KR101631274B1 - Method and apparatus for encoding/decoding mode information - Google Patents

Abstract

A method and apparatus for hierarchical mode information decoding that determines whether a current block is coded according to the same encoding mode as a plurality of consecutive previous blocks and selectively decodes mode information based on the determination result, a mode information encoding method and apparatus corresponding thereto Lt; / RTI >

Mode, information, encoding, decoding, hierarchical

Description

[0001] The present invention relates to a method and an 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 technologies evolve, interconnection between devices over wireless networks is becoming an issue. Many companies are making efforts to secure interconnection technology between devices over wireless networks. Recently, WiHD (Wireless HD) standardization, which is an uncompressed HD interconnect technology to replace HDMI (High Definition Multimedia Interface), is under way. According to WiHD, TVs, home theater, DVD players, Blu-ray players, camcorders and other devices are interconnected via wireless networks.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for encoding and decoding mode information of an image encoded according to a plurality of modes, and a computer readable recording medium having recorded thereon a program for executing the method .

According to an aspect of the present invention, there is provided a method for decoding mode information, the method comprising the steps of: determining whether a current block is coded according to the same encoding mode as a plurality of consecutive previous blocks based on information on a repetition number of a predetermined encoding mode ; Determining a decoding mode of the current block in the same manner as the decoding modes of the plurality of blocks if it is determined to be the same; And parsing second information indicating whether the current block is coded according to the first mode and second mode indicating whether the current block is coded according to a mode among the other modes, And determining a decoding mode of the current block, wherein the first mode includes information indicating that the first block is the same as the previously encoded second block adjacent to the first block and is encoded according to the first mode And encoding is performed instead of the pixel value of the first block.

According to another embodiment of the present invention, the step of 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; Parsing second information indicating whether the current block is encoded according to a mode of the second mode or a third mode if it is determined that the current block is not encoded according to the first mode as a result of the parsing of the first information, ; And determining a decoding mode of the current block based on 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 on the pixel values of the first block, and outputs the coefficients generated as the discrete cosine to a plurality of bit planes from the most significant bit to the least significant bit, And coding is performed in units of bit planes.

According to another embodiment of the present invention, the third mode is a mode of 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 pixel values in units of bit planes.

According to another embodiment of the present invention, when the same encoding mode is repeated for two consecutive blocks, the information on the number of repetitions of the predetermined encoding mode is set such that, for the third and subsequent blocks having the same encoding mode, And information that is 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 information on repetition times 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, including: determining a coding mode of a current block; Determining whether a coding mode of the determined current block is the same as a coding mode of a plurality of consecutive previous blocks; Encoding the 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 to be the same as the determination result; And encoding the first information indicating whether the current block is coded according to the first mode and the second information indicating whether the current block is coded according to which mode among the other modes, Wherein the first mode includes information indicating that the first block is encoded in accordance with the first mode, which is the same as the previously encoded second block adjacent to the first block, instead of the pixel value of the first block Encoding mode.

According to an aspect of the present invention, there is provided an apparatus for decoding mode information, the apparatus comprising: a decoding unit configured to decode mode information according to an encoding mode of a current block, An execution determiner for determining whether the encoded data is coded; And determining a decoding mode of the current block in the same manner as the decode mode of the plurality of blocks if it is determined to be the same as a result of the determination, And a mode determiner for determining a decoding mode of the current block based on first information indicating whether the current block is coded and second information indicating a mode in which the current block is coded according to another mode, One block is encoded in place of the pixel value of the first block, the information indicating that the block is encoded according to the first mode, which is the same as the previously encoded second block adjacent to the first block.

According to an aspect of the present invention, there is provided an apparatus for encoding mode information, the apparatus including: a run determining unit for determining whether a current encoding mode of a current block is identical to a plurality of consecutive encoding modes of a previous block; A puncturing unit that encodes the information on the number of repetitions of the same encoding mode instead of the information on the encoding mode of the current block, And a first information encoding unit for indicating whether the current block is coded according to a first mode if it is determined that the current block is not the same as a result of the determination; And a second information encoding unit encoding second information indicating whether the current block is encoded according to which mode among the other modes, wherein the first mode is a mode in which the first block is a previously encoded The second mode is a mode for encoding information in accordance with the first mode instead of the pixel value of the first block.

According to another aspect of the present invention, there is provided a computer-readable recording medium storing a program for executing the mode information encoding method and the mode information decoding method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

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

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

The mode determination unit 110 determines a mode used for encoding the current block. Technologies for effective connection of devices over a wireless network are intended to transmit and receive high definition content over HD over a wireless network. However, standardization is under way with focus on low memory and low complexity to enable interconnection between various devices. Accordingly, the present invention is directed to a video encoding method according to the related art such as MPEG-1, MPEG-2 and MPEG-4 H.264 / MPEG-4 AVC (Advanced Video Coding) It does not use complicated techniques for increasing the compression ratio.

However, since transmitting pixel values of an image without compressing at all requires a wireless network with a high data rate, this can also be an obstacle to interconnection between various devices. Accordingly, it is possible to guarantee low complexity and an appropriate level of compression rate 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.

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 mode for discrete cosine transform (DCT) and a discrete cosine transform And a current block is encoded using a bit plane division. The graphics mode is a mode for encoding a current block 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 among the plurality of modes described above to code the current block. First, the mode determination unit 110 determines whether the current block is the same as or similar to another block of a current slice that has been coded adjacent to the current block. The pixel value of the current block is compared with the pixel value of the previously coded block of the current slice to determine whether they are the same or similar. Will be described in detail with reference to Figs. 2 and 3. Fig.

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

Referring to FIG. 2, the image encoding apparatus 100 encodes an image in slice units, block units, and bit plane units. The current picture 210 is divided into a plurality of slices 212 to 216. [ Can be divided into a plurality of slices (212 to 216) having a length of N. Then, each slice is divided into NxN sized blocks. The block may again be divided into a plurality of bitplanes from the bitplane for the most significant bit to the bitplane for the least significant bit. If the pixel value of the block or the discrete cosine coefficient is represented by M bits, it can be divided into M bit planes.

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

Referring to FIG. 3, the current picture 310 may be divided into a plurality of slices, as described above with respect to FIG. The case where the image coding apparatus 100 codes the slice 320 shown in FIG. 3 will be described as an example.

The mode determination unit 110 of the image encoding apparatus 100 determines whether or not the current block 322 is the same as the previously encoded block 324 adjacent to the current block to encode the current block 322 of the current slice 320, . The current block 322 to be coded is likely to be the same or similar to a previously coded block that is spatially adjacent. Accordingly, if the current block 322 is the same as or similar to the previously encoded block 324 adjacent to the current block 322, the mode determination unit 110 can determine the encoding mode of the current block 322 as a skip mode. The adjacent block 324 may be a block immediately before the encoding of the current block.

The determination as to whether the current block 322 and the adjacent block 324 are the same or similar can be performed in various ways. A cost is calculated based on a Sum of Absolute Difference (SAD), a Mean Square Error (MSE), a Signal to Noise Ratio (SNR), a Max Difference, etc. between the current block 322 and the adjacent block 324 And 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, maximum difference approaches '0', it can be determined that the current block 322 and the adjacent block 324 are the same or similar.

The mode determination unit 110 may determine the encoding mode of the current block 322 to be a skip mode only when the current block 322 and the neighboring block 324 are completely the same, (322) may be determined as a skip mode. In other words, the coding mode of the current block 322 may be determined to be a skip mode only when the above-described SAD, MSE, maximum difference, etc. is '0' 324) is determined to be similar, and the encoding mode of the current block 322 may be determined as a skip mode.

If the mode determination unit 110 determines that the current block is not the skip mode as a result of determining whether or not the current block is the same as or similar to the current block, the mode determination unit 110 again determines the current block as a natural mode, Mode to be encoded according to which mode. If it is determined that the current block is a natural associative block, that is, a block for an artificially generated image, the encoding mode of the current block is determined to be the natural mode. On the contrary, if the current block is a block for artificially generated images such as text, The encoding mode of the current block is determined to be the graphic mode.

There is no limitation on the criterion for determining whether to encode the current block according to the mode of the natural mode or the graphic mode, and it is possible to determine whether the current block is a block for an artificially generated image by using various algorithms. For example, since an artificial image has a high probability that the same pixel values are distributed in a specific region, the pixel values of the current block are compared, and if the same pixel values are equal to or more than a predetermined number, it is determined that the block is an artificially generated image .

According to another embodiment of the present invention, the current block is encoded according to the natural mode and the graphic mode, and the encoding result is encoded in the natural mode or the graphics mode on the basis of the RD cost (Rate Distortion Cost) Mode, which will be described later in detail with reference to FIG.

When the mode determination unit 110 determines a mode to be used for encoding the current block, the encoding unit encodes the current block according to the encoding mode determined by the mode determination unit 110.

If the current block is the same as or similar to the previously encoded neighboring block and the encoding mode of the current block is determined to be the skip mode, 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 coded according to the skip mode can be encoded in place of the pixel value of the current block.

The current block can be encoded with 1-bit flag information instead of directly encoding the pixel value of the current block, thereby improving the compression rate of the image. In addition, since only a block immediately before the current block is coded to encode the current block according to the skip mode, a skip mode can be implemented with a low complexity.

If it is determined that the current block is not the skip mode because the current block is not the same as or similar to the previously encoded neighboring block, the encoding unit 130 encodes the current block according to the natural mode or the graphic mode. If the mode determining unit 110 determines that the encoding mode of the current block is the natural mode, the current block is encoded according to the natural mode. If the mode determining unit 110 determines the encoding mode of the current block as the graphic mode, . The encoding method according to the natural mode and the graphic mode will be described in detail with reference to FIGS.

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

4, an image encoding apparatus 400 according to an exemplary embodiment of the present invention includes a mode determination unit 410, a natural mode encoding unit 420, a graphic mode encoding unit 430, and a mode information encoding unit 440). 1, and the natural mode encoding unit 420, the graphic mode encoding unit 430, and the mode information encoding unit 440 correspond to the encoding unit (not shown) of FIG. 1 120).

The mode determination unit 410 determines the encoding mode of the current block. A mode to be used for encoding the current block, among the skip mode, the natural mode and the graphic mode, can be determined.

When the mode determination unit 410 determines the encoding mode of the current block as a skip mode, the mode information encoding unit 440 encodes information indicating that the current block has been encoded according to the skip mode. It is possible to encode flag information indicating that the current block is coded according to the skip mode instead of the pixel value of the current block.

If the mode determination unit 410 determines that the encoding mode of the current block is the natural mode, the natural mode encoding unit 420 encodes the current block according to the natural mode. The current block is subjected to discrete cosine transform to generate discrete cosine coefficients, the generated coefficients are divided into a plurality of bit planes, and each bit plane is encoded using a bit plane basis encoding method. Will be described in detail with reference to FIG.

FIG. 5 illustrates a natural mode encoding unit according to an embodiment of the present invention.

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

The transform unit 510 generates discrete cosine transform coefficients by performing a discrete cosine transform (DCT) on the current block. Discrete cosine transform is merely an example of a method of transforming a pixel value of a pixel domain into a frequency domain to generate coefficients of the frequency domain and it is possible that another method can be used for transforming a current block. A person with knowledge can easily know.

The bit stream for the DC (direct current) coefficient of the discrete cosine transform coefficients generated by the transform unit 510 by discrete cosine transforming the current block is inserted into the bit stream as it is. However, the coefficients of the AC (alternating current) 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. From the bit plane constituted by the most significant bits of the coefficients of the AC component to the bit plane constituted by the least significant bits. And separates the coefficients of the AC component of M bits in bit units to generate M bit planes. Separates a first bit plane composed of the most significant bits of the bit strings for coefficients of the AC component, and separates a second bit plane composed of bits following the most significant bit. The separation of the bit planes is repeated up to the least significant bit to separate the M bit planes.

When the bit plane selector 520 separates a plurality of bit planes, the bit plane encoder 530 encodes each of the plurality of generated bit planes using a bit plane based encoding method. There is no limitation on the method of coding the bit plane, and the present invention can be applied to all the bit plane based coding methods according to the related art. Also, according to an embodiment of the present invention, each bit plane can be encoded using a bit mask. It is possible to set a region where significant bits exist in each bit plane using a bit mast and to perform bit plane based encoding only on the set region.

As described above, the method of separating the DC coefficients and the AC coefficients separately and coding them separately has been described with reference to FIG. However, the encoding method described above with reference to FIG. 5 is an exemplary one, and all the methods using the current block using the discrete cosine transform and the bit plane based encoding method can be applied to the natural mode encoding unit 420. FIG.

Referring again to FIG. 4, when the mode determination unit 410 determines the encoding mode of the current block to be a graphic mode, the graphic mode encoding unit 430 encodes the current block according to the graphic mode. The pixel values of the current block are divided into a plurality of bit planes and each bit plane is encoded using a bit plane basis coding method. Will be described in detail with reference to FIG. 6A.

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

Referring to FIG. 6A, the graphic mode encoding unit 430 includes a bit plane selecting unit 610 and a bit plane encoding unit 620.

The bit plane selector 610 separates the pixel values of the current block into a plurality of bit planes. Separates pixel values of P bits in a bit unit, and generates P bit planes from a bit plane constituted by the most significant bits of the pixel value to a bit plane constituted by the least significant bits of the pixel value.

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

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

Referring to FIG. 6B, the bit plane encoding unit 620 encodes bit planes 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 encoding unit 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 a group 631 of '0' and a group 632 of '1'. Since the bit plane for the most significant bit 7 does not contain the same bit, '1' is encoded first and '000111111111000' is encoded to indicate the division type.

The bit planes for bit 6 are encoded according to whether groups are again divided by different bit values based on the groups of bits 7. 00 'indicating that the group 631 of' 0 'is not divided because the group 631 of' 0 'and the group 632 of' 1 'are not all divided in the embodiment shown in FIG. 6B, And '01' indicating that the group 632 of '1' is not divided.

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

In the bit plane for bit 4, the group 632 of '1' is divided and the group 633 of '0' among the generated groups 633 and 634 is once again divided. Accordingly, '00' is encoded first to indicate that the group 631 of '0' is not divided. 1 'is encoded to indicate that the group 633 of' 0 'among the groups 633 and 634 generated by dividing the group 632 of' 1 'is divided, and the group of' 0 ' ≪ RTI ID = 0.0 > 633). ≪ / RTI > Then, '01' is encoded to indicate that the group 634 of '1' is not segmented.

The bit-plane coding unit 620 codes each bit-plane by repeatedly applying the bit-plane-based coding method based on the bit group generated by grouping the same bit values to the least significant bit.

Referring again to FIG. 4, the mode information encoding unit 440 encodes information on the mode used for encoding the current block. When the mode determination unit 410 determines the encoding mode of the current block as a skip mode, the mode information encoding unit 440 encodes information indicating that the current block has been encoded according to the skip mode. The flag information indicating that the current block has been coded according to the skip mode can be encoded as described above.

If the mode determination unit 410 determines the encoding mode of the current block to be a natural mode or a graphic mode, the mode information encoding unit 440 outputs information indicating that the current block has been encoded according to the natural mode, or information indicating that the current block has been encoded according to the graphic mode Can be encoded. Like the skip mode, flag information indicating that the current block has been encoded according to the natural mode or the graphic mode can be encoded.

In addition, the mode information encoding unit 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 graphics mode. Since it is the flag information for the current slice, the flag information can be encoded as a syntax element of the current slice.

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

7, an image encoding apparatus 700 according to another embodiment of the present invention includes a skip mode determination unit 710, a natural mode encoding unit 720, a graphics mode encoding unit 730, a mode determination unit 730, 740 and a mode information encoding unit 750.

The skip mode determination unit 710 and the mode determination unit 740 correspond to the mode determination unit 110 of FIG. 1 and include a natural mode encoding unit 720, a graphic mode encoding unit 730, and a mode information encoding unit 750 Corresponds to the encoding unit 120 in Fig.

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

When the skip mode determination unit 710 determines the skip mode of the current block, the mode information encoding unit 750 encodes information indicating that the current block has been encoded according to the skip mode. Flag information indicating that the current block has been coded according to the skip mode can be encoded by the mode information encoding unit 750 as described above.

If the skip mode determining unit 710 determines that the current block encoding mode is not the skip mode, the natural mode encoding unit 720 and the graphic mode encoding unit 730 encode the current block in the natural mode and the graphic mode, respectively do.

The mode determination unit 740 compares the encoding result of the natural mode encoding unit 720 with the encoding result of the graphic mode encoding unit 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 results coded according to the natural mode and the results coded according to the graphic mode. The cost is calculated according to the cost = (Rate) + (lambda) x (distortion), and the mode with a small cost is determined as the encoding mode of the current block. 'lambda' can be set differently according to the embodiment, and the selection ratio of the natural mode and the graphic mode can be changed by adjusting 'lambda'.

When the mode determination unit 740 determines the encoding mode of the current block to be the natural mode or the graphic mode, the mode information encoding unit 750 encodes information on the determined encoding mode. Flag information indicating that the current block is coded according to the natural mode or flag information indicating that the current block is coded according to the graphic mode can be encoded.

In addition, as described above, the mode information encoding unit 750 may encode information indicating whether the current slice includes a block coded according to a skip mode, a natural mode, or a graphics mode, in addition to the mode information of each block.

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

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

The mode information decoding unit 810 decodes information on the encoding mode of the current block included in the bitstream. And parses the bitstream to decode information indicating whether the current block is coded according to a skip mode, a natural mode, or a graphic mode.

The decoding unit 820 decodes the current block based on the mode information decoded by the mode information decoding unit 810. [ If the current block is coded according to the skip mode as the decoding result of the mode information, the current block is restored based on the same or similar block as the current block, i.e., based on the adjacent previously decoded block. Adjacent blocks may be blocks decoded immediately prior to decoding of the current block. If the current block is coded according to the natural mode or the graphic mode, the encoding methods described above with reference to FIGS. 5 and 6A are reversed to restore the current block. Will be described in detail with reference to FIG.

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

9, the image decoding apparatus 900 according to another exemplary embodiment of the present invention includes a mode information decoding unit 910, a skip mode decoding unit 920, a natural mode decoding unit 930, and a graphics mode decoding unit 940). 8, the skip mode decoding unit 920, the natural mode decoding unit 930, and the graphic mode decoding unit 940 correspond to the mode information decoding unit 810 of FIG. 8, and the mode information decoding unit 910 corresponds to the mode information decoding unit 810 of FIG. 820 < / RTI >

The mode information decoding unit 910 decodes the information on the encoding mode of the current block included in the bitstream like the mode information decoding unit 810 of FIG.

If the decoded mode information is information on the skip mode, the skip mode decoding unit 920 decodes the current block according to the skip mode. And restores the current block based on the previously decoded block adjacent to the current block. The current block can be restored by copying the adjacent block as it is.

If the decoded mode information is information on the natural mode, the natural mode decoding unit 930 decodes the current block according to the natural mode. The natural mode decoding unit 930 first parses the coefficient of the DC component among the discrete cosine coefficients included in the bitstream. Then, the bit plane-based decoding method is used to recover a plurality of bit planes for the coefficients of the AC component among the discrete cosine coefficients. When the reconstructed plurality of bit planes are combined and the coefficients of the AC component are reconstructed, the inverse discrete cosine transform is performed based on the coefficients of the reconstructed 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 on the graphics mode, the graphics mode decoding unit 940 decodes the current block according to the graphics mode. And reconstructs a plurality of bit planes for the pixel values of the current block using the bit plane-based decoding method. Then, the reconstructed bit planes are combined to reconstruct the pixel values of the current block.

FIG. 10 is a flow chart for explaining an image encoding method according to an embodiment of the present invention.

Referring to FIG. 10, in step 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 coding information indicating that the current block is coded according to the skip mode instead of the pixel value of the current block if the current block and the neighboring blocks 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, the image encoding apparatus 100 or 400 determines in step 1020 whether to encode the current block according to the natural mode or the graphic mode. 1, it is determined whether the current block is a block for a natural image or an artificially generated image, and the current block is coded according to a natural mode or coded according to a graphic mode .

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 a block for the natural image, 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.

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 artificially generated video, the current block is encoded according to the graphics mode. The coding 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 on the encoding mode used for encoding the current block. If the coding mode of the current block is determined to be a skip mode in step 1010, information indicating that the current block is coded according to the skip mode is encoded instead of the pixel value of the current block. If it is determined in step 1010 that the encoding mode of the current block is not skip mode and the current block is coded according to the natural mode or the graphic mode in steps 1030 to 1040, information indicating that the current block is encoded according to the natural mode, And encodes the information indicating that it has been coded according to the following equation.

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

Referring to FIG. 11, in step 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 in FIG.

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

In operation 1140, the image encoding apparatus 100 or 700 determines the encoding mode of the current block by comparing the current block encoding result according to the natural mode and the encoding result according to the graphic mode. (Rate Distortion Cost) is calculated based on the result of encoding in accordance with the natural mode and the result of encoding in accordance with the graphic mode. The cost calculation result is determined to be the encoding mode of the current block.

In operation 1150, the image encoding apparatus 100 or 700 encodes the information on the encoding mode used for encoding the current block. If the coding mode of the current block is determined to be the skip mode in step 1110, information indicating that the current block is coded according to the skip mode is encoded instead of the pixel value of the current block. If it is determined in step 1110 that the encoding mode of the current block is not a skip mode and the encoding mode of the current block is determined to be the natural mode or the graphic mode in step 1140, information indicating that the current block is encoded according to the natural mode, And encodes the information indicating that it is coded according to the mode.

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

Referring to FIG. 12, in operation 1210, an apparatus 800 or 900 according to an embodiment of the present invention decodes information on a coding mode of a current block included in a bitstream. And parses the bit stream to decode the information on the encoding mode indicating which mode the current block is coded according to the skip mode, the natural mode, and the graphic mode.

In operation 1220, the image decoding apparatus 800 or 900 decodes the current block based on the decoded mode information. If the current block is coded according to the skip mode as a result of the decoding of the mode information in step 1210, the current block is restored based on the same or similar block as the current block, i.e., based on the adjacent previously decoded block. If the current block is coded according to the natural mode or the graphic mode, the encoding methods described above with reference to FIGS. 5 and 6A are reversed to restore the current block.

FIG. 13 illustrates a mode information encoding apparatus according to an embodiment of the present invention. The mode information encoding apparatus shown in FIG. 13 corresponds to the mode information encoding unit 440 of FIG. 4 and the mode information encoding unit 750 of FIG.

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

The run determination unit 1310 determines whether the current block is coded according to the same encoding mode as a plurality of previous 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 described above.

Adjacent blocks have a high probability of having the same pixel value, and are also likely to have the same encoding mode. In this case, if the information on the encoding mode is not all encoded for each block but only the information on the number of times the same encoding mode is repeated is encoded, the compression rate of encoding can be improved. Accordingly, the run determination unit 1310 determines whether the encoding mode of the current block is identical to the encoding mode of a plurality of previously decoded blocks. According to an embodiment of the present invention, it can 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, since the modes used for encoding a predetermined block may be three kinds of skip mode, natural mode, and graphic mode, it is also possible to repeat all of the skip, repeat all of the natural, Lt; / RTI > Accordingly, the run determination unit 1310 can determine whether the skip mode is repeated, whether the natural mode is repeated, and whether the graphic mode is repeated.

However, according to one embodiment of the present invention, the run determination unit 1310 can determine whether or not the specific mode is repeated. For example, since the probability that the skip mode, the natural mode, and the graphic mode are repeatedly used for the encoding for the consecutive blocks is higher than the natural mode and the graphic mode, the run determination unit 1310 determines that the skip mode It can be judged only whether it is.

The combination of the two modes can be a skip mode-graphic mode, a skip mode-natural mode, or a natural mode-graphic mode.

14 is a diagram for explaining 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 a current block 1410, the current block 1410 is coded in the same skip mode as the plurality of previously encoded blocks 1420 and 1430. Accordingly, the run determination unit 1310 can determine that the encoding mode of the current block 1410 is the same as the encoding mode of the previously encoded blocks 1420 and 1430, and the repetition number is '1' . When the number of repetition times is determined, only a repetition number '1' may be coded in place of the encoding mode of the current block 1410 in a later-described run encoding unit 1340.

However, as shown in FIG. 14, the fourth block 1412 is also encoded in the same graphic mode as the current block 1410, so that the number of repetitions is not encoded for the current block 1410. It is necessary to determine the encoding mode of the blocks after the current block 1410 to determine how long the same encoding mode is repeated. Therefore, when encoding the information on the encoding mode of the current block 1410, the run determination unit 1410 And the run encoding unit 1340 does not directly encode the repetition times.

Since the fourth block 1412 of the current slice 1400 is also coded in the graphic mode, the run determining unit 1410 increases the number of iterations by '1' again, and the number of iterations becomes 2. However, since the encoding mode of the fifth block 1414 is a skip mode different from the encoding mode of the previous blocks, it is not possible to encode the repetition times instead of the encoding mode of the fifth block 1414. [

Accordingly, the run encoding unit 1340 encodes '2', which is the number of repetitions up to the fourth block, and stores the first information and second information, which will be described later, in order to indicate the skip mode, which is the encoding mode of the fifth block 1414 .

The first information encoding unit 1320 encodes the first information indicating whether the current block is coded according to the skip mode. The first information may be flag information indicating whether the current block is coded according to the skip mode. For example, if the current block is coded according to the skip mode based on the determination of the encoding modes of the mode determination units 110, 410, and 740 and the skip mode determination unit 710, the flag information is set to '1' If the current block is not coded according to the skip mode, flag information can be set to '0'.

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

According to another embodiment of the present invention, even if the current slice includes a block coded according to the skip mode, if the current slice does not include a block encoded according to the natural mode or the graphics mode, Lt; / RTI > Therefore, even when the current slice includes a block encoded according to the skip mode, the first information can be encoded only when the current slice includes the block encoded according to the natural mode or the block encoded according to the graphic mode.

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

For example, if the current block is coded according to the natural mode, the flag information is set to '0', and if the current block is coded according to the graphic mode, the flag information can be set to '1'. If the current block is coded according to the skip mode, the information on the skip mode is already coded by the first information encoding unit 1310, so that the second information encoding unit 1320 needs to encode information on the natural mode and the graphic mode There is no.

Information indicating whether a current block is coded according to a skip mode or not is selectively encoded according to a mode of a second mode (e.g., a natural mode) and a third mode (e.g., a graphics mode) It is possible to reduce the number of bits necessary for encoding the information on the mode.

In other words, the mode information is encoded according to the Hoffman code, so that information on the mode can be encoded more efficiently. For example, if the current block is coded according to the skip mode, information indicating that the current block is coded according to the skip mode can be encoded with one bit of '1'. If the current block is coded according to the natural mode, The information indicating that the encoding has been performed in accordance with the natural mode can be encoded. In addition, if the current block is coded according to the graphic mode, information indicating that the current block is coded according to the graphic mode with two bits of '01' can be encoded. The first bit '0' in the information on the natural mode and the information on the graphic mode is information indicating that the current block is not coded according to the skip mode as first information, and the second bits' 0 'and' 1 'is information indicating whether the current block is coded according to the mode of the natural mode or the graphic mode as the second information.

In addition, the second encoder 1330 can selectively encode the second information according to whether the current slice includes all of the blocks encoded according to the natural mode and the blocks encoded according to the graphic mode.

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

However, if the current slice includes only the blocks encoded according to the natural mode, the current block is an explicitly encoded block according to the natural mode. Therefore, even if the second information is not encoded, it can be known from the decoding side that the encoding mode of the current block is the natural mode. The same is true when the current slice includes only the blocks coded according to the graphic mode. Even if the second information encoding unit 1330 does not encode the second information, it can be known from the decoding side that the current block is a block encoded according to the graphic mode.

However, if the current slice contains both blocks coded according to the natural mode and blocks coded according to the graphic mode, it can not be known from the coding side that the current block is coded according to the natural mode or the graphic mode, The information encoding unit 1330 encodes the second information for specifying the mode used for encoding the current block, out of the natural mode and the graphic mode.

The run encoding unit 1340 encodes information on the number of repetitions of the same encoding mode. If the encoding mode of the consecutive plural previous blocks is the same as the encoding mode of the current block, the number of repetition is increased by '1'. If the same encoding mode is continuously repeated, the number of repetition times is incremented by '1', and when a block to be encoded in a different mode after the repetition of the same encoding mode is generated, information on the repetition number is encoded.

14, since the repetition number '2' is encoded instead of the encoding mode of the current block 1410 and the fourth block 1412, the encoding mode of the current block 1410 and the encoding of the fourth block 1412 It is possible to reduce the number of bits consumed to encode information on the bitstream. Since the encoding mode of the current block 1410 and the fourth block 1412 is a graphical mode, a maximum of four bits are required to encode the first information and the second information to encode the encoding modes of the two blocks. However, if the information on the repetition frequency '2' is encoded in place of the information on the encoding mode, it can be represented by 2 bits, so that the compression rate of the encoding is improved.

The slice information encoding unit 1350 encodes third information indicating whether the current slice includes a block encoded according to the skip mode, fourth information indicating whether the slice is encoded according to the natural mode, do. The fourth information may include flag information indicating that the encoded block is included according to the natural mode, and flag information indicating whether the block includes encoded blocks according to the graphic mode.

As described above, the first information encoding unit 1310 and the second information encoding unit 1320 determine whether the current slice includes a block encoded according to the skip mode, whether it contains a block encoded according to the natural mode, The first information and the second information may be selectively encoded depending on whether the encoded block is included according to the mode. Therefore, the slice information encoding unit 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. FIG. 15 shows a method of coding information on a coding mode of all blocks of a current slice.

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

In step 1520, the mode information encoding apparatus 1300 determines the encoding mode of the i-th block. Mode determining units 110, 410, and 740 and the skip mode determining unit 710, and determines which of the skip mode, the natural mode, and the graphic mode is encoded in the i-th block.

In step 1530, the mode information encoding apparatus 1300 determines whether the encoding mode is the same as a plurality of previous blocks in which the i-th block is continuous. it can be determined whether the encoding mode is the same as the previous two blocks in which the i-th block is continuous.

'I = 0 or 1', that is, the first block and the second block of the current slice are smaller than the number of the previously coded consecutive blocks, , It can not be determined whether the two previous consecutive blocks and the encoding mode are the same. Therefore, in this case, it is determined that the encoding modes of the consecutive plural previous blocks and the i-th block are not the same.

In step 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 a plurality of blocks previously coded, the number of repetitions is increased by '1'. The initial value of the number of repetition times may be set to '0'.

In step 1550, the mode information encoding apparatus 1300 encodes information on the number of repetitions. If it is determined in step 1530 that the encoding mode is not the same as a plurality of consecutive previous blocks in the i-th block, information on the number of repetitions is encoded. information on the number of repetitions up to the (i-1) th block is encoded before information on the encoding mode of the i-th block is encoded. Information on the number of repetitions can be encoded and the number of repetitions can be reset to the initial value '0' again.

In step 1560, the mode information encoding apparatus 1300 encodes the information on the encoding mode of the i-th block. The first information indicating whether the current block is coded according to the skip mode and the second information indicating whether the current block is coded according to the natural mode or the graphic mode. Details of step 1560 will be described later in detail with reference to FIGS.

In step 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' indicating the order of the blocks is incremented by '1', and steps 1520 to 1560 are repeated.

In step 1590, the mode information encoding apparatus 1300 encodes information on the current slice. Third information indicating whether the current slice includes the encoded block in accordance with the skip mode, and fourth information indicating whether the current slice includes the block encoded according to the natural mode and the block encoded according to the graphics mode.

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

FIG. 16 shows step 1560 of FIG. 15 in detail. and a case where the i-th block is the current block, a method for coding the hypothesis regarding the coding mode of the current block is shown in detail.

In step 1610, the mode information encoding apparatus 1300 encodes the information on the skip mode. And the first information indicating whether the current block is coded according to the skip mode. The flag information is set to '1' if the current block encoding mode is the skip mode, and the flag information can be set to '0' if the current block encoding mode is not the skip mode.

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

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

Figure 17 illustrates step 1560 of Figure 15 according to another embodiment of the present invention.

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

If it is determined in step 1710 that the current slice includes the coded block according to the skip mode, the mode information encoding apparatus 1300 encodes the first information indicating whether the current block is coded according to the skip mode in step 1720. If the current block is coded according to the skip mode, the flag information is set to '1', and if it is not coded according to the skip mode, the flag information can be set to '0'.

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

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

In step 1750, the mode information encoding apparatus encodes the second information indicating whether the current block is coded according to the natural mode or the graphic mode. If the current block is coded according to the natural mode, the flag information is set to '0', and if the current block is coded according to the graphic mode, it 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 according to another embodiment of the present invention, similar to Fig.

Comparing the embodiment shown in FIG. 18 with the embodiment shown in FIG. 17, the addition of step 1820 is different. According to the embodiment shown in FIG. 17, the first information is encoded even when the current slice includes only the block encoded according to the skip mode. However, according to the embodiment shown in FIG. 18, step 1820 is added so that the first information is not encoded when the current slice includes only the blocks encoded according to the skip mode.

The mode information encoded according to FIG. 18 can be summarized as the following table.

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

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

The mode information encoding apparatus shown in FIG. 19 corresponds to the mode information decoding unit 810 of FIG. 8 and the mode information decoding unit 910 of FIG.

19, a mode information decoding apparatus 1900 according to an embodiment of the present invention includes a slice information decoding unit 1910, a first information decoding unit 1920, a second information encoding unit 1930, a run decoding A run determination unit 1950, and a mode determination unit 1960. The mode determination unit 1960 determines whether or not the operation mode is an operation mode.

The slice information decoding unit 1910 receives third information indicating whether the current slice includes a block encoded according to the skip mode, a block encoded according to the natural mode, and a block encoded according to the graphics mode, Parses information. The fourth information may include flag information indicating that the encoded block is included according to the natural mode, and flag information indicating whether the block includes encoded blocks according to the graphic mode.

If the current block is not coded in the same encoding mode as a plurality of consecutive previous blocks, the first information decoding unit 1920 determines whether the current block is coded according to the skip mode, Parses information. The first information may be flag information indicating whether the current block is coded according to the skip mode. If the current block is coded according to the skip mode, the flag information may be '1', and if the current block is not coded according to the skip mode, the flag information may be '0'.

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

In addition, according to another embodiment of the present invention, even when the current slice includes a block encoded according to the skip mode, the mode information encoding apparatus 1300 may be configured to encode the current slice according to a block or graphic mode And encodes the first information only when the encoded block is included. Accordingly, the first information decoding unit 1920 refers to the fourth information decoded by the slice information decoding unit 1910, and when the current slice includes a block encoded according to the natural mode or a block encoded according to the graphic mode Only the first information can be parsed.

The second information decoding unit 1930 decodes the second information only if the current block is not coded in the same encoding mode as a plurality of consecutive previous blocks as a result of the run decision unit 1950, Decrypt information.

When the current block is coded according to the skip mode, the information about the skip mode is already parsed by the first information decoding unit 1920 and the mode to be used for decoding the current block is determined as the skip mode. There is no need to parse the information. Accordingly, if it is determined that the current block is not coded according to the skip mode, the second information decoding unit 1930 parses the second information indicating whether the current block is coded according to the natural mode or the graphic mode. The second information may be flag information for specifying a mode used for encoding the current block, of the natural mode and the graphic mode.

The second information decoding unit 1930 can selectively encode the second information with reference to the fourth information decoded by the slice information decoding unit 1910. [ If the current slice includes only the block encoded according to the natural mode, the block coded according to the natural mode of the current block is clear, and since the mode information encoding apparatus 1300 does not encode the second information, the second information decoding unit 1930 Need not parse the second information. In addition, if the current slice includes only a block encoded according to the graphics mode, the block encoded in accordance with the graphics mode of the current block is clear, and since the mode information encoding apparatus 1300 does not encode the second information, Section 1930 does not need to parse the second information.

In other words, the second information decoding unit 1930 parses the second information only when the current slice includes all of the blocks encoded in the natural mode and the blocks encoded in the graphic mode as a result of referring to the fourth information.

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

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

If the information on the number of repetitions is not included in the bitstream, or if the information on the number of parsed repetitions indicates that the repetition count is '0', then the current block is not encoded in the same encoding mode as a plurality of consecutive previous blocks . Information on the number of repetitions of the same encoding mode is parsed, and if the value is larger 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. Therefore, like the run decision unit 1310, the run determination unit 1950 determines whether the skip mode is repeated, whether the natural mode is repeated or whether the graphic mode is repeated, or whether only the skip mode is repeated or not It is possible.

The combination of the two modes can be a skip mode-graphic mode, a skip mode-natural mode, or a natural mode-graphic mode.

The mode determination unit 1960 decodes the first information decoded by the first information decoding unit 1920, the second information decoded by the second information decoding unit 1930, and the second information decoded by the run decoding unit 1940, And determines a mode to be used for decoding the current block based on at least one of the information on the number of repetitions. Determines whether the mode to be used for decoding the current block is a skip mode based on the first information and determines whether to decode the current block using the natural mode or the graphic mode based on the second information if the mode is not the skip mode do.

If the current block is coded in the same encoding mode as a plurality of consecutive previous blocks as a result of the determination by the run determination unit 1950, the decoding mode of the current block is determined to be the same mode as the decode 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 step 2010, the mode information decoding apparatus 1700 decodes, from the bitstream, 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 parses the fourth information indicating whether it contains an encoded block.

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

In step 2030, the mode information decoding apparatus 1700 determines whether the i < th > block is coded in the same mode as the coding mode of a plurality of consecutive blocks decoded previously. It is determined whether the number of repetition times is still remaining by referring to the information on the repetition number of the same encoding mode. If the number of repetitions is greater than zero, it can be determined that the number of repetitions remains. If the number of repetition is greater than 0, the number of repetition is decreased by 1 in step 2040.

If the number of repetition is not enough, that is, if the repetition number is '0', the i-th block is not coded in the same encoding mode as a plurality of consecutive previous blocks. Therefore, in step 2050, information on the encoding mode of the i- do. the first information indicating whether the i-th block is coded according to the skip mode and the second information indicating whether the current block is coded according to the natural mode or the graphic mode. Will be described later in detail with reference to FIGS.

In step 2060, the mode information decoding apparatus 1900 determines whether the i-th block is coded in the same coding mode as the previous block, i.e., the (i-1) -th block. If it is determined that the i-th block is coded in the same encoding mode as the (i-1) -th block, since a plurality of consecutive blocks are coded in the same encoding mode, the next block, i + .

Therefore, in step 2062, the mode information decoding apparatus 1900 parses information on the number of repetitions of the same encoding mode in order to refer to the determination of the encoding mode of the next block. If the (i + 1) -th block is coded in the same coding mode as the i-th block, information on the number of iterations of the same coding mode is parsed in step 2062, and if there is no information on the number of iterations to be parsed , The number of repetitions is '0' even if it is not parsed or parsed.

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

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

Figure 21 details step 2050 of Figure 20 in accordance with an embodiment of the present invention.

Referring to FIG. 21, in step 2110, the mode information decoding apparatus 1900 decodes first information indicating whether a current block is coded according to a skip mode. And parses the first information in the bitstream.

In step 2120, the mode information decoding apparatus 1900 determines whether the current block is coded according to the skip mode on the basis of the first information decoded in step 2110.

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

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

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

Referring to FIG. 22, in step 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, whether the current slice includes a block encoded according to the skip mode. If the current slice does not include the coded block according to the skip mode, it is not necessary to parse the first information indicating whether the current block is coded according to the skip mode.

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

In step 2230, the mode information decoding apparatus 1900 determines whether the current block is coded according to the skip mode. It is determined whether the current block is coded according to the skip mode based on the first information parsed in step 2220. If the current block is coded according to the skip mode, it is not necessary to parse the information indicating which mode the current block is encoded in, either the natural mode or the graphic mode.

In step 2240, the mode information decoding apparatus 1900 determines whether the current slice includes all of the blocks coded according to the natural mode and blocks coded according to the graphic mode. Based on the parsed fourth information. If the current slice contains only the blocks encoded according to the natural mode, it is obvious that the current block is also the 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 graphic mode is parsed no need. Also, if the current slice contains 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, so that it is not necessary to parse the second information.

In step 2250, the mode information decoding apparatus 1900 parses the second information indicating whether the current block is encoded according to the natural mode or the graphic mode.

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

FIG. 23 shows step 2050 of FIG. 20 according to another embodiment of the present invention, similar to FIG.

Comparing the embodiment shown in FIG. 23 with the embodiment shown in FIG. 22 differs in that step 2320 is added. According to the embodiment shown in FIG. 22, the first information is parsed even when the current slice includes only the block encoded according to the skip mode. However, according to the embodiment shown in FIG. 23, step 2320 is added so that the first information is not parsed if the current slice contains only the blocks encoded according to the skip mode.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all of the equivalent or equivalent variations will fall within the scope of the present 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, the image encoding apparatus, the image decoding apparatus, the mode information encoding apparatus, and the mode information decoding apparatus according to the exemplary embodiments of the present invention can be applied to various types of apparatuses such as those shown in Figs. 1, 4, 7, 8, 9, 13 and 19 A bus coupled to each unit of the device, 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 the at least one processor for performing the instructions as described above.

In addition, the computer-readable recording medium includes all kinds of recording apparatuses 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 a carrier wave (for example, transmission via the Internet). The computer-readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner.

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

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

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

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

FIG. 5 illustrates a natural mode encoding unit according to an embodiment of the present invention.

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

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

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

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

FIG. 9 illustrates 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 an image 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.

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

14 is a diagram for explaining 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 illustrating a mode information encoding method according to another embodiment of the present invention.

17 is a flowchart illustrating 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.

FIG. 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.

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

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

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

Claims (17)

Determining whether a coding mode of a current block is the same as a coding mode of a plurality of previous previous blocks based on information on a repetition number of a predetermined coding mode; Determining a decoding mode of the current block in the same manner as the decoding modes of the plurality of previous blocks if it is determined to be the same; And If it is determined that the current block is not the same as the current block, the first information indicating whether the current block is coded according to the first mode and the second information indicating whether the current block is coded according to which mode among the other modes are parsed, Determining a decoding mode of the block, Wherein the first mode is a mode for coding the information indicating that the first block is encoded in accordance with the first mode, which is the same as the previously encoded second block adjacent to the first block, instead of the pixel value of the first block And decodes the mode information. 2. The method of claim 1, wherein determining a mode to be used for decoding the current block by parsing the first information and the second information comprises: Parsing the first information; Parsing the second information indicating whether the current block is coded according to the mode of the second mode or the third mode if it is determined that the current block is not coded according to the first mode as a result of parsing the first information step; And And determining a decoding mode of the current block based on at least one decoding result of the first information and the second information. 3. The method of claim 2, A mode in which the pixel values of the first block are subjected to discrete cosine transform and the coefficients generated as a result of the discrete cosine are divided into a plurality of bit planes from the most significant bit to the least significant bit and encoded in bit plane units. Information decoding method. 3. The method of claim 2, wherein the third mode And dividing the pixel values of the first block into a plurality of bit planes from a most significant bit to a least significant bit, and encoding the pixel values in units of bit planes. 2. The method of claim 1, wherein the information on the number of repetitions of the predetermined encoding mode is Wherein when the same encoding mode is repeated for two consecutive blocks, the information is parsed in place of the first information and the second information for the third and subsequent blocks having the same encoding mode. 6. The method of claim 5, wherein the information on the number of repetitions of the predetermined encoding mode is And information on the number of repetitions of each of the plurality of encoding modes that can be used for encoding the current block. Determining a coding mode of the current block; Determining whether a coding mode of the determined current block is the same as a coding mode of a plurality of consecutive previous blocks; Encoding the 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 to be the same as the determination result; And If it is determined that the current block is coded according to the first mode and the second information indicating that the current block is coded according to the mode among the other modes, Including, Wherein the first mode is a mode for coding the information indicating that the first block is encoded in accordance with the first mode, which is the same as the previously encoded second block adjacent to the first block, instead of the pixel value of the first block And a mode information encoding step of encoding the mode information. 8. The method of claim 7, wherein encoding the first information and the second information comprises: Encoding the first information; And encoding the second information indicating whether the current block is coded according to a mode of the second mode or the third mode if it is determined that the current block is not coded according to the first mode, Information encoding method. 9. The method of claim 8, wherein the second mode A mode in which the pixel values of the first block are subjected to discrete cosine transform and the coefficients generated as a result of the discrete cosine are divided into a plurality of bit planes from the most significant bit to the least significant bit and encoded in bit plane units. Information encoding method. 9. The method of claim 8, wherein the third mode Dividing the pixel values of the first block into a plurality of bit planes from a most significant bit to a least significant bit, and encoding the pixel values in units of bit planes. 8. The method of claim 7, wherein the information on the number of repetitions of the same encoding mode is Wherein when the same encoding mode is repeated for two consecutive blocks, the information is encoded in place of the first information and the second information for the third and subsequent blocks having the same encoding mode. 12. The method of claim 11, wherein the information on the number of repetitions of the same encoding mode is And information on a repetition number of each of the plurality of encoding modes that can be used for decoding the current block. An execution determiner for determining whether a coding mode of the current block is the same as a coding mode of a plurality of preceding previous blocks based on information on the number of repetition of a predetermined coding mode; And If it is determined that the current block is not the same as the current block, the decoding mode of the current block is determined in the same manner as the decoding modes of the plurality of previous blocks. If it is determined that the current block is not the same, And a mode determiner for determining a decoding mode of the current block based on first information indicating whether the current block is coded and second information indicating which mode the current block is coded according to another mode, Wherein the first mode is a mode for coding the information indicating that the first block is encoded in accordance with the first mode, which is the same as the previously encoded second block adjacent to the first block, instead of the pixel value of the first block And outputs the mode information. 14. The method of claim 13, wherein the information on the number of repetitions of the predetermined encoding mode is Wherein the information is parsed in place of the first information and the second information for the third and subsequent blocks having the same encoding mode if the same encoding mode is repeated for two consecutive blocks. An execution determiner for determining whether a coding mode of the determined current block is the same as a coding mode of a plurality of consecutive previous blocks; A puncturing unit that encodes the information on the number of repetitions of the same encoding mode instead of the information on the encoding mode of the current block, A first information encoding unit for indicating whether the current block is coded according to a first mode if it is determined that the current block is not the same; And And a second information encoding unit encoding second information indicating which mode of the current block is encoded according to the mode, Wherein the first mode is a mode for coding the information indicating that the first block is encoded in accordance with the first mode, which is the same as the previously encoded second block adjacent to the first block, instead of the pixel value of the first block And outputs the mode information. 16. The method of claim 15, wherein the information on the number of repetitions of the same encoding mode is Wherein when the same encoding mode is repeated for two consecutive blocks, the information is encoded in place of the first information and the second information for the third and subsequent blocks having the same encoding mode. A computer-readable recording medium storing a program for executing the method according to any one of claims 1 to 12.

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