KR101911587B1 - Apparatus and method for video coding/decoding using adaptive intra prediction - Google Patents

Abstract

A technique relating to an image encoding / decoding apparatus and method using adaptive intra prediction is disclosed. An apparatus for decoding an image using adaptive intra prediction includes an entropy decoding unit that generates reconstruction information including a quantized residual coefficient and an intra prediction method by decoding a bitstream, An intra prediction unit for generating a prediction block of A size B by partitioning an M × N size prediction block or an M × N size current block according to an intra prediction method according to an intra prediction mode of the current block; And an adder for adding a residual block of size M M sized by A or B and a residual block of A size B and a prediction block of M × N size or A × B size prediction block to generate a reconstructed image.

Description

[0001] APPARATUS AND METHOD FOR VIDEO CODING / DECODING USING ADAPTIVE INTRA PREDICTION [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image encoding / decoding, and more particularly, to an apparatus and method for encoding / decoding an image using adaptive intra prediction according to an intra prediction mode.

Recently, the emergence of smartphones and smart TVs has led to explosive use of video dating via wired and wireless communication networks. Video data has superior information transmission capability than plain text data, but has a very large capacity, which makes it difficult to transmit, reproduce and store data in a network channel having a limited bandwidth. In addition, since a large amount of moving picture information is appropriately processed according to the demand of an application, a system for processing a moving picture also requires a high specification.

In order to solve these problems, video encoding algorithms, which are techniques for compressing moving picture data into small information, have been actively studied. The video data has temporal, spatial, and statistical redundancies. Temporal redundancy means redundancy between consecutive frames, and pixels of consecutive frames have a very high correlation. Spatial redundancy means redundancy existing in a frame, and a brightness value of one pixel has a high correlation with brightness values of neighboring pixels. Finally, statistical redundancy means redundancy between coded data, which is the redundancy due to the probability distribution of brightness values of pixels. In order to encode a moving image, a large amount of moving image data can be compressed into a smaller amount of data by eliminating the three redundancies.

Intra prediction is a method of compressing an image by eliminating spatial redundancy by using the degree of pixel correlation between blocks in one picture. The intra prediction is performed by using pixels adjacent to the current block restored by performing the previous encoding as reference pixels A predicted value of the current block is generated, and a difference value between the generated predicted value and the pixel value of the current block is compressed.

Referring to FIG. 1, H.264 / AVC performs prediction using an intra prediction mode considering nine directions. That is, in H.264 / AVC, nine prediction modes according to the prediction direction in 4 × 4 block and 8 × 8 block intra prediction are the vertical mode (mode 0), the horizontal mode (mode 1) A diagonal downward mode (Diagonal_Down_Light mode), a diagonal downward mode (mode 4), a vertical right mode (Vertical_Right) (mode 5), a horizontal down mode (Horizontal_Down mode) (Mode 6), Vertical_Left mode (Mode 7), and Horizontal Up mode (Mode 8).

However, in the conventional intraprediction method, there is a problem that prediction accuracy is poor in the case of a pixel in a current block which is far from the adjacent pixel according to the characteristics of an image, and there is a region in which prediction is not performed well. The decrease in the accuracy of the prediction increases the difference between the pixel value of the original pixel and the predicted pixel value, which ultimately leads to a problem of lowering the compression efficiency.

In order to solve the above problems, an aspect of the present invention is to provide an apparatus for encoding / decoding an image by performing adaptive intra prediction with a block size corresponding to an intra prediction mode.

It is another object of the present invention to provide a method of encoding / decoding an image by performing adaptive intra prediction with a block size corresponding to an intra prediction mode.

According to an aspect of the present invention, there is provided an apparatus for encoding an image using adaptive intraprediction, the apparatus comprising: an intra prediction unit configured to perform intra prediction using one of at least two intraprediction methods according to an intra prediction mode of an M × N current block; An intra prediction unit for generating an A × B size prediction block by partitioning an M × N size prediction block or an M × N size current block according to intra prediction according to a determined intra prediction method; And a subtractor for generating an M × N residual block or an A × B residual block based on an M × N size prediction block or an A × B size prediction block.

Here, the prediction method determining unit may determine one of at least two intraprediction methods as an intra prediction method when the intra prediction mode of the current block of the M x N size is the horizontal mode or the vertical mode.

Here, the intra predictor may include a first intraprediction unit for generating an M × N size prediction block, and a second intraprediction unit for generating an A × B size prediction block.

Here, if the intra prediction mode of the current block of the M × N size is the horizontal mode, the second intraprediction unit performs intraprediction on the pixel line located in the odd-numbered row of the current block of the M × N size, Size B prediction block, or intra-prediction is performed on the pixel line located in the even-numbered row of the current block of M × N size to generate a prediction block of A × B size.

Here, the second intraprediction unit refers to the pixels reconstructed by intraprediction on the pixel lines located in the odd-numbered rows of the current block of the MxN size, and outputs the even- Or by performing intra prediction on a pixel line located in an even-numbered row of an M × N current block and referring to the reconstructed pixel to obtain an odd number of the current block of M × N size Th < th > row.

Here, if the intra-prediction mode of the current block of the M × N size is the vertical mode, the second intraprediction unit performs intra-prediction on the pixel line located in the odd-numbered column of the current block of the M × N size, A prediction block of size B may be generated or an intra-prediction may be performed on a pixel line located in an even-numbered column of an M × N current block to generate a prediction block of A size B size.

Here, the second intraprediction unit refers to the pixels reconstructed by intraprediction on the pixel lines located in the odd-numbered columns of the current block of M × N size and is located in the even-numbered column of the M × N current block Pixel lines, or by intra-prediction of pixel lines located in even-numbered columns of an M × N current block and referring to the reconstructed pixels and located in odd-numbered columns of the current block of M × N size It is possible to perform intra prediction on the pixel line.

Here, the encoding apparatus includes a first transforming unit for transforming an M × N residual block to generate an M × N transform block, and a second transforming unit for transforming an A × B residual block into an A × B transform block And a second conversion unit for generating the second conversion unit.

Here, the second conversion unit may perform one of Hadamard transform, discrete cosine transform, and discrete cosine transform.

According to another aspect of the present invention, there is provided an apparatus for decoding an image using an adaptive intra prediction, the apparatus including: an entropy decoding unit for decoding a bitstream to generate reconstructed information including quantized residual coefficients, And a prediction block of M × N size or a current block of M × N size is divided according to an intra prediction method according to an intra prediction mode of the current block of M × N size based on reconstruction information, And a prediction block of an M × N size or a residual block of an A × B size and an M × N size prediction block or an A × B size prediction block generated based on reconstruction information, And an adder for generating a reconstructed image.

According to another aspect of the present invention, there is provided a method of decoding an image using adaptive intra prediction, the method comprising: decoding a bitstream to generate reconstruction information including quantized residual coefficients and information about an intra prediction method; And a prediction block of M × N size or a current block of M × N size according to the intra prediction method according to the intra prediction mode of the current block of M × N size based on the reconstruction information, An M × N size residual block or an A × B size residual block and an M × N size prediction block or an A × B size prediction block generated based on reconstruction information, .

When an apparatus and method for encoding / decoding an image by performing the adaptive intra prediction according to the present invention as described above, the current block is divided according to the intra prediction mode of the current block to perform adaptive intra prediction, Accuracy can be improved.

In addition, there is an advantage that the coding efficiency can be improved by improving the accuracy of intra prediction.

1 is a conceptual diagram illustrating an intra prediction mode according to H.264 / AVC.
2 is a block diagram illustrating the image encoding apparatus.
3 is a conceptual diagram showing a partially changing current block and neighboring pixels.
4 is a conceptual diagram illustrating adaptive intra prediction according to an embodiment of the present invention.
5 is a conceptual diagram illustrating adaptive intra prediction according to another embodiment of the present invention.
6 is a block diagram illustrating an image encoding apparatus using adaptive intra prediction according to an embodiment of the present invention.
7 is a block diagram illustrating an image decoding apparatus using adaptive intra prediction according to an embodiment of the present invention.
8 is a flowchart illustrating an image decoding method using adaptive intra prediction according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

The Video Encoding Apparatus and the Video Decoding Apparatus to be described below may be implemented as a personal computer (PC), a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP) Such as a portable multimedia player (PSP), a PlayStation Portable (PSP), a wireless communication terminal, a smart phone, a TV application server and a service server. A communication device such as a communication modem for performing communication with a user terminal or a wired or wireless communication network, a memory for storing various programs and data for inter-screen or intra-screen prediction for coding or decoding a picture, coding or decoding, And a microprocessor for executing and operating and controlling It can mean a variety of devices.

In addition, the image encoded by the video encoding apparatus can be transmitted in real time or in non-real time through a wired or wireless communication network such as the Internet, a local area wireless communication network, a wireless LAN network, a WiBro network, a mobile communication network, A serial bus, and the like, and can be decoded and reconstructed into an image and reproduced by an image decoding apparatus.

The moving picture may be generally composed of a series of pictures, and each picture may be divided into a predetermined area such as a frame or a block. In the case where an image area is divided into blocks, the divided blocks can be classified into an intra block and an inter block according to a coding method. The in-picture block refers to a block that is coded using an Intra Prediction Coding scheme. The intra-picture prediction coding refers to a method of coding a block of pixels of previously decoded and decoded blocks in a current picture, A prediction block is generated by predicting the pixels of the current block and a difference value between the current block and the pixel of the current block is encoded. Inter-block refers to a block that is coded using Inter Prediction Coding. Inter-prediction coding refers to one or more past pictures or a future picture to generate a prediction block by predicting a current block in the current picture, And the difference value is encoded. Here, a frame to be referred to in encoding or decoding a current picture is referred to as a reference frame. It is also to be understood that the term "picture" described below may be used in place of other terms having equivalent meanings such as image, frame, etc., If you are a child, you can understand.

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

2 is a block diagram illustrating the image encoding apparatus.

2, the image encoding apparatus includes a subtracting unit 110, a transforming unit 120, a quantizing unit 130, an entropy encoding unit 140, an inverse transforming unit 160, an inverse quantizing unit 150, A memory 170, a memory 180, and a predicting unit 190.

The subtraction unit 110 generates a residue image between the current image and the predicted image by subtracting the predicted image generated by the predictor 190 from the supplied target image (current image) to be encoded.

The transforming unit 120 transforms the residual image generated by the subtracting unit 110 from the spatial domain to the frequency domain. Here, the transform unit 120 transforms the residual image into a frequency domain using a technique of transforming an image signal of a spatial axis into a frequency axis, such as a Hadamard transform, a Discrete Cosine Transform, a Discrete Cosine Transform, . ≪ / RTI >

The quantization unit 130 quantizes the transformed data (frequency coefficients) supplied from the transform unit 120. [ That is, the quantization unit 130 calculates a quantization result value by approximating the frequency coefficients, which are data converted by the transform unit 120, by dividing the frequency coefficients by a quantization step size.

The entropy encoding unit 140 generates a bit stream by entropy encoding the quantization result value calculated by the quantization unit 130. The entropy encoding unit 140 may entropy-encode the quantization result value calculated by the quantization unit 130 using a Context-Adaptive Variable Length Coding (CAVLC) or a Context-Adaptive Binary Arithmetic Coding (CABAC) In addition to quantization result values, index information of a reference frame, information of a motion vector, and the like, which are information necessary for decoding an image, can be entropy-encoded.

The inverse quantization unit 150 dequantizes the quantization result value calculated by the quantization unit 130. [ That is, the inverse quantization unit 150 restores the frequency domain value (frequency coefficient) from the quantization result value.

The inverse transform unit 160 transforms the frequency domain values (frequency coefficients) supplied to the inverse quantization unit 150 from the frequency domain into the spatial domain to restore the residual image, and the adder 170 adds The reconstructed image of the input image is generated and stored in the memory 180 by adding the residual image reconstructed by the inverse changing unit to the predicted image generated by the reconstructed image.

The prediction unit 190 may include an intra prediction unit 190 for performing intra prediction and an inter prediction unit for performing inter prediction. The intraprediction unit generates a prediction block using pixels of previously reconstructed and decoded blocks in the current image, and the inter-prediction unit generates a prediction block in the current image with reference to one or more past or future images. That is, the prediction unit 190 performs intra or inter prediction to generate a prediction image.

3 is a conceptual diagram showing a partially changing current block and neighboring pixels.

Referring to FIG. 3, an intra prediction block to be subjected to intraprediction includes a region that has directionality in a horizontal direction as a whole but partially changes. In this case, when the prediction error is calculated based on the difference value between the pixels located in the horizontal direction pixel line, a region having a large difference value is generated, so that the bit increases as a whole to lower the coding efficiency.

For example, in the case of the first pixel line and the second pixel line from the top in the prediction block, the current pixel located in the pixel line along the intra-prediction direction (horizontal direction) and the current pixel corresponding to the intra- The difference value between the previous pixel located at the previous position is large and the coding efficiency can be lowered. That is, when compared with the case of the third pixel line and the fourth pixel line from the top in the prediction block, in the case of the first pixel line and the second pixel line from the top in the prediction block, Value can be generated.

4 is a conceptual diagram illustrating adaptive intra prediction according to an embodiment of the present invention.

Referring to FIG. 4, an apparatus and method for encoding an image using adaptive intra-prediction according to an embodiment of the present invention can perform intra-prediction by dividing a current block.

For example, as shown in FIG. 4A, when the current block size is M × N (M and N may be the same or different), and the intra prediction mode is the horizontal mode, the odd- Prediction is performed using the existing extrapolation for the pixel line located in the row. That is, when intra-prediction is performed on the pixel lines located in odd-numbered rows, an A × B size prediction block can be generated. Here, M represents the number of pixels in the row of the current block, N may represent the number of pixels in the column of the current block, A may be equal to M, and B may be 1/2 of N

Since the A × B size prediction block is predicted from a pixel adjacent to the left of the current block as in the conventional intra prediction, there is no difference from the existing intra prediction in terms of accuracy of prediction.

Referring to FIG. 4B, a pixel line located in an even-numbered row that has not yet been coded is divided into pixels that are already coded and reconstructed, as well as pixels adjacent to the left side of the current block, ) ≪ th > row can be used for prediction, so that more accurate prediction can be performed.

In addition, prediction is performed using the existing extrapolation for the pixel lines located in the even-numbered rows of the current block, and prediction is performed on the pixel lines located in odd-numbered rows of the current block as well as pixels adjacent to the left- The pixel value of the already-coded and restored even-numbered row can be used for prediction, so that more accurate prediction can be performed.

Meanwhile, although FIG. 4 illustrates a case where the intra-prediction mode is the horizontal mode, when the intra-prediction mode is the vertical mode, the intra-prediction can be performed based on the pixel lines located in the odd- Of course.

For example, when the intra-prediction mode is the vertical mode, prediction is performed using the existing extrapolation for the pixel lines located in the odd-numbered columns of the current block, and intra-prediction is performed for the pixel lines located in the even- As a result, not only the pixels adjacent to the left side of the current block but also the pixel values of the already encoded and recovered odd-numbered columns can be used for prediction, so that more accurate prediction can be performed.

In addition, prediction is performed using the existing extrapolation for the pixel lines located in the even-numbered columns of the current block, and prediction is performed on the pixel lines located in the odd-numbered columns of the current block as well as pixels adjacent to the left- The pixel value of the encoded and restored even-numbered column can be used for prediction, so that more accurate prediction can be performed.

5 is a conceptual diagram illustrating adaptive intra prediction according to another embodiment of the present invention.

Referring to FIG. 5, an apparatus and method for encoding an image using adaptive intra prediction according to another embodiment of the present invention can perform adaptive intra prediction after dividing a current block.

For example, as shown in FIG. 5A, if the size of the current block is M × N (M and N may be the same or different), and the intra prediction mode is the horizontal mode, Intra prediction can be performed.

If the current block is divided in the vertical direction, the current block is divided into two blocks of size M × (1/2) N. That is, the current block is divided into a block of M × (1/2) N size on the left side and a block of M × (1/2) N size on the right side.

The prediction is performed using the existing extrapolation of the pixel line located in the odd-numbered row of the M × (1/2) N-sized block on the left side. That is, the intra-prediction is performed on the pixel lines located in the odd-numbered rows of the left M × (1/2) N-sized block to generate the A × B size prediction block. Where A can be 1/2 of M and B can be 1/2 of N. [

Since the A × B size prediction block is predicted from a pixel adjacent to the left of the current block as in the conventional intra prediction, there is no difference from the existing intra prediction in terms of accuracy of prediction.

Referring to FIG. 5B, for a pixel line located in an even-numbered yet-coded block of a block of M × (1/2) N size on the left, as in the conventional intra prediction, It is possible to use a pixel value of an even-numbered row of a block of M × (½) N size which is already coded and reconstructed on the left side, as well as adjacent pixels on the left side, to perform prediction more accurately.

In addition, prediction is performed using the existing extrapolation of pixel lines located in even-numbered rows of the M × (1/2) N size block on the left, and odd The pixel value of an even-numbered row of a block of M × (1/2) N size already coded and restored, as well as the pixels adjacent to the left side of the current block, So that more accurate prediction can be performed.

Referring to FIGS. 5 (c) and 5 (d), after intraprediction for the left M × (1/2) N size block is completed, the right M × (1/2) The intra prediction can be performed. Intra prediction for a block of size M × (1/2) N on the right can be performed by the same method as intra prediction for a block of M × (1/2) N size on the left.

Meanwhile, although FIG. 5 illustrates a case where the intra-prediction mode is the horizontal mode, when the intra-prediction mode is the vertical mode, the intra-prediction can be performed based on the pixel lines located in the odd- Of course.

5 illustrates an apparatus and a method for performing intra prediction by dividing a current block of M × N size into two blocks of M × (½) N size or (½) M × N size However, it is needless to say that intraprediction can be performed by partitioning into blocks of a smaller size.

6 is a block diagram illustrating an image encoding apparatus using adaptive intra prediction according to an embodiment of the present invention.

Referring to FIG. 6, an image encoding apparatus using adaptive intra prediction according to an embodiment of the present invention includes a subtracting unit 210, a prediction method checking unit 220, a first intra prediction unit 222, The first inverse transform unit 270, the second inverse transform unit 271, the first quantization unit 240, the second quantization unit 270, and the second quantization unit 270. The predictor 223, the first transform unit 230, the second transform unit 231, the first inverse transform unit 270, A second inverse quantization unit 261, a prediction method determination unit 221, an addition unit 280, a memory 290, and an entropy encoding unit 250. The first inverse quantization unit 241, the first inverse quantization unit 260, the second inverse quantization unit 261, .

That is, an image encoding apparatus using adaptive intra prediction according to an embodiment of the present invention can be understood with reference to the description of the image encoding apparatus described with reference to FIG. For example, the subtractor 210, the adder 280, the memory 290, and the entropy encoder 250 may include a subtractor 110, an adder 170, a memory 180, and an entropy encoding Unit 140 can perform the same function.

The prediction method determining unit 221 may determine one of at least two intra prediction methods as an intra prediction method according to the intra prediction mode of the current block. That is, the prediction method determining unit 221 may determine one of at least two intra prediction methods as an intra prediction method when the intra prediction mode of the current block is the horizontal mode or the vertical mode. Here, the size of the current block can be M × N.

In particular, the encoding apparatus using adaptive intra prediction according to an embodiment of the present invention may include a first intrapredictor 222 and a second intrapredictor 223 that perform different intraprediction methods.

The first intraprediction unit 222 generates a prediction block having the same size as the current block and the second intraprediction unit 223 can generate a prediction block having a smaller size than the current block. That is, the intra-prediction unit may include a first intra-prediction unit 222 and a second intra-prediction unit 223.

For example, the first intra predictor 222 may generate an M × N size prediction block for the current block of M × N size. In addition, the second intra predictor 223 can generate an A × B size prediction block.

In particular, when the intra prediction mode of the current block of the M × N size is the horizontal mode, the second intraprediction unit 223 performs intraprediction on pixel lines located in odd-numbered rows of the current block of M × N size Thereby generating an A × B size prediction block.

The second intraprediction unit 223 generates an A × B size prediction block and then outputs the restored pixel by performing intra prediction on the pixel line located in the odd-numbered row of the current block of M × N size And perform intra-prediction on pixel lines located in even-numbered rows of the current block of M × N size.

Here, the second intraprediction unit 223 first performs intraprediction on the pixel lines located in the even-numbered rows of the current block of the MxN size, and then performs intra prediction on the pixels located in the odd-numbered rows of the MxN- It is of course possible to perform intra prediction on the line.

When the intra prediction mode of the current block of the M × N size is the vertical mode, the second intraprediction unit 223 performs intraprediction on the pixel line located in the odd-numbered column of the current block of M × N size An A × B size prediction block can be generated.

The second intraprediction unit 223 generates an A × B size prediction block and then generates a prediction block having a size of M × N by referring to the reconstructed pixel which is encoded through intraprediction on a pixel line located in an odd- It is possible to perform intra prediction on the pixel lines located in the even-numbered columns of the current block of size N.

Here, the second intraprediction unit 223 performs intraprediction on the pixel lines located in the even-numbered columns of the current block of the MxN size, and then performs intraprediction on the pixel lines located in the odd-numbered columns of the MxN- It is needless to say that intra prediction can be performed.

Meanwhile, the encoding apparatus using the adaptive intra prediction according to the embodiment of the present invention can perform adaptive intra prediction after dividing the current block as described with reference to FIG.

It is also possible to perform prediction by further dividing the current block into smaller blocks. Information on the block may be transmitted in a unit of a sequence, a picture, a block, or the like, or how to divide the encoding device and the decoding device May share information about the user.

The prediction method confirmation unit 220 can confirm the intra prediction method determined by the prediction method determination unit 221. [ That is, the prediction method check unit 220 can confirm whether the intra prediction is performed in the first intra prediction unit 222 or in the second intra prediction unit 223. The prediction method check unit 220 transfers the residual block based on the prediction block generated by the first intra prediction unit 222 to the first transform unit 230 and outputs the residual block generated by the second intra prediction unit 223 The residual block based on the prediction block can be transferred to the second conversion unit 231.

Accordingly, the first transform unit 230 transforms the residual block based on the prediction block having the same size as the current block, and the second transform unit 231 transforms the residual block based on the prediction block smaller than the current block Can be performed.

For example, if the current block is of size M × N, the first transform unit 230 transforms an M × N residual block to generate an M × N transform block, The transform unit 231 can transform the A × B residual block to generate an A × B transform block. Here, the residual block is generated in the subtracting unit 210.

In particular, the second conversion unit 231 can perform any one of Hadamard transform, discrete cosine transform, and discrete cosine transform.

The first quantization unit 240 and the second quantization unit 241 may quantize the transform blocks generated by the first transform unit 230 and the second transform unit 231, respectively. The first quantization unit 240 and the second quantization unit 241 may perform quantization according to different steps. For example, since the transform block generated through the second transform unit 231 is based on intraprediction using pixels that have already been coded and reconstructed, the prediction accuracy is higher than that of the existing intraprediction method, The second quantization unit 241 can perform quantization in consideration of this point.

The first inverse transform unit 270 and the second inverse transform unit 271 respectively perform inverse transform corresponding to the first transform unit 230 and the second transform unit 231, And the second inverse quantization unit 261 may perform inverse quantization in correspondence with the first quantization unit 240 and the second quantization unit 241, respectively.

Here, quantization and dequantization can be understood with reference to the description of quantization and dequantization described above in Fig.

7 is a block diagram illustrating an image decoding apparatus using adaptive intra prediction according to an embodiment of the present invention.

7, an apparatus for decoding an image using adaptive intraprediction according to an exemplary embodiment of the present invention includes an entropy decoding unit 310, a first inverse quantization unit 320, a second inverse quantization unit 321, 1 inverse transform unit 330, a second inverse transform unit 331, an adding unit 340, a memory 350, a first intraprediction unit 361, a second intraprediction unit 362, and a prediction method determination unit 360 ).

The entropy decoding unit 310 can receive and decode the bitstream from the encoding device. That is, the entropy decoding unit 310 may generate reconstruction information including information on the quantized residual coefficient and intra prediction method by decoding the bitstream.

The prediction method determination unit 360 may determine one of at least two intra prediction methods as an intra prediction method. That is, the prediction method determination unit 360 may determine one of at least two intra prediction methods as an intra prediction method when the intra prediction mode of the current block is the horizontal mode or the vertical mode based on the reconstruction information.

The apparatus for decoding using adaptive intra prediction according to an embodiment of the present invention may include a first intrapredictor 361 and a second intrapredictor 362 that perform different intraprediction methods. The first intrapredictor 361 and the second intrapredictor 362 can perform intra prediction according to the intra prediction method determined by the prediction method determination unit 360. [

The first intraprediction unit 361 generates a prediction block having the same size as the current block and the second intraprediction unit 362 can generate a prediction block having a smaller size than the current block. That is, the intra-prediction unit may include a first intra-prediction unit 361 and a second intra-prediction unit 362.

That is, the intra-prediction unit may perform an intra-prediction based on the intra-prediction mode of the current block of the M × N size based on the reconstruction information generated by the entropy decoding unit 310, It is possible to generate a prediction block of A 占 사이즈 size by dividing the current block.

For example, the first intra predictor 361 can generate a prediction block of M × N size for the current block of M × N size. In addition, the second intra predictor 362 can generate an A × B prediction block.

In particular, when the intra prediction mode of the current block of the M × N size is the horizontal mode, the second intraprediction unit 362 performs intraprediction on pixel lines located in odd-numbered rows of the current block of M × N size Thereby generating an A × B size prediction block.

The second intraprediction unit 362 generates an A × B size prediction block and then outputs the reconstructed pixel through intra prediction on the pixel line located in the odd-numbered row of the current block of M × N size And perform intra-prediction on pixel lines located in even-numbered rows of the current block of M × N size.

Here, the second intraprediction unit 362 first performs intraprediction on the pixel lines located in the even-numbered rows of the current block of the MxN size, and then performs intra prediction on the pixels located in the odd-numbered rows of the MxN- It is of course possible to perform intra prediction on the line.

If the intra-prediction mode of the current block of the M × N size is the vertical mode, the second intra-prediction unit 362 performs intra-prediction on the pixel line located in the odd-numbered column of the current block of M × N size An A × B size prediction block can be generated.

The second intraprediction unit 362 generates an A × B size prediction block, and then, based on the intra prediction of the pixel line located in the odd-numbered column of the M × N current block, It is possible to perform intra prediction on the pixel lines located in the even-numbered columns of the current block of size N.

Here, the second intraprediction unit 362 performs intraprediction on the pixel lines located in the even-numbered columns of the current block of the M x N size, and then performs intraprediction on the pixel lines located in odd-numbered columns of the M x N- It is needless to say that intra prediction can be performed.

Meanwhile, the decoding apparatus using adaptive intra prediction according to an embodiment of the present invention may perform adaptive intra prediction after dividing a current block as described with reference to FIG.

It is also possible to perform prediction by further dividing the current block into smaller blocks. Information on the block may be transmitted in a unit of a sequence, a picture, a block, or the like, or how to divide the encoding device and the decoding device May share information about the user.

The adder 340 adds the residual block of M × N size or the residual block of A × B size generated based on the reconstruction information and the prediction block of the M × N size or the prediction block of the A × B size A restored image can be generated.

The memory 350 performs functions corresponding to the memories 180 and 290 of FIGS.

The first inverse transform unit 330 and the second inverse transform unit 331 perform inverse transform corresponding to the first transform unit 230 and the second transform unit 231 shown in FIG. The quantization unit 320 and the second inverse quantization unit 321 may respectively perform inverse quantization corresponding to the first quantization unit 240 and the second quantization unit 241 shown in FIG.

8 is a flowchart illustrating an image decoding method using adaptive intra prediction according to an embodiment of the present invention.

Referring to FIG. 8, an image decoding method using adaptive intraprediction according to an embodiment of the present invention includes generating reconstructed information (S810), generating a predicted block (S820), and generating reconstructed image (S830).

The step of generating reconstruction information (S810) generates reconstruction information by decoding the bit stream received from the encoding apparatus. The reconstruction information includes residual coefficient and information on the intra prediction method.

The step of generating a prediction block (S820) includes a step of generating a prediction block of M × N size or a current block of M × N size according to the intra prediction method according to the intra prediction mode of the current block of M × N size based on the reconstruction information It is possible to generate an A × B size prediction block.

For example, if the intra-prediction mode of the current block of the M × N size is the horizontal mode, the step of generating the prediction block (S820) Prediction can be performed to generate an A × B size prediction block. The prediction block is encoded by intraprediction of a pixel line located in an odd-numbered row of an M × N current block, Prediction of the pixel line located in the even-numbered row of the current block of the current block.

In addition, the step of generating the prediction block S820 may generate the prediction block of the A × B size by performing intra-prediction on the pixel line located in the even-numbered row of the current block of the M × N size, It is possible to perform intra prediction on a pixel line located in an odd-numbered row of an M × N current block with reference to a reconstructed pixel which is encoded through intraprediction on a pixel line located in an even- have.

If the intra-prediction mode of the current block of the M × N size is the vertical mode, the prediction block generating step S820 performs intra-prediction on the pixel line located in the odd-numbered column of the M × N current block A prediction block having an A × B size can be generated. An intra-prediction is performed on a pixel line located in an odd-numbered column of an M × N current block, Lt; th > column can be performed.

In addition, an A × B size prediction block can be generated by performing intra-prediction on a pixel line located in an even-numbered column of an M × N current block, And intra-prediction can be performed on the pixel line located in the odd-numbered column of the current block of the M × N size with reference to the reconstructed pixel.

Furthermore, the decoding method using the adaptive intra prediction according to the embodiment of the present invention can perform adaptive intra prediction after dividing the current block as described with reference to FIG.

An apparatus and method for encoding / decoding an image using adaptive intra prediction according to an embodiment of the present invention may improve intra-prediction accuracy by performing intra-prediction by dividing a current block according to an intra-prediction mode of a current block . Thus, the image coding efficiency can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

110, 210: Subtraction unit 120:
130: quantization unit 140, 250: entropy coding unit
150: inverse quantization unit 160: inverse transform unit
170, 280, 340: adder 180, 290, 350: memory
190: prediction unit 220: prediction method verification unit
221, 360: prediction method determining section 222, 361: first intra prediction section
223, 362: second intraprediction unit 230: first intra-prediction unit
231: second transform unit 240: first quantization unit
241: second quantization unit 260, 320: first inverse quantization unit
261, 321: a second inverse quantization unit 270, 330: a first inverse transform unit
271, 331: second inverse transform unit 310: entropy decoding unit

Claims (20)

In an image decoding method using a prediction block having an adaptive size,
Receiving a bitstream;
Decoding the received bit stream to generate reconstruction information;
Dividing a current block to be subjected to intra-picture prediction by referring to the reconstruction information, and determining an area of a prediction block smaller than the current block;
Performing intra-frame prediction on a region of the determined prediction block to generate a prediction block; And
And generating a reconstruction block by adding the generated prediction block to the residual block decoded in the bitstream. In claim 1,
The region of the prediction block includes:
Wherein the current block is determined by dividing the current block only in a predetermined prediction mode among the prediction modes according to the intra prediction. In claim 2,
The selected partial prediction mode includes:
And at least one of a horizontal mode and a vertical mode. In claim 1,
The region of the prediction block includes:
And pixel lines located in at least two or more rows of the current block. In claim 1,
The region of the prediction block includes:
And pixel lines located in at least two or more columns of the current block. In claim 4,
Wherein the pixel lines located in the at least two rows,
Wherein the pixel blocks are pixel lines located at odd or even rows of the current block. In claim 5,
The pixel lines located in the at least two or more columns,
Wherein the pixel lines are pixel lines located in odd or even columns of the current block. In claim 4,
Wherein the generating the prediction block comprises:
In-picture prediction for pixel lines located in rows other than the row in which the restored pixels are located, with reference to pixels restored by intra-picture prediction on pixel lines located in at least two rows of the current block The method comprising the steps of: In claim 5,
Wherein the generating the prediction block comprises:
Performs in-picture prediction on pixel lines located in columns other than the column in which the restored pixels are located, with reference to the pixels restored through intra-frame prediction on pixel lines located in at least two columns of the current block The method comprising the steps of: In claim 1,
The region of the prediction block includes:
Wherein the current block has a size of MxN / 2 or M / 2xN when the current block has a size of MxN. In an image coding method using a prediction block having an adaptive size,
Dividing a current block to be subjected to in-picture prediction and adaptively determining an area of a prediction block smaller than the current block;
Performing intra-frame prediction on a region of the determined prediction block to generate a prediction block;
Generating a residual block by subtracting the generated prediction block from the current block; And
And generating a bitstream by coding the generated residual block and reconstruction information indicating an area of the adaptively determined prediction block. In claim 11,
The region of the prediction block includes:
Wherein the current block is determined by dividing the current block only in a predetermined prediction mode among the prediction modes according to the intra prediction. In claim 12,
The selected partial prediction mode includes:
A vertical mode, a horizontal mode, and a vertical mode. In claim 11,
The region of the prediction block includes:
And pixel lines located in at least two or more rows of the current block. In claim 11,
The region of the prediction block includes:
And pixel lines located in at least two or more columns of the current block. In claim 14,
Wherein the pixel lines located in the at least two rows,
Wherein the pixel blocks are pixel lines located at odd or even rows of the current block. In claim 15,
The pixel lines located in the at least two or more columns,
Wherein the pixel blocks are pixel lines located in an odd or even column of the current block. In claim 14,
Wherein the generating the prediction block comprises:
In-picture prediction for pixel lines located in rows other than the row in which the restored pixels are located, with reference to pixels restored by intra-picture prediction on pixel lines located in at least two rows of the current block The method comprising the steps of: In claim 15,
Wherein the generating the prediction block comprises:
Performs in-picture prediction on pixel lines located in columns other than the column in which the restored pixels are located, with reference to the pixels restored through intra-frame prediction on pixel lines located in at least two columns of the current block The method comprising the steps of: In claim 11,
The region of the prediction block includes:
Wherein the current block has a size of MxN / 2 or M / 2xN when the current block has a size of MxN.

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