KR20140093869A - Method and apparatus for intra prediction, and apparatus for processing picture - Google Patents

Abstract

The present invention relates to a method and an apparatus for intra prediction and an apparatus for processing images. The method for intra prediction according to an embodiment of the present invention comprises a step of calculating difference value between pixels neighboring blocks; a step of determining the block type based on the calculated difference value of the pixels; a step of determining candidate intra prediction modes by selecting some intro prediction modes depending on the block type; and a step of determining a intra prediction mode among the selected modes to be used for encoding the block.

Description

TECHNICAL FIELD [0001] The present invention relates to an intra prediction method, an intra prediction method,

The present invention relates to an intra prediction method and apparatus, and an image processing apparatus.

Recently, there is an increasing demand for high definition and high definition video such as HD (High Definition) video and UHD (Ultra High Definition) video in various applications. As the image data becomes high resolution and high image quality, the data amount increases relative to the existing image data. Therefore, when the image data is transmitted using a medium such as a wired / wireless broadband line or stored in an existing storage medium, The cost increases. High-efficiency image compression technology is required to solve such problems as image data becomes high-resolution and high-quality.

An inter prediction technique for predicting a pixel value included in a current picture from a previous or a subsequent picture of a current picture using an image compression technique, an intra prediction technique for predicting a pixel value included in a current picture using pixel information in the current picture, there are a variety of techniques such as intra prediction technology, entropy coding technique in which short codes are assigned to values having a high appearance frequency, and long codes are assigned to values having a low appearance frequency. It can be compressed and transmitted or stored effectively.

An embodiment of the present invention aims to provide an intra prediction method and apparatus for reducing an amount of calculation required for intraprediction of an image and improving an encoding speed, and an image processing apparatus.

An embodiment of the present invention aims to provide an intra prediction method and apparatus for improving an encoding speed without reducing the compression efficiency of an image, and an image processing apparatus.

An intra prediction method according to an exemplary embodiment of the present invention includes: calculating a difference between pixel values of neighboring pixels adjacent to a block; Determining a type of the block based on the difference; Determining a candidate intra prediction mode by selecting a portion of the intra prediction modes according to the type of the block; And determining an intra prediction mode to be used for coding the block among the selected partial modes.

Calculating the difference comprises: calculating a difference between upper neighboring pixels on the upper side of the block; And calculating a difference between left neighboring pixels adjacent to the left side of the block.

Wherein calculating the difference of the upper neighboring pixels comprises: calculating an upper neighboring pixel difference value by summing an absolute value of the difference of pixel values between adjacent pixels of the upper neighboring pixels, Calculating a difference between the left neighboring pixel and the left neighboring pixel may include calculating a left neighboring pixel difference value by summing an absolute value of a difference between pixel values between adjacent pixels among the left neighboring pixels.

Wherein determining the type of the block comprises: if the upper surrounding pixel difference value is greater than a predetermined upper boundary value and the left surrounding pixel difference value is less than or equal to a predetermined left boundary value, As a difference block.

Wherein the step of determining the type of the block comprises the steps of: if the upper surrounding pixel difference value is less than or equal to a predetermined upper boundary value, and the left surrounding pixel difference value is greater than a predetermined left boundary value, As a difference block.

The upper boundary value and the left boundary value may be inversely proportional to the size of the block.

Wherein the determining of the block type comprises: if the upper surrounding pixel difference value is greater than a preset upper first boundary value and the left surrounding pixel difference value is less than or equal to a predetermined left second boundary value, And determining the type as an upper side high differential block.

Wherein determining the type of the block comprises: if the upper surrounding pixel difference value is less than or equal to a preset upper second boundary value and the left surrounding pixel difference value is greater than a predetermined left first boundary value, And determining the type as a left high differential block.

The step of determining the candidate intra prediction mode may include a step of selecting a plane mode, a DC mode, and an upward direction mode among the intra prediction modes in the case of the upper side high-differential block.

The step of determining the candidate intra prediction mode may include: selecting a plane mode, a DC mode, and a leftward mode among the intra prediction modes in the case of the left high-difference block.

The step of determining the candidate intra prediction mode may further include a step of selecting a horizontal direction mode among the intra prediction modes in the case of the upper side high differential block.

The step of determining the candidate intra prediction mode may further include a step of selecting a vertical direction mode among the intra prediction modes in the case of the left high differential block.

The step of determining the candidate intra prediction mode may further include: selecting an intra prediction mode to be used for coding a neighboring block adjacent to the block.

The intra prediction method according to an embodiment of the present invention selects a part of the intra prediction modes according to a difference between pixel values of neighboring pixels adjacent to the block and performs intra prediction based on the selected partial mode.

The intra prediction method according to an embodiment of the present invention may be implemented as a program that can be executed by a computer, and may be recorded in a computer-readable recording medium.

An intraprediction apparatus according to an embodiment of the present invention includes a difference calculator that calculates a difference between pixel values of neighboring pixels adjacent to a block; A block type determination unit for determining a type of a block based on the difference; A mode selection unit for selecting a part of the intra prediction mode according to the type of the block; And an intra prediction mode determiner for determining an intra prediction mode to be used for coding the block among the selected partial modes.

Wherein the difference calculator calculates a first difference value by summing an absolute value of a difference between pixel values of adjacent pixels among neighboring upper neighboring pixels on the upper side of the block to calculate a first difference value, The second difference value can be calculated by summing the absolute values of the differences of the pixel values between the pixels.

Wherein the block type determination unit classifies the block into a first type when the first difference value is greater than a predetermined upper boundary value and the second difference value is less than or equal to a predetermined left boundary value, If the difference value is smaller than or equal to the upper boundary value and the second difference value is larger than the left boundary value, the block can be classified into the second type.

The upper boundary value and the left boundary value may be set to be in inverse proportion to the size of the block.

Wherein the block type determination unit classifies the block into a first type when the first difference value is greater than a preset upper boundary value and the second difference value is less than or equal to a predetermined left second boundary value And classifying the block into a second type when the first difference value is less than or equal to a preset upper second boundary value and the second difference value is greater than a predetermined left boundary value.

The upper first boundary value, the upper second boundary value, the left first boundary value, and the left second boundary value may be set to be in inverse proportion to the size of the block.

The upper first boundary value may be set to be larger than the upper second boundary value, and the left first boundary value may be set to be larger than the left second boundary value.

Wherein the mode selection unit selects a plane mode, a DC mode, and an upward direction mode among the intra prediction modes when the block is the first type, and selects a plane mode, a DC mode, and an upward mode when the block is the first type, The DC mode and the left-facing mode can be selected.

Wherein the mode selection unit further selects a mode in a horizontal direction among the intra prediction modes when the block is the first type and selects a mode in the vertical direction among the intra prediction modes when the block is the second type have.

The mode selector may further select an intra prediction mode used for coding a neighboring block adjacent to the block.

An image processing apparatus according to an exemplary embodiment of the present invention includes an intra predictor for generating intra prediction based on a reference pixel positioned around an input block to generate a prediction block; A motion prediction unit for calculating a motion vector of an input block using a reference image; A motion compensation unit for performing motion compensation based on the motion vector to generate a prediction block; A subtracter for calculating a difference between an input block and a prediction block to generate a residual block; A transform unit for transforming the residual block to output a transform coefficient; And a quantization unit for quantizing the transform coefficients and outputting the quantized coefficients, wherein the intraprediction unit comprises: a difference calculation unit for calculating a difference between pixel values of neighboring pixels adjacent to the input block; A block type determination unit for determining a type of an input block based on the difference; A mode selection unit for selecting a part of the intra prediction mode according to the type of the input block; And an intra prediction mode determiner for determining an intra prediction mode to be used for coding the input block among the selected partial modes.

According to one embodiment of the present invention, the amount of computation for intraprediction is reduced and the encoding speed can be improved.

According to an embodiment of the present invention, it is possible to shorten the encoding time without losing the compression efficiency of the image.

1 is a block diagram of an intra prediction apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram exemplarily showing an image to be encoded and blocks constituting the image according to an embodiment of the present invention.
3 is an exemplary diagram illustrating a current block to be encoded and neighboring pixels thereof according to an embodiment of the present invention.
4 is a diagram illustrating pixel values of upper neighboring pixels for which a difference is calculated according to an embodiment of the present invention.
5 is a diagram showing pixel values of left neighboring pixels for which a difference is calculated according to an embodiment of the present invention.
FIGS. 6 and 7 illustrate directions of intraprediction modes that are likely to occur according to the difference of neighboring pixels.
8 is an exemplary diagram illustrating the types of blocks that are determined based on the difference of neighboring pixels according to an embodiment of the present invention.
9 is an exemplary diagram illustrating the types of blocks that are determined based on the difference of neighboring pixels according to another embodiment of the present invention.
10 is a diagram for explaining a direction of an intra prediction mode used for intra prediction according to an embodiment of the present invention.
11 is a diagram illustrating an exemplary direction of a candidate intra prediction mode for an upper high-order differential block according to an embodiment of the present invention.
12 is a diagram illustrating an exemplary direction of a candidate intra prediction mode for a left high-order differential block according to an embodiment of the present invention.
13 is a diagram illustrating an exemplary direction of a candidate intra prediction mode for an upper high-order differential block according to another embodiment of the present invention.
FIG. 14 is a diagram illustrating an exemplary direction of a candidate intra prediction mode for a left high-order differential block according to another embodiment of the present invention.
15 is a diagram for explaining a direction of a candidate intra prediction mode for an upper high-order differential block according to another embodiment of the present invention.
16 is a diagram illustrating an exemplary direction of a candidate intra prediction mode for a left high-order differential block according to another embodiment of the present invention.
17 is a view for explaining an intra prediction method according to an embodiment of the present invention.
18 is a diagram illustrating steps of calculating a difference and determining a type of a block according to an embodiment of the present invention.
19 is a diagram illustrating steps of calculating a difference and determining a type of a block according to another embodiment of the present invention.
20 is a view for explaining a step of selecting a candidate intra prediction mode for a first type block and a step of determining an intra prediction mode to be used for encoding according to an embodiment of the present invention.
FIG. 21 is a view for explaining a step of selecting a candidate intra prediction mode for a block of a second type and determining an intra prediction mode to be used for encoding according to an embodiment of the present invention.
22 is a block diagram illustrating an image encoding apparatus according to an embodiment of the present invention.
23 is a block diagram illustrating an image decoding apparatus according to an embodiment of the present invention.

Other advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Unless defined otherwise, all terms (including technical or scientific terms) used herein have the same meaning as commonly accepted by the generic art in the prior art to which this invention belongs. Terms defined by generic dictionaries may be interpreted to have the same meaning as in the related art and / or in the text of this application, and may be conceptualized or overly formalized, even if not expressly defined herein I will not.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms' comprise 'and / or various forms of use of the verb include, for example,' including, '' including, '' including, '' including, Steps, operations, and / or elements do not preclude the presence or addition of one or more other compositions, components, components, steps, operations, and / or components. The term 'and / or' as used herein refers to each of the listed configurations or various combinations thereof.

It should be noted that the terms such as '~', '~ period', '~ block', 'module', etc. used in the entire specification may mean a unit for processing at least one function or operation. For example, a hardware component, such as a software, FPGA, or ASIC. However, '~ part', '~ period', '~ block', '~ module' are not meant to be limited to software or hardware. Modules may be configured to be addressable storage media and may be configured to play one or more processors. ≪ RTI ID = 0.0 >

Thus, by way of example, the terms 'to', 'to', 'to block', 'to module' refer to components such as software components, object oriented software components, class components and task components Microcode, circuitry, data, databases, data structures, tables, arrays, and the like, as well as components, Variables. The functions provided in the components and in the sections ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ' , '~', '~', '~', '~', And '~' modules with additional components.

An intra prediction apparatus and method and an image encoding method using the intra prediction apparatus according to an embodiment of the present invention are configured to calculate a difference between pixel values of neighboring pixels adjacent to a block and to generate an intra prediction mode, You can select in prediction mode. Then, by determining the intra prediction mode to be used for coding the block among the candidate intra prediction modes, it is possible to reduce the amount of operations performed in intra prediction and improve the encoding speed.

1 is a block diagram of an intra prediction apparatus according to an embodiment of the present invention.

1, the intra prediction apparatus 100 may include a difference calculation unit 11, a block type determination unit 12, a mode selection unit 13, and an intra prediction mode determination unit 14 have.

The difference calculator 11 may calculate a difference between pixel values of neighboring pixels adjacent to the block. The block type determination unit 12 can determine the type of the block based on the difference. The mode selector 13 can select a part of the intra prediction modes according to the type of the block. The intra prediction mode determination unit 14 may determine an intra prediction mode to be used for coding the block among the selected partial modes.

FIG. 2 is a block diagram exemplarily showing an image to be encoded and blocks constituting the image according to an embodiment of the present invention.

The image 20 is coded in an intra mode or an inter mode, and an intra prediction method or an inter prediction method may be selectively applied to each block to determine an optimal prediction method for blocks constituting the image. An embodiment of the present invention provides an apparatus and method for intraprediction of a block 201 constituting an image 20.

In this specification, the current block refers to a current block to be currently encoded among a plurality of blocks constituting the image 20. The neighboring pixels may include neighboring pixels on the upper side of the current block and neighboring neighboring pixels on the left side of the current block, according to an embodiment of the present invention.

3 is an exemplary diagram illustrating a current block to be encoded and neighboring pixels thereof according to an embodiment of the present invention.

3, the neighboring pixels 202 and 203 according to an embodiment of the present invention include upper neighboring pixels 202 positioned on the upper side of the current block 201, Left neighboring pixels 203 located adjacent to the left side of the pixel 201.

However, the peripheral pixels 202 and 203 are not limited to the pixels positioned on the upper and left sides as described above, but may be formed on the upper and right sides, the lower and left sides, or the lower and right sides of the current block 201, As shown in FIG.

3, when the size of the current block 201 is n x n, the upper peripheral pixels 202 may be n pixels composed of A ₁ through A _n , and the left peripheral pixels 203 ) May be n pixels composed of L ₁ to L _n .

The difference calculator 11 may calculate a difference between pixel values of neighboring pixels 202 and 203 adjacent to the block 201. [

According to an embodiment of the present invention, the difference calculator 11 sums the absolute values of the differences of pixel values between adjacent pixels of the upper peripheral pixels 202 adjacent to the upper side of the block 201, The pixel difference value may be calculated and the left neighboring pixel difference value may be calculated by adding the absolute value of the difference of pixel values between adjacent pixels among the left neighboring pixels 203 adjacent to the left side of the block 201. [

4 is a diagram illustrating pixel values of upper neighboring pixels 202 whose difference is calculated according to an embodiment of the present invention. (203). ≪ / RTI >

The difference calculation section 11 is the upper side close to the pixel 202 of neighboring pixels of the (e. G., A ₁ and A _2, A ₂ and A _3, A ₃ and A _4, ..., A _{n -1} and A _n ) can be calculated. Here, the pixel value means the luminance value, but the present invention is not limited thereto, and may mean a color difference value, an R, a G, and a B value according to an embodiment.

For example, referring to FIG. 4, the difference calculator 11 calculates a difference between pixel values of adjacent pixels among the pixels belonging to the upper peripheral pixels 202, for example, Y ₁ - Y ₂ , Y ₂ - Y ₃ , ..., Y _{n -1} - Y _n and summing their absolute values to obtain the upper surrounding pixel difference value (D _A ).

Similarly, the difference calculator 11 calculates the difference between adjacent pixels (for example, L ₁ and L ₂ , L ₂ and L ₃ , L ₃ and L ₄ , ..., L _{n -1} And L _n ) can be calculated.

For example, referring to FIG. 5, the difference calculator 11 calculates Y ₁ - Y ₂ , Y ₂ - Y ₃ , ..., Y _{n -1} - Y _n , To obtain the left neighboring pixel difference value D _L.

The block type determination unit 12 can determine the type of the block based on the calculated difference. According to one embodiment, the block type determination unit 12 may determine the type of the block 201 by comparing the upper peripheral pixel difference value D _A and the left peripheral pixel difference value D _L with boundary values, respectively have.

According to an embodiment of the present invention, the block type determining unit 12 determines that the upper surrounding pixel difference value D _A is larger than the predetermined upper boundary value B _A and the left surrounding pixel difference value D _L Is smaller than or equal to the predetermined left boundary value B _L , the type of the block 201 may be determined as the upper side high differential block.

According to one embodiment, the block type determination section 12 is the upper side close to the pixel difference value (D _A) is pre-set upper boundary value is smaller than or equal to (B _A), wherein the left peripheral pixel difference value ( D _L ) is greater than a predetermined left boundary value (B _L ), the type of the block 201 may be determined as a left high-difference block.

The block type determining unit 12 determines that the upper surrounding pixel difference value D _A is larger than the predetermined upper boundary value B _A and the left surrounding pixel difference value D _L is greater than the predetermined upper boundary value B _A , Is greater than the predetermined left boundary value (B _L ), the type of the block 201 may be determined as another block.

According to one embodiment, the block type determination section 12 is the upper side close to the pixel difference value (D _A) is pre-set upper boundary value is smaller than or equal to (B _A) of the left around the pixel difference value (D _L is less than or equal to the left boundary value B _L , the type of the block 201 may be determined as another block.

Hereinafter, for convenience of description, the upper high-order difference block is described as a first type, the left high-order difference block as a second type, and the other blocks as a third type.

FIGS. 6 and 7 illustrate directions of intraprediction modes that are likely to occur in accordance with a difference between neighboring pixels of a block.

In one embodiment of the present invention, when the difference value of one neighboring pixel among the neighboring pixels of the block is large and the difference value of the neighboring neighboring pixels is small, it is highly likely that the intra prediction mode of the corresponding block is directed toward one side having a large difference value It is possible to select the candidate intra prediction mode.

6, when the difference value D _A of the upper peripheral pixels 202 is larger than the predetermined upper boundary value B _A and the difference value D _A of the left peripheral pixels 203 D _L is less than or equal to the predetermined left boundary value B _L , the pixels constituting the block 201 may have a large difference in pixel values in the horizontal direction, Is high. Therefore, in this case, it can be expected that the intra prediction mode of the block 201 is likely to be upward as in the vertical mode.

7, when the difference value D _A of the upper peripheral pixels 202 is less than or equal to the predetermined upper boundary value B _{A and} the difference value D _A of the left peripheral pixels 203 D _L is larger than the predetermined left boundary value B _L , the pixels constituting the block 201 are also likely to have a large difference in pixel values in the vertical direction but a small difference in pixel values in the horizontal direction . Therefore, in this case, it is expected that the intra prediction mode of the block 201 is likely to be directed to the left side as in the horizontal mode.

8 is an exemplary diagram illustrating the types of blocks that are determined based on the difference of neighboring pixels according to an embodiment of the present invention.

8, the block type determining unit 12 determines that the upper peripheral pixel difference value D _A is larger than the upper boundary value B _A and the left peripheral pixel difference value D _L is greater than the left boundary Is less than or equal to the value B _L , the block 201 can be determined as the first type.

Further, the block type determination section 12, the upper side around the pixel difference value (D _A) is the upper boundary value is smaller than or equal to (B _A), the left side close to the pixel difference value (D _L) the left boundary value (B _L ), The block 201 can be determined as the second type.

In addition, the block type determination unit 12 determines whether or not the upper peripheral pixel difference value D _A is larger than the upper boundary value B _A and the left peripheral pixel difference value D _L is greater than the left boundary value B _L , If greater than; Or the upper surrounding pixel difference value D _A is smaller than or equal to the upper boundary value B _A and the left surrounding pixel difference value D _L is less than or equal to the left boundary value B _L , ) Can be determined as the third type.

According to an embodiment of the present invention, the boundary value may be set to be in inverse proportion to the size of the block 201. [ For example, when the size of the block 201 constituting the image 20 can be variously set to two or more sizes (for example, 4x4, 8x8, 16x16, 32x32) The left boundary value B _A and the left boundary value B _L may be set to a smaller value as the size of the block 201 increases.

In the embodiment shown in FIG. 8, the boundary value is set for each of the upper surrounding pixel difference value and the left surrounding pixel difference value. However, according to the embodiment, the boundary value may be set to a difference value between the upper peripheral pixel difference value and the left peripheral pixel difference value More than two of each may be set.

9 is an exemplary diagram illustrating the types of blocks that are determined based on the difference of neighboring pixels according to another embodiment of the present invention.

In the embodiment shown in FIG. 9, two boundary values are set for the upper peripheral pixel difference value D _A and the left peripheral pixel difference value D _L , respectively.

9, the block type determining unit 12 determines that the upper surrounding pixel difference value D _A is larger than the predetermined upper first boundary value B _AH and the left surrounding pixel difference value D _A D _L ) is less than or equal to the preset left second boundary value B _LL , the block 201 can be determined as the first type.

The block type determination unit 12 determines whether or not the upper surrounding pixel difference value D _A is less than or equal to a preset upper second boundary value B _AL and the left surrounding pixel difference value D _L is greater than or equal to And determines the block 201 as the second type when the first left boundary value is greater than the predetermined left boundary value B _LH .

In addition, the block type determining unit 12 determines whether or not (i) the upper surrounding pixel difference value D _A is greater than a predetermined upper first boundary value B _AH and the left surrounding pixel difference value D _L ) Is greater than a predetermined first left boundary value (B _LH ); (ii) when the upper surrounding pixel difference value D _A is less than or equal to a preset upper second boundary value B _AL and the left surrounding pixel difference value D _L is less than or equal to a predetermined left second boundary value B _LL ); (iii) when the upper peripheral pixel difference value D _A is smaller than or equal to a predetermined upper first boundary value B _AH and larger than a predetermined upper second boundary value B _AL ; And (iv) if the left neighboring pixel difference value D _L is less than or equal to a predetermined left boundary first value B _LH and greater than a predetermined left second boundary value B _LL , Can be determined as the third type.

8, the upper first boundary value B _AH , the upper second boundary value B _AL , the left first boundary value B _LH , and the left second boundary value ( B _LL ) may be inversely proportional to the size of the block.

The mode selector 13 can select a part of the intra prediction modes according to the type of the block. In other words, the mode selection unit 13 may select a portion of the intra-prediction mode according to the type of the block determined based on the difference value of the neighboring pixels to determine the candidate intra-prediction mode for the block.

10 is a diagram for explaining a direction of an intra prediction mode used for intra prediction according to an embodiment of the present invention.

As shown in FIG. 10, the intra-prediction mode may be composed of a plane mode, a DC mode, modes directed toward the upper side of the block, and modes directed toward the left side of the block. The intra-prediction mode shown in FIG. 10 shows 35 modes used for intraprediction of HEVC (High Efficiency Video Coding). The intra prediction according to an exemplary embodiment of the present invention may be performed based on the HEVC, but may be performed based on other encoding standard techniques such as H.264 and MPEG in addition to the HEVC according to the embodiment.

The mode selector 13 can select a candidate intra prediction mode by selecting a mode likely to occur in the intra prediction mode according to the type of the block 201. [

11 is a diagram illustrating an exemplary direction of a candidate intra prediction mode selected for a first type block according to an embodiment of the present invention.

11, for the first type block, the mode selection unit 13 selects one of the intra-prediction mode (mode 0 to mode 34), the plane mode (mode 0), the DC mode (Modes 18 to 34) may be included in the candidate intra prediction mode. In other words, the mode selection unit 13 can determine the candidate intra-prediction mode by excluding the left-side mode (modes 2 to 17) of the entire intra-prediction modes (modes 0 to 34) have.

As described above, since the differential value (D _A ) of the upper peripheral pixels and the difference value (D _L ) of the left peripheral pixels are small, the intra prediction mode of the block of the first type is determined to be an upward facing mode It can be expected that the possibility is high. In consideration of this point, in the case of the first type block, the mode selection unit 13 may exclude the leftward direction mode from the entire intra prediction mode and include the upward direction mode in the candidate intra prediction mode.

12 is an exemplary diagram illustrating directions of candidate intraprediction modes selected for a second type of block according to an embodiment of the present invention.

12, for the second type of block, the mode selection unit 13 selects one of the intra mode (mode 0 to mode 34), the DC mode (mode 1), and the left side (Modes 2 to 18) may be included in the candidate intra prediction mode. In other words, the mode selector 13 can determine the candidate intra prediction mode by excluding the modes (modes 19 to 34) directed upward from the entire intra prediction modes (modes 0 to 34) for the second type block have.

As described above, since the difference value D _A of the upper peripheral pixels and the difference value D _L of the left peripheral pixels are large, the intra prediction mode of the block of the second type is determined to be a leftward mode It can be expected that the possibility is high. In consideration of this point, in the case of the block of the second type, the mode selection unit 13 may exclude the upward direction mode from the entire intra prediction mode and include the leftward direction mode in the candidate intra prediction mode.

According to one embodiment, in the case of the block of the third type, the mode selection unit 13 may determine all of the intra prediction modes (0 to 34) as the candidate intra prediction mode without excluding the specific mode. In other words, in the case of the third type of block, the mode selection process as described above may not be performed.

13 is a diagram illustrating an exemplary direction of a candidate intra prediction mode selected for a first type of block according to another embodiment of the present invention.

According to this embodiment, in addition to the plane mode (mode 0), DC mode (mode 1), and upward mode (modes 18 to 34) for the first type block, (Mode 10) of the intra prediction mode can be further included in the candidate intra prediction mode.

In this case, the mode selector 13 may further include a horizontal mode (mode 10) in the candidate intra-prediction mode, and a mode (mode 34) of the upward-facing mode toward the upper right side is excluded from the candidate intra- .

14 is an exemplary diagram illustrating directions of a candidate intra prediction mode selected for a second type of block according to another embodiment of the present invention.

According to this embodiment, in addition to the plane mode (mode 0), the DC mode (mode 1), and the leftward mode (modes 2 to 18), the mode selection unit 13 selects, (Mode 26) of the intra prediction mode can be further included in the candidate intra prediction mode.

In this case, the mode selector 13 further includes a mode (mode 26) in the vertical direction in the candidate intra prediction mode, and a mode (mode 2) in the lower left direction in the leftward mode is excluded from the candidate intra prediction mode .

15 is a diagram illustrating an exemplary direction of a candidate intra prediction mode selected for a first type of block according to another embodiment of the present invention.

(Mode 0), a DC mode (mode 1), and a mode directed to the upper side (modes 18 to 34) with respect to the first type block, according to another embodiment of the present invention, The intra prediction mode used for coding the neighboring block adjacent to the block 201 may be further included in the candidate intra prediction mode.

It is highly likely that the intra prediction mode of the current block is directed in the same direction as the intra prediction mode of the neighboring block adjacent to the block. In this embodiment, the mode selector 13 selects the intra prediction mode The intra prediction mode can be further included in the candidate intra prediction mode of the current block.

For example, when the intra-prediction mode of the neighboring block is mode 14, the mode selector 13 selects one of a plane mode (mode 0), a DC mode (mode 1) (Modes 18 to 34), mode 14 may be further included in the candidate intra prediction mode.

According to the embodiment, the mode selection unit 13 selects the mode of the first type from among a plane mode (mode 0), a DC mode (mode 1), an upward mode (modes 18 to 34) (Mode 10), and a neighboring block's intra-prediction mode (e.g., mode 14) may be included in the candidate intra-prediction mode.

In this case, as shown in Fig. 15, a mode (mode 34) toward the upper right side and a mode (mode 33) adjacent to the upper right side mode may be excluded from the candidate intra prediction mode.

According to an embodiment, when there are two or more neighboring blocks and the intra prediction modes of the neighboring blocks are different from each other, the mode selection unit 13 may include the intra prediction mode of two or more neighboring blocks in the candidate intra prediction mode.

For example, when there are two intra prediction modes of the neighboring blocks in modes 14 and 15, the mode selection unit 13 selects one of the following four modes: plane mode (mode 0), DC mode (mode 1) (Modes 14 and 15) of the neighboring blocks can be included in the candidate intra prediction mode.

In this case, a mode (mode 34) toward the upper right side and two modes (modes 32 and 33) adjacent thereto may be excluded from the candidate intra-prediction mode.

For example, when the intraprediction mode of the neighboring block is three in modes 14, 15, and 16, the mode selection unit 13 selects one of the planar mode (mode 0), the DC mode (mode 1) (Modes 18 to 34), a horizontal mode (mode 10), and a neighboring block's intra-prediction modes (modes 14, 15, and 16) may be included in the candidate intra-prediction mode.

In this case, a mode (mode 34) toward the upper right side and three modes (modes 31, 32, 33) adjacent thereto of the upward facing mode may be excluded from the candidate intra prediction mode.

16 is a diagram illustrating an exemplary direction of a candidate intra prediction mode selected for a second type of block according to another embodiment of the present invention.

According to another embodiment of the present invention, the mode selector 13 selects one of the planar mode (mode 0), the DC mode (mode 1), the leftward mode (modes 2 to 18) The intra prediction mode used for coding the neighboring blocks adjacent to the block may be further included in the candidate intra prediction mode.

For example, when the intra-prediction mode of the neighboring block is mode 22, the mode selector 13 selects one of a plane mode (mode 0), a DC mode (mode 1), a leftward mode (Modes 2 to 18), mode 22 may be further included in the candidate intra prediction mode.

According to the embodiment, the mode selection unit 13 selects the mode of the second type from among a plane mode (mode 0), a DC mode (mode 1), a leftward mode (modes 2 to 18) (Mode 26), and the intra-prediction mode (e.g., mode 22) of the neighboring block in the candidate intra-prediction mode.

In this case, as shown in Fig. 16, the left-downward mode (mode 2) and the left-side downward mode (mode 3) may be excluded from the candidate intra-prediction mode.

According to an embodiment, when there are two or more neighboring blocks and the intra prediction modes of the neighboring blocks are different from each other, the mode selection unit 13 may include the intra prediction mode of two or more neighboring blocks in the candidate intra prediction mode.

For example, when there are two intra prediction modes of the neighboring blocks in the modes 21 and 22, the mode selection unit 13 selects one of the planar mode (mode 0), the DC mode (mode 1) (Modes 2 to 18), a vertical mode (mode 26), and a neighboring block's intra-prediction mode (modes 21 and 22) can be included in the candidate intra-prediction mode.

In this case, a left-downward mode (mode 2) and two adjacent modes (modes 3 and 4) may be excluded from the candidate intra-prediction mode.

For example, when the intra-prediction mode of the neighboring block is divided into three modes 20, 21, and 22, the mode selector 13 selects one of the planar mode (mode 0), the DC mode (mode 1) (Modes 2 to 18), the vertical mode (mode 26), and the intra-prediction modes (modes 20, 21 and 22) of the neighboring blocks can be included in the candidate intra-prediction mode.

In this case, a left-downward mode (mode 2) and three adjacent modes (modes 3, 4, 5) may be excluded from the candidate intra-prediction mode.

17 is a view for explaining an intra prediction method according to an embodiment of the present invention.

17, the intraprediction method 400 includes a step S41 of calculating a difference between pixel values of neighboring pixels adjacent to a block, a step S42 of determining a type of the block based on the difference A step (S43) of selecting a candidate intra prediction mode by selecting a part of the intra prediction modes according to the type of the block, and determining an intra prediction mode to be used for coding the block in the candidate intra prediction mode S44).

18 is a diagram illustrating steps of calculating a difference and determining a type of a block according to an embodiment of the present invention.

According to one embodiment, calculating the difference (S41) includes calculating a difference between upper neighboring pixels 202 adjacent to the upper side of the block 201, and calculating a difference between neighboring neighboring neighboring pixels 203). ≪ / RTI > In other words, the surrounding pixels of the block may include upper peripheral pixels adjacent to the upper side of the block and left peripheral pixels adjacent to the left side of the block.

According to an exemplary embodiment, the calculating of the difference of the upper neighboring pixels may include calculating an upper neighboring pixel difference value D _A by summing absolute values of differences between pixel values between neighboring pixels of the upper neighboring pixels 202, And the step of calculating According to one embodiment, the step of calculating the difference of the left neighboring pixels may include calculating a left neighboring pixel difference value D _L by summing absolute values of differences of pixel values between adjacent pixels of the left neighboring pixels 203, And the step of calculating

As shown in Figure 18, according to one embodiment of the present invention, more step (S42), the image side around the pixel difference value (D _A) is pre-set upper boundary value (B _A) for determining the type of the block If the left neighboring pixel difference value D _L is smaller than or equal to the predetermined left boundary value B _L (NO in S 4212), the type of the block is referred to as an upper high-difference block, that is, (Step S4214). ≪ / RTI >

According to one embodiment of the invention, the step (S42) of determining the type of the block, the upper side close to the pixel difference value (D _A) is pre-set upper boundary value is smaller than or equal to (B _A) (NO in S4211) (S4216), the type of the block is determined as the left high-differential block, that is, the second type, if the left neighboring pixel difference value D _L is larger than the predetermined left boundary value B _L (Yes in S4213) . ≪ / RTI >

According to an embodiment of the present invention, the step of determining the type of the block S42 may be such that the upper peripheral pixel difference value D _A is larger than the predetermined upper boundary value B _A (YES in S4211) If the pixel difference value D _L is greater than the predetermined left boundary value B _L (YES in S 4212), the step of determining the block type as the other block, that is, the third type (S4215) have.

According to one embodiment of the invention, the step (S42) of determining the type of the block, the upper side close to the pixel difference value (D _A) is pre-set upper boundary value is smaller than or equal to (B _A) (NO in S4211) If the left neighboring pixel difference value D _L is less than or equal to the predetermined left boundary value B _L (NO in S4213), determining the type of the block as the other block, that is, the third type (S4215) . ≪ / RTI >

According to one embodiment, the boundary value may be set to be in inverse proportion to the size of the block.

19 is a diagram illustrating steps of calculating a difference and determining a type of a block according to another embodiment of the present invention.

As shown in FIG. 19, according to another embodiment of the present invention, the step of determining the type of the block (S42) may further comprise the step of, when the upper peripheral pixel difference value D _A is smaller than a predetermined upper first boundary value B _AH (Yes in S4221), and the left peripheral pixel difference value D _L is less than or equal to the preset left second boundary value B _LL (NO in S4223), the block is classified as the first type Step S4226.

According to another embodiment of the present invention, the step of determining the type of the block S42 may be such that the upper peripheral pixel difference value D _A is less than or equal to the preset upper second boundary value B _AL If the left neighboring pixel difference value D _L is greater than the preset left boundary value B _LH (Yes in S4225), then sorting the block into a second type (S4228) have.

According to another embodiment of the present invention, the step of determining the type of the block S42 may be such that the upper peripheral pixel difference value D _A is larger than the predetermined upper boundary value B _AH (YES in S4221) And sorting the block into a third type (S4227) if the left neighboring pixel difference value D _L is greater than a predetermined left boundary value B _LH (Yes in S4222).

According to another embodiment of the present invention, the step of determining the type of the block S42 may be such that the upper peripheral pixel difference value D _A is less than or equal to the preset upper second boundary value B _AL (S4225); and classifying the block into a third type (S4227) if the left neighboring pixel difference value D _L is less than or equal to the preset left second boundary value B _LL can do.

According to another embodiment of the present invention, the step of determining the type of the block S42 may be such that the upper peripheral pixel difference value D _A is less than or equal to the preset upper boundary value B _AH (Yes in S4224), and classifying the block into a third type (S4227) if it is larger than a preset upper boundary second value B _AL (No).

According to another embodiment of the present invention, the step of determining the type of the block S42 may include determining whether the left neighboring pixel difference value D _L is less than or equal to the predetermined left boundary value B _LH (Yes in S4223), and sorting the block into a third type (S4227) if it is larger than a preset left second boundary value B _LL .

According to one embodiment, the boundary value may be set to be in inverse proportion to the size of the block.

FIG. 20 is a view for explaining a step of determining a candidate intra prediction mode for a first type block and a step of determining an intra prediction mode to be used for encoding according to an embodiment of the present invention.

As shown in FIG. 20, the step S43 of determining the candidate intra-prediction mode includes a step S431 of selecting a plane mode, a DC mode, and an upward-facing mode among the intra-prediction modes when the block is the first type ).

According to an embodiment, the step S43 of determining the candidate intra prediction mode may further include a step S432 of selecting a horizontal direction mode among the intra prediction modes.

According to an embodiment, the step of determining the candidate intra prediction mode (S43) may further include a step (S433) of selecting an intra prediction mode used for coding a neighboring block in the intra prediction mode.

The selected modes may constitute a candidate intra prediction mode for the first type block, and step S44 may determine an intra prediction mode to be used for coding the block among the candidate intra prediction modes.

FIG. 21 is a view for explaining a step of determining a candidate intra prediction mode for a second type block and a step of determining an intra prediction mode to be used for encoding according to an embodiment of the present invention.

As shown in FIG. 21, the step S43 of determining the candidate intra-prediction mode includes a step S434 of selecting a plane mode, a DC mode, and a left-side mode among the intra-prediction modes when the block is the second type ).

According to an embodiment, the step S43 of determining the candidate intra prediction mode may further include a step S435 of selecting a vertical direction mode among the intra prediction modes.

According to an embodiment, the step of determining the candidate intra prediction mode (S43) may further include a step (S436) of selecting an intra prediction mode used for coding a neighboring block in the intra prediction mode.

The selected modes may constitute a candidate intra prediction mode for a block of a second type, and step S44 may determine an intra prediction mode to be used for coding the block among the candidate intra prediction modes.

According to an embodiment of the present invention, the number of modes used for intraprediction is reduced, the amount of computation is reduced, and the time required for encoding can be shortened. In particular, when intra prediction according to an embodiment of the present invention is applied to the HEVC, the bit length allocated to the mode coding can be reduced, and the compression ratio of the image can be improved.

The conventional HEVC calculates the difference between the pixel of the current block and the reference pixel for the 35 intra prediction modes and selects the optimal mode with the highest compression ratio. As described above, the HEVC has a problem that the encoding speed is remarkably slowed due to a large increase in the number of modes used for intraprediction compared to H.264 using nine intra prediction modes. However, when the intra prediction according to an embodiment of the present invention is applied to the HEVC, the number of modes used for intraprediction is greatly reduced, and the encoding speed can be improved.

In addition, the conventional HEVC uses a Fixed Length Coding (FLC) scheme in which 5 bits of bit length are allocated for 32 modes except for 3 MPM (Most Probable Mode) among 35 intra prediction modes. When intraprediction according to an embodiment of the present invention is applied to an HEVC and intra prediction is performed using 19 modes excluding 16 modes out of 35 intra prediction modes according to a block type, Mode coding can be performed with only a bit length of 4 bits for the remaining 16 modes.

As a result, intraprediction according to an embodiment of the present invention can reduce the bit length allocated to mode coding by one bit, thereby improving the compression rate of an image Effect can be achieved.

22 is a block diagram illustrating an image encoding apparatus according to an embodiment of the present invention. 22, the image encoding apparatus 200 includes a motion prediction unit 211, a motion compensation unit 212, an intra prediction unit 220, a switch 215, a subtractor 225, a transform unit 230, A quantization unit 240, an entropy encoding unit 250, an inverse quantization unit 260, an inverse transformation unit 270, an adder 275, a filter unit 280, and a reference image buffer 290.

The image encoding apparatus 200 performs encoding in an intra prediction mode or an inter prediction mode on an input image and outputs a bit stream. An intra prediction method and an inter prediction method may be selectively used for a prediction unit in order to determine an optimal prediction method for a prediction unit. The image encoding apparatus 200 generates a prediction block for the original block of the input image, and then encodes the difference between the original block and the prediction block.

In the intra-prediction mode, the intra-prediction unit 220 performs spatial prediction using the pixel values of the already-coded blocks around the current block to generate a prediction block.

The intraprediction unit 220 calculates a SATD for the intra prediction mode for a predetermined prediction unit, calculates a first intra-picture prediction mode corresponding to the calculated first and second SATD values, and a first SATD value The predicted block of the predetermined prediction unit can be generated by storing the predicted block in the candidate intra prediction mode list and determining whether the difference between the first SATD value and the second SATD value is less than a predetermined threshold value. If the difference between the first SATD value and the second SATD value is greater than the predetermined threshold value, the intra prediction mode corresponding to the first SATD value is determined as the final intra prediction mode of the current prediction unit, And the second SATD value is less than or equal to a predetermined threshold value, the additional intra prediction mode is included in the intra prediction mode list to calculate the RD cost calculated based on the intra prediction mode stored in the intra prediction mode list To determine the final in-picture prediction mode.

In addition, the intra-prediction unit 220 determines whether or not the SATD value for a predetermined encoding unit exceeds the threshold SATD value, and when the SATD value for a predetermined encoding unit is smaller than the threshold SATD value, the encoding unit is not further divided And if the SATD value for a predetermined encoding unit is equal to or larger than the threshold SATD value, the encoding unit can be further divided.

Here, the intraprediction unit 220 may include an intraprediction apparatus according to an embodiment of the present invention.

In the case of the inter-view prediction mode, the motion prediction unit 211 finds a motion vector by searching an area where the best match with the input block is obtained from the reference image stored in the reference image buffer 290 in the motion prediction process. The motion compensation unit 212 generates a prediction block by performing motion compensation using a motion vector.

The subtractor 225 generates a residual block by a difference between the input block and the generated prediction block. The transform unit 230 performs a transform on the residual block to output a transform coefficient. The quantization unit 240 quantizes the input transform coefficients according to the quantization parameters and outputs a quantized coefficient. The entropy encoding unit 250 entropy-codes the input quantized coefficients according to a probability distribution to output a bit stream.

Since the HEVC performs inter prediction coding, the currently encoded image needs to be decoded and stored for use as a reference image. Accordingly, the quantized coefficients are inversely quantized in the inverse quantization unit 260 and inversely transformed in the inverse transformation unit 270. The inverse quantized and inverse transformed coefficients are added to the prediction block through an adder 275, and a reconstruction block is generated.

The restoration block passes through the filter unit 280 and the filter unit 280 applies at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) can do. The filter unit 280 may be referred to as an adaptive in-loop filter. The deblocking filter can remove block distortion occurring at the boundary between the blocks. The SAO may add a proper offset value to the pixel value to compensate for coding errors. The ALF may perform filtering based on a comparison between the reconstructed image and the original image, and may be performed only when high efficiency is applied. The reconstruction block having passed through the filter unit 280 is stored in the reference image buffer 290.

23 is a block diagram illustrating an image decoding apparatus according to an embodiment of the present invention.

23, the image decoding apparatus 300 includes an entropy decoding unit 310, an inverse quantization unit 320, an inverse transform unit 330, an intra prediction unit 340, a motion compensation unit 350, (360) and a reference image buffer (370).

The video decoding apparatus 300 receives the bit stream output from the encoder and decodes the video stream into an intra mode or an inter mode, and outputs a reconstructed video, that is, a reconstructed video. In the intra mode, a prediction block is generated using an intra prediction mode, and a prediction block is generated using an inter prediction method in an inter mode. The video decoding apparatus 300 obtains a residual block from the input bitstream, generates a prediction block, and then adds the residual block and the prediction block to generate a reconstructed block, that is, a reconstruction block.

The entropy decoding unit 310 entropy-decodes the input bitstream according to a probability distribution and outputs a quantized coefficient. The quantized coefficients are inversely quantized in the inverse quantization unit 320 and inversely transformed in the inverse transformation unit 330. As a result of inverse quantization / inverse transformation of the quantized coefficients, a residual block is generated.

In the intra-prediction mode, the intra-prediction unit 340 performs spatial prediction using the pixel values of the already-coded blocks around the current block to generate a prediction block.

In the inter prediction mode, the motion compensation unit 350 generates a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference image buffer 370.

The residual block and the prediction block are added through the adder 355, and the added block is passed through the filter unit 360. [ The filter unit 360 may apply at least one of a deblocking filter, SAO, and ALF to a restoration block or a restored picture. The filter unit 360 outputs a reconstructed image, that is, a reconstructed image. The restored image is stored in the reference image buffer 370 and can be used for inter prediction.

Methods for improving the prediction performance of the encoding / decoding apparatus include a method of increasing the accuracy of the interpolation image and a method of predicting the difference signal. Here, the difference signal is a signal indicating the difference between the original image and the predicted image. In the present invention, the term " difference signal " may be replaced by a " difference signal ", " residual block ", or " difference block " depending on the context. Those skilled in the art may influence the idea You will be able to distinguish this within the scope of not giving.

In the present specification, a coding unit (coding unit) is used as a coding unit for convenience of explanation, but it may be a unit for performing not only coding but also decoding. The intraprediction method according to an embodiment of the present invention described above can be implemented according to the functions of the modules described in FIGS. 23 and 23, and the encoder and the decoder are included in the scope of the present invention. That is, the intraprediction method according to an embodiment of the present invention can be performed in each component included in the image encoder and the image decoder described with reference to FIG. 23 and FIG. The meaning of the constituent part may include not only a hardware meaning but also a software processing unit which can be performed through an algorithm.

In addition, the intraprediction method according to an embodiment of the present invention described above can be stored in a computer-readable recording medium made of a program to be executed in a computer. The computer-readable recording medium includes all kinds of storage devices in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like.

100: Intra prediction device
11: Difference calculation section
12: Block type determination section
13: Mode selector
14: Intra prediction mode determining unit

Claims (27)

Calculating a difference between pixel values of neighboring pixels adjacent to the block;
Determining a type of the block based on the difference;
Determining a candidate intra prediction mode by selecting a portion of the intra prediction modes according to the type of the block; And
Determining an intra prediction mode to be used for coding the block among the candidate intra prediction modes;
/ RTI > The method according to claim 1,
Wherein the step of calculating the difference comprises:
Calculating a difference of upper neighboring pixels on the upper side of the block; And
Calculating a difference of left neighboring pixels adjacent to the left side of the block;
/ RTI > 3. The method of claim 2,
Wherein calculating the difference of the upper neighboring pixels comprises:
Calculating an upper peripheral pixel difference value by summing an absolute value of a difference of pixel values between adjacent pixels among the upper peripheral pixels,
Wherein calculating the difference of the left neighboring pixels comprises:
Calculating a left neighboring pixel difference value by summing an absolute value of a difference of pixel values between adjacent pixels among the left neighboring pixels. The method of claim 3,
Wherein determining the type of block comprises:
Determining a type of the block as an upper side high differential block when the upper neighboring pixel difference value is greater than a preset upper boundary value and the left neighboring pixel difference value is less than or equal to a predetermined left boundary value, Prediction method. The method of claim 3,
Wherein determining the type of block comprises:
Determining a type of the block as a left high differential block if the upper neighboring pixel difference value is less than or equal to a predetermined upper boundary value and the left neighboring pixel difference value is greater than a predetermined left boundary value, Prediction method. The method according to claim 4 or 5,
Wherein the upper boundary value and the left boundary value are inversely proportional to the size of the block. The method of claim 3,
Wherein determining the type of block comprises:
Determining the type of the block as an upper side high differential block if the upper neighboring pixel difference value is greater than a preset upper first boundary value and the left neighboring pixel difference value is less than or equal to a preset left second boundary value / RTI > The method of claim 3,
Wherein determining the type of block comprises:
Determining the type of the block as a left high differential block if the upper neighboring pixel difference value is less than or equal to a preset upper second boundary value and the left neighboring pixel difference value is greater than a preset left first boundary value / RTI > 8. The method according to claim 4 or 7,
Wherein the step of determining the candidate intra prediction mode comprises:
And selecting an intra-prediction mode for the upper-side high-differential block, the intra-prediction mode being a plane mode, a DC mode, and an upward mode. 9. The method according to claim 5 or 8,
Wherein the step of determining the candidate intra prediction mode comprises:
And selecting a plane mode, a DC mode, and a leftward mode among the intra prediction modes in the case of the left high-order difference block. 10. The method of claim 9,
Wherein the step of determining the candidate intra prediction mode comprises:
And in the case of the upper side high-differential block, selecting a mode in the horizontal direction among the intra prediction modes. 11. The method of claim 10,
Wherein the step of determining the candidate intra prediction mode comprises:
And selecting a mode in the vertical direction among the intra prediction modes in the case of the left high-order difference block. 10. The method of claim 9,
Wherein the step of determining the candidate intra prediction mode comprises:
And selecting an intra prediction mode to be used for coding a neighboring block adjacent to the block. 11. The method of claim 10,
Wherein the step of determining the candidate intra prediction mode comprises:
And selecting an intra prediction mode used for coding a neighboring block adjacent to the block. Selecting a part of the intra-prediction modes according to a difference between pixel values of neighboring pixels adjacent to the block, and performing intra-prediction based on the selected partial mode. A computer-readable recording medium,
16. A recording medium on which a program for executing the intra prediction method according to any one of claims 1 to 15 is recorded. A difference calculator for calculating a difference between pixel values of neighboring pixels adjacent to the block;
A block type determination unit for determining a type of a block based on the difference;
A mode selection unit for selecting a part of the intra prediction mode according to the type of the block; And
An intra prediction mode determination unit for determining an intra prediction mode to be used for coding the block among the selected partial modes;
And an intra prediction unit. 18. The method of claim 17,
Wherein the difference calculator comprises:
Calculating a first difference value by summing absolute values of differences of pixel values between adjacent pixels among upper neighboring pixels adjacent to the upper side of the block,
Wherein the second difference value is calculated by summing absolute values of differences of pixel values between adjacent pixels among left neighboring pixels adjacent to the left side of the block. 19. The method of claim 18,
Wherein the block type determining unit comprises:
Classifying the block into a first type when the first difference value is greater than a predetermined upper boundary value and the second difference value is less than or equal to a predetermined left boundary value,
And classifies the block into a second type when the first difference value is less than or equal to the upper boundary value and the second difference value is greater than the left boundary value. 20. The method of claim 19,
Wherein the upper boundary value and the left boundary value are set in inverse proportion to the size of the block. 19. The method of claim 18,
Wherein the block type determining unit comprises:
Classifying the block into a first type if the first difference value is greater than a preset upper boundary value and the second difference value is less than or equal to a predetermined left second boundary value,
And classifies the block into a second type when the first difference value is less than or equal to a predetermined upper second boundary value and the second difference value is greater than a predetermined left boundary value. 22. The method of claim 21,
Wherein the upper first boundary value, the upper second boundary value, the left first boundary value, and the left second boundary value are set in inverse proportion to the size of the block. 22. The method of claim 21,
Wherein the upper first boundary value is set to be larger than the upper second boundary value,
Wherein the left first boundary value is set to be larger than the left second boundary value. The method according to claim 19 or 21,
Wherein the mode selector comprises:
When the block is the first type, selects a plane mode, a DC mode, and an upward direction mode among the intra prediction modes,
And selects a plane mode, a DC mode, and a leftward mode among the intra prediction modes when the block is the second type. 25. The method of claim 24,
Wherein the mode selector comprises:
When the block is the first type, further selecting a mode in the horizontal direction among the intra prediction modes,
And selects a mode in the vertical direction among the intra prediction modes when the block is the second type. 25. The method of claim 24,
Wherein the mode selector comprises:
And further selects an intra prediction mode used for coding a neighboring block adjacent to the block. An intra prediction unit that performs intra prediction on the basis of a reference pixel located in the vicinity of an input block to generate a prediction block;
A motion prediction unit for calculating a motion vector of an input block using a reference image;
A motion compensation unit for performing motion compensation based on the motion vector to generate a prediction block;
A subtracter for calculating a difference between an input block and a prediction block to generate a residual block;
A transform unit for transforming the residual block to output a transform coefficient; And
A quantization unit for quantizing the transform coefficients and outputting the quantized coefficients;
Wherein the intraprediction unit comprises:
A difference calculator for calculating a difference between pixel values of neighboring pixels adjacent to the input block;
A block type determination unit for determining a type of an input block based on the difference;
A mode selection unit for selecting a part of the intra prediction mode according to the type of the input block; And
An intra prediction mode determining unit that determines an intra prediction mode to be used for coding the input block among the selected partial modes;
And the image processing apparatus.

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