KR20130116196A - Method and apparatus for decoding of intra prediction mode - Google Patents

Abstract

PURPOSE: An intra prediction mode decoding method and an apparatus for the same are provided to use an integrated signaling method in order to apply some of various intra prediction methods to an image selectively or altogether. CONSTITUTION: A decoding apparatus parses intra prediction mode information about a current block in a depth information map image (S1010). The decoding apparatus determines an intra prediction mode about the current block based on the intra prediction mode information (S1020). The decoding apparatus draws a final intra prediction mode about the current block by renewing the intra prediction mode according to a predetermined condition (S1030). The intra prediction mode information includes at least one of remaining intra prediction mode information and most probable mode (MPM) information. [Reference numerals] (S1010) Parse intra prediction mode information about a current block; (S1020) Determine an intra prediction mode about the current block based on the intra prediction mode information; (S1030) Draw a final intra prediction mode about the current block by renewing the intra prediction mode based on a GMPM

Description

Intra prediction mode decoding method and apparatus {METHOD AND APPARATUS FOR DECODING OF INTRA PREDICTION MODE}

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

3D video vividly provides a user with a three-dimensional effect as seen and felt in the real world through a three-dimensional display device. In this regard, three-dimensional video standards are underway at the Moving Picture Experts Group (MPEG) from ISO / IEC, a video standardization organization. The 3D video standard includes standards for advanced data formats and related technologies that can support not only stereoscopic images but also autostereoscopic images using real images and their depth information maps.

The present invention provides a method and apparatus for encoding / decoding a depth map image capable of improving image encoding / decoding efficiency.

The present invention provides an intra prediction mode encoding / decoding method and apparatus capable of improving the accuracy of a depth map image.

According to an aspect of the present invention, an intra prediction mode decoding method is provided. The method may include parsing intra prediction mode information on a current block in a depth map image, determining an intra prediction mode for the current block based on the intra prediction mode information, and determining a predetermined condition for the intra prediction mode. And deriving a final intra prediction mode for the current block, wherein the intra prediction mode information includes at least one of residual intra prediction mode information and Most Probable Mode (MPM) information. .

Encoding / decoding efficiency may be improved by using an integrated signaling method for selectively applying various intra prediction methods to an image or all of them.

1 is a view schematically showing an embodiment of a three-dimensional video system.
2 is a diagram illustrating an example of an actual image and a depth map image used to generate a virtual view image.
3 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment.
4 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment.
5 is a diagram illustrating an example of an intra prediction mode applicable to 16 × 16 blocks in H.264 / AVC.
6 is a diagram illustrating an example of an intra prediction mode applicable to an 8x8 block or a 4x4 block in H.264 / AVC.
FIG. 7 is a diagram for describing a method of encoding intra prediction mode information when a plane segmentation method is applied to a depth map.
FIG. 8 is a diagram for describing a method of encoding intra prediction mode information when a gradient-based highest probability mode (GMPM) is applied to a depth map.
9 is a block diagram schematically illustrating an example of a decoding apparatus for decoding an integrated intra prediction mode according to an embodiment of the present invention.
10 is a flowchart schematically illustrating an example of a method of decoding an integrated intra prediction mode according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the description may be omitted.

When a component is referred to herein as being "connected" or "connected" to another component, it may mean that it is directly connected to or connected to that other component, and another component in between. It may also mean that an element exists. In addition, the description "includes" a specific configuration in this specification does not exclude a configuration other than the configuration, it means that additional configuration may be included in the scope of the technical spirit of the present invention or the present invention.

Terms such as first and second may be used to describe various configurations, but the configurations are not limited by the terms. The terms are used to distinguish one configuration from another. For example, without departing from the scope of the present invention, the first configuration may be referred to as the second configuration, and similarly, the second configuration may also be referred to as the first configuration.

In addition, the components shown in the embodiments of the present invention are independently shown to represent different characteristic functions, and do not mean that each component is made of separate hardware or one software component unit. In other words, each component is listed as a component for convenience of description, and at least two of the components may form one component, or one component may be divided into a plurality of components to perform a function. The integrated and separated embodiments of each component are also included in the scope of the present invention without departing from the spirit of the present invention.

1 is a view schematically showing an embodiment of a three-dimensional video system.

Referring to FIG. 1, the 3D video system 100 generates image content including multi-view video information and depth information from a transmitting side and transmits the image content to a receiving side through a network. . In this case, the transmitted video content may be reproduced in various ways according to the display device of the receiver.

The transmitting side of the 3D video system 100 may generate video information using the stereo camera 110 and the multi-view camera 114, and generate a depth map using the depth camera 112. In addition, the 2D / 3D converter 116 may convert a 2D image into a 3D image. The 3D content generator 118 may generate image content of an N (N≥2) view using video information, a depth map, and the like.

The image content of the N view may include video information of the N view, a depth map thereof, additional information related to a camera, and the like. The video content at the N time point is compressed using a multiview video encoding method, and the compressed video content (bitstream) may be transmitted to a terminal on the receiving side through a network.

The receiving side of the 3D video system 100 may decode the received bitstream using a multiview video decoding method to reconstruct an image of N views. The depth map based rendering unit 120 may generate the received N view images as virtual view images of the N view or more through a depth-image-based rendering (DIBR) process. The virtual viewpoint images of more than N viewpoints are reproduced for various stereoscopic display apparatuses to provide a stereoscopic image to a user.

For example, a 2D image of a desired view may be freely selected from the N views and reproduced through the 2D display apparatus 122. Alternatively, the multi-view 3D display apparatus 124 may play a stereoscopic image of various views, or the head-tracked stereo display apparatus 126 may determine the position of the viewer to match the position of the viewer. Stereoscopic images can also be played back.

2 is a diagram illustrating an example of an actual image and a depth map image used to generate a virtual view image.

The depth map used to generate the virtual view image represents a distance between the camera and the real object (depth information corresponding to each pixel at the same resolution as the real image) in the real world in a certain number of bits.

The image shown in (a) of FIG. 2 is a "Champagne Tower" image used in the 3D video coding standard of MPEG, which is an international standardization organization, and the image shown in (b) of FIG. The depth map of the illustrated image is shown. The depth map illustrated in FIG. 2B represents depth information displayed on the screen at 8 bits per pixel.

In order to encode a depth map as shown in FIG. 2B, in general, H.264 / AVC, which is a video encoding method having the highest coding efficiency among video coding standards developed to date, may be used.

Hereinafter, a process of encoding and decoding using H.264 will be described with reference to FIGS. 3 and 4.

3 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment.

Referring to FIG. 3, the image encoding apparatus 300 may include a motion predictor 311, a motion compensator 312, an intra predictor 320, a switch 315, a subtractor 325, a converter 330, A quantization unit 340, an entropy encoding unit 350, an inverse quantization unit 360, an inverse transform unit 370, an adder 375, a deblocking filter unit 380, and a reference image buffer 390 are included.

In the case of H.264, the image encoding apparatus 300 processes data in units of a macroblock having a size of 16x16 pixels, encodes an input image in an intra mode or an inter mode. A bitstream can be output. In the intra mode, the switch 315 may be switched to intra, and in the inter mode, the switch 315 may be switched to inter.

The image encoding apparatus 300 may generate a prediction block for an input block of an input image, obtain a difference between the input block and the prediction block, and encode the difference. Generation of the prediction block may be performed according to the intra mode and the inter mode.

In the intra mode, the intra predictor 320 may generate a predictive block by performing spatial prediction using pixel values of blocks already encoded around the current block.

In the inter mode, the motion predictor 111 searches for a region that best matches an input block in the reference image stored in the reference image buffer 390 in the motion prediction process, and finds a motion vector (MV). You can get it. The motion compensator 312 may generate a prediction block by performing motion compensation using the motion vector.

The subtractor 325 may generate a residual block by the difference between the input block and the prediction block. The image encoding apparatus 300 may perform encoding on the residual block.

In this case, the intra mode may be divided into 16x16, 8x8, and 4x4 intra modes according to the size of the prediction block, and may be divided into 16x16, 16x8, 8x16, and 8x8 inter modes in the inter mode. In addition, in the case of the 8x8 inter mode, it may be divided into 8x8, 8x4, 4x8, and 4x4 sub inter modes.

In the case of a block encoded in the 16x16 intra mode, the transform unit 330 performs transform on the residual block to output transform coefficients, and collects only DC coefficients among the output transform coefficients. Hadamard) transform to output the Hadamard transformed DC coefficients.

In the case of a block encoded in another encoding mode except for the 16x16 intra mode, the transform unit 330 may perform transform on the residual block to output transform coefficients.

The quantization unit 340 may output the quantized coefficient by quantizing the input transform coefficient according to the quantization parameter.

The entropy encoding unit 350 may output a bit stream by performing entropy encoding based on values calculated by the quantization unit 340 or encoding parameter values calculated in the encoding process.

Since H.264 performs inter prediction encoding, the currently encoded picture needs to be decoded and stored to be used as a reference picture of a later input picture. Accordingly, the quantized coefficient may be inversely quantized by the inverse quantizer 360 and inversely transformed by the inverse transformer 370. Inverse quantized, inversely transformed coefficients are added to the predictive block via adder 375 and a reconstructed block (reconstructed block) can be generated.

The reconstruction block may pass through the deblocking filter 380 and may be stored in the reference image buffer 390. The deblocking filter 380 may remove a blocking artifact generated during the encoding process.

4 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment.

Referring to FIG. 4, the image decoding apparatus 400 may include an entropy decoder 410, an inverse quantizer 420, an inverse transform unit 430, an intra predictor 440, a motion compensator 450, and an adder 455. ), A deblocking filter unit 460, and a reference image buffer 470.

In the case of H.264, the image decoding apparatus 400 processes data in units of macroblocks having a size of 16x16 pixels and decodes the input bitstream in an intra mode or an inter mode. The reconstructed image may be output. In the intra mode, the switch is switched to the intra mode, and in the inter mode, the switch can be switched to the inter mode.

The image decoding apparatus 400 may decode the input bitstream to obtain a residual block, generate a prediction block, and then add the residual block and the prediction block to generate a reconstructed block, that is, a reconstruction block.

The entropy decoding unit 410 may entropy decode the input bitstream according to a probability distribution, and output a quantized coefficient.

The quantized coefficients are inversely quantized using the quantization parameter in the inverse quantization unit 420 and inversely transformed in the inverse transform unit 430. As a result of the inverse quantization / inverse transformation of the quantized coefficients, a reconstructed residual block may be generated.

In the intra mode, the intra predictor 440 may generate a prediction block by performing spatial prediction using pixel values of blocks already decoded around the current block. In the inter mode, the motion compensator 450 may generate a prediction block by performing motion compensation by searching for an area in a reference picture stored in the reference picture buffer 470 using a motion vector.

The residual block and the prediction block may be added through the adder 455, and the added block may be stored in the reference image buffer 470 after the blocking artifact is removed by the deblocking filter 460.

On the other hand, since the depth map is an image representing the distance between the camera and the object in the real world, the pixel change may be considerably slower than the actual image in the background of the image and the region inside the object. However, a sharp edge component may appear due to a large difference between pixels in the object boundary portion of the depth map. Therefore, when the depth map is encoded by using the existing discrete cosine transform (DCT) based video encoding method, the high frequency component is remarkably increased due to the sharp edge component that may exist at the object boundary. If the high frequency component is increased, the loss in the quantization step results in severe crushing at the object boundary.

H.264 / AVC provides an intra prediction coding method based on various directions. This method generates a prediction block using adjacent pixels of the current block according to the directionality of the intra prediction mode.

5 is a diagram illustrating an example of an intra prediction mode applicable to a 16x16 block in H.264 / AVC, and FIG. 6 is an example of an intra prediction mode applicable to an 8x8 block or a 4x4 block in H.264 / AVC. It is a figure which shows.

When intra prediction is performed on a 16x16 block in H.264 / AVC, four intra prediction modes exist according to the prediction direction. Each of the four intra prediction modes has a different prediction direction and is assigned a different mode number.

For example, as shown in FIG. 5, when the mode number is 0, the mode number may be a vertical direction mode, and a prediction block may be generated using pixels adjacent to the current block. When the mode number is 1, the mode number may be a horizontal direction mode, and a prediction block may be generated using pixels adjacent to the left side of the current block. If the mode number is 2, it may be a DC mode, and the DC mode may generate a prediction block using an average of pixels adjacent to the upper and left sides of the current block. If the mode number is 3, it may be a plane mode. In the plane mode, prediction may be performed by interpolating pixels adjacent to the upper and left sides of the current block in a diagonal direction.

When intra prediction is performed on an 8x8 block or a 4x4 block in H.264 / AVC, nine intra prediction modes exist according to the prediction direction. Each of the nine intra prediction modes have different prediction directions and are assigned different numbers.

For example, as shown in Fig. 6, the vertical direction mode of mode number 0, the horizontal direction mode of mode number 1, the DC mode of mode number 2, the diagonal down-left of mode number 3 ( diagonal down-left direction mode, diagonal down-right direction mode with mode number 4, vertical-right direction mode with mode number 5, horizontal-down mode mode mode 6 down direction mode, a vertical-left direction mode of mode number 7, and a horizontal-up direction mode of mode number 8 may exist. According to the directions of each of the nine prediction modes, a prediction block may be generated using pixels adjacent to the current block having an 8x8 or 4x4 size.

The prediction direction mode having the directionality as shown in FIGS. 5 and 6 occupies a relatively large portion in the bitstream. Therefore, since the prediction direction mode has a high correlation with neighboring blocks located around the current block, the prediction direction mode for the current block may be inferred and encoded based on the intra prediction mode of the neighboring blocks. In this case, an encoding method using a mode having a small mode number among the prediction modes of the neighboring blocks, that is, whether the most probable mode (MPM) matches the prediction mode information of the current block may be used. That is, it may be encoded using flag information indicating whether the prediction mode of the current block is predicted from the neighboring block. If the value of the flag is 1, the current block uses the mode predicted from the neighboring block, that is, the highest probability mode (MPM). If the value of the flag is 0, the actual prediction mode information for the current block may be encoded. When the value of the flag is 0, the actual prediction mode for the current block performs encoding on 8 prediction modes except the highest probability mode (MPM), so that the actual prediction mode for the current block can be encoded with residual intra prediction mode information (3 bits). have.

Meanwhile, when encoding the depth map, there is an intra prediction method using plane segmentation in order to preserve the object boundary portion in the depth map as much as possible.

FIG. 7 is a diagram for describing a method of encoding intra prediction mode information when a plane segmentation method is applied to a depth map. The method of FIG. 7 may be performed by the encoding apparatus of FIG. 3.

Referring to FIG. 7, the encoding apparatus may separate a predetermined region (block) into two regions 710 and 720 based on an object boundary in the depth map. In this case, the encoding apparatus may encode and transmit bitmap information to the decoding apparatus to represent the two divided regions 710 and 720. In this case, encoded pixel (to-be-encoded pixels) is (C ₁ ~ C ₁₆₎ currently encoded pixel to which the block to be coded efficiently predict the bit map information of the (C ₁ ~ C ₁₆₎ the available pixels around the The bitmap information may be predicted and encoded by referring to the reference regions R ₁ to R ₉ composed of (available pixels), for example, indicating whether a specific block is encoded using a plane segmentation method. In order to do this, DC mode among intra prediction modes may be used. That is, if the intra prediction mode of the block is the DC mode, it can be seen that the block is encoded using the plane segmentation method.

As described above, unlike the case where the DC mode is used to indicate whether the corresponding block is coded by using a plane segmentation method, the variation-based method is used to efficiently infer the intra prediction mode information on the depth map. There is a method using the gradient-based Most Probable Mode (GMPM). The gradient-based highest probability mode (GMPM) is a method of inferring an intra prediction mode of a current block (the current block in the current depth map) by using correlation of neighboring pixel information located around the current block to be encoded.

FIG. 8 is a diagram for describing a method of encoding intra prediction mode information when a gradient-based highest probability mode (GMPM) is applied to a depth map. The method of FIG. 8 may be performed by the encoding apparatus of FIG. 3.

Referring to FIG. 8, the gradient-based highest probability mode (GMPM) performs intra prediction using pixel values of neighboring blocks 820 and 830 located near the current block 810, and neighbors blocks 820 and 830. Find the distortion rate for. In this case, five of nine modes may be used as the intra prediction mode. The intra prediction mode having the lowest value among the distortion rates for the neighboring blocks 820 and 830 is used as the highest probability mode (MPM) of the current block 810.

Therefore, since the neighboring blocks of the current block can be used only after all of them are encoded / decoded, the method can be performed in a decoding step instead of a parsing step of the decoding apparatus.

For example, suppose that a 16x16 block is divided into four 8x8 blocks, so that each 8x8 block performs intra prediction encoding. In the parsing step of the decoding apparatus, the intra prediction mode for each 8x8 block is parsed. In this parsing step, the prediction mode having the smallest mode number among the prediction modes of the neighboring blocks is determined as the highest probability mode (MPM). In this case, each 8x8 block is not restored in the parsing step of the decoding apparatus but is restored in the decoding step. Therefore, since neighboring blocks have not yet been restored, the method using gradient based highest probability mode (GMPM) is not applicable in the parsing step. That is, gradient-based highest probability mode (GMPM) may be applied in the decoding step. In the decoding step, the intra prediction mode for the current block obtained in the parsing step is updated again using the gradient-based highest probability mode (GMPM) and applied to the current block.

As described above, a method of intra-prediction encoding of a depth map image such as an intra prediction method of H.264 / AVC, an intra prediction method using plane segmentation, and an intra prediction method using gradient based highest probability mode (GMPM) Varies.

These intra prediction methods may be selectively applied to the image or all of them. In this case, signaling information for distinguishing a prediction method applied to an image is required. However, when signaling information is allocated to each method, the bit amount may increase.

In addition, the intra prediction method using the gradient-based highest probability mode (GMPM) does not apply the intra prediction mode for the current block using the highest probability mode (MPM), and the gradient-based highest probability mode ( GMPM) is used to obtain the intra prediction mode and apply it to the current block. Therefore, the intra prediction mode obtained using the highest probability mode (MPM) in the parsing step may be an incorrect mode that does not apply to the current block.

In the intra prediction method using the plane segmentation method, the decoding apparatus determines whether to decode bitmap information by using the intra prediction mode information obtained in the parsing step. However, the intra prediction mode information obtained at the parsing step may be inaccurate information. Therefore, when encoding / decoding the depth map, when the plane segmentation method and the method using the gradient-based highest probability mode (GMPM) are integrated and applied, parsing information may be parsed incorrectly (intra prediction mode information). Can cause problems. There is a need for an integrated signaling method to solve this problem.

Hereinafter, the present invention provides a method and apparatus for encoding / decoding integrated intra prediction mode information for applying various intra prediction coding methods.

As described above, the intra prediction method using plane segmentation signals using the DC mode among the intra prediction modes. The intra prediction method using the gradient-based highest probability mode (GMPM) is coded using five of nine intra prediction modes. Accordingly, the present invention provides a method of using the prediction mode, which is not used in the gradient-based highest probability mode (GMPM) method, among nine intra prediction modes to signal the intra prediction method using plane segmentation.

For example, the least generated mode among nine intra prediction modes may be set as an intra prediction mode using plane segmentation. For example, a mode number '8', which is a mode number having the largest value among intra prediction modes, may be set as an intra prediction mode using plane segmentation. In this case, when the intra prediction mode using plane segmentation (eg, '8' mode) is selected as the highest probability mode (MPM), and the current block uses the gradient-based highest probability mode (GMPM) method, the current block Can be prevented from being predicted in the same intra prediction mode as the gradient based highest probability mode (GMPM).

In summary, when the encoding apparatus encodes a current block using an arbitrary intra prediction mode, the encoding apparatus does not use the arbitrary intra prediction mode for the current block when all of the following cases are satisfied.

1) The current image is a depth map.

2) An intra prediction method using plane segmentation may be applied to the current block.

3) The highest probability mode (MPM) is mode eight. (Ie, the highest probability mode (MPM) is an intra prediction mode using plane segmentation.)

4) The current block uses gradient based highest probability mode (GMPM).

5) The gradient based highest probability mode (GMPM) is the same as any intra prediction mode for the current block.

9 is a block diagram schematically illustrating an example of a decoding apparatus for decoding an integrated intra prediction mode according to an embodiment of the present invention.

When various intra prediction coding methods are applied to the depth map image such as an intra prediction method using plane segmentation and an intra prediction method using gradient based highest probability mode (GMPM), the decoding apparatus of FIG. 9 is applied to the depth map. It is possible to derive an accurate prediction mode for the

Referring to FIG. 9, the decoding apparatus 900 includes a parser 910 and a decoder 920.

The parsing unit 910 parses the input bitstream to restore the intra prediction mode information on the current block, and determines the intra prediction mode of the current block based on the reconstructed intra prediction mode information.

More specifically, the parser 910 may include an intra prediction information parser 911 and an intra prediction information corrector 912.

The intra prediction information parsing unit 911 parses the input bitstream and restores the intra prediction mode information on the current block. The intra prediction mode information may be residual intra prediction mode information and highest probability mode (MPM) information.

The intra prediction information correction unit 912 modifies the intra prediction mode information parsed by the intra prediction information parser 911 according to the situation and the condition. For example, the intra prediction mode for the current block may be determined based on at least one of the remaining intra prediction mode information and the highest probability mode (MPM) information parsed by the intra prediction information parser 911.

For example, if the remaining intra prediction mode information (3 bits) has a value of '7', the intra prediction mode actually means mode '8', and thus the intra prediction information corrector 912 determines the intra prediction mode for the current block. You can decide with '8'. In this case, as described above, when the least generated mode (for example, '8' mode) of the nine intra prediction modes is used as the intra prediction mode using the plane segmentation, the prediction mode for the current block is used as the plane. Set to intra prediction mode using segmentation.

As another example, when the current block is encoded in the highest probability mode (MPM) and the highest probability mode (MPM) has a value of '8', the intra prediction information corrector 912 sets the intra prediction mode for the current block to '0'. Can be decided.

The intra prediction information correction unit 912 may be applied when decoding the depth map image.

The decoder 920 updates the intra prediction mode for the current block input from the parser 910 based on the gradient-based highest probability mode (GMPM) to derive the final intra prediction mode.

More specifically, the decoder 920 may include an intra prediction information updater 921 and an intra prediction decoder 922.

The intra prediction information updater 921 updates the intra prediction mode for the current block input from the parser 910. For example, the intra prediction mode for the current block determined by the parser 910 may be updated using the gradient-based highest probability mode (GMPM), and the updated intra prediction mode may be derived as the final intra prediction mode for the current block. have.

The intra prediction decoder 922 generates a prediction block by performing prediction on the current block by using the final intra prediction mode derived from the intra prediction information updater 921. The reconstructed image may be output by adding the prediction block and the residual block.

In summary, when all of the following cases are satisfied, the decoding apparatus may change the intra prediction mode for the current block to the intra prediction mode using plane segmentation ('8' mode).

1) The current image is a depth map.

2) An intra prediction method using plane segmentation may be applied to the current block.

3) The remaining intra prediction mode information (3 bits) has a value of '7'.

10 is a flowchart schematically illustrating an example of a method of decoding an integrated intra prediction mode according to an embodiment of the present invention. The method of FIG. 10 may be performed by the decoding apparatus of FIG. 9 described above.

When various intra prediction coding methods such as intra prediction using plane segmentation and intra prediction using gradient based highest probability mode (GMPM) are applied to the depth map image, the method of FIG. Accurate prediction modes can be derived.

Referring to FIG. 10, the decoding apparatus parses and reconstructs intra prediction mode information on a current block (S1010). The intra prediction mode information may be residual intra prediction mode information and highest probability mode (MPM) information.

The decoding apparatus determines an intra prediction mode for the current block based on the parsed intra prediction mode information (S1020). That is, the intra prediction mode for the current block may be determined using at least one of the remaining intra prediction mode information and the highest probability mode (MPM) information.

For example, if the parsed residual intra prediction mode has a value of '7', the decoding apparatus may determine the intra prediction mode for the current block as the '8' mode (intra prediction mode using plane segmentation). Alternatively, when the current block is encoded in the highest probability mode MPM and the highest probability mode MPM has a value of '8', the decoding apparatus may determine the intra prediction mode for the current block as the '0' mode.

The decoding apparatus updates the intra prediction mode for the current block determined in step S1020 according to a predetermined condition (or situation), and derives the updated intra prediction mode as the final intra prediction mode for the current block (S1030). For example, if the intra-prediction mode for the current block is performed by applying the above-described gradient-based highest probability mode (GMPM), the decoding apparatus changes the intra prediction mode for the current block determined in step S1020 to the gradient-based highest probability mode ( GMPM), and the updated intra prediction mode may be derived as the final prediction mode for the current block.

The decoding apparatus may generate the prediction block by performing prediction on the current block using the final intra prediction mode.

As described above, a method for signaling by applying various intra prediction coding methods such as an intra prediction method using plane segmentation and an intra prediction method using gradient based highest probability mode (GMPM) is described with reference to FIGS. 9 and 10. In addition to the following methods, various methods can be used as follows.

1) According to an embodiment, the intra prediction encoding method may be distinguished by encoding using the flag information for each intra prediction encoding method.

2) In another embodiment, a new intra prediction mode may be used to signal an intra prediction method using plane segmentation. That is, in nine intra prediction modes, ten intra prediction modes may be used by adding a mode for an intra prediction method using plane segmentation.

3) In another embodiment, the method using the gradient-based highest probability mode (GMPM) may be applied when all neighboring blocks located near the current block are restored.

As described above, a method for applying various intra prediction encoding methods may be variously changed.

In the above-described embodiments, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive, that other steps may be included, or that one or more steps in the flowchart may be deleted without affecting the scope of the present invention. You will understand.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of the claims should be construed as being included in the scope of the present invention.

Claims (1)

Parsing intra prediction mode information on a current block in a depth map image;
Determining an intra prediction mode for the current block based on the intra prediction mode information; And
Updating the intra prediction mode according to a predetermined condition to derive a final intra prediction mode for the current block,
The intra prediction mode information includes at least one of residual intra prediction mode information and Most Probable Mode (MPM) information.

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