a plurality of consecutive previous blocks; A run coder for encoding information on the number of repetitions of the same encoding mode instead of information on the encoding mode of the current block, if it is determined that the determination is the same; And a first information encoder indicating whether the current block is encoded according to a first mode when it is determined that the difference is not the same. And a second information encoder for encoding second information indicating which of the other modes the current block is encoded in, wherein the first mode is a coded previously encoded signal adjacent to the first block. In the same manner as the second block, information indicating that the information is encoded according to the first mode is characterized in that the mode instead of the pixel value of the first block.

In order to solve the above technical problem, the present invention provides a computer-readable recording medium having recorded thereon a program for executing the mode information encoding method and the mode information decoding method.

Hereinafter, with reference to the drawings will be described embodiments of the present invention;

1 illustrates an image encoding apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the image encoding apparatus 100 according to an embodiment of the present invention includes a mode determiner 110, an encoder 120, and a mode information encoder 130.

The mode determiner 110 determines a mode used for encoding the current block. Techniques for effective connection of devices over a wireless network aim to transmit and receive high definition content over HD over a wireless network. However, standardization is underway to focus on low memory and low complexity to enable interconnection between various devices. Therefore, even in the encoding of video, the lowest complexity is pursued, and video encoding methods according to the prior art such as MPEG-1, MPEG-2, MPEG-4 H.264 / MPEG-4 AVC (Advanced Video coding) and Otherwise, it does not use complicated techniques to increase the compression rate.

However, transmitting without compressing pixel values of the image at all requires a high data rate wireless network, which can also be an obstacle to the interconnection between various devices. Therefore, by encoding and decoding an image using three modes of a skip mode, a natural mode, and a graphic mode, which will be described later, a low complexity and an appropriate level of compression may be guaranteed.

The skip mode is a mode for encoding a current block based on whether the current block is the same as a block adjacent to the current block. The natural mode is a discrete cosine transform (DCT) if the current block is a block for natural video. This mode encodes the current block using bit plane division. The graphic mode is a mode in which the current block is encoded using bit plane division if the current block is a block for an artificially generated image such as text. The skip mode, the natural mode and the graphic mode will be described later in detail with reference to FIGS. 3 to 5.

The mode determination unit 110 determines which mode of the plurality of modes described above is to be encoded. First, the mode determiner 110 determines whether the current block is the same as or similar to another block of a previously encoded current slice adjacent to the current block. The pixel value of the current block and the pixel value of a previously encoded block of the current slice are compared to determine whether they are the same or similar. This will be described in detail with reference to FIGS. 2 and 3.

2 illustrates an image coding unit according to an embodiment of the present invention.

Referring to FIG. 2, the image encoding apparatus 100 splits and encodes an image in a slice unit, a block unit, and a bit plane unit. The current picture 210 is divided into a plurality of slices 212 through 216. The slice may be divided into a plurality of slices 212 to 216 having a vertical length of N. Then, each slice is divided into NxN sized blocks. The block may be further divided into a plurality of bit planes from the bit plane for the most significant bit to the bit plane for the least significant bit. If the pixel value or discrete cosine coefficient of the block is expressed in M bits, it can be divided into all M bit planes.

3 is a view for explaining a method of determining a skip mode according to an embodiment of the present invention.

Referring to FIG. 3, as described above with reference to FIG. 2, the current picture 310 may be divided into a plurality of slices. A case where the image encoding apparatus 100 encodes the slice 320 shown in FIG. 3 will be described as an example.

In order to encode the current block 322 of the current slice 320, the mode determiner 110 of the image encoding apparatus 100 is the same as the previously encoded block 324 in which the current block 322 is adjacent to the current block. Determine if it is similar. The current block 322 to be encoded has a higher probability of being the same or similar to a previously encoded block that is spatially adjacent. Therefore, if the current block 322 is the same as or similar to the previously encoded block 324 adjacent to the left side, the mode determiner 110 may determine the encoding mode of the current block 322 as the skip mode. The adjacent block 324 may be a block encoded immediately before encoding of the current block.

Determination of whether the current block 322 and the adjacent block 324 are the same or similar may be performed in various ways. Cost based on the sum of absolute difference (SAD), mean square error (MSE), signal to noise ratio (SNR), and maximum difference between the current block 322 and the adjacent block 324. The calculation determines whether the current block 322 and the adjacent block 324 are the same or similar according to the calculated cost. As the SAD, MSE, and maximum difference are closer to '0', it may be determined that the current block 322 and the adjacent block 324 are the same or similar.

The mode determiner 110 may determine the encoding mode of the current block 322 as the skip mode only when the current block 322 and the adjacent block 324 are exactly the same, or even when the current block 322 is similar to the current block 322. The encoding mode of 322 may be determined as a skip mode. In other words, only when the above-described SAD, MSE, maximum difference, etc. is '0', the encoding mode of the current block 322 may be determined as the skip mode. 324 may determine that the encoding mode of the current block 322 is the skip mode.

When the mode determiner 110 determines whether the current block is the same or similar to the adjacent block, and determines that the encoding mode of the current block is not the skip mode, the mode determiner 110 again selects the current block in the natural mode and the graphic. Determine which of the modes is to be encoded. If it is determined that the current block is a natural association, that is, a block for an image that is not artificially generated, the encoding mode of the current block is determined to be a natural mode, and conversely, the current block is a block for an artificially generated image such as text or computer graphics. If it is determined to be, the encoding mode of the current block is determined as the graphics mode.

There is no limit to a criterion for determining whether the current block is encoded according to a natural mode or a graphic mode, and it may be determined whether the current block is a block for an artificially generated image using various algorithms. For example, since an artificial image has a high probability of distributing the same pixel values in a specific region, if the same pixel values are greater than or equal to a predetermined number by comparing pixel values of a current block, it may be determined that the artificial image is a block for an artificially generated image. Can be.

In addition, according to another embodiment of the present invention, after encoding the current block according to the natural mode and the graphics mode, respectively, and then encoding the encoding result of the current block in the natural mode or the graphic mode based on the RD cost (Rate Distortion Cost). The mode may be determined, which will be described later with reference to FIG. 7.

When the mode determiner 110 determines the mode to be used for encoding the current block, the encoder encodes the current block according to the encoding mode determined by the mode determiner 110.

If the encoding mode of the current block is determined to be the skip mode because the current block is the same as or similar to a previously encoded adjacent block, information indicating that the current block is encoded in the skip mode is encoded instead of the pixel value of the current block. Flag information indicating that the current block is encoded according to the skip mode may be encoded instead of the pixel value of the current block.

Instead of directly encoding pixel values of the current block, the current block can be encoded with one bit of flag information, thereby improving the compression ratio of the image. In addition, in order to encode the current block according to the skip mode, since only the block encoded immediately before the current block is referred to, the skip mode may be implemented with low complexity.

If it is determined that the encoding mode of the current block is not the skip mode because the current block is not the same as or similar to a previously encoded adjacent block, the encoder 130 encodes the current block according to the natural mode or the graphic mode. If the mode determiner 110 determines the encoding mode of the current block as the natural mode, and if the mode determiner 110 determines the encoding mode of the current block as the graphics mode, the graphics mode. Encode according to The encoding method according to the natural mode and the graphic mode will be described in detail with reference to FIGS. 4 to 6.

4 illustrates an image encoding apparatus according to another embodiment of the present invention.

Referring to FIG. 4, the image encoding apparatus 400 according to an embodiment of the present invention may include a mode determiner 410, a natural mode encoder 420, a graphic mode encoder 430, and a mode information encoder ( 440). The mode determiner 410 corresponds to the mode determiner 110 of FIG. 1, and the natural mode encoder 420, the graphic mode encoder 430, and the mode information encoder 440 are the encoders of FIG. 1. 120).

The mode determiner 410 determines the encoding mode of the current block. The mode used for encoding the current block among the skip mode, the natural mode, and the graphic mode may be determined.

When the mode determiner 410 determines the encoding mode of the current block as the skip mode, the mode information encoder 440 encodes information indicating that the current block is encoded according to the skip mode. Instead of pixel values of the current block, flag information indicating that the current block is encoded according to a skip mode may be encoded.

When the mode determiner 410 determines the encoding mode of the current block as the natural mode, the natural mode encoder 420 encodes the current block according to the natural mode. Discrete cosine transforms the current block to generate discrete cosine coefficients, separates the generated coefficients into a plurality of bit planes, and encodes each bit plane using a bit plane basis encoding method. This will be described in detail with reference to FIG. 5.

5 illustrates a natural mode encoder according to an embodiment of the present invention.

Referring to FIG. 5, a natural mode encoder 420 according to an embodiment of the present invention includes a converter 510, a bit plane selector 520, and a bit plane encoder 530.

The transform unit 510 generates discrete cosine transform coefficients by discrete cosine transform (DCT) of the current block. The discrete cosine transform is merely an example of a method of generating pixel coefficients in the frequency domain by converting pixel values in the pixel domain into the frequency domain, and other methods may be used for transforming the current block. People with knowledge can easily know.

The bitstream of the coefficient of the direct current (DC) component among the discrete cosine transform coefficients generated by the discrete cosine transform coefficient of the current block is inserted into the bitstream as it is. However, the coefficients of the alternating current (AC) component are encoded according to the bit plane based encoding method.

The bit plane selector 520 separates the coefficients of the AC component into a plurality of bit planes. A plurality of bit planes are separated from a bit plane consisting of the most significant bits of the coefficients of the AC component to a bit plane consisting of the least significant bits. M bit planes are separated by bit coefficients of AC components of M bits. Separating the first bit plane consisting of the most significant bits of the bit strings for the coefficients of the AC component, and separating the second bit plane consisting of the bits following the most significant bit. The separation of the bit planes is repeated to the least significant bit to separate the M bit planes.

When the bit plane selector 520 separates the plurality of bit planes, the bit plane encoder 530 encodes each of the generated bit planes using a bit plane-based encoding method. There is no limitation on the method of encoding the bit plane, and it can be used in the present invention for all the bit plane-based encoding methods according to the prior art. In addition, according to an embodiment of the present invention, each bit plane may be encoded by using a bit mask. An area in which a significant bit exists in each bit plane may be set using a bit mask, and bit plane-based encoding may be performed only on the set area.

In the above, the method of separately encoding the DC coefficient and the AC coefficient has been described with reference to FIG. 5. However, the encoding method described above with reference to FIG. 5 is exemplary, and all methods using the current block may be applied to the natural mode encoder 420 using the discrete cosine transform and the bit plane-based encoding method.

Referring back to FIG. 4, when the mode determiner 410 determines the encoding mode of the current block as the graphics mode, the graphic mode encoder 430 encodes the current block according to the graphics mode. The pixel values of the current block are separated into a plurality of bit planes, and each bit plane is encoded using a bit plane basis encoding method. This will be described in detail with reference to FIG. 6A.

6A illustrates a graphic mode encoder according to an embodiment of the present invention.

Referring to FIG. 6A, the graphic mode encoder 430 according to an embodiment of the present invention includes a bit plane selector 610 and a bit plane encoder 620.

The bit plane selector 610 divides pixel values of the current block into a plurality of bit planes. The pixel values of the P bits are separated bit by bit to generate P bit planes from a bit plane consisting of the most significant bits of the pixel value to a bit plane consisting of the least significant bits of the pixel value.

When the bit plane selector 610 separates the plurality of bit planes, the bit plane encoder 620 encodes each of the generated bit planes using a bit plane-based encoding method.

6B illustrates a bit plane based encoding method according to an embodiment of the present invention.

Referring to FIG. 6B, the bit plane encoder 620 encodes the bit plane by grouping the same bit values. For example, when the size of the block is 4x4 and the pixel value is 8 bits, the bit plane encoder 620 first encodes the bit plane for bit 7, which is the most significant bit, as shown in FIG. 6B. The bit plane for bit 7 is divided into groups 631 of '0' and groups 632 of '1' and encoded. Since the bit plane for the most significant bit 7 does not contain the same bits, first encode '1' and then encode '000111111111000' to indicate the partitioning form.

The bit plane for bit 6 is encoded based on the groups of bit 7 depending on whether each group is divided again by a different bit value. In the embodiment shown in FIG. 6B, since the group 631 of '0' and the group 632 of '1' are not divided, '00' indicating that the group 631 of '0' is not divided. And '01' which indicates that the group 632 of '1' is not divided.

In the bit plane for bit 5, the group 632 of '1' of the bit plane for bit 6 is divided into two groups 634 and 644. Accordingly, '00' is first encoded to indicate that the group of '0' is not divided, and '1' is encoded to indicate that the group 632 of '1' is divided. Then, '0000011111' is encoded to indicate the group 632 of '1' is divided.

In the bit plane for bit 4, the group 633 of '1' is split once again among the groups 633 and 634 created by splitting. Therefore, '00' is encoded first to indicate that the group 631 of '0' is not divided. Also, to indicate that the group 633 of '0' is divided among the groups 633 and 634 generated by dividing the group 632 of '1', '1' is encoded, and the group of '0' ( '11100' is encoded to indicate the division type of 633). Then, '01' is encoded to indicate that the group 634 of '1' is not divided.

The bit plane encoder 620 encodes each bit plane by repeatedly applying the bit plane-based encoding method based on the bit group generated by grouping the same bit values described above to the least significant bit.

Again, referring to FIG. 4, the mode information encoder 440 encodes information about a mode used for encoding a current block. When the mode determiner 410 determines the encoding mode of the current block as the skip mode, the mode information encoder 440 encodes information indicating that the current block is encoded according to the skip mode. As described above, flag information indicating that a current block is encoded according to a skip mode may be encoded.

When the mode determiner 410 determines the encoding mode of the current block as the natural mode or the graphic mode, the mode information encoder 440 may indicate that the current block is encoded according to the natural mode or information indicating that the current block is encoded according to the graphic mode. Can be encoded. Like the skip mode, flag information indicating that the current block is encoded according to the natural mode or the graphic mode may be encoded.

In addition, the mode information encoder 440 may encode information indicating whether the current slice including the current block includes a block encoded according to a skip mode, a natural mode, or a graphic mode. Since the flag information is for the current slice, the flag information may be encoded as a syntax element of the current slice.

7 illustrates an image encoding apparatus according to another embodiment of the present invention.

Referring to FIG. 7, the image encoding apparatus 700 according to another embodiment of the present invention may include a skip mode determiner 710, a natural mode encoder 720, a graphic mode encoder 730, and a mode determiner ( 740 and the mode information encoder 750.

The skip mode determiner 710 and the mode determiner 740 correspond to the mode determiner 110 of FIG. 1, and include a natural mode encoder 720, a graphic mode encoder 730, and a mode information encoder 750. ) Corresponds to the encoder 120 of FIG. 1.

The skip mode determiner 710 determines whether to encode the current block according to the skip mode. If the pixel value of the current block is compared with the pixel value of a previously encoded block adjacent to the current block, and the block adjacent to the current block is determined to be the same or similar, the encoding mode of the current block is determined as the skip mode.

When the skip mode determiner 710 determines the encoding mode of the current block as the skip mode, the mode information encoder 750 encodes information indicating that the current block is encoded according to the skip mode. As described above, the flag information indicating that the current block is encoded according to the skip mode may be encoded by the mode information encoder 750.

When the skip mode determiner 710 determines that the encoding mode of the current block is not the skip mode, the natural mode encoder 720 and the graphic mode encoder 730 encode the current block according to the natural mode and the graphic mode, respectively. do.

The mode determiner 740 compares the encoding result of the natural mode encoder 720 with the encoding result of the graphic mode encoder 730 to determine whether to encode the current block according to the natural mode or the graphic mode.

The RD cost is calculated based on the result encoded in the natural mode and the result encoded in the graphic mode. The cost is calculated according to cost = (Rate) + (lambda) x (distortion) to determine a mode having a small cost as an encoding mode of the current block. The 'lambda' may be set differently according to an embodiment, and the selection ratio of the natural mode and the graphic mode may be changed by adjusting the 'lambda'.

When the mode determiner 740 determines the encoding mode of the current block as the natural mode or the graphic mode, the mode information encoder 750 encodes the information about the determined encoding mode. Flag information indicating that the current block is encoded according to the natural mode or flag information indicating that the current block is encoded according to the graphics mode may be encoded.

In addition, as described above, the mode information encoder 750 may encode information indicating whether the current slice includes a block encoded according to a skip mode, a natural mode, or a graphic mode, in addition to the mode information for each block.

8 illustrates an image decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 8, an image decoding apparatus 800 according to an embodiment of the present invention includes a mode information decoder 810 and a decoder 820.

The mode information decoder 810 decodes the information about the encoding mode of the current block included in the bitstream. The bitstream is parsed to decode information indicating whether a current block is encoded according to a skip mode, a natural mode, or a graphics mode.

The decoder 820 decodes the current block based on the mode information decoded by the mode information decoder 810. If the current block is encoded according to the skip mode as a result of decoding the mode information, the current block is restored based on the same or similar block as the current block, that is, the adjacent previously decoded block. The adjacent block may be a block decoded just before the decoding of the current block. If the current block is encoded according to the natural mode or the graphic mode, the current block is restored by performing the encoding methods described above with reference to FIGS. 5 and 6A in reverse. This will be described in detail with reference to FIG. 9.

9 shows an image decoding apparatus according to another embodiment of the present invention.

Referring to FIG. 9, the image decoding apparatus 900 according to another embodiment of the present invention may include a mode information decoder 910, a skip mode decoder 920, a natural mode decoder 930, and a graphics mode decoder ( 940). The mode information decoder 910 corresponds to the mode information decoder 810 of FIG. 8, and the skip mode decoder 920, the natural mode decoder 930, and the graphics mode decoder 940 decode the decoder of FIG. 8. Corresponds to the unit 820.

The mode information decoder 910 decodes information about an encoding mode of the current block included in the bitstream, as in the mode information decoder 810 of FIG. 9.

If the decoded mode information is information about the skip mode, the skip mode decoder 920 decodes the current block according to the skip mode. Restore the current block based on the previously decoded block adjacent to the current block. The current block can be restored by copying adjacent blocks as they are.

If the decoded mode information is information about the natural mode, the natural mode decoder 930 decodes the current block according to the natural mode. The natural mode decoder 930 first parses a coefficient of a DC component among the discrete cosine coefficients included in the bitstream. Then, the bit plane-based decoding method is used to recover the plurality of bit planes for the coefficients of the AC component among the discrete cosine coefficients. When the coefficients of the AC component are recovered by combining the recovered plurality of bit planes, an inverse discrete cosine transform is performed based on the coefficients of the restored AC component and the coefficients of the parsed DC component. As a result of the inverse discrete cosine transform, the current block is restored.

If the decoded mode information is information about the graphic mode, the graphic mode decoder 940 decodes the current block according to the graphic mode. A plurality of bit planes for pixel values of the current block are restored using a bit plane based decoding method. Then, the recovered plurality of bit planes are combined to recover the pixel values of the current block.

10 is a flowchart illustrating a video encoding method according to an embodiment of the present invention.

Referring to FIG. 10, in operation 1010, the image encoding apparatus 100 or 400 according to an embodiment of the present invention determines whether to encode a current block according to a skip mode. The skip mode is a mode for encoding information indicating that the current block is encoded according to the skip mode when the blocks adjacent to the current block are the same or similar.

If it is determined in step 1010 that the encoding mode of the current block is not the skip mode, in operation 1020, the image encoding apparatus 100 or 400 determines whether to encode the current block according to the natural mode or the graphic mode. As described above with respect to the mode determiner 110 of FIG. 1, it is determined whether the current block is a block for a natural image or a block for an artificially generated image, and the current block is encoded according to a natural mode. Decide if you want to.

In operation 1030, the image encoding apparatus 100 or 400 encodes the current block according to the natural mode. If it is determined in step 1020 that the current block is the block for the natural video, the current block is encoded according to the natural mode. The encoding method of the natural mode has been described above with reference to FIG. 5.

In operation 1040, the image encoding apparatus 100 or 400 encodes the current block according to the graphic mode. If it is determined in step 1020 that the current block is a block for an artificially generated image, the current block is encoded according to a graphic mode. The encoding method of the graphic mode has been described above with reference to FIG. 6A.

In operation 1050, the image encoding apparatus 100 or 400 encodes information about an encoding mode used for encoding the current block. If it is determined in step 1010 that the encoding mode of the current block is the skip mode, information indicating that the current block is encoded according to the skip mode is encoded instead of the pixel value of the current block. Also, if it is determined in step 1010 that the encoding mode of the current block is not the skip mode and the current block is encoded according to the natural mode or the graphic mode in steps 1030 to 1040, the information or the graphic mode indicating that the current block is encoded according to the natural mode. Information indicating that the data is encoded according to the "

11 is a flowchart illustrating a video encoding method according to another embodiment of the present invention.

Referring to FIG. 11, in operation 1110, the image encoding apparatus 100 or 700 according to an embodiment of the present invention determines whether to encode a current block according to a skip mode. Step 1110 corresponds to step 1010 of FIG. 10.

If it is determined in step 1110 that the encoding mode of the current block is not the skip mode, the image encoding apparatus 100 or 700 encodes the current block according to the natural mode and the graphic mode, respectively, in steps 1120 and 1130.

In operation 1140, the image encoding apparatus 100 or 700 compares the encoding result of the current block with the natural mode and the encoding result with the graphic mode to determine the encoding mode of the current block. The RD cost is calculated based on the result encoded in the natural mode and the result encoded in the graphic mode. As a result of the cost calculation, the mode having the smallest cost is determined as the encoding mode of the current block.

In operation 1150, the image encoding apparatus 100 or 700 encodes information about an encoding mode used for encoding the current block. If it is determined in step 1110 that the encoding mode of the current block is the skip mode, information indicating that the current block is encoded according to the skip mode is encoded instead of the pixel value of the current block. Also, if it is determined in step 1110 that the encoding mode of the current block is not the skip mode, and if the encoding mode of the current block is determined as the natural mode or the graphic mode in step 1140, the information or the graphic indicating that the current block is encoded according to the natural mode. Information indicating that the signal is encoded according to the mode is encoded.

12 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

Referring to FIG. 12, in operation 1210, the image decoding apparatus 800 or 900 according to an embodiment of the present invention decodes information about an encoding mode of a current block included in a bitstream. The bitstream is parsed to decode information about an encoding mode indicating whether a current block is encoded according to a skip mode, a natural mode, or a graphics mode.

In operation 1220, the image decoding apparatus 800 or 900 decodes the current block based on the decoded mode information. In operation 1210, if the current block is encoded according to the skip mode as a result of decoding the mode information, the current block is restored based on a block that is the same as or similar to the current block, that is, an adjacent previously decoded block. If the current block is encoded according to the natural mode or the graphic mode, the current block is restored by performing the encoding methods described above with reference to FIGS. 5 and 6A in reverse.

13 shows a mode information encoding apparatus according to an embodiment of the present invention. The mode information encoding apparatus illustrated in FIG. 13 corresponds to the mode information encoder 440 of FIG. 4 and the mode information encoder 750 of FIG. 7.

Referring to FIG. 13, the mode information encoding apparatus 1300 according to an embodiment of the present invention may include a run determination unit 1310, a first information encoder 1320, a second information encoder 1330, and a run encoder. 1340 and the slice information encoder 1350.

The run determination unit 1310 determines whether the current block is encoded according to the same encoding mode as a plurality of consecutive previous blocks. The encoding mode is a method used for encoding the current block, and may be one of the skip mode, the natural mode, and the graphic mode.

Adjacent blocks have a high probability of having the same pixel value, as well as a same encoding mode. In this case, if the information about the encoding mode is not encoded for each block and only the information about the number of times the same encoding mode is repeated, the compression rate of the encoding can be improved. Accordingly, the run determining unit 1310 determines whether the encoding mode of the current block is the same as the encoding mode of the plurality of blocks previously decoded. According to an embodiment of the present invention, it may be determined whether the encoding mode of the current block is the same as the encoding mode of two consecutive blocks encoded before the current block.

According to the present invention, the mode used to encode a given block may be three modes of skip mode, natural mode and graphic mode, so that the same mode of repetition may be repeated all of the skips, all of the natural and all of the graphic modes. Can be. Accordingly, the run determination unit 1310 may determine whether the skip mode is repeated, whether the natural mode is repeated, and whether the graphics mode is repeated.

However, according to one embodiment of the present invention, the run determination unit 1310 may determine only whether to repeat a particular mode. For example, since the probability that the skip mode is repeatedly used for a continuous block among the skip mode, the natural mode, and the graphic mode is higher than that of the natural mode and the graphic mode, the run determination unit 1310 may repeat the skip mode. You can only judge whether or not.

In addition, it may be determined whether the repetition is performed only for the combination of the two modes, and the combination of the two modes may be the skip mode-graphic mode, the skip mode-natural mode, or the natural mode-graphic mode.

14 is a diagram for describing repetition of an encoding mode according to an embodiment of the present invention.

Referring to FIG. 14, when the third block of the current slice is referred to as the current block 1410, the current block 1410 encodes the same skip mode as the plurality of previously encoded blocks 1420 and 1430. Accordingly, the run determination unit 1310 may determine that the encoding mode of the current block 1410 is the same as the encoding mode of the plurality of previously encoded blocks 1420 and 1430, and the number of repetitions is '1'. . When the number of repetitions is determined, instead of encoding the encoding mode of the current block 1410, the run encoder 1340 to be described later may encode only the repetition number '1'.

However, as shown in FIG. 14, since the fourth block 1412 is also encoded in the same graphics mode as the current block 1410, the number of repetitions of the current block 1410 is not encoded. Since the encoding mode of the blocks after the current block 1410 may be determined until the same encoding mode is repeated, the run determination unit 1410 repeats when encoding information about the encoding mode of the current block 1410. Only the number of times is increased by '1', and the run coder 1340 does not immediately encode the number of repetitions.

Since the fourth block 1412 of the current slice 1400 is also encoded in the graphics mode, the run determination unit 1410 increases the number of repetitions by '1' again, and the number of repetitions becomes '2'. However, since the encoding mode of the fifth block 1414 is a skip mode different from that of the previous blocks, it is not possible to encode the number of repetitions instead of the encoding mode of the fifth block 1414.

Accordingly, the run encoder 1340 encodes '2', which is the number of repetitions to the fourth block, and first and second information, which will be described later, to indicate a skip mode which is the encoding mode of the fifth block 1414. Encode

The first information encoder 1320 encodes first information indicating whether a current block is encoded according to a skip mode. The first information may be flag information indicating whether a current block is encoded according to a skip mode. For example, if the current block is encoded according to the skip mode based on the encoding mode of the mode determiner 110, 410 and 740 and the skip mode determiner 710, the flag information is set to '1', If the current block is not encoded according to the skip mode, the flag information may be set to '0'.

According to another embodiment of the present invention, the first information encoder 1320 may selectively encode the first information based on whether the current slice includes a block encoded according to a skip mode. If the current slice does not include a block coded according to the skip mode, the information on the skip mode is the same for all blocks of the current slice. In other words, all of the flag information indicating whether all blocks of the current slice are encoded according to a skip mode is '0'. Therefore, if the current slice does not include a block encoded according to the skip mode, it is not necessary to encode the first information for each block. In other words, the first information encoder 1320 encodes the first information for each block only when the current slice includes a block encoded according to a skip mode.

Further, according to another embodiment of the present invention, even when the current slice includes a block coded according to the skip mode, the current block does not include a block coded according to the natural mode or the graphic mode. It is obvious that it is encoded according to. Therefore, even when the current slice includes a block encoded according to the skip mode, the first information may be encoded only when the current slice includes a block encoded according to the natural mode or a block encoded according to the graphic mode.

If it is determined that the current block is not encoded according to the skip mode, the second information encoder 1330 encodes second information indicating whether the current block is encoded according to a natural mode or a graphics mode. The first information may be flag information for specifying a mode used for encoding a current block among the natural mode and the graphic mode as information on the natural mode and the graphic mode.

For example, if the current block is encoded according to the natural mode, the flag information may be set to '0', and if the current block is encoded according to the graphic mode, the flag information may be set to '1'. If the current block is encoded according to the skip mode, since the information about the skip mode is already encoded by the first information encoder 1310, the second information encoder 1320 needs to encode the information about the natural mode and the graphics mode. There is no.

Since it encodes information indicating whether the current block is encoded according to a second mode (for example, natural mode) or a third mode (for example, graphic mode) depending on whether the current block is encoded according to the skip mode. It is possible to reduce the number of bits required to encode information about the mode.

In other words, the information on the mode is encoded according to the Hoffman code, so that the information on the mode can be encoded more efficiently. For example, when the current block is encoded according to the skip mode, information indicating that the current block is encoded according to the skip mode may be encoded with one bit of '1'. When the current block is encoded according to the natural mode, two of '00' may be encoded. Information indicating that the encoding is performed according to the natural mode may be encoded using bits of. In addition, when the current block is encoded according to the graphics mode, information indicating that the current block is encoded according to the graphics mode may be encoded with two bits of '01'. In the information about the natural mode and the information about the graphic mode, the first bit '0' is the first information indicating that the current block is not encoded according to the skip mode, and the second bits' 0 'and' 1 'is information indicating whether the current block is encoded according to which of the natural mode and the graphic mode as second information.

In addition, the second encoder 1330 may selectively encode the second information according to whether the current slice includes both the block encoded according to the natural mode and the block encoded according to the graphic mode.

The second encoder 1330 encodes the second information only when it is determined by the first encoder 1320 that the encoding mode of the current block is not the skip mode. Therefore, the encoding mode of the current block is natural mode or graphic mode.

However, if the current slice includes only blocks encoded according to the natural mode, the current block is clearly a block encoded according to the natural mode. Therefore, it can be seen from the decoding side that the encoding mode of the current block is natural mode even if the second information is not encoded. The same is true when the current slice includes only blocks encoded according to the graphics mode. Even if the second government encoder 1330 does not encode the second information, it can be seen from the side of decoding that the current block is a block encoded according to the graphics mode.

However, if the current slice includes both a block coded according to the natural mode and a block coded according to the graphics mode, the second side may not know whether the current block is encoded according to which of the natural mode and the graphic mode. The information encoder 1330 encodes second information for specifying a mode used for encoding the current block among the natural mode and the graphic mode.

The run encoder 1340 encodes information about the number of repetitions of the same encoding mode. If the encoding mode of the plurality of consecutive previous blocks and the encoding mode of the current block are the same, the number of repetitions is increased by '1'. If the same encoding mode is repeated repeatedly, the number of repetitions is continuously increased by '1', and when the repetition of the same encoding mode ends and a block is encoded in a different mode, information on the number of repetitions is encoded.

Referring to the embodiment of FIG. 14, since the repetition number '2' is encoded instead of the encoding modes of the current block 1410 and the fourth block 1412, the encoding mode of the current block 1410 and the fourth block 1412. It is possible to reduce the number of bits consumed for encoding information about. Since the encoding modes of the current block 1410 and the fourth block 1412 are graphic modes, up to four bits are required to encode the encoding mode of the two blocks by encoding the aforementioned first information and the second information. However, if the information about the number of repetitions '2' is encoded instead of the information about the encoding mode, it can be represented by two bits, thereby improving the compression rate of the encoding.

The slice information encoder 1350 encodes third information indicating whether the current slice includes a block coded according to the skip mode, a block code coded according to the natural mode, and fourth information indicating whether a block coded according to the graphics mode is included. do. The fourth information may include flag information indicating a block encoded according to the natural mode and flag information indicating whether the block encoded according to the graphics mode is included.

As described above, the first information encoder 1310 and the second information encoder 1320 include whether a current slice includes a block coded according to a skip mode, a block coded according to a natural mode, and a graphic. The first information and the second information may be selectively encoded according to whether the block encoded according to the mode is included. Therefore, the slice information encoder 1350 encodes the third information and the fourth information so that the decoding side can specify the encoding mode of the current block even if the first information and the second information are not encoded.

15 is a flowchart illustrating a mode information encoding method according to an embodiment of the present invention. 15 shows a method of encoding information about an encoding mode of all blocks of a current slice.

In operation 1510, the mode information encoding apparatus 1300 sets the index 'i' indicating the order of blocks to '0'.

In operation 1520, the mode information encoding apparatus 1300 determines an encoding mode of the i th block. The mode determiner 110, 410, and 740 and the skip mode determiner 710 determine whether the i-th block is encoded according to a skip mode, a natural mode, or a graphics mode.

In operation 1530, the mode information encoding apparatus 1300 determines whether the encoding mode is the same as a plurality of previous blocks having the i-th block consecutive. It may be determined whether the encoding mode is the same as two previous blocks in which the i-th block is continuous.

When determining whether two consecutive previous blocks and the encoding mode are the same, 'i = 0 or 1', that is, the number of previously encoded contiguous blocks is smaller than two since the first block and the second block of the current slice are smaller. For example, it is not possible to determine whether two consecutive previous blocks and the encoding mode are the same. Therefore, in this case, it is determined that the encoding modes of the plurality of consecutive previous blocks and the i th block are not the same.

In operation 1540, the mode information encoding apparatus 1300 increases the number of repetitions by '1'. If it is determined in step 1530 that the i-th block has the same encoding mode as the plurality of blocks previously encoded, the number of repetitions is increased by '1'. The initial value of the repetition number may be set to '0'.

In operation 1550, the mode information encoding apparatus 1300 encodes information about the number of repetitions. If it is determined in step 1530 that the encoding mode is not the same as a plurality of previous blocks in which the i-th block is continuous, information about the number of repetitions is encoded. Before encoding information about the encoding mode of the i-th block, information about the number of repetitions to the i-1 th block is encoded. The information on the number of repetitions may be encoded and the number of repetitions may be reset to an initial value of '0'.

In operation 1560, the mode information encoding apparatus 1300 encodes information about an encoding mode of the i th block. First information indicating whether the current block is encoded according to a skip mode and second information indicating whether the current block is encoded according to a natural mode or a graphic mode may be encoded. A detailed description of step 1560 will be provided later with reference to FIGS. 16 to 18.

In operation 1570, the mode information encoding apparatus 1300 determines whether the i th block is the last block. If it is not the last block, the index 'i' representing the order of the blocks is increased by '1', and steps 1520 to 1560 are repeated.

In operation 1590, the mode information encoding apparatus 1300 encodes information about the current slice. Third information indicating whether the current slice includes a block encoded according to the skip mode and fourth information indicating whether the current slice includes a block encoded according to the natural mode and a block encoded according to the graphics mode are encoded.

16 is a flowchart illustrating a mode information encoding method according to an embodiment of the present invention.

FIG. 16 illustrates step 1560 of FIG. 15 in detail. When the i-th block is the current block, a method of encoding low information about an encoding mode of the current block is shown in detail.

In operation 1610, the mode information encoding apparatus 1300 encodes information about a skip mode. First information indicating whether a current block is encoded according to a skip mode is encoded. If the encoding mode of the current block is the skip mode, the flag information may be set to '1', and if the encoding mode of the current block is not the skip mode, the flag information may be set to '0'.

In operation 1620, the mode information encoding apparatus 1300 determines whether an encoding mode of the current block is a skip mode. If the encoding mode of the current block is not the skip mode, in operation 1630, second information indicating which of the natural mode and the graphic mode is encoded is encoded. If the encoding mode of the current block is the natural mode, the flag information may be set to '0', and if the encoding mode of the current block is the graphic mode, the flag information may be set to '1'.

17 is a flowchart for explaining a mode information encoding method according to another embodiment of the present invention.

17 illustrates step 1560 of FIG. 15 in accordance with another embodiment of the present invention.

In operation 1710, the mode information encoding apparatus 1300 determines whether the current slice includes a block encoded according to a skip mode. If the current slice does not include a block encoded according to the skip mode, it is not necessary to encode first information indicating whether the current slice is encoded according to the skip mode.

If it is determined in operation 1710 that the current slice includes a block encoded according to the skip mode, in operation 1720, the mode information encoding apparatus 1300 encodes first information indicating whether the current block is encoded according to the skip mode. If the current block is encoded according to the skip mode, the flag information may be set to '1'. If the current block is not encoded according to the skip mode, the flag information may be set to '0'.

In operation 1730, the mode information encoding apparatus 1300 determines whether the current block is encoded according to the skip mode. If the current block is encoded according to the skip mode, information indicating whether the current block is encoded according to the natural mode or the graphic mode is not encoded.

In operation 1740, the mode information encoding apparatus determines whether the current slice includes both a block encoded according to the natural mode and a block encoded according to the graphic mode. If the current slice includes only blocks encoded according to the natural mode, it is apparent that the current block is also a block encoded according to the natural mode, so that the second information indicating whether the current block is encoded according to the natural mode or the graphics mode is encoded. no need. In addition, if the current slice includes only blocks encoded according to the graphics mode, it is obvious that the current block is also a block encoded according to the graphics mode, and thus it is not necessary to encode the second information.

In operation 1750, the mode information encoding apparatus encodes second information indicating whether the current block is encoded according to a natural mode or a graphics mode. If the current block is encoded according to the natural mode, the flag information is set to '0', and if the current block is encoded according to the graphic mode, the flag information is set to '1'.

18 is a flowchart illustrating a method of encoding mode information according to another embodiment of the present invention.

FIG. 18 shows step 1560 of FIG. 15 in accordance with another embodiment of the present invention as in FIG. 17.

Comparing the embodiment shown in FIG. 18 with the embodiment shown in FIG. 17, step 1820 is added. According to the embodiment shown in FIG. 17, even when the current slice includes only blocks encoded according to a skip mode, the first information is encoded. However, according to the embodiment illustrated in FIG. 18, when step 1820 is added and the current slice includes only blocks encoded according to a skip mode, the first information is not encoded.

The mode information encoded according to FIG. 18 may be summarized in the following table.

'skip_mode_used' is flag information indicating whether the current slice includes a block encoded according to a skip mode and corresponds to the aforementioned third information. 'nat_mode_used' is flag information indicating whether the current slice includes a block encoded according to the natural mode, and 'graphic_mode_used' is flag information indicating whether the current slice includes a block encoded according to the graphics mode. 'nat_mode_used' and 'graphic_mode_used' correspond to the fourth information described above. The first information is flag information indicating whether a current block is encoded according to a skip mode, and the second information is flag information indicating whether a current block is encoded according to a natural mode or a graphics mode.

19 illustrates a mode information decoding apparatus according to an embodiment of the present invention.

The mode information encoding apparatus illustrated in FIG. 19 corresponds to the mode information decoder 810 of FIG. 8 and the mode information decoder 910 of FIG. 9.

Referring to FIG. 19, the mode information decoding apparatus 1900 according to an embodiment of the present invention may include a slice information decoder 1910, a first information decoder 1920, a second information encoder 1930, and run decoding. A unit 1940, a run determination unit 1950, and a mode determination unit 1960 are included.

The slice information decoder 1910 may include third information indicating whether a current slice includes a block encoded according to a skip mode, a block encoded according to a natural mode, and a block encoded according to a graphic mode, from the bitstream. Parse the information. The fourth information may include flag information indicating a block encoded according to the natural mode and flag information indicating whether the block encoded according to the graphics mode is included.

The first information decoder 1920 determines that the current block is encoded according to the skip mode if the current block is not encoded in the same encoding mode as a plurality of consecutive previous blocks as a result of the determination by the run determination unit 1950. Parse the information. The first information may be flag information indicating whether a current block is encoded according to a skip mode. If the current block is encoded according to the skip mode, the flag information may be '1', and if the current block is not encoded according to the skip mode, the flag information may be '0'.

According to another embodiment of the present invention, the first information decoder 1920 may selectively encode the first information based on whether the current slice includes a block encoded according to a skip mode. If the current slice does not include blocks encoded according to the skip mode, it is apparent that all blocks of the current slice are not encoded according to the skip mode, and the mode information encoding apparatus 1300 does not encode the first information. Thus, if the current slice does not include blocks encoded according to the skip mode, it is not necessary to parse the first information for each block. Therefore, the first information decoder 1920 parses the first information for each block only when the current slice includes a block encoded according to a skip mode.

Further, according to another embodiment of the present invention, even when the current slice includes a block encoded according to a skip mode, the mode information encoding apparatus 1300 may perform the block according to the natural mode or the block in which the current slice is encoded according to the natural mode. The first information is encoded only when the encoded block is included. Therefore, when the first information decoder 1920 refers to the fourth information decoded by the slice information decoder 1910, the current slice includes a block encoded according to the natural mode or a block encoded according to the graphics mode. Only the first information can be parsed.

Like the first information decoder 1920, the second information decoder 1930 determines that the second block is only encoded when the current block is not encoded in the same encoding mode as a plurality of consecutive previous blocks. Decode the information.

When the current block is encoded according to the skip mode, since the information about the skip mode is already parsed by the first information decoder 1920 and the mode to be used for decoding the current block is determined as the skip mode, the natural mode and the graphic mode are used. You don't need to parse information about it. Therefore, when it is determined that the current block is not encoded according to the skip mode, the second information decoder 1930 parses second information indicating which mode of the natural mode and the graphics mode is encoded. The second information may be flag information for specifying a mode used for encoding the current block among the natural mode and the graphic mode.

Also, the second information decoder 1930 may selectively encode the second information with reference to the fourth information decoded by the slice information decoder 1910. If the current slice includes only blocks encoded according to the natural mode, the current block is a block encoded according to the natural mode, and since the mode information encoding apparatus 1300 does not encode the second information, the second information decoder 1930 Does not need to parse the second information. In addition, if the current slice includes only a block encoded according to the graphics mode, the current block is clearly a block encoded according to the graphics mode, and since the mode information encoding apparatus 1300 does not encode the second information, decoding the second information. The unit 1930 does not need to parse the second information.

In other words, as a result of referring to the fourth information, the second information decoder 1930 parses the second information only when the current slice includes both a block encoded according to the natural mode and a block encoded according to the graphics mode.

The run decoder 1940 parses information on the number of repetitions of the same encoding mode. If information on the number of repetitions of the same encoding mode is included in the bitstream, it is parsed and provided to the run determination unit 1950.

The run determination unit 1950 determines whether the current block is encoded in the same encoding mode as a plurality of consecutive previous blocks. If the current block is the k-th block of the current slice, it is determined whether a plurality of consecutive previous blocks, the k-1 th block and the k-2 th block are encoded in the same encoding mode. If it is determined that the k-1 th block and the k-2 th block are encoded in the same encoding mode, the run decoding unit 1940 parses information about the number of repetitions of the same encoding mode.

If the information about the number of repetitions is not included in the bitstream, or if the information about the number of parsed repetitions indicates that the number of repetitions is '0', then the current block is not encoded in the same encoding mode as a plurality of consecutive previous blocks. To judge. When information on the number of repetitions of the same encoding mode is parsed and the value is greater than '0', it is determined that the current block is encoded in the same encoding mode as a plurality of consecutive previous blocks.

The run determination unit 1950 of the mode information decoding apparatus 1900 corresponds to the run determination unit 1310 of the mode information encoding apparatus 1300. Thus, like the run determination unit 1310, the run determination unit 1950 determines whether the skip mode is repeated, whether the natural mode is repeated, and whether the graphics mode is repeated, or only whether the skip mode is repeated. It may be.

In addition, it may be determined whether the repetition is performed only for the combination of the two modes, and the combination of the two modes may be the skip mode-graphic mode, the skip mode-natural mode, or the natural mode-graphic mode.

The mode determiner 1960 may include the first information decoded by the first information decoder 1920, the second information decoded by the second information decoder 1930, and the same encoding mode decoded by the run / decoder 1940. The mode to be used for decoding the current block is determined based on at least one of the information about the number of repetitions. First, it is determined whether the mode to be used for decoding the current block is the skip mode based on the first information, and if not the skip mode, it is determined whether to decode the current block using the natural mode or the graphics mode based on the second information. do.

As a result of the determination of the run determination unit 1950, if the current block is encoded in the same encoding mode as the plurality of consecutive previous blocks, the decoding mode of the current block is determined to be the same as the decoding mode of the previous block.

20 is a flowchart illustrating a mode information decoding method according to an embodiment of the present invention.

Referring to FIG. 20, in operation 2010, the mode information decoding apparatus 1700 according to third information indicating whether a current slice includes a block encoded according to a skip mode, a block encoded according to a natural mode, and a graphic mode from a bitstream Parsing fourth information indicating whether the encoded block is included.

In operation 2020, the mode information decoding apparatus 1700 sets the index 'i' indicating the order of blocks to '0'.

In operation 2030, the mode information decoding apparatus 1700 determines whether the i th block is encoded in the same mode as the encoding mode of a plurality of consecutively decoded blocks. It is determined whether the number of repetitions still remains with reference to the information on the number of repetitions of the same encoding mode. If the number of repetitions is greater than '0', it may be determined that the number of repetitions remains. If the number of repetitions is greater than '0', the number of repetitions is reduced to '1' in step 2040.

If the number of repetitions does not remain, that is, if the number of repetitions is '0', since the i th block is not encoded in the same encoding mode as a plurality of consecutive previous blocks, the information about the encoding mode of the i th block is parsed in step 2050. do. First information indicating whether the i th block is encoded according to the skip mode and second information indicating whether the current block is encoded according to a natural mode or a graphic mode may be parsed. It will be described later in detail with reference to Figure 21 to 23.

In operation 2060, the mode information decoding apparatus 1900 determines whether the i th block is encoded in the same encoding mode as the previous block, that is, the i-1 th block. If it is determined that the i-th block is encoded in the same encoding mode as the i-1 th block, since a plurality of consecutive blocks are encoded in the same encoding mode, the next block, i.e., the i + 1 th block, may also be encoded in the same encoding mode. Can be.

Accordingly, the mode information decoding apparatus 1900 parses information about the number of repetitions of the same encoding mode in step 2062 to refer to determining the encoding mode of the next block. If the i + 1 th block is encoded in the same encoding mode as the i th block, information about the number of repetitions of the same encoding mode is parsed in step 2062, and if it is not encoded in the same encoding mode, there is no information about the number of repetitions to be parsed. Even if not parsed or parsed, the number of repetitions indicates '0'.

In operation 2070, the mode information decoding apparatus 1900 determines the decoding mode of the i-th block. If it is determined that the number of repetitions remains in step 2030 by being encoded in the same encoding mode as a plurality of consecutive previous blocks, the decoding mode of the i-th block is determined in the same manner as the decoding mode of the i-1 th block, and repeated in step 2030. If it is determined that the number of times remains, and the first information and the second information are parsed in step 2050, the decoding mode of the i th block is determined based on the parsed first information and the second information.

In operation 2080, the mode information decoding apparatus 1900 determines whether the i th block is the last block. If not, the index I is increased by '1' in step 2090 and steps 2030 to 2070 are repeated.

21 is a flowchart for describing a method of decoding mode information according to another embodiment of the present invention.

21 illustrates in detail step 2050 of FIG. 20 in accordance with an embodiment of the present invention.

Referring to FIG. 21, in operation 2110, the mode information decoding apparatus 1900 decodes first information indicating whether a current block is encoded according to a skip mode. Parse the first information from the bitstream.

In operation 2120, the mode information decoding apparatus 1900 determines whether the current block is encoded according to the skip mode, based on the first information decoded in operation 2110.

If it is determined in step 2120 that the current block is not encoded according to the skip mode, in operation 2130, the mode information decoding apparatus 1900 decodes second information indicating whether the current block is encoded according to which encoding mode, natural mode or graphic mode. do. Parse second information in the bitstream.

22 is a flowchart for describing a method of decoding mode information according to another embodiment of the present invention.

FIG. 22 illustrates step 2050 of FIG. 20 in accordance with another embodiment of the present invention.

Referring to FIG. 22, in operation 2210, the mode information decoding apparatus 1900 determines whether a current slice includes a block encoded according to a skip mode. Based on the parsed third information, it is determined whether the current slice includes a block encoded according to a skip mode. If the current slice does not include a block coded according to the skip mode, it is not necessary to parse first information indicating whether the current slice is coded according to the skip mode.

If it is determined in step 2210 that the current slice includes a block encoded according to the skip mode, in operation 2220, the mode information decoding apparatus 1900 parses first information indicating whether the current block is encoded according to the skip mode.

In operation 2230, the mode information decoding apparatus 1900 determines whether the current block is encoded according to the skip mode. It is determined whether the current block is encoded according to the skip mode based on the first information parsed in operation 2220. If the current block is encoded according to the skip mode, it is not necessary to parse information indicating which of the natural mode and the graphics mode is encoded.

In operation 2240, the mode information decoding apparatus 1900 determines whether the current slice includes both a block encoded according to the natural mode and a block encoded according to the graphic mode. The determination is made based on the parsed fourth information. If the current slice contains only blocks coded according to the natural mode, it is obvious that the current block is also coded according to the natural mode, so that the second information indicating whether the current block is coded according to the natural mode or the graphics mode is parsed. no need. In addition, if the current slice includes only blocks encoded according to the graphics mode, it is obvious that the current block is also a block encoded according to the graphics mode, and thus it is not necessary to parse the second information.

In operation 2250, the mode information decoding apparatus 1900 parses second information indicating whether the current block is encoded according to which of the natural mode and the graphic mode.

23 is a flowchart for explaining a method of decoding mode information according to another embodiment of the present invention.

FIG. 23 shows step 2050 of FIG. 20 in accordance with another embodiment of the present invention as with FIG. 22.

Comparing the embodiment shown in FIG. 23 with the embodiment shown in FIG. 22, step 2320 is added. According to the embodiment shown in FIG. 22, even when the current slice includes only blocks encoded according to a skip mode, first information is parsed. However, according to the embodiment illustrated in FIG. 23, when step 2320 is added and the current slice includes only blocks encoded according to the skip mode, the first information is not parsed.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited to the above-described embodiments, which can be modified by those skilled in the art to which the present invention pertains. Modifications are possible. Accordingly, the spirit of the invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications will fall within the scope of the invention. In addition, the system according to the present invention can be embodied as computer readable codes on a computer readable recording medium.

For example, an image encoding apparatus, an image decoding apparatus, a mode information encoding apparatus, and a mode information decoding apparatus according to an exemplary embodiment of the present invention are as shown in FIGS. 1, 4, 7, 8, 9, 13, and 19. A bus coupled to respective units of the apparatus, and at least one processor coupled to the bus. It may also include a memory coupled to the bus for storing instructions, received messages or generated messages and coupled to at least one processor for performing instructions as described above.

The computer-readable recording medium also includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and also include a carrier wave (for example, transmission through the Internet). The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

1 illustrates an image encoding apparatus according to an embodiment of the present invention.

2 illustrates an image coding unit according to an embodiment of the present invention.

3 is a view for explaining a method of determining a skip mode according to an embodiment of the present invention.

4 illustrates an image encoding apparatus according to another embodiment of the present invention.

5 illustrates a natural mode encoder according to an embodiment of the present invention.

6A illustrates a graphic mode encoder according to an embodiment of the present invention.

6B illustrates a bit plane based encoding method according to an embodiment of the present invention.

7 illustrates an image encoding apparatus according to another embodiment of the present invention.

8 illustrates an image decoding apparatus according to an embodiment of the present invention.

9 shows an image decoding apparatus according to another embodiment of the present invention.

10 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.

11 is a flowchart illustrating a video encoding method according to another embodiment of the present invention.

12 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

13 shows a mode information encoding apparatus according to an embodiment of the present invention.

14 is a diagram for describing repetition of an encoding mode according to an embodiment of the present invention.

15 is a flowchart illustrating a mode information encoding method according to an embodiment of the present invention.

16 is a flowchart for explaining a mode information encoding method according to another embodiment of the present invention.

17 is a flowchart for explaining a mode information encoding method according to another embodiment of the present invention.

18 is a flowchart for explaining a mode information encoding method according to another embodiment of the present invention.

19 illustrates a mode information decoding apparatus according to an embodiment of the present invention.

20 is a flowchart illustrating a mode information decoding method according to an embodiment of the present invention.

21 is a flowchart illustrating a mode information decoding method according to an embodiment of the present invention.

22 is a flowchart illustrating a mode information decoding method according to another embodiment of the present invention.

23 is a flowchart for describing a mode information decoding method according to another embodiment of the present invention.

Claims (17)

Determining whether the current block is encoded according to the same encoding mode as a plurality of consecutive previous blocks based on the information on the number of repetitions of the predetermined encoding mode; Determining that the decoding mode of the current block is the same as the decoding mode of the plurality of blocks when it is determined that the same is the same; And As a result of the determination, if it is determined that the information is not the same, first information indicating whether the current block is encoded according to a first mode and second information indicating which mode the current block is encoded according to among other modes are parsed to determine the current. Determining a decoding mode of the block, The first mode is a mode for encoding information indicating that the first block is encoded according to the first mode by being identical to a previously encoded second block adjacent to the first block, instead of the pixel value of the first block. Mode information decoding method, characterized in that. The method of claim 1, wherein parsing the first information and the second information to determine a mode to be used for decoding the current block includes: Parsing the first information; As a result of parsing the first information, if it is determined that the current block is not encoded according to the first mode, parsing second information indicating which of the second mode and the third mode is encoded is the current block. step; And And determining a decoding mode of the current block based on a decoding result of at least one of the first information and the second information. The method of claim 2, wherein the second mode is A mode for performing discrete cosine transform on pixel values of the first block and encoding the coefficients generated as a result of the discrete cosine into a plurality of bit planes from the most significant bit to the least significant bit and encoding the data in bit plane units Information Decryption Method. The method of claim 2, wherein the third mode is And dividing the pixel values of the first block into a plurality of bit planes from the most significant bit to the least significant bit and encoding the data in the bit plane unit. The method of claim 1, wherein the information on the number of repetitions of the predetermined encoding mode is And if the same encoding mode is repeated for two consecutive blocks, the encoding mode is information parsed in place of the first information and the second information with respect to the third and subsequent same blocks. The method of claim 5, wherein the information on the number of repetitions of the predetermined encoding mode is And at least one of information on the number of repetitions for each of a plurality of encoding modes that can be used for encoding the current block. Determining an encoding mode of the current block; Determining whether the determined encoding mode of the current block is the same as the encoding mode of a plurality of consecutive previous blocks; If it is determined that it is the same, encoding information on the number of repetitions of the same encoding mode instead of information about the encoding mode of the current block; And If it is determined that it is not the same, encoding the first information indicating whether the current block is coded according to the first mode and the second information indicating which mode the current block is coded according to other modes. Including, The first mode is a mode for encoding information indicating that the first block is encoded according to the first mode by being identical to a previously encoded second block adjacent to the first block, instead of the pixel value of the first block. Mode information encoding method, characterized in that. The method of claim 7, wherein the encoding of the first information and the second information comprises: Encoding the first information; And if it is determined that the current block is not encoded according to the first mode, encoding second information indicating which of the second and third modes the current block is encoded. Information coding method. The method of claim 8, wherein the second mode is A mode for performing discrete cosine transform on pixel values of the first block and encoding the coefficients generated as a result of the discrete cosine into a plurality of bit planes from the most significant bit to the least significant bit and encoding the data in bit plane units Information coding method. The method of claim 8, wherein the third mode is And dividing the pixel values of the first block into a plurality of bit planes from the most significant bit to the least significant bit and encoding the data in the bit plane unit. The method of claim 7, wherein the information about the number of repetitions of the same encoding mode is And if the same encoding mode is repeated for two consecutive blocks, encoding mode is information that is encoded instead of the first information and the second information for blocks after the same third code. The method of claim 11, wherein the information about the number of repetitions of the same encoding mode is And at least one of information on the number of repetitions for each of a plurality of encoding modes that can be used for decoding the current block. A run determining unit determining whether the current block is encoded according to the same encoding mode as a plurality of consecutive previous blocks based on the information about the repetition number of the predetermined encoding mode; And If it is determined that it is the same, the decoding mode of the current block is determined in the same manner as the decoding mode of the plurality of blocks. If the determination is not the same, the current block is encoded according to the first mode. And a mode determination unit that determines a decoding mode of the current block based on first information indicating whether the current block has been determined and second information indicating which mode the current block is encoded according to among other modes. The first mode is a mode for encoding information indicating that the first block is encoded according to the first mode by being identical to a previously encoded second block adjacent to the first block, instead of the pixel value of the first block. Mode information decoding apparatus characterized in that the. The method of claim 13, wherein the information about the number of repetitions of the predetermined encoding mode is And if the same encoding mode is repeated for two consecutive blocks, the encoding mode is information parsed in place of the first information and the second information with respect to the third and subsequent same blocks. A run determining unit determining whether the determined encoding mode of the current block is the same as the encoding mode of a plurality of consecutive previous blocks; A run coder for encoding information on the number of repetitions of the same encoding mode instead of information on the encoding mode of the current block, if it is determined that the determination is the same; A first information encoder which indicates whether the current block is encoded according to a first mode when it is determined that it is not identical; And A second information encoder which encodes second information indicating which mode the current block is encoded according to among other modes; The first mode is a mode for encoding information indicating that the first block is encoded according to the first mode by being identical to a previously encoded second block adjacent to the first block, instead of the pixel value of the first block. Mode information encoding apparatus, characterized in that. The method of claim 15, wherein the information about the number of repetitions of the same encoding mode is And if the same encoding mode is repeated for two consecutive blocks, the encoding mode is information encoded in place of the first information and the second information with respect to the third and subsequent blocks having the same encoding mode. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1 to 12.

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