KR20090103675A - Method for coding/decoding a intra prediction mode of video and apparatus for the same - Google Patents

Abstract

PURPOSE: A method for coding/decoding an intra prediction mode of video and an apparatus for the same are provided to encode/decode IPM information based on a relationship between a current block and neighboring blocks, to thereby effectively increase compression rate. CONSTITUTION: An intra-prediction video coding apparatus includes an intra predictor(110), a subtractor(125), a memory(130), a residual data encoder(140), a residual data decoder(150), an adder(155), an entropy encoder(160), a controller(180), and a MUX(Multiplexer)(190). The controller indicates an IPM to the intra predictor. The intra predictor predicts a CS according to the IPM, referring to previously predicted pixels stored in the memory, for example, neighboring pixels above or to the left of the CS and calculates the cost of the IPM for the CS. In this manner, the intra predictor performs intra prediction on the CS in the IPMs and calculates the costs of the respective IPMs. Then the intra predictor selects an IPM with a minimum cost for the CS. While the controller notifies the intra predictor of IPMs one by one in an embodiment of the present invention, to which the present invention is not limited, it can be further contemplated that upon receipt of a command indicating intra-prediction for a sub-unit from the controller, the intra predictor predicts the sub-unit sequentially in the IPMs.

Description

TECHNICAL FOR CODING / DECODING A INTRA PREDICTION MODE OF VIDEO AND APPARATUS FOR THE SAME

The present invention relates to an image encoding / decoding method and apparatus, and more particularly, to an encoding method / decoding method and apparatus in an intra prediction mode.

Various digital video compression techniques have been proposed to obtain a low data rate or a small storage area while maintaining high image quality in transmission or storage of a video signal. These video compression technologies are international standards such as H.261, H.263, H.264, MPEG-2, MPEG-4, and the like. Such a compression technique achieves a relatively high compression ratio by a Discrete Cosine Transform (DCT) technique or a Motion Compensation (MC) technique. Such video compression technology is applied to efficiently stream streams of video data to various digital networks, such as mobile phone networks, computer networks, cable networks, satellite networks, and the like. It is also applied to storage media such as hard disks, optical disks, and digital video disks (DVD).

For high quality, a large amount of data is required for video encoding. However, a communication network that delivers video data may limit the data rate applicable to encoding. For example, data channels of satellite broadcasting systems or data channels of digital cable television networks generally transmit data at a constant bit rate (CBR). In addition, the storage capacity of a storage medium such as a disk is also limited.

Therefore, the video encoding process trades off the image quality and the number of bits necessary for image compression. Also, since video encoding requires a relatively complicated process, for example, to implement it in software, the video encoding process requires a relatively large number of CPU cycles. Moreover, when attempting to process this in real time, time constraints limit the precision in performing encoding, thereby limiting the image quality that can be achieved.

As described above, video encoding is an important issue in an actual use environment, and video encoding schemes are being developed to obtain high quality while reducing the complexity of the processing scheme and the transmission data rate.

In particular, the H.264 / AVC standard performs intra prediction encoding in a spatial domain by using neighboring pixel values during intra encoding. Determining which pixel value to use is important for improving coding efficiency. For this purpose, an optimal intra prediction direction is determined and the prediction value of the pixel to be encoded is calculated using the neighboring pixel values corresponding to the direction. In this case, the encoder delivers the intra prediction direction information for performing the intra prediction to the decoder so that the decoder can calculate the prediction value of the pixel to be decoded using the neighboring pixel values in the same direction.

1 illustrates an intra prediction mode in units of 4 × 4 pixels based on the H.264 standard, and FIG. 2 illustrates an intra prediction mode in units of 16 × 16 pixels based on the H.264 standard.

Referring to FIG. 1, intra prediction modes in units of 4 × 4 pixels include vertical mode (0 mode), horizontal mode (1 mode), DC mode (2 mode), diagonal left mode (3 mode), and diagonal right mode (4). Mode), vertical right mode (5 modes), vertical left mode (6 modes), horizontal top mode (7 modes) and horizontal bottom mode (8 modes).

Meanwhile, operation of encoding in the intra prediction mode using the intra prediction mode in units of 4x4 pixels will be described as follows. First, when the prediction mode of the current block is the horizontal mode (one mode), first, pixel values of pixels I to L adjacent to the left of the 4x4 pixel unit are used as the prediction pixel value of the current 4x4 pixel unit. That is, the value of pixel I is used as the prediction value of four pixels included in the first row, the value of pixel J is used as the prediction value of four pixels included in the second column of the current 4x4 pixel unit, and pixel K Use the value of as the predicted value of the four pixels in the third column of the current 4x4 pixel unit, and use the value of pixel L as the predicted value of the four pixels in the fourth row of the current 4x4 pixel unit. . After calculating the error between the calculated values and the pixel value of the current 4x4 block, the residual data is obtained, and then the excess data is encoded and decoded. Then, the decoded surplus data is combined with the current 4x4 pixel to reconstruct the image data in units of 4x4 pixels. Then, the cost between the reconstructed image data and the image data in units of 4x4 pixels of the original image is calculated. In the same manner, the current 4x4 pixel unit is predicted for each of the nine modes and the cost of each mode is obtained. The intra prediction mode is selected as the mode having the lowest cost value, and the decoder is informed (signaled) of the selected mode.

Furthermore, in order to improve the coding efficiency of the intra prediction mode information, the intra prediction mode of a predetermined pixel unit (for example, 4x4 pixel unit) is not encoded as it is, but intra prediction of neighboring pixel unit (for example, 4x4 pixel unit) is performed. The encoding is performed by using correlation with the mode.

3 is an exemplary diagram of sub-units that are intra prediction coded according to the H.264 / AVC standard. Referring to FIG. 3, a coding unit exemplifies a macroblock that is 16 × 16 pixel units, and a sub-unit that is 4 × 4 pixel units that is a unit for performing intra prediction encoding. In addition, it exemplifies that intra prediction encoding of the C portion is currently performed, and parts A and B exemplify that intra prediction encoding has already been performed.

First, the intra prediction mode of the C block is selected through the above-described process. Then, the highest priority mode (most_probable_mode) of intra prediction modes of A and B blocks, which are neighboring intra prediction coding units, is calculated. The calculation of the highest priority mode uses Equation 1 below.

Here, best_mode (A) and best_mode (B) are intra prediction modes of A and B blocks, respectively, and the min function is a function of selecting a mode having a small value among two modes.

As described above, after determining the most probable mode, the intra prediction mode of the C block is compared with the highest priority mode, and the result is transmitted. For example, in the H.264 / AVC standard, if the highest priority mode and the intra prediction mode of the C block are the same, one bit flag (use_most_probable_mode) is set to '1' and transmitted; otherwise, the bit is set to '0'. A codeword of 3 bits indicating one of the eight intra prediction modes except for the highest priority mode is encoded and transmitted with fixed length coding. Specifically, when the current mode is the same as or greater than the highest priority mode, a value obtained by subtracting 1 from the current mode is encoded as a 3-bit fixed length codeword. For example, assuming that the intra prediction modes of the A, B, and C blocks are three modes, four modes, and four modes, respectively, the highest priority mode is three. Since the highest priority mode and the mode of the C block, which is the current block, are different from each other, use_most_probable_mode is set to '0'. In the 3-bit fixed-length encoding, 3 subtracted 1 in 4 modes is encoded and set to '011' and transmitted.

As described above, in the case of performing intra prediction mode encoding on a coding unit (eg, macroblock) in units of 16 4 × 4 pixels, even if the intra prediction mode of each unit is the same as the highest priority mode, intra in 4 × 4 pixel units is used. At least 16 bits of transmission are required for encoding the prediction mode.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for encoding / decoding an intra prediction mode that can effectively increase a compression rate by using a relationship with an intra prediction mode of a neighboring block.

In order to achieve the above object, the encoding method of the intra prediction mode according to an aspect of the present invention includes the steps of: receiving a unit to perform encoding in the method of performing the intra prediction mode, and included in the coding unit Determining an intra prediction mode of a plurality of subunits, identifying a relationship between the intra prediction mode of the current subunit determined in the step, and an intra prediction mode with respect to the neighboring subunit of the current subunit; In consideration of the relationship, a process of integrating and encoding a plurality of sub-prediction intra prediction modes is included.

The determining of the relationship between the intra prediction modes of the subunits may include identifying the intra prediction modes of subunits neighboring the current subunit, and using the intra prediction modes of the neighboring subunits. Setting a representative intra mode of the current sub-unit, and checking whether the intra prediction mode of the current sub-unit is the same as the representative intra mode, wherein the intra prediction mode and the representative intra mode are the same sub-unit. Units can be encoded by integrating them.

A process of defining a pattern in which the sub-units in which the intra prediction mode and the representative intra mode are the same are distributed in advance, and the sub-prediction mode and the representative intra mode are distributed in correspondence to a pattern in which the same sub-unit is predefined, The method may include encoding information indicating the pattern.

When the intra prediction mode of the subunit included in the coding unit and the representative intra mode are the same, it is preferable to encode information indicating a pattern corresponding thereto.

When the intra prediction mode of some sub-units included in the coding unit and the representative intra mode are the same, it is preferable to encode information indicating a corresponding pattern and the intra prediction mode of the sub-unit not integrated and encoded.

In addition, when the intra prediction mode of the subunit included in the coding unit and the representative intra mode are not the same, it is preferable to encode information indicating a pattern corresponding thereto and the intra prediction mode of the subunit included in the coding unit. Do.

The representative intra mode may be an intra prediction mode having a minimum value among intra prediction modes of neighboring subunits.

An apparatus for encoding an intra prediction mode according to another aspect of the present invention is an apparatus for encoding an intra prediction mode, and determines an intra prediction mode of a plurality of subunits included in a coding unit, and determines a periphery of the current subunit. An intra prediction mode determiner for confirming a relationship between intra prediction modes for subunits, a pattern analyzer for confirming a pattern formed based on the relationship, information indicating the pattern, or information indicating the pattern, and An integrated intra prediction mode encoder which encodes information about an intra prediction mode of a sub unit is included.

The intra prediction mode determiner determines the intra prediction mode of subunits neighboring the current subunit, and sets the representative intra mode of the current subunit by using the intra prediction mode of the neighboring subunits. Then, it is checked whether the intra prediction mode of the current subunit and the representative intra mode are the same.

The pattern analyzer may predefine a pattern in which subunits having the same intra prediction mode and the representative intra mode are distributed, and a pattern in which subunits having the same two modes are distributed within a current coding unit. The pattern matching with and is confirmed, and the identified pattern is provided to the integrated intra prediction mode encoder.

When the intra prediction mode of the sub-unit included in the coding unit and the representative intra mode are the same, it is preferable that the integrated intra prediction mode encoder encodes information indicating a pattern corresponding thereto.

The integrated intra prediction mode encoder may further include information indicating a pattern corresponding to the intra prediction mode of the partial subunits included in the coding unit and the representative intra mode, and intra units of the subunits that are not integrated and encoded. It is preferable to encode the prediction mode.

Further, when the intra prediction mode of the sub unit included in the coding unit and the representative intra mode are not the same, the integrated intra prediction mode encoder may include information indicating a pattern corresponding to the sub prediction unit included in the coding unit and the sub unit included in the coding unit. It is preferable to encode the intra prediction mode.

In a method of decoding an intra prediction mode according to another aspect of the present invention, a method of decoding an encoded intra prediction mode includes: receiving an encoded bitstream, checking the bitstream, and indicating an integrated coded pattern And decoding the co-encoded sub-unit intra prediction mode and / or the un-co-coded sub-unit intra prediction mode corresponding to the information indicating the pattern.

And when the information indicating the pattern indicates that the subunits included in the coding unit are encoded together, decoding the representative intra mode of the subunit included in the coding unit, and converting the representative intra mode into the subunit of the subunit. The method may further include setting a prediction mode.

And when the information indicating the pattern indicates that the partial subunits included in the coding unit are encoded together, decoding the representative intra mode of the integrated and encoded subunits, and converting the representative intra mode into the subunits of the subunits. The method may include setting to a prediction mode and decoding a sub prediction intra prediction mode that is not integrated and not encoded.

When the information indicating the pattern indicates that the subunits included in the coding unit are not integrated and encoded, the method may include decoding the intra prediction modes of the subunits included in the coding unit, respectively.

In accordance with another aspect of the present invention, an apparatus for decoding an intra prediction mode includes: a demultiplex for receiving an encoded bitstream and extracting information indicating an integrated coded pattern; And an intra decoder configured to decode the intra prediction mode of the co-encoded sub-unit, and optionally, to decode the intra prediction mode of the sub-unit that is not co-encoded, corresponding to the information indicating the pattern.

When the information indicating the pattern indicates that the subunits included in the coding unit are encoded together, the intra decoder decodes the representative intra mode of the subunits included in the coding unit to subtract the representative intra mode. Set to intra prediction mode in units.

When the information indicating the pattern indicates that the partial subunits included in the coding unit are encoded together, the intra decoder decodes the representative intra mode of the integrated and encoded subunit to subtract the representative intra mode. The intra prediction mode of the unit is set, and the intra prediction mode of the sub unit, which is not encoded by being integrated, is decoded from the information included in the bitstream.

When the information indicating the pattern indicates that the sub-units included in the coding unit are not encoded by combining the sub-units, the intra decoding mode of the sub-units included in the coding unit is included from the information included in the bitstream. Restore each of them.

According to the present invention, a subunit that can be demodulated in the intra prediction mode without directly transmitting the intra prediction mode in the coding unit may be encoded using information indicating a predetermined pattern.

In addition, by encoding using the information indicating a predetermined pattern without encoding the information indicating the intra prediction mode, respectively, it is possible to maintain a more stable and superior compression performance than the conventional compression method.

Furthermore, the compression ratio can be effectively increased by minimizing the redundancy to the minimum by utilizing the feature that the spatial and temporal correlations of the image are high.

1 is an exemplary diagram of an intra prediction mode in units of 4 × 4 pixels based on the H.264 standard.

2 is an exemplary diagram of an intra prediction mode in units of 16 × 16 pixels based on the H.264 standard.

3 is an exemplary diagram of sub-units that are intra prediction coded according to the H.264 / AVC standard.

4 is a block diagram of a video encoding apparatus to which an intra prediction mode encoding apparatus is applied, according to an embodiment of the present invention;

5 is a block diagram showing a detailed configuration of an intra prediction unit according to an embodiment of the present invention;

6A is an exemplary diagram of an intra prediction mode for a coding unit, according to an embodiment of the present invention;

6B is an exemplary diagram of a representative intra mode for a coding unit according to an embodiment of the present invention;

7 is an exemplary view of a first pattern according to an embodiment of the present invention;

8A is an exemplary diagram of a second pattern according to an embodiment of the present invention;

8B is an exemplary view of a third pattern according to an embodiment of the present invention;

9A is an exemplary diagram of a fourth pattern according to an embodiment of the present invention;

9B is an exemplary diagram of a fifth pattern according to an embodiment of the present invention;

10A is an exemplary diagram of a sixth pattern according to an embodiment of the present invention;

10B is an exemplary view of a seventh pattern according to an embodiment of the present invention;

10c is an exemplary view of an eighth pattern according to an embodiment of the present invention;

10D is an exemplary view of a ninth pattern according to an embodiment of the present invention;

11 is a flowchart illustrating a procedure of an encoding method of an intra prediction mode according to an embodiment of the present invention;

12 is a block diagram illustrating a video decoding apparatus to which an intra decoding unit is applied according to an embodiment of the present invention;

13 is a flowchart illustrating a procedure of a decoding method of an intra prediction mode according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific details appear in the following description, which is provided to help a more general understanding of the present invention, and it is common knowledge in the art that such specific matters may be changed or modified within the scope of the present invention. It is self-evident to those who have.

The embodiment of the present invention illustrates the application of the method and apparatus for encoding the intra prediction mode of the present invention to the H.264 / AVC standard. Therefore, in the embodiment of the present invention, the coding unit uses a macroblock unit that is a unit for encoding pixels included in a picture of an image in the H.264 / AVC standard.

In an embodiment of the present invention, as a unit for obtaining an intra prediction mode, a unit obtained by dividing a coding unit (eg, a macroblock) into a plurality of units is defined as a subunit. Furthermore, in an embodiment of the present invention illustrating the H.264 / AVC standard, the subunit may be a unit consisting of 8 × 8, 4 × 4 pixels, and the like.

Although a method of encoding and decoding an intra prediction mode in one embodiment of the present invention, a coding unit is illustrated as a macroblock while an encoding and decoding method based on the H.264 / AVC standard is illustrated, and a subunit is 8x8. , 4 × 4 pixels and the like. However, the present invention is not limited thereto and may be variously applied to a method of encoding and decoding a video.

Furthermore, according to an embodiment of the present invention, a picture being encoded is defined as a current picture (CP), a macroblock being encoded is defined as a current macroblock (CMB), and is intra The subunit in which the prediction mode is being encoded is defined as a current subunit (CS). 1 and 2, an intra prediction mode predicted in a predetermined unit (eg, 16 × 16, 8 × 8, and 4 × 4 pixel units) is defined as an intra prediction mode (IPM). In addition, an intra prediction mode predicted using an intra prediction mode of a neighboring coding unit (or sub-unit) is defined as a representative intra mode (RIM).

Furthermore, significant correlation may exist between intra prediction modes of subunits included in a coding unit. Therefore, the intra prediction mode encoding method of the present invention is characterized by integrating and encoding sub-units that can integrate and encode the intra prediction mode based on the correlation. For example, a pattern formed by a subunit capable of integrated encoding of the intra prediction mode is defined based on the correlation, and the intra prediction mode is encoded based on the pattern. Here, the pattern formed by the sub-unit capable of the integrated encoding in the intra prediction mode is defined as an intra prediction mode interference pattern (IMIP).

Correspondingly, the decoding method of the intra prediction mode of the present invention checks information (eg, integrated coding pattern (IMIP)) about the co-encoded subunit. The intra prediction mode of the coding unit is decoded by applying the identified information to a pre-defined condition corresponding to the encoding method.

4 is a block diagram of a video encoding apparatus to which an intra prediction mode encoding apparatus is applied, according to an embodiment of the present invention. Referring to FIG. 4, the video encoding apparatus to which the motion information encoding apparatus of an embodiment of the present invention is applied includes an intra predictor 110, a subtractor 125, a memory 130, a redundant data encoder 140, and a surplus. The data decoder 150, the adder 155, the entropy encoder 160, the controller 180, and the multiplexer 190 are included.

The intra prediction unit 110 receives one of the intra prediction modes (IPM) shown in FIG. 1 from the controller 180. The unit corresponding to the input mode IPM (for example, the pixel neighboring the upper or left side of the current subunit CS), which has been previously intra-prepared in the memory 130, is referred to. Intra prediction is performed in units of 8x8 and 4x4 pixels. The intra prediction unit 110 calculates the cost of the subunit reconstructed through intra prediction. The intra prediction unit 110 performs intra prediction on the intra prediction mode (IPM) illustrated in FIG. 1, and calculates a cost for each mode (IPM). Furthermore, the intra prediction unit 110 selects a mode having the least cost among the intra prediction modes IPM shown in FIG. 1 as an intra prediction mode (ICM) of the current subunit CS.

However, in an embodiment of the present invention, it is illustrated that the intra prediction unit 110 receives one of intra prediction modes (IPM) from the controller 180. However, the present invention is not limited to this. For example, the sub-intra prediction may be instructed by the controller 180, and the intra prediction unit 110 may perform intra prediction on each of the modes sequentially.

In particular, the intra prediction unit 110 according to an embodiment of the present invention determines a representative intra mode (RIM) by using an intra prediction mode (ICM) of sub-units located around the current sub-unit (CS). . Representative intra mode (RIM) is set in consideration of the correlation between the intra mode of the current sub-unit (CS) and the intra prediction mode (ICM) of the sub-units located nearby, it can be set as shown in Equation 2 below. .

For example, in one embodiment of the present invention, the function may be a min function that selects the minimum of two values. Although in one embodiment of the present invention, the function is illustrated as a min function, the present invention is not limited to this, for example, may be a max function for selecting the maximum value.

In addition, the intra prediction unit 110 confirms whether the intra prediction mode (ICM) and the representative intra mode (RIM) selected in sub-units are the same, and confirms the distribution of the sub-units in which the two modes (ICM and RIM) are the same. After checking whether the distribution of the subunits corresponds to a predetermined integrated encoding pattern IMIP, the corresponding integrated encoding pattern IMIP is selected. Then, information indicating the selected integrated coding pattern IMIP is generated.

When the intra prediction mode is encoded, the subtractor 125 performs a difference operation between a subunit of the original image and an intra predicted subunit (hereinafter, referred to as a prediction unit) input from the intra prediction unit 110. Outputs the residual data.

The surplus data encoder 140 converts the surplus data output from the subtractor 125 into DCT transform and quantization operation and then converts the surplus data into encoded data. The surplus data decoder 150 restores the encoded surplus data and outputs the encoded surplus data.

The adder 155 combines the predictor unit input from the intra predictor 110 and the surplus data output through the surplus data decoder 150 (hereinafter, referred to as a reconstruction unit). Create an image.

The entropy encoder 160 entropy encodes and outputs the intra prediction mode (IPM) output from the intra predictor 110 and the surplus data output from the redundant data encoder 140.

The multiplexer 190 outputs a bitstream by arranging information about entropy coded data, integrated coding pattern (IMIP), intra prediction mode (IPM), and coded redundant data.

The controller 180 collectively controls the operations of the respective functional units. In particular, the controller 180 may select the intra prediction mode (ICM) of the current sub-unit (CS), the intra predictor 110, the subtractor 125, the memory 130, and the redundant data encoder 140. The operations of the redundant data decoding unit 150 and the adding unit 155 are controlled.

That is, the controller 180 controls the intra prediction unit 110 to generate a plurality of prediction unit units by performing intra prediction corresponding to a plurality of intra prediction modes (IPMs), and corresponds to each mode (IPM). Controlling the operations of the subtractor 125, the redundant data encoder 140, and the redundant data decoder 150 to encode and decode the surplus data between the prediction unit unit and the current subunit CS of the original, The operation of the adder 155 and the memory 130 is controlled to generate and store a reconstruction unit by combining the prediction unit and the reconstructed surplus data.

5 is a block diagram illustrating a detailed configuration of an intra prediction unit according to an embodiment of the present invention. Referring to FIG. 5, the intra predictor 110 according to an embodiment of the present invention includes an intra prediction mode determiner 111, a pattern analyzer 113, and an integrated intra prediction mode encoder 115. .

The intra prediction mode determiner 111 determines the intra prediction mode IPM of the current subunit CS. Each intra prediction mode IPM is input from the controller 180, the peripheral pixel values are checked based on the input mode IPM, and a prediction unit unit is generated according to the mode IPM. For example, the intra prediction mode determiner 111 generates a prediction unit unit corresponding to the plurality of modes illustrated in FIG. 1. In addition, the intra prediction mode determiner 111 receives a reconstructed unit unit reconstructed based on a plurality of prediction unit units, calculates the costs of the reconstructed unit units, and identifies the reconstructed unit having the minimum cost. do. The intra prediction mode IPM corresponding to the reconstruction unit having the minimum cost is determined as the intra mode of the current subunit CS.

The intra prediction mode determiner 111 repeats the above operations to determine the intra prediction mode of the subunit included in the coding unit.

In addition, the intra prediction mode determiner 111 determines the representative intra mode (RIM) using the intra prediction mode of the neighboring coding unit (or sub unit). Preferably, the intra prediction mode determiner 111 may determine the representative intra mode RIM of the current subunit CS by calculating Equation 2 above. Here, the function disclosed in Equation 2 may be a min function. That is, the intra prediction mode determiner 111 represents an intra prediction mode (IPM) having a minimum identification value among subunits located above the current subunit (CS) and subunits located on the left side. Can be determined.

6A is an exemplary diagram of an intra prediction mode for a coding unit according to an embodiment of the present invention, and FIG. 6B is an exemplary diagram of a representative intra mode for a coding unit according to an embodiment of the present invention. In FIG. 6A, the numbers described in each subunit indicate the order of setting the intra prediction mode (IPM) of the subunit.

The intra prediction mode determiner 111 determines an intra prediction mode (IPM) of sub-units included in the coding unit as shown in FIG. 6A, and a representative intra mode (RIM) of the sub-units as shown in FIG. 6B. ) Can be determined. For example, the intra prediction mode IPM of the seventh intra prediction subunit 7 is the second intra prediction mode IPM2, and the representative intra mode RIM is the smallest of the upper and left blocks 5 and 6. An example of determining the first intra prediction mode IPM0 having the identification value is shown.

Although, in one embodiment of the present invention, the function is illustrated as a min function, the present invention is not limited to this, for example, may be a max function.

On the other hand, the pattern analyzer 113 previously defines a predetermined integrated encoding pattern (IMIP).

The predetermined integrated coding pattern IMIP may be defined as shown in FIGS. 7 to 10. That is, the predetermined integrated coding pattern IMIP may include a case in which subunits in which the two modes IPM and RIM are identical to each other are distributed in the entire region of the subunits included in the coding unit as illustrated in FIG. 7. The second pattern is distributed in the area of the right 8x16 block as shown in 8a, and the second pattern is distributed in the area of the left 8x16 block as shown in FIG. 8b. The fourth pattern is distributed in the area of the upper 16 × 8 block as shown in FIG. 9B in the fourth pattern, and the sixth pattern is distributed in the remaining area except the upper left 8 × 8 block as shown in FIG. 10A. The case where the pattern is distributed in the remaining areas except for the upper right 8 × 8 block as shown in FIG. 10B, and the case in which the pattern is distributed in the remaining areas except the lower left 8 × 8 block as shown in FIG. 10C, the eighth pattern and FIG. 10D As shown in the ninth case, the distribution is performed in the remaining area except for the lower left 8 × 8 block. Turn, defines if the distribution of the region other than the nine patterns in the 10 patterns.

The pattern analyzer 113 receives the sub prediction intra prediction mode (IPM) and the representative intra mode (RIM) included in the coding unit from the intra prediction mode determiner 111.

The pattern analyzer 113 checks whether the intra prediction mode (IPM) and the representative intra mode (RIM) of the sub-units are the same, and confirms the distribution of the sub-units of the two modes (IPM, RIM) that are the same. Then, it is checked whether the sub-units in which the two modes IPM and RIM are equal to each other are distributed to match the predetermined integrated coding pattern IMIP, and thus, one pattern IMIP of the predetermined integrated coding pattern IMIP. Select.

The integrated intra prediction mode encoder 115 receives information indicating the integrated encoding pattern IMIP from the pattern analyzer 113. The integrated intra prediction mode encoder 115 encodes and outputs information indicating the received integrated encoding pattern (IMIP). In response to the pattern IMIP, an intra prediction mode IPM of sub-units in which the two modes IPM and RIM are not identical to each other is encoded and output.

The encoding apparatus according to the embodiment of the present invention described above may further include a motion predictor, a motion compensator, and a deblocking filter based on the H.264 / AVC standard. In addition, the redundant data encoder 140 and the redundant data decoder 150 may not only perform DCT transform and quantization (inverse DCT transform and inverse quantization) of redundant data, but also specific pictures (based on the H.264 / AVC standard). For example, DCT transform and quantization (inverse DCT transform and inverse quantization) operations on P or B pictures may be further performed.

In addition, the above-described encoding apparatus according to an embodiment of the present invention exemplifies a DCT transform by a transform method, but the present invention is not limited thereto and various transform techniques besides the DCT transform may be used.

Furthermore, the encoding apparatus according to an embodiment of the present invention may further perform encoding of image data based on the H.264 / AVC standard as well as encoding of the intra prediction mode of the present invention.

Hereinafter, an intra prediction mode encoding method according to an aspect of the present invention will be described based on the operations of the controller 180 and the intra predictor 110.

11 is a flowchart illustrating a procedure of an intra prediction mode encoding method according to an embodiment of the present invention. Referring to FIG. 11, in operation 410, a block of a coding unit, for example, a macroblock, is first received.

Next, in step 420, intra prediction of sub-units included in the coding unit is performed to select an intra prediction mode (IPM) having an optimal cost. That is, the controller 180 sequentially provides the nine intra prediction modes (IPMs) shown in FIG. 1 to the intra prediction unit 110 and simultaneously instructs the operation of the intra prediction unit 110. Then, the intra prediction mode determiner 111 included in the intra prediction unit 110 generates an prediction unit by performing intra prediction on each mode IPM. The generated prediction unit is provided to the subtraction unit 125. The prediction unit passes sequentially through the subtractor 125, the redundant data encoder 140, and the redundant data decoder 150, thereby generating redundant data reconstructed. The prediction unit and the restored surplus data are transferred to the adder 155 to be combined to generate a restoration unit. Through this process, reconstruction units corresponding to nine intra prediction modes (IPMs) are generated, and the reconstruction units generated are stored in the memory 130. Furthermore, the reconstruction unit is provided to the intra prediction unit 110, and the intra prediction unit 110 calculates the cost between the original subunit and the reconstruction unit. The intra prediction mode IPM corresponding to the cost having the smallest value is determined as the sub prediction intra prediction mode IPM. In operation 420, the above process is repeated to determine an intra prediction mode (IPM) of subunits included in a coding unit.

Next, in step 430, a representative intra mode (RIM) is determined using the intra prediction mode (IPM) of a neighboring coding unit (or sub unit). Preferably, the representative intra mode RIM may determine the representative intra mode RIM of the current subunit CS through the operation of Equation 2. Here, the function disclosed in Equation 2 may be a min function.

This operation 430 may be performed by an operation of the intra prediction mode determiner 111. The intra prediction mode determiner 111 checks the intra prediction mode IPM of the subunit located above the current subunit CS and the subunit located to the left. The intra prediction mode (IPM) having the smallest identification value is determined as the representative intra mode (RIM) among the two subunits.

For example, referring to FIG. 6A, a number indicates an order of encoding an intra prediction mode of a subunit included in a coding unit. 6A illustrates a process of setting a representative intra mode (RIM) of the subunit 9 in which encoding is performed for the ninth time. The intra prediction mode IPM of the subunit 3 located above the ninth coding unit 9 is the second intra prediction mode IPM2, and the intra prediction of the subunit 8 located on the left is performed. The mode IPM is the first intra prediction mode IPM1. Accordingly, as shown in FIG. 6B, the representative intra mode of the subunit 9 in which the first intra prediction mode IPM1 having the smallest identification value is encoded for the ninth time among the two subunits 3 and 8 is performed. Determined by (RIM).

Further, when the pattern analyzer 113 receives the intra prediction mode (IPM) and the representative intra mode (RIM) from the intra prediction mode determiner 111, the sub-unit intra prediction mode (IPM) and the representative intra mode ( RIM) is checked to be identical to each other, and the two modes (IPM and RIM) are identified to have the same subunit distribution. In this case, it is first checked whether the two modes (IPM, RIM) of the sub-units included in the coding unit are the same (step 440).

If the two modes (IPM, RIM) of the sub-units included in the coding unit are the same (440-Yes), steps 450 and 460 are performed. That is, the pattern analysis unit 113 determines that the first pattern indicating that the two modes (IPM, RIM) of the sub-units included in the coding unit among the predefined integrated coding patterns (IMIP) are the same as each other, Information about this is provided to the integrated intra prediction mode encoder 115 (step 450). In operation 460, the integrated intra prediction mode encoder 115 encodes only an identifier indicating the first pattern as information on the intra prediction mode of the coding unit.

On the other hand, when the two modes (IPM, RIM) of at least one subunit are not the same as each other, steps 470, 480, and 490 are performed to perform intra prediction mode (IPM) encoding.

In detail, in step 470, the pattern analyzer 113 determines which of the above-described second patterns to tenth patterns is a subunit having the same two modes (IPM, RIM). In operation 480, an intra prediction mode (IPM) is identified for each subunit of the subunits included in the current coding unit, for which integrated coding is not possible, based on the identified pattern.

Next, the information identified by the pattern analyzer 113, for example, information indicating an integrated coding pattern (IMIP) and an intra prediction mode (IPM) of sub-units in which integrated coding is not possible, may be integrated intra prediction mode encoder 115. Is provided. Then, the integrated intra prediction mode encoder 115 encodes the information and the intra prediction mode (IPM) indicating the integrated encoding pattern IMIP provided from the pattern analyzer 113 (step 490).

Furthermore, the integrated intra prediction mode encoder 115 may encode fixed length length or variable length length encoding information indicating one intra prediction mode among the remaining modes except the representative intra mode (RIM) of each subunit. desirable.

As described above, according to the intra prediction mode encoding method according to the present invention, it is necessary to encode and transmit an intra prediction mode for each sub unit included in a coding unit or a coding unit as the intra prediction mode is integrated and encoded. It is possible to encode a plurality of intra prediction modes (IPMs) simply by encoding information indicating an integrated coding pattern (IMIP) formed by the same sub-unit as the intra prediction mode (IPM) and the representative intra mode (RIM). It is possible. Accordingly, the intra prediction mode (IPM) may be encoded in an accurate unit while minimizing the number of bits of the identifier indicating the intra prediction mode (IPM) of the coding unit. Specifically, in the case of the first pattern mentioned in the embodiment of the present invention, only information indicating the pattern (IMIP) of a coding unit may be encoded, and in the case of the second to fifth patterns, the pattern (IMIP) Information indicating)) and information indicating an intra prediction mode (IPM) in eight sub-units, and information indicating the pattern (IMIP) and four parts in the case of the sixth to ninth patterns Information indicating an intra prediction mode (IPM) of a unit may be encoded. Therefore, the number of bits required for encoding the intra prediction mode (IPM) of the coding unit can be significantly reduced.

12 is a block diagram illustrating a video decoding apparatus to which an intra decoder is applied according to an embodiment of the present invention. 12, a video decoding apparatus according to an embodiment of the present invention may include a demultiplexer 410, an intra decoder 420, a memory 430, an entropy decoder 460, a redundant data decoder 470, An adder 475 and a controller 480 are included.

The demultiplexer 410 parses an encoded bitstream, decodes information indicating an integrated encoding pattern (IMIP) among information on an intra prediction mode (IPM), and provides the decoded bitstream to the intra decoder 420. do. Here, the information indicating the integrated coding pattern IMIP is predefined in advance with the intra prediction mode encoding apparatus. The demultiplexer 410 does not acquire the information about the intra prediction mode (IPM) when the entire subunit included in the coding unit is integrally coded (that is, when the integrated coded pattern IMIP is the first pattern). . On the other hand, when a part of the subunits included in the coding unit is uncoded or there is no co-coded subunit (that is, when the integrated coded pattern IMIP is the second to tenth pattern), the demultiplexer 410 Decodes the information indicating the integrated encoding pattern (IMIP) from the data stream and the encoded intra prediction mode (IPM) in subunits that are not integrated coded. The demultiplexer 410 provides the decoded information (information indicating an integrated encoding pattern (IMIP) and an encoded intra prediction mode (IPM)) to an intra decoder 420, and the encoded redundant data is entropy decoded. Provided to section 460.

The intra decoder 420 receives information indicating the integrated coding pattern IMIP received from the demultiplexer 410, performs decoding of the intra prediction mode in response to the information indicating the pattern IMIP, and A prediction subunit corresponding to the decoded intra prediction mode (IPM) is generated using the reconstructed neighboring pixel values.

In detail, when the information indicating the pattern indicates that the entire subunit included in the coding unit indicates the integrated coding, the intra decoder 420 checks the intra prediction mode (IPM) of the neighboring subunit that has been already decoded. The representative intra mode RIM is calculated, and the calculated representative intra mode RIM is determined as the intra prediction mode IPM of the current subunit CS. At this time, the operation of the representative intra mode (RIM) is performed in the same manner as the operation of the representative intra mode (RIM) in the apparatus (or method) for encoding the intra prediction mode. To this end, the calculation of the representative intra mode (RIM) uses a predetermined method in advance. For example, in the intra mode encoding method according to an embodiment of the present invention, the representative intra mode (RIM) is exemplified by the calculation of Equation 2. Accordingly, the intra decoder 420 according to the exemplary embodiment of the present invention also determines the representative intra mode (RIM) through the operation of Equation 2 in the same manner.

In addition, when the information indicating the pattern IMIP indicates that a part of the sub-units included in the coding unit is integrally encoded, that is, when the pattern IMIP is the second to ninth patterns, the intra decoding unit ( 420 identifies a region in which the co-encoded subunit is distributed, corresponding to the predefined definition. The representative intra mode RIM of the integrated coded subunit is calculated, and the calculated representative intra mode RIM is determined as the intra prediction mode IPM of the current subunit CS. In addition, the intra decoder 420 decodes an encoded intra prediction mode (IPM) received from the demultiplexer 410, and sets an intra prediction mode (IPM) of sub-units of the remaining areas that are not integrated coded.

Further, when the information indicating the pattern IMIP indicates that there is no co-encoded subunit, that is, when the pattern IMIP is the tenth pattern, the intra decoding unit 420 may enter the data stream. The encoded intra prediction mode (IPM) included is decoded to set the sub prediction intra prediction mode (IPM) included in the coding unit.

The intra decoder 420 generates an intra prediction subunit using neighboring pixels based on the intra prediction mode (IPM) decoded in the above manner.

Meanwhile, the entropy decoder 460 receives the compressed bitstream and performs entropy decoding to generate quantized coefficients, and the redundant data decoder 470 performs inverse quantization and inverse transformation on the quantized coefficients to perform redundant data. Restore it.

The adder 475 reconstructs the image information by adding the prediction subunit data generated by the intra decoder 420 to the reconstructed redundant data.

The controller 480 controls the overall operations of the image decoding apparatus by collectively controlling the operations of the functional units.

The video decoding apparatus according to the embodiment of the present invention described above may further include a motion predictor, a motion compensator, a deblocking filter, and the like based on the H.264 / AVC standard. In addition, the redundant data decoder 470, based on the H.264 / AVC standard, as well as the inverse DCT transform and inverse quantization operation of the surplus data, as well as the inverse DCT transform and inverse for a specific picture (eg, P or B picture) The quantization operation may be further performed. Furthermore, the video decoding apparatus according to an embodiment of the present invention may further perform reconstruction of image data encoded based on the H.264 / AVC standard as well as decoding the intra prediction mode of the present invention.

Hereinafter, a video reconstruction process using the decoding method of the intra prediction mode according to the present invention will be described with reference to the above-described components.

13 is a flowchart illustrating a procedure of a decoding method of the intra prediction mode according to an embodiment of the present invention. Referring to FIG. 13, in operation 610, the demultiplexer 410 receives a bitstream and decodes information indicating an integrated encoding pattern (IMIP) from the bitstream in operation 620. In addition, the demultiplexer 410 checks the information indicating the integrated coding pattern (IMIP) to determine whether the entire subunit included in the coding unit is integrated coded (that is, whether the integrated coding pattern IMIP is the first pattern). Check (step 630).

If the entire subunit included in the coding unit is integrally coded, the intra prediction mode (IPM) of the coding unit is decoded in steps 640 and 650. That is, the demultiplexer 410 provides only the information indicating the integrated coding pattern (IMIP) to the intra decoding unit 420, and the intra decoding unit 420 provides the intra prediction mode (IPM) of the neighboring sub-unit, which is already decoded. In operation 640, a representative intra mode (RIM) is calculated. The intra decoding unit 420 decodes the calculated representative intra mode RIM as the intra prediction mode IPM of the current subunit CS. In this case, the operation of the representative intra mode (RIM) is performed in the same manner as the operation of the representative intra mode (RIM) used in the apparatus (or method) for encoding the intra prediction mode. For example, the representative intra mode (RIM) is determined through the operation of Equation 2 (step 650).

On the other hand, when the entire subunit included in the coding unit is not co-coded (630-No), the demultiplexer 410 encodes the information indicating the integrated coding pattern (IMIP) and the coded intra of the uncoated subunit. The prediction mode (IPM) is provided to the intra decoder 420. Then, the intra decoder 420, when the information indicating the integrated coding pattern (IMIP) indicates that a part of the sub-unit included in the coding unit is integrally coded (635-Yes), that is, the pattern is second to first. In the case of 9 patterns, if the intra prediction mode (IPM) is decoded by performing steps 660, 670, and 680, and the information indicating the integrated coding pattern (IMIP) indicates that there is no integrated coded subunit. 635-No, that is, if the pattern is the tenth pattern, steps 660 and 670 are omitted, and step 680 is immediately performed.

Steps 660 and 670 are performed by the intra decoder 420. First, in operation 660, the intra decoder 420 may identify a region in which the co-encoded subunits are distributed, as previously defined, and may determine the co-coded subunit using the intra prediction mode (IPM). Decode representative intra mode (RIM). Next, in step 670, each of the decoded representative intra modes (RIM) is set to an intra prediction mode (IPM) of each subunit.

In operation 680, the intra decoder 420 sequentially decodes the encoded intra prediction mode (IPM) received from the demultiplexer 410, and sequentially sub-intra prediction mode (IPM) for the uncoded region. Will be decrypted.

In addition, the intra prediction mode (IPM) decoded in this manner is used as information necessary for performing intra prediction.

As described above, according to the method and apparatus for encoding / decoding of an intra prediction mode according to the present invention, information indicating an intra prediction mode is encoded for a subunit that can be decoded using only an intra prediction mode of a neighboring subunit. It is possible to encode using information indicating one pattern per coding unit. This makes it possible to maintain a relatively more stable and excellent compression performance than the conventional compression method. In addition, it is possible to effectively increase the compression ratio by reducing the surplus to the minimum by utilizing the feature that the spatial and temporal correlations of the image are high.

The encoding / decoding method of the intra prediction mode according to the present invention may be embodied as computer readable codes on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical disk, and the like, and may also include those implemented in the form of carrier waves (eg, transmission over the Internet). do. 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.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto, and various modifications and changes may be made by those skilled in the art to which the present invention pertains.

Claims (21)

In the method of performing intra prediction mode encoding, Receiving a unit to perform encoding; Determining an intra prediction mode of a plurality of subunits included in a coding unit, Identifying a relationship between the intra prediction mode of the current subunit determined in the process and an intra prediction mode with respect to a peripheral subunit of the current subunit; In consideration of the relationship, the encoding method of the intra prediction mode, characterized in that it comprises the step of combining and encoding the intra prediction mode of a plurality of sub-units. The method of claim 1, wherein the checking of the relationship between the sub prediction intra prediction modes comprises: Identifying the intra prediction mode of the current subunit and neighboring subunits; Setting a representative intra mode of the current subunit by using the intra prediction mode of the neighboring subunit; Checking whether the current intra-unit intra prediction mode and the representative intra mode are the same; And encoding the same subunits in which the intra prediction mode and the representative intra mode are the same. The method of claim 2, Defining a pattern in which subunits having the same intra prediction mode and the representative intra mode are distributed in advance; And encoding information indicating the pattern as the sub-prediction mode and the sub-unit having the same sub-unit are distributed corresponding to a predefined pattern. The method of claim 3, When the intra prediction mode of the subunit included in the coding unit and the representative intra mode are the same, And encoding information indicating a pattern corresponding thereto. The method of claim 3, When the intra prediction mode and the representative intra mode of some subunits included in the coding unit are the same, And an information indicating a pattern corresponding thereto and an intra prediction mode of sub-units which are not integrated and not encoded. The method of claim 3, When the intra prediction mode and the representative intra mode of the subunit included in the coding unit are not the same, The intra prediction mode encoding method characterized by encoding information corresponding to the pattern corresponding to the intra prediction mode of the sub-unit included in the information and coding unit. The representative intra mode according to any one of claims 2 to 6, wherein A method of encoding an intra prediction mode, wherein the intra prediction mode has a minimum value among the intra prediction modes of a neighboring subunit. In the apparatus for performing intra prediction mode encoding, An intra prediction mode determiner which determines an intra prediction mode of a plurality of subunits included in a coding unit, and checks an intra prediction mode relationship between a current subunit and a neighboring subunit; A pattern analysis unit for confirming a pattern formed based on the relationship; And an integrated intra prediction mode encoder configured to encode the information indicating the pattern, the information indicating the pattern, and the information about the sub prediction mode of the sub-unit. The apparatus of claim 8, wherein the intra prediction mode determiner comprises: Identify the intra prediction mode of the current subunit and neighboring subunits, Setting a representative intra mode of the current subunit by using the intra prediction mode of the neighboring subunits, And confirming whether the current intra-unit intra prediction mode and the representative intra mode are the same. The method of claim 8, wherein the pattern analysis unit, A pattern in which the sub-units in which the intra prediction mode and the representative intra mode are identical are distributed is defined in advance, Intra prediction mode, wherein a pattern in which subunits having the same two modes are distributed within a current coding unit identifies a pattern that matches a predefined pattern and provides the identified pattern to an integrated intra prediction mode encoder. Encoding device. The method of claim 10, wherein the integrated intra prediction mode encoder, When the intra prediction mode of the subunit included in the coding unit and the representative intra mode are the same, And encoding information indicating a pattern corresponding thereto. The method of claim 10, wherein the integrated intra prediction mode encoder, When the intra prediction mode and the representative intra mode of some subunits included in the coding unit are the same, And an information indicating a pattern corresponding thereto and an intra prediction mode of a sub-unit not integrated and not encoded. The method of claim 10, wherein the integrated intra prediction mode encoder, When the intra prediction mode and the representative intra mode of the subunit included in the coding unit are not the same, And an intra prediction mode of sub units included in the coding unit and information indicating a pattern corresponding thereto. In the method of decoding the encoded intra prediction mode, Receiving an encoded bitstream, Identifying the bitstream and decoding information indicating a co-encoded pattern; And decoding the co-encoded sub-unit intra prediction mode and / or the un-co-coded sub-unit intra prediction mode in response to the information indicating the pattern. The method of claim 14, When the information indicating the pattern indicates that the sub-units included in the coding unit are encoded together, Decoding a representative intra mode of a subunit included in a coding unit, And setting the representative intra mode to a sub-unit intra prediction mode. The method of claim 14, When the information indicating the pattern indicates that the partial subunits included in the coding unit are encoded together, Decoding a representative intra mode of the integrated sub-coded unit, Setting the representative intra mode to a sub-unit intra prediction mode; And decoding an intra prediction mode of sub-units which are not integrated and not encoded. The method of claim 14, When the information indicating the pattern indicates that the subunits included in the coding unit are not integrated and encoded, A method of decoding an intra prediction mode, wherein the intra prediction modes of sub-units included in the coding unit are decoded, respectively. In the apparatus for performing the decoding of the intra prediction mode, A demultiplex for receiving an encoded bitstream and extracting information indicative of an integrated coded pattern; And an intra decoder configured to decode the intra prediction mode of the co-encoded sub-unit and, optionally, to decode the intra prediction mode of the non-co-coded sub-unit, corresponding to the information indicating the pattern. Mode decoding device. The apparatus of claim 18, wherein the intra decoding unit, When the information indicating the pattern indicates that the sub-units included in the coding unit are encoded together, And decoding the representative intra mode of the subunit included in the coding unit and setting the representative intra mode to the intra prediction mode of the subunit. The apparatus of claim 18, wherein the intra decoding unit, When the information indicating the pattern indicates that the partial subunits included in the coding unit are encoded together, Decoding the representative intra mode of the sub-unit integrated and encoded, and setting the representative intra mode to the intra prediction mode of the sub unit, And decoding an intra prediction mode of sub-units which are not encoded by being integrated from the information included in the bitstream. The apparatus of claim 18, wherein the intra decoding unit, When the information indicating the pattern indicates that the subunits included in the coding unit are not integrated and encoded, And an intra prediction mode of each subunit included in a coding unit, from the information included in the bitstream.