KR20170142860A - Method and apparatus for encoding or decoding video signal - Google Patents

Abstract

The present invention relates to a method for decoding a video signal and an apparatus thereof. The method for decoding a video signal according to the present invention includes the steps of: setting a structure of a coding block constituting a current image; setting a structure of transform blocks corresponding to the coding block; and generating a prediction signal using the transform blocks, wherein the coding block includes at least one of a square block and a non-square block. Accordingly, the present invention can improve coding efficiency.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for encoding or decoding a video signal,

The present invention relates to a method and apparatus for encoding or decoding a video signal, and more particularly, to a method and apparatus for encoding or decoding a video signal using a non-square coding block and / or a non-square conversion block.

Recently, the demand for high resolution and high quality images such as high definition (HD) image and ultra high definition (UHD) image is increasing in various applications. Since the amount of data increases relative to the conventional image data as the image data becomes high resolution and high quality, when the image data is transmitted using a medium such as a wired / wireless broadband line or stored using an existing storage medium, The cost and the storage cost increase. High-efficiency image compression techniques can be utilized to solve such problems as image data is high-resolution and high-quality.

Video compression techniques include spatial prediction and / or temporal prediction to reduce or eliminate redundancy inherent in video sequences. In block-based video coding, a video frame or slice may be divided into blocks. Each block can be further divided. Blocks in an intra-coded I frame or slice are encoded using spatial prediction for reference samples in neighboring blocks in the same frame or slice. Blocks in an intercoded P or B frame or slice may use spatial prediction for reference samples in neighboring blocks in the same frame or slice, or temporal prediction for reference samples in different reference frames. The spatial or temporal prediction generates a prediction block for the block to be coded. The residual data represents the pixel difference between the original block to be coded and the prediction block.

Generally, the current block is encoded using a forward coding block (CU) and a transform block (TU) of the same size, and conversion blocks based on each coding block or prediction block size are applied to a coding block do. However, when the forward coding block is used, since the prediction mode and the prediction information must be transmitted for each coding block, unnecessary information may be transmitted according to the type of the image, thereby reducing the coding efficiency. In addition, there is a disadvantage in that characteristics of an image corresponding to a coding block and characteristics of a residual signal generated according to a prediction mode can not be considered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for encoding and decoding a video signal that improves coding efficiency by using coding blocks and transform blocks of various shapes according to images.

Another object of the present invention is to provide a method of determining a coding order of a transform block capable of increasing a coding efficiency according to an intra-picture prediction mode of a current block, and a method and apparatus for encoding and decoding a video signal .

According to an aspect of the present invention, there is provided a method of decoding a video signal, the method comprising: setting a structure of a coding block constituting a current image; Setting a structure of transform blocks corresponding to the coding block; And generating a prediction signal using the transform blocks, wherein the coding block includes at least one of a square block and a non-square block.

The transform block includes at least one of a square transform block and a non-square transform block having the same size or a small size of the coding block.

In one embodiment, the square transform block may be a transform block having a quadtree structure, and the non-square transform block may be a transform block having a non-square binary tree structure or an unquadratic quadtree structure. The method may further include receiving transform block division information indicating the shape and size of the transform block.

In one embodiment, the transform block may be divided to include at least one of a non-square transform sub-block and a square transform sub-block, further comprising re-dividing the transform block into sub-transform blocks, When re-divided into transform blocks, the prediction signal may be generated for each sub-transform block. In addition, the sub-transform blocks may include at least one of a non-square sub-transform block and a square sub-transform block.

In one embodiment, when the current block performs intra-frame prediction, the intra-frame prediction mode of the current block is divided into a first mode area having an angle of 90 degrees or more and less than 180 degrees, A second mode area having an angle, and a third area having an angle of more than 45 degrees and less than 90 degrees; And a step of variably determining a coding order of the transform block based on a mode area to which the intra prediction mode belongs.

And if the direction of the intra prediction mode is the second mode area, the transform block may be coded in order from the lower left to the upper right direction, and if the transform block is a square transform block, the lower left, lower right, And the upper right corner, and if the transform block is a square transform block, it can be coded in the order of the lower left, upper left, lower right, and upper right.

Further, if the transform block is a vertically-divided non-square transform block, it can be coded in order from left to right. If the transform block is a horizontally divided non-square transform block, it can be coded in order from bottom to top have.

When the direction of the intra prediction mode is the third region mode, the transform block may be coded in order from the upper right to the lower left, and if the transform block is a square transform block, the upper right, upper left, lower right, And the lower left end, and if the transform block is a square transform block, it can be coded in the order of the right upper end, the lower right end, the upper left end, and the lower left end.

In addition, if the transform block is a vertically-divided non-square transform block, it can be coded in the order from right to left. If the transform block is a horizontally divided non-square transform block, have.

According to another aspect of the present invention, there is provided an apparatus for decoding a video signal, the apparatus comprising: a block setting unit configured to set a structure of a coding block constituting a current image and to set a structure of conversion blocks corresponding to the coding block; ; And a prediction signal generator for generating a prediction signal using the transform blocks, wherein the coding block and the transform block include at least one of a square block and a non-square block, The predictive signal generator may code the transform blocks according to a mode coding mode in which the intra-picture prediction mode of the coding block belongs to which mode area among the mode areas classified according to the prediction direction.

According to an embodiment of the present invention, there is provided an apparatus for encoding and decoding a video signal that improves coding efficiency by using non-square coding blocks and non-square conversion blocks according to an image.

According to another embodiment of the present invention, by changing the coding order of the transform block in accordance with the direction of the intra-picture prediction mode of the current block, a high-resolution image can be encoded and decoded, A method for determining a coding order of a block, and a method and apparatus for decoding a video signal to perform the method.

1 is a block diagram schematically illustrating a video encoding apparatus according to an embodiment of the present invention.
2 is a block diagram schematically showing a video decoding apparatus according to an embodiment of the present invention.
FIG. 3 illustrates a coding block of a current block according to a general method.
4A to 4C illustrate examples of non-square coding blocks of a current block according to an embodiment of the present invention.
5A-6D illustrate examples of transform blocks for a current coding block according to an embodiment of the present invention.
7A to 10 illustrate examples of sub-transform blocks according to an embodiment of the present invention.
Fig. 11 is a diagram for explaining a coding procedure and a coding method of a transform block according to a general method.
Figures 12A-12C illustrate examples of transform blocks in accordance with an embodiment of the present invention.
13 illustrates mode regions to which an intra prediction mode according to an embodiment of the present invention belongs.
FIGS. 14A and 14B show the coding order of transform blocks when the intra-picture prediction mode of the current block belongs to the first mode region according to an embodiment of the present invention. FIGS. 16A through 16C illustrate the coding order of the transform blocks when the intra-picture prediction mode of the current block according to the present invention belongs to the second mode area. And the coding order of the transform blocks when belonging to the mode area.
FIGS. 17A to 19C show various examples of a procedure for coding square and non-square transform blocks by applying a coding order of transform blocks considering an intra prediction mode according to an embodiment of the present invention.

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

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the drawings, the thickness and the size of each unit are exaggerated for convenience and clarity of description, and the same reference numerals denote the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Although the terms first, second, etc. are used herein to describe various elements, members, parts, regions, and / or sections, these elements, members, parts, It should be understood that the present invention should not be construed as being limited thereto. These terms are only used to distinguish one element, element, component, region, or portion from another region or portion. Thus, a first component, element, component, region, or section described below may refer to a second component, element, component, region, or portion without departing from the teachings of the present invention. Furthermore, and / or terms include any combination of the plurality of related described items or any of the plurality of related items described.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it is understood that the element is not directly connected or connected to the other element, And < / RTI > the case where other components are present. However, when an element is referred to as being "directly connected" or "directly connected" to another element, there is no other element in between and the element and the other element are directly connected or connected It should be understood that

Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically showing ideal embodiments of the present invention. In the drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of explanation, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, embodiments of the present invention should not be construed as limited to any particular shape of the regions shown herein.

1 is a block diagram schematically showing an image encoding apparatus according to an embodiment of the present invention.

1, the image encoding apparatus 100 includes a picture dividing unit 105, an inter-picture predicting unit 110, an intra-picture predicting unit 115, a transform unit 120, a quantization unit 125, An entropy encoding unit 135, an inverse quantization unit 140, an inverse transformation unit 145, a filter unit 150, and a memory 155.

Each component shown in FIG. 1 is shown independently to represent different characteristic functions in the image encoding apparatus, and does not mean that each component is composed of separate hardware or one software constituent unit. That is, each component is listed as a separate component for convenience of explanation. At least two components of each component are combined to form one component, or one component is divided into a plurality of components, Can be performed. It is to be understood that the embodiments in which each of these components is integrated or the separate embodiments can be included in the scope of the present invention without departing from the essential aspect of the present invention.

The picture dividing unit 105 can divide the inputted picture into at least one processing unit. The processing unit may be a prediction unit (PU), a transform unit (TU), a coding unit (CU) ). However, for the sake of convenience of explanation, the prediction block may be expressed as a prediction unit, the conversion block as a conversion unit, and the encoding or decoding block as a coding unit or a decoding unit.

In one embodiment, the picture dividing section 105 divides a picture into a combination of a plurality of coding blocks, a prediction block, and a conversion block, and generates a picture based on a predetermined criterion (for example, a cost function) It is possible to encode a picture by selecting a combination of an encoding block, a prediction block, and a transform block.

For example, one picture may be divided into a plurality of coding blocks. In one embodiment, a picture may be partitioned using a recursive tree structure, such as a quad tree structure or a binary tree structure, and may include one picture or a maximum coding unit) as a root can be divided by the number of child nodes as many as the number of the divided coding blocks. Through this process, the coding block that is not further divided can become a leaf node. For example, in a case where it is assumed that only a square division is possible for one coding block, one coding block may be divided into four coding blocks, for example. However, in the present invention, the coding block, the prediction block, and / or the transform block are not limited to the symmetric division at the time of division. Asymmetric division is also possible. However, the number of divisions is only an example, and the present invention is not limited thereto. A method and apparatus for coding and decoding a video signal using a non-square block that is asymmetrically divided into a coding block and a transform block will be described with reference to FIGS. 3 to 19C.

The prediction block may also be divided into at least one square or non-square shape having the same size in one coding block, and one of the divided prediction blocks in one coding block One prediction block may be divided so as to have a different shape and size from the other prediction block. In one embodiment, the coding block and the prediction block may be the same. That is, the prediction may be performed based on the divided coding blocks without distinguishing between the coding blocks and the prediction blocks.

The predicting unit may include an inter-picture predicting unit 110 for performing inter-prediction and an intra-picture predicting unit 115 for performing intra-prediction. In order to improve the coding efficiency, instead of encoding the video signal as it is, the video is predicted using a specific area in the already coded and decoded picture, and the residual value between the original video and the predicted video is encoded. In addition, the prediction mode information and the motion vector information used for the prediction may be encoded by the entropy encoding unit 135 together with the residual value, and then transmitted to the decoding unit. When a particular encoding mode is used, it is also possible that the original block is encoded as it is without generating a prediction block through the predicting units 110 and 115, and is transmitted to the decoding unit.

In one embodiment, the predicting units 110 and 115 determine whether to perform intra-picture prediction or intra-picture prediction for a prediction block, and determine whether the intra-picture prediction mode, the motion vector, Specific information according to each method can be determined. In this case, the processing unit in which the prediction is performed, the prediction method, and the detail processing unit may be different from each other. For example, even if the prediction mode and the prediction method are determined according to the prediction block, the prediction can be performed according to the conversion block.

The predicting units 110 and 115 can predict a processing unit of a divided picture in the picture dividing unit 105 to generate a prediction block composed of predicted samples. The picture processing unit in the predicting units 110 and 115 may be a coding block unit, a conversion block unit, or a prediction block unit.

The inter picture prediction unit 110 may predict a prediction block based on information of at least one of a previous picture or a following picture of the current picture and may predict a prediction block based on information of a partial area in which coding in the current picture is completed The block can be predicted. The inter-picture predicting unit 110 may include a reference picture interpolating unit, a motion predicting unit, and a motion compensating unit.

In one embodiment, the information of the at least one picture used for prediction in the inter picture prediction unit 110 may be information of already coded and decoded pictures, have. For example, the picture modified and stored by any of the above methods may be a picture enlarged or reduced in a picture in which encoding and decoding has been performed, or may be a picture in which the brightness of all pixel values in a picture is changed, It is possible.

The reference picture interpolator can generate the pixel information of integer pixels or less from the reference picture by receiving the reference picture information from the memory 155. [ In the case of luminance pixels, it is possible to generate pixel information of less than or equal to a whole number in units of a quarter pixel by using a DCT-based 8-tap interpolation filter having different coefficients of the filter. In the case of a color difference signal, pixel information less than or equal to a certain integer can be generated in units of 1/8 pixel by using a DCT-based 4-tap interpolation filter having different coefficients of a filter. However, the unit for generating the pixel information of the type and the integer of the filter is not limited to this, and a unit for generating pixel information below the integer using various interpolation filters may be determined.

The motion prediction unit may perform motion prediction based on the reference pictures interpolated by the reference picture interpolation unit. Various methods can be used to calculate the motion vector. The motion vector may have an integer pixel unit or a motion vector value of 1/4 or 1/8 pixel unit based on the interpolated pixel. In one embodiment, a prediction unit of the current block can be predicted by differentiating the motion prediction method in the motion prediction unit. The motion prediction method may include a merge method, an AMVP (Advanced Motion Vector Prediction) method, and a skip method. In this way, the information including the index of the reference picture selected in the inter-picture prediction unit 110, the motion vector predictor (MVP), and the residual signal can be entropy-coded and transmitted to the decoder.

Unlike the inter-picture prediction, the intra-frame prediction unit 115 can generate a prediction block based on reference pixel information around the current block, which is pixel information in the current picture. In the case where the neighboring blocks of the prediction block are blocks in which the inter-picture prediction is performed, that is, when the reference pixels are pixels performing inter-picture prediction, the reference pixels included in the inter- May be replaced with the reference pixel information of the block.

If the reference pixel is unavailable, it must be set up to be available. Generally, in such a case, the non-available reference pixel has been used by replacing at least one reference pixel among available peripheral pixels or by assigning a predetermined sample value.

However, a method of copying and using reference pixels available for such unavailable reference pixels may cause a problem of degrading the intra-picture prediction coding efficiency in decoding the current image. According to various embodiments of the present invention, in order to solve this problem, in order to perform intra prediction using an available reference pixel area rather than a reference pixel area that is not available in the coding of a transform block, The coding order of the transform blocks can be changed in various ways depending on the direction. A detailed description thereof will be described later.

In addition, the intra-picture predicting unit 115 may use the most probable intra-picture prediction mode (MPM: Most Probable mode) obtained from the neighboring blocks to encode the intra-picture prediction mode. According to various embodiments of the present invention, the most probable intra-picture prediction mode list (MPM List) composed of the most probable intra-picture prediction modes may be configured in various ways.

Even when the intra-frame prediction unit 115 performs intra-frame prediction, the processing unit in which the prediction is performed, the prediction method, and the processing unit in which the concrete contents are determined may be different from each other. For example, the prediction mode may be defined as a prediction unit (PU), the prediction may be performed in the prediction unit, the prediction mode may be defined as a prediction unit, and the prediction may be performed in a conversion unit (TU). In one embodiment, the prediction mode may be determined in units of coding blocks (CU), and the prediction may be performed in units of the coding blocks, because the coding unit and the prediction unit are the same.

The prediction mode of the intra prediction can include 65 directional prediction modes and at least two non-directional modes. The non-directional mode may include a DC prediction mode and a planar mode. The number of the 67 inter picture prediction modes is only an example, and the present invention is not limited thereto, and intra prediction can be performed in more directional or non-directional modes to predict in various ways.

In one embodiment, intra prediction may generate a prediction block after applying a filter to a reference pixel. In this case, whether to apply the filter to the reference pixel can be determined according to the intra-picture prediction mode and / or size of the current block.

The prediction unit (PU) can be determined in various sizes and forms from a coding unit (CU) which is no longer divided. For example, in case of inter-picture prediction, the prediction unit may have the same size as 2N x 2N, 2N x N, N x 2N or N x N. In case of the intra prediction, the prediction unit may have the same size as 2N x 2N or N x N (N is an integer), but the intra prediction can be performed not only in the forward direction but also in the non-directional size. In this case, the N x N size prediction unit may be set to be applied only in a specific case. An intra prediction unit having the same size as N x mN, mN x N, 2N x mN or mN x 2N (m is a fraction or an integer) may be further defined and used in addition to the prediction unit of the above-described size.

A residual value (a residual block or a residual signal) between the prediction block and the original block generated by the intra prediction unit 115 may be input to the transform unit 120. [ In addition, the prediction mode information, the interpolation filter information, and the like used for prediction can be encoded by the entropy encoding unit 135 together with the residual value and transmitted to the decoder.

The transforming unit 120 transforms the residual block including the residual value information of the prediction unit generated through the original block and the prediction units 110 and 115 into a DCT (Discrete Cosine Transform), a DST (Discrete Sine Transform) , And KLT (Karhunen Loeve Transform). Whether the DCT, DST, or KLT is applied to transform the residual block can be determined based on the intra prediction mode information of the prediction unit used to generate the residual block.

The transform block in transformer 120 may be a TU and may be a square, a non-square, a square quad tree structure, a non-square quad tree ) Structure or a binary tree structure. In one embodiment, the size of the conversion unit may be determined within a range of predetermined maximum and minimum sizes. Also, one transform block may be further divided into sub transform blocks, which may be a square structure, a non-square structure, a square quad tree structure, a non-square quad A non-square quad tree structure or a binary tree structure.

The quantization unit 125 may quantize the residual values transformed by the transform unit 120 to generate a quantization coefficient. In one embodiment, the transformed residual values may be a frequency domain transformed value. The quantization coefficient may be changed according to the conversion unit or the importance of the image and the value calculated by the quantization unit 125 may be provided to the dequantization unit 140 and the rearrangement unit 130.

The reordering unit 130 may rearrange the quantization coefficients provided from the quantization unit 125. [ The reordering unit 130 can improve the coding efficiency in the entropy encoding unit 135 by rearranging the quantization coefficients. The reordering unit 130 may rearrange the quantization coefficients of the two-dimensional block form into a one-dimensional vector form through a coefficient scanning method. In the coefficient scanning method, it may be determined which scanning method is used according to the size of the conversion unit and the intra prediction mode. The coefficient scanning method may include a jig-jag scan, a vertical scan that scans a coefficient of a two-dimensional block form in a column direction, and a horizontal scan that scans a block form coefficient of a two-dimensional row in a row direction. In one embodiment, the reordering unit 130 may increase the entropy encoding efficiency in the entropy encoding unit 135 by changing the order of the coefficient scanning based on the probabilistic statistics of the coefficients transmitted from the quantization unit.

The entropy encoding unit 135 may perform entropy encoding on the rearranged quantization coefficients by the rearrangement unit 130. For entropy encoding, various encoding methods such as Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Content-Adaptive Binary Arithmetic Coding (CABAC) may be used.

The entropy encoding unit 135 quantizes the quantization coefficient information, block type information, prediction mode information, division unit information, prediction unit information, and transmission unit information of the coding unit received from the reordering unit 130 and the prediction units 110 and 115, Various information such as motion vector information, reference picture information, interpolation information of a block, and filtering information can be encoded. Further, in one embodiment, the entropy encoding unit 135 may apply a certain change to the parameter set or syntax to be transmitted, if necessary.

The inverse quantization unit 140 dequantizes the quantized values in the quantization unit 125 and the inverse transformation unit 145 inversely changes the dequantized values in the inverse quantization unit 140. [ The residual values generated by the inverse quantization unit 140 and the inverse transform unit 145 may be combined with prediction blocks predicted by the prediction units 110 and 115 to generate a reconstructed block. The reconstructed block may be a motion compensated image or an MC image (Motion Compensated Picture).

The motion compensation image may be input to the filter unit 150. The filter unit 150 may include a deblocking filter unit, a sample adaptive offset (SAO), and an adaptive loop filter (ALF). In summary, A deblocking filter is applied in the filter section to reduce or eliminate blocking artifacts, and then input to the offset correction section to correct the offset. The picture output from the offset correcting unit is input to the adaptive loop filter unit, passes through an ALF (Adaptive Loop Filter) filter, and the picture passed through the filter can be transmitted to the memory 155.

To describe the filter unit 150 in detail, the deblocking filter unit can remove distortion in a block generated at a boundary between blocks in a reconstructed picture. In order to determine whether deblocking is to be performed, it may be determined whether to apply a deblocking filter to a current block based on pixels included in a few columns or rows included in the block. When a deblocking filter is applied to a block, a strong filter or a weak filter may be applied according to the required deblocking filtering strength. In applying the deblocking filter, horizontal filtering and vertical filtering may be performed concurrently in performing vertical filtering and horizontal filtering.

The offset correcting unit may correct the offset from the original image in units of pixels for the residual block to which the deblocking filter is applied. In order to correct an offset for a specific picture, a method of dividing a pixel included in an image into a predetermined number of regions, determining an area to be subjected to the offset, and applying an offset to the area (Band Offset) (Edge Offset) in which information is taken into consideration. However, in one embodiment, the filtering unit 150 may not apply the filtering to the reconstruction block used in inter-view prediction.

The adaptive loop filter (ALF) can be performed only when high efficiency is applied based on a value obtained by comparing the filtered reconstructed image with the original image. After dividing the pixels included in the image into a predetermined group, one filter to be applied to the group may be determined and different filtering may be performed for each group. Information related to whether or not to apply the ALF may be transmitted for each coding unit (CU), and the shape and filter coefficient of an ALF filter to be applied may be different according to each block. In addition, an ALF filter of the same type (fixed form) may be applied regardless of the characteristics of the application target block.

The memory 155 may store restored blocks or pictures calculated through the filter unit 150. [ The restored block or the picture stored in the memory 155 may be provided to the inter-picture predicting unit 110 or the intra-picture predicting unit 115 for performing inter-picture prediction. The pixel values of the reconstruction blocks used in the intra prediction unit 115 may be data to which the deblocking filter unit, the offset correction unit, and the adaptive loop filter unit are not applied.

2 is a block diagram schematically showing an image decoding apparatus according to an embodiment of the present invention. 2, the image decoding apparatus 200 includes an entropy decoding unit 210, a reordering unit 215, an inverse quantization unit 220, an inverse transform unit 225, an inter-picture prediction unit 230, A filter unit 240, and a memory 245. The memory unit 245 includes a memory unit 235, a filter unit 240,

When an image bitstream is input from the image encoding apparatus, the input bitstream can be decoded in an inverse process of a process in which image information is processed in the encoding apparatus. For example, when variable length coding (VLC), such as CAVLC, is used to perform entropy coding in the image coding apparatus, the entropy decoding unit 210 is also used in an encoding apparatus It is possible to implement entropy decoding by implementing the same VLC table as the used VLC table. When CABAC is used to perform entropy encoding in the encoding apparatus, the entropy decoding unit 210 can perform entropy decoding using CABAC in correspondence thereto.

The entropy decoding unit 210 provides the information for generating a prediction block among the decoded information to the inter-picture predicting unit 230 and the intra-picture predicting unit 235. The entropy decoding unit 210 calculates residual values of entropy- May be input to the reordering unit 215. [

The reordering unit 215 may rearrange the entropy-decoded bitstream in the entropy decoding unit 210 based on a method of rearranging the entropy-decoded bitstream in the image encoder. The reordering unit 215 can perform reordering by providing information related to the coefficient scanning performed by the encoder and performing a reverse scanning based on the scanning order performed by the encoder.

The inverse quantization unit 220 may perform inverse quantization based on the quantization parameters provided by the encoding apparatus and the coefficient values of the re-arranged blocks. The inverse transform unit 225 may perform inverse DCT, inverse DST, or inverse KLT on the DCT, DST, or KLT performed by the transform unit of the encoding apparatus, on the quantization result performed by the image encoding apparatus. The inverse transform can be performed based on the transmission unit determined by the encoding apparatus or the division unit of the image. The transforming unit of the encoding apparatus can selectively perform DCT, DST, or KLT according to the prediction method, information such as the size and prediction direction of the current block, and the inverse transform unit 225 of the decoding apparatus transforms The inverse transform method is determined based on the transformed information to perform inverse transform.

The prediction units 230 and 235 may generate a prediction block based on the information related to the prediction block generation provided by the entropy decoding unit 210 and the previously decoded block and / or picture information provided in the memory 245. The reconstruction block may be generated using the prediction block generated by the prediction units 230 and 235 and the residual block provided by the inverse transform unit 225. [ The concrete prediction method performed by the prediction units 230 and 235 may be the same as the prediction method performed by the prediction units 110 and 115 of the encoding apparatus.

The prediction units 230 and 235 may include a prediction unit determination unit (not shown), an inter picture prediction unit 230, and an intra prediction unit 235. The prediction unit determination unit receives various information such as prediction unit information input from the entropy decoding unit 210, prediction mode information of the intra prediction method, motion prediction related information of the inter picture prediction method, And it is possible to discriminate whether the prediction block performs intra-picture prediction or intra-picture prediction.

The inter-picture predicting unit 230 predicts information included in at least one of a previous picture or a following picture of a current picture including a current prediction block, based on information necessary for inter-picture prediction of a current prediction block provided by an image encoder Inter prediction can be performed on the current prediction block.

Specifically, in the inter-picture prediction, a reference block having the same size as the current block is selected for a current block, and a prediction block for the current block can be generated. At this time, information of neighboring blocks of the current picture can be used to use the information of the reference picture. For example, a prediction block for a current block can be generated based on information of a neighboring block using a skip mode, a merge mode, and an AMVP (Advanced Motion Vector Prediction) method.

The prediction block can be generated in units of samples below integer, such as a half pixel sample unit and a quarter pixel sample unit. In this case, the motion vector may also be expressed in units of integer pixels or less. For example, it can be expressed in units of 1/4 pixel for luminance pixels and 1/8 pixels for chrominance pixels.

The motion information including the motion vector and the reference picture index necessary for inter-picture prediction of the current block can be derived corresponding to the skip flag and the merge flag received from the encoding device.

The intra prediction unit 235 can generate a prediction block based on the pixel information in the current picture. If the prediction unit is a prediction unit that performs intra prediction, the intra prediction can be performed based on the intra prediction mode information of the prediction unit provided by the image encoder. In the case where the neighboring blocks of the predictive unit are the blocks on which the inter-view prediction is performed, that is, the reference pixels are the pixels performing the inter-view prediction, the reference pixels included in the block in which the inter- May be replaced with the reference pixel information of the block.

If the reference pixel is unavailable, it must be set up to be available. Generally, in such a case, the unavailable reference pixel has been used by substituting at least one reference pixel among available neighbor pixel values or assigning a predetermined sample value.

However, a method of copying and using reference pixels available for such unavailable reference pixels may cause a problem of degrading the intra-picture prediction coding efficiency in decoding the current image. According to various embodiments of the present invention, in order to solve this problem, in order to perform intra prediction using an available reference pixel area rather than a reference pixel area that is not available in the coding of a transform block, The coding order of the transform blocks can be changed in various ways depending on the direction. A detailed description related thereto will be described later.

In addition, the intra prediction unit 235 may use the most probable intra prediction mode (MPM) obtained from the neighboring blocks to encode the intra prediction mode. In one embodiment, the most probable intra-picture prediction mode may use an intra-picture prediction mode of a spatial neighbor block of the current block.

In one embodiment, the processing unit in which the prediction is performed in the intra prediction unit 235, the prediction method, and the processing unit in which the concrete contents are determined may be different from each other. For example, the prediction mode may be determined as a prediction unit, the prediction may be performed in the prediction unit, the prediction mode may be determined in the prediction unit, and the intra prediction may be performed in the conversion unit.

In this case, the prediction block PU may be determined in various sizes and shapes from the coding block (CU) which is not further divided. For example, in the case of the intra prediction, the prediction block may have the same size as 2N x 2N or N x N (N is an integer), but the N x mN, mN x N , 2N x mN or mN x 2N (m is a fraction or an integer). In this case, the N x N size prediction unit may be set to be applied only in a specific case.

Also, the transform block TU may be determined in various sizes and shapes. For example, the transform block may have a size such as 2N x 2N or N x N (where N is an integer), but not only such a normal size but also N x mN, mN x N, 2N x mN, mN x 2N (m is a fraction or an integer). In this case, the N x N size prediction unit may be set to be applied only in a specific case. In one embodiment, the transform block may be a square, a non-square, a square quad tree, a non-square quad tree, or a binary tree binary tree structure. In one embodiment, the size of the transform block may be determined within a range of predetermined maximum and minimum sizes. In addition, one transform block may be divided into sub-transform blocks. In this case, the sub transform blocks may have a square structure, a non-square structure, a square quad tree structure, A quad-tree structure, a non-square quad tree structure, or a binary tree structure.

The intra picture prediction unit 235 may include an AIS (Adaptive Intra Smoothing) filter unit, a reference pixel interpolation unit, and a DC filter unit. The AIS filter unit performs filtering on the reference pixels of the current block, and may determine whether to apply the filter according to the prediction mode of the current prediction unit. The AIS filtering can be performed on the reference pixels of the current block using the prediction mode of the prediction unit provided in the image encoder and the AIS filter information. If the prediction mode of the current block is a mode in which AIS filtering is not performed, the AIS filter unit may not be applied to the current block.

The reference pixel interpolator can interpolate a reference pixel to generate a reference pixel in a pixel unit less than an integer value when the prediction mode of the prediction unit is a prediction unit that performs intra-frame prediction based on a sample value obtained by interpolating a reference pixel have. If the prediction mode of the current prediction unit does not interpolate the reference pixel and generates a prediction block, the reference pixel may not be interpolated. The DC filter unit may generate a prediction block through filtering when the prediction mode of the current block is the DC mode.

The restored blocks and / or pictures may be provided to the filter unit 240. The filter unit 240 may include a deblocking filter unit, a sample adaptive offset, and / or an adaptive loop filter unit on the restored block and / or the picture. The deblocking filter unit may receive information indicating whether a deblocking filter is applied to a corresponding block or a picture from the image encoder and information indicating whether a strong or weak filter is applied when a deblocking filter is applied. The deblocking filter unit may receive the deblocking filter related information provided by the image encoder and may perform deblocking filtering on the corresponding block in the image decoder.

The offset correcting unit may perform offset correction on the reconstructed image based on the type and offset value information of the offset correction applied to the image at the time of encoding. The adaptive loop filter unit may be applied as a coding unit based on information such as information on whether the adaptive loop filter provided from the encoder is applied or coefficient information of the adaptive loop filter. The information associated with the adaptive loop filter may be provided in a specific parameter set.

The memory 245 stores the reconstructed picture or block, and can later use the reconstructed picture or reference block as a reference picture or reference block, and can provide the reconstructed picture to the output unit.

Although omitted herein for the sake of convenience, the bit stream input to the decoding apparatus may be input to the entropy decoding unit through a parsing step. In addition, the entropy decoding unit may perform the parsing process.

In this specification, coding may be interpreted as encoding or decoding in some cases, and information includes both values, parameters, coefficients, elements, flags, and the like. . ≪ / RTI > A 'slice', a 'frame', or the like refers to a unit of a picture in a specific time zone, and a 'picture' Is a unit constituting a part, and can be used in combination with a picture as needed.

'Pixel', 'pixel' or 'pel' represents the smallest unit of a single image. Also, as a term indicating the value of a specific pixel, 'sample' can be used. The sample may be divided into luminance (Luma) and chroma (chroma) components, but generally it can be used as a term including both of them. The chrominance component represents a difference between predetermined colors, and is generally composed of Cb and Cr.

A 'unit' refers to a specific unit of an image processing unit or an image, such as the encoding unit, the prediction unit, and the conversion unit described above. In some cases, terms such as 'block' or 'area' Can be used in combination with each other. The block may also be used as a term indicating a set of samples or transform coefficients consisting of M columns and N rows.

FIG. 3 illustrates a coding block for a current block according to the prior art.

Referring to FIG. 3, an image corresponding to the current block 10 may be encoded or decoded using square-sized coding blocks 11, 12, 13, and 14 of the same size. For example, even when the image of the current block 10 is shifted to one side in the current block and located only in the CU1 12 and the CU3 14 among the square coding blocks, the image is divided into four square coding blocks, The CU0 11 and the CU2 13 which are not present in the CU0 11 and the CU2 13 must also be encoded or decoded so that the CU0 11 and the CU2 13 should also transmit the prediction mode and prediction information. In such a method, since there are many pieces of information to be transmitted irrespective of the characteristics of the image of the block, the coding efficiency can be lowered. In order to solve such a problem, a coding block according to an embodiment of the present invention may include a non-square coding block as well as a square coding block.

4A to 4C illustrate examples of non-square coding blocks of a current block according to an embodiment of the present invention.

As shown in FIGS. 4A-4C, the coding block may include non-square coding blocks. Also, the prediction mode and prediction information for each coding block can be independently determined and transmitted. In one embodiment, the non-square coding block may include a longitudinal non-square coding block having a longer length in the longitudinal direction than the lateral direction and a non-square coding block in the horizontal direction longer in the lateral direction than the longitudinal direction. have.

First, referring to FIG. 4A, coding blocks 21 to 27 for coding a current block represent an example including coding blocks 21, 24 and 25 of non-square shape in the longitudinal direction. For example, vertically oriented non-square coding blocks may have a size of 16 x 32 (21) and a size of 8 x 32 (24, 25), but the aspect ratio of the coding block in the present invention is It is not limited. In one embodiment, the non-square shaped coding blocks in the vertical direction can be used when the image corresponding to the current block is largely changed in the vertical direction as compared with the horizontal direction.

4B, the coding blocks 31 to 37 for coding the current block represent an example including the non-square shaped coding blocks 31, 34 and 35 in the horizontal direction. For example, the horizontal non-square coding block may have a size of 32 x 16 (31) or 32 x 8 (34, 35), but the ratio of the horizontal and vertical size of the coding block It is not limited. In one embodiment, the non-square shaped coding blocks in the horizontal direction can be used when the image corresponding to the current block is largely changed in the horizontal direction as compared with the vertical direction. However, this is merely an example, and a method for determining whether or not to use the non-square coding block in which direction for the current block is not limited in the present invention and does not limit the maximum and minimum size of the non-square coding block. Also, the number of non-square coding blocks and the ratio of the horizontal length to the vertical length are not limited, and the current block can be also divided into 1: N.

In one embodiment, not the prediction block PU corresponding to the current coding block CU but the current coding block CU can be directly used as the prediction block PU. Also in this case, the coding block CU may be a non-forward block as well as a forward block as in a general method, and a current block including the coding blocks CU may have a 1: N division structure. Also, in another embodiment, the current coding block (CU) may be used equally to both the prediction block (PU) and the transform block (TU), and in this case also, the current block containing the current coding block Can be divided using a structure divided into square blocks, a structure divided into non-square blocks, and structures divided into 1: N.

Referring to FIG. 4C, a coding tree unit (CTU) includes square-shaped coding blocks CB0 to CB4, CB8, CB9, CB11, CB12 and CB15 of various sizes and non-square coding blocks CB5 to CB7 , CB10, CB13, CB14, CB17 to CB19). As described above, by coding the current block using the square coding block as well as the non-square coding block, it is possible to improve the coding efficiency by reducing the transmission of the unnecessary prediction mode and the prediction information.

In the coding of a conventional video signal, not only a square block is used as a coding block but only a square conversion block is used as a conversion block. The transform blocks based on the size of each coding block or prediction block can be subdivided into a quadtree partition structure. For example, when one transform block is divided into a quad tree structure, the transform block has four square sub- Blocks. Conventional coding methods using only such square transform blocks are difficult to consider characteristics of an image corresponding to a coding block and characteristics of a residual signal generated according to a prediction mode. Therefore, the coding method of a video signal according to an embodiment of the present invention can use non-square transform blocks and non-square transform blocks as transform blocks, as well as non-square coding blocks.

Figures 5A-6C illustrate examples of transform blocks for a current coding block according to an embodiment of the present invention. FIGS. 5A and 5B are examples of the configuration of an initial transform block for a current coding block (not shown) of a square of N x N size, and FIGS. 6A to 6C illustrate a configuration of an initial transform block for a non-square current coding block Lt; / RTI >

 When one or a plurality of transform blocks are used for a current coding block in a square, the transform block constituting the current coding block may include a square transform block and a non-square transform block. The transform block may transform the residual signal into a frequency domain using a transform matrix.

Referring to FIG. 5A, the square coding block may be constituted by one square transform block 41 or four square transform blocks 42 to 45 as a configuration of an initial transform block. Referring to FIG. 5B, in the case of using a square coding block, it may be composed of two non-square conversion blocks 46 to 48 or four non-square conversion blocks 51 to 58 as an initial conversion block. The two non-square conversion blocks may be N / 2 x N longitudinal non-square conversion blocks 46 and 47 or N x N / 2 horizontal non-square conversion blocks 48 and 49 , The four non-square conversion blocks may be N / 4 x N longitudinal non-square conversion blocks 51 to 54 or N x N / 4 horizontal non-square conversion blocks 55 to 58 have.

 In this manner, when a transform block for a square coding block is constructed, an initial transform block can be constituted by a square transform block as well as a non-square transform block. Although two or four non-square conversion blocks have been described above, the size and the number of the non-square conversion blocks in the present invention are not limited thereto. In addition, when the current coding block performs intra prediction, the transform block configuration of the current coding block can be determined differently according to the direction of the intra prediction mode. For example, when the current coding block uses the in-picture intra prediction mode in the vertical direction, by using the non-square transform block that is horizontally divided as the transform block for the current coding block, The block can generate the prediction signal.

6A to 6D, even in the case of using one or a plurality of transform blocks with respect to a non-square current coding block (not shown), the transform block constituting the current coding block includes a square transform block Square conversion block.

Referring to FIG. 6A, in the present invention, the coding block may be non-square coding blocks 60a and 60b having different widths A and B from each other. In this case, when the current non-square coding block is initially configured with one or a plurality of transform blocks, a square transform block may be used or a non-square transform block may be used to evenly divide the coding block.

Referring to FIG. 6B, as the initial transform block configuration for the non-square coding blocks 60a and 60b, N a x a size square transform blocks 61 may be used. In this case, the horizontal and vertical length a of the square transform block 61 may be the same as the smallest of the horizontal and vertical lengths of the non-square coding block. In one embodiment, the horizontal and vertical lengths of the square transform block 61 can be calculated from the upper parameters or obtained through a predetermined method.

Referring to FIG. 6C, M (where M is an integer) number of non-square transform blocks 62 to 65 may be used as an initial transform block configuration for the non-square coding blocks 60a and 60b. The non-square conversion blocks 62 and 63 may be the same size as the non-square coding block 60a or the non-square conversion blocks 64 and 65 smaller than the non-square coding blocks 60a and 60b It is possible. In one embodiment, the horizontal length (a) and the vertical length (b) of the non-square conversion blocks 62 and 63 may be set equal to the horizontal and vertical lengths of the coding blocks 60a and 60b. In another embodiment, the transverse and vertical lengths of the non-square transform blocks 64 and 65 may be computed from the upper parameters or obtained through a predetermined method.

6D, M non-square or square transform blocks 66 and 67 of a quad tree structure may be used as the configuration of the initial transform block for non-square coding blocks 60a and 60b. The non-square or square conversion block 66, 67 may be used when the size of the non-square coding block is not corresponded to one large conversion block as a block smaller than the non-square coding block. Although the conversion blocks of the quad tree structure are described in the present invention, the number of the non-square or square conversion blocks 66 and 67 is not limited thereto.

The transform block constituting the current coding block can be divided into sub-transform blocks of a smaller size. The sub-transform blocks may perform independent transform processes to generate transform coefficients, and may have various shapes and sizes. In addition, the dividing method can be determined differently based on the size and shape of the upper transform block before being divided into the sub transform blocks, and the shape can be different from the shape of the upper transform block independently.

7A-10 illustrate examples of sub-transform blocks in accordance with an embodiment of the present invention. FIGS. 7A to 7D show examples of sub-transform blocks of the transform block when the transform block is a square transform block, and FIGS. 8A to 8D show the case where the transform block is a non-square transform block in the vertical direction, 9A to 9D illustrate examples of sub-transform blocks for a transversal non-square transform block. FIG. 10 shows a transform block composed of various sub-transform blocks.

7A to 7D, when the current transform block is an N x N size square transform block 70, the square transform block 70 is divided into various methods to generate the sub transform blocks 71a to 74d . The square transform block 70 may be divided into four sub-transform blocks 71a to 71d (FIG. 7b) using a square quadtree division method, and may be divided into four vertically or horizontally And can be divided into two non-square sub-transform blocks 72a to 72d (Fig. 7C). One embodiment can be divided into four non-square sub-transform blocks 73a through 73h in the longitudinal or transverse direction using the non-square quad tree segmentation method (Fig. 7d). The number and size of the sub-transform blocks to be divided are illustrative only and are not limited to the description of the present invention.

Referring to FIGS. 8A to 8D, when the current transform block is a non-square transform block 80 having a size of A (width) x B (length) as shown in FIG. 8A, the non- To generate sub-transform blocks 81a through 84d. The non-square conversion block 80 can be divided into four sub-transform blocks 81a to 81d (FIG. 8B) using square quad tree segmentation method, and four or more sub-transform blocks (not shown) Lt; / RTI > In this case, the horizontal and vertical lengths of the square sub-transform blocks may be the same as the short length (A in FIG. 8A) of the horizontal and vertical lengths of the non-square conversion block 80, but the present invention is not limited thereto. When the vertical length B of the non-square conversion block 80 is an integral multiple of the horizontal length A, the non-square conversion block 80 may be divided into sub-conversion blocks according to the square division method as shown in FIG. 8B.

Referring to FIG. 8C, the non-square transform block 80 may be divided into two sub-transform blocks 82a to 82d in non-square vertical or horizontal direction using a binary tree segmentation method. Referring to FIG. 8D, the non-square transform block 80 may be divided into four non-square sub transform blocks 83a to 83d using the non-square quad tree segmentation method. The number and size of the sub-transform blocks to be divided are illustrative only and are not limited to the description of the present invention.

9A to 9D, when the current transform block is a non-square transform block 90 having a size of A (width) x B (length) as shown in FIG. 9A, the non- To generate the sub-transform blocks 91a to 94d. The non-square conversion block 90 can be divided into four sub-transform blocks 91a to 91d (FIG. 9B) using square quad tree segmentation method, and four or more sub-transform blocks (not shown) Lt; / RTI > In this case, the horizontal and vertical lengths of the square sub-transform blocks may be the same as the short length (B in FIG. 9A) of the horizontal and vertical length of the non-square conversion block 90, but the present invention is not limited thereto. When the horizontal length A of the non-square conversion block 90 is an integral multiple of the vertical length B, the non-square conversion block 90 can be divided into sub-conversion blocks according to the square division method as shown in FIG. 9B.

Referring to FIG. 9C, the non-square conversion block 90 may be divided into two sub-transformation blocks 92a to 92d, which are non-square longitudinal or transverse directions, using a binary tree segmentation method. Referring to FIG. 9D, the non-square conversion block 90 may be divided into four non-square sub-conversion blocks 93a to 93d using the non-square quad tree segmentation method. The number and size of the sub-transform blocks to be divided are illustrative only and are not limited to the description of the present invention.

FIG. 10 shows an example in which a current coding block is transformed using the dividing method as shown in FIGS. 7A to 9D. According to FIG. 10, the current coding block can be a square transform block, as well as a non-square transform block, and the square or non-square transform block can be divided into a square sub-transform block as well as a non-square sub transform block. Applying such a transform block and dividing it into sub transform blocks may be applied in combination with one or more of the methods as shown in Figs. 7A to 9D. Also, the shape and the number of the transform block or the shape and the number of the sub transform block are not limited to the example of the present invention.

Generally, when the current block performs intra prediction, a transform block is decoded using a raster scan method, and reference samples used for generating a prediction signal according to a direction of an intra prediction mode are determined .

Fig. 11 is a diagram for explaining a coding procedure and a coding method of a transform block according to a general method. 11, when the direction of the intra prediction mode of the current block is 2 to 10, each transform block TU0 to TU3 always generates a prediction signal using only reference samples located on the left side of the transform block . In this case, the first transform block TU0, which generates the prediction signal first among the transform blocks, generates a prediction signal using the first reference sample region 111 located in the transform block. The first reference sample region 111 may comprise available reference samples and / or reference samples that are not available. Since the second transform block TU1 also constitutes the second reference sample area 112 for the second transform block TU1 because some pixels of the first transform block TU0 are included in the second reference sample area 112, Is composed of some pixels of the first transform block TU0, i.e., available reference samples, which are decoded samples.

Since the third transform block TU2 for generating the prediction signal then uses the pixels located on the left side of the third transform block TU2 as reference samples, the decoded first transform block TU0 and the second transform block TU2, The third reference sample area 113 used for prediction can be composed of reference samples that are not available because pixels of the first reference sample area TU1 are not used. Since the fourth transform block TU3 constitutes the fourth reference sample area 114 for the fourth transform block TU3 by some pixels of the third transform block TU2, (TU2), i.e., the available reference samples.

In this manner, when a prediction signal is generated from a transform block in accordance with a conventional coding order, there may occur cases where a prediction signal is generated using reference samples that are not available according to the direction of the intra prediction mode. Therefore, the coding method of the video signal according to an embodiment of the present invention can increase the coding efficiency by variably determining the coding order of the transform blocks according to the direction of the intra-picture prediction mode of the current coding block.

Figures 12A-12C illustrate examples of transform blocks in accordance with an embodiment of the present invention.

12A to 12C, the transform blocks according to an embodiment of the present invention may have a structure in which four transform blocks of the same size are composed of two lines (Fig. 12A), and the transform blocks of the same size Or may be arranged horizontally or vertically (Figs. 12B and 12C). The transform blocks may be subdivided into smaller-sized sub-transform blocks, and the sub-transform blocks may have a structure as shown in FIGS. 12A to 12C when re-divided.

If the transform blocks are coded without considering the intra-picture prediction mode of the current block, neighbor blocks that have not been decoded can be used in the generation of the predictive signal of each transform block. In this case, since the reference samples used for generating the prediction signal may be unavailable samples, the neighboring available sample values may use the copied unavailable samples, resulting in poor coding efficiency . Accordingly, the present invention proposes a method of variably determining a coding order of a transform block by considering which mode area the intra-picture prediction mode of the current block corresponding to the transform blocks belongs to.

In order to variably determine the coding order of the transform blocks according to the intra prediction mode, the intra prediction mode may be firstly classified according to the prediction direction. 13 illustrates mode regions to which an intra prediction mode according to an embodiment of the present invention belongs.

Referring to FIG. 13, intra-picture prediction modes having directionality can be classified into a first mode region to a third mode region 131 to 133 according to a prediction direction. 13, except for the intra-picture prediction modes in the horizontal direction and the vertical direction, are in-picture prediction modes constituting the first mode area 131 . The second mode region may be an intra prediction mode having a horizontal prediction mode and an angle of 180 to 225 degrees and the third mode region may be a prediction mode in the vertical direction and a Prediction mode. The coding order of the transform blocks can be variably determined according to the mode area to which the transform blocks belong, based on the thus-classified mode area.

FIGS. 14A and 14B show a coding order of transform blocks when the intra-picture prediction mode of the current block belongs to the first mode region according to an embodiment of the present invention. The coding order of the transform blocks in the case of belonging to the first mode area is the same as the coding order of the conventional transform blocks. Figure 14A shows the coding order when the transform blocks have an N x N structure and can be coded in order TB0, TB1, TB2, TB3. Fig. 14B shows a coding order when the transform blocks are non-square transform blocks in the longitudinal direction and the transverse direction, and is coded in order from left to right and from top to bottom. For example, TB4, TB5, TB6, TB7, TB8, TB9, and TB10.

FIGS. 15A to 15C show coding sequences of transform blocks in which the intra prediction mode according to an embodiment of the present invention belongs to the second mode region. The plurality of transform blocks may be coded in order from the bottom left to the top right, and the transform blocks having the N x N structure may be coded as shown in Figs. 15A and 15B. Referring to FIG. 15A, TB2, TB0, and TB1 may be coded in the order of TB2, TB0, and TB1 located at the lower left, and TB2, TB3, and TB1 may be coded in the order of TB2, .

Further, the non-square conversion blocks in the vertical and horizontal directions can be coded in order from left to right and bottom to top. Referring to FIG. 15C, TB5 to TB6 are coded from TB4 located on the left side, and TB10 to TB9, TB8, and TB7 located on the lower right side are coded.

FIGS. 16A to 16C show coding sequences of transform blocks in which the intra prediction mode according to an embodiment of the present invention belongs to the third mode region. The plurality of transform blocks may be coded in order from the upper right to the lower left, and the transform blocks having the N x N structure may be coded as shown in Figs. 16A and 16B. Referring to FIG. 16A, TB1, TB3, and TB2 may be coded in the order of TB1, TB3, and TB2 located at the upper right, TB1 to TB3, TB0, and TB2 may be coded in the order of TB1, .

Further, the non-square conversion blocks in the vertical and horizontal directions can be coded in order from right to left, top to bottom. Referring to FIG. 16C, TB8, TB9, and TB10 are sequentially coded down from the TB7 located at the right upper end, and TB6, TB5, and TB4 located at the right of the left vertical direction non- Lt; / RTI >

In this manner, by determining the coding order of the transform block in consideration of the shape of the transformed block and the mode region classified in consideration of the direction of the intra-picture prediction mode of the current block, each transform block can determine the available reference Since the prediction signal can be generated using the samples, the coding efficiency can be improved.

In one embodiment, when the transform blocks have a structure of the type shown in Figs. 12A to 12C, the transform blocks are determined according to the mode region to which the intra prediction mode of the current coding block corresponding to the transform blocks belongs The coding order is shown in Table 1 below.

Conversion block
Structure type In-picture prediction mode area Area 1 Area 2 Area 3 Type 1
(Fig. 12A) TB0-> TB1-> TB2-> TB3 TB2 -> TB3 -> TB0 -> TB1 TB1-> TB0-> TB3-> TB2 Type 2
(Fig. 12B) TB0-> TB1-> ... -> TBN TB0-> TB1-> ... -> TBN TBN-> ... -> TB1-> TB1 Type 3
(Fig. 12C) TB0-> TB1-> ... -> TBN TBN-> ... -> TB1-> TB1 TB0-> TB1-> ... -> TBN

FIGS. 17A to 17C are examples showing coding sequences of square and non-square transform blocks constituting a current block using the coding sequence of the transform block shown in Table 1. FIG. 17A shows the coding order of the transform blocks for the current block when the intra-picture prediction mode of the current block belongs to the first mode area, FIG. 17B shows the coding order of the transform blocks for the current block when the intra- FIG. 17C shows the coding order of the transform blocks for the current block when the intra-picture prediction mode of the current block belongs to the third mode area.

Referring to FIG. 17A, when the intra prediction mode of the current block belongs to the first mode region, the transform blocks may be coded in order from the upper left to the lower right in the same manner as the normal coding order regardless of the shape of the transform block. When the intra prediction mode of the current block belongs to the second mode area, the transform block uses the reference samples belonging to the lower left block at the time of generating the prediction signal. Thus, coding the transform block from the lower left end to the upper right end The coding efficiency can be improved. Referring to FIG. 17B, a current block may be coded in the order of the left lower end, the lower right end, the upper left end, and the upper right end in coding in the order from the lower left end to the upper right end.

When the intra-prediction mode of the current block belongs to the third mode area, since the transform block uses the reference samples belonging to the upper right corner at the time of generating the prediction signal, coding the transform block in the order from the upper right to the lower left improves the coding efficiency . Referring to FIG. 17C, it is possible to select a method of coding in the order of right upper end, left upper end, right lower end, and left lower end.

In another embodiment, the coding order of the transform block considering the intra prediction mode can be determined as shown in Table 2 below.

Conversion block
Structure type In-picture prediction mode area The first mode area The second mode area The third mode area Type 1
(Fig. 12A) TB0-> TB1-> TB2-> TB3 TB2-> TB0-> TB3-> TB1 TB1-> TB0-> TB3-> TB2 Type 2
(Fig. 12B) TB0-> TB1-> ... -> TBN TB0-> TB1-> ... -> TBN TBN-> ... -> TB1-> TB1 Type 3
(Fig. 12C) TB0-> TB1-> ... -> TBN TBN-> ... -> TB1-> TB1 TB0-> TB1-> ... -> TBN

FIGS. 18A to 18C are examples showing the coding order of square and non-square conversion blocks constituting the current block using the coding order of the conversion blocks shown in Table 2. FIG. 18A shows the coding order of the transform blocks for the current block when the intra-frame prediction mode of the current block belongs to the first mode area, FIG. 18B shows the coding order of the transform blocks for the current block when the intra- FIG. 18C shows the coding order of the transform blocks for the current block when the intra-picture prediction mode of the current block is the third mode region.

Referring to FIG. 18A, when the intra prediction mode of the current block belongs to the first mode region, the transform blocks may be coded in order from the upper left to the lower right in the same manner as the normal coding order regardless of the shape of the transform block. If the intra-picture prediction mode of the current block belongs to the second mode area, the transform block uses the reference samples belonging to the lower-left block at the time of generating the prediction signal, so coding the transform block from the lower- The efficiency can be improved. Referring to FIG. 18B, when coding the current block in order from the lower left to the upper right, a method of coding in the order of the lower left, upper left, lower right, and upper right can be selected.

When the intra-prediction mode of the current block belongs to the third mode area, since the transform block uses the reference samples belonging to the upper right corner at the time of generating the prediction signal, coding the transform block in the order from the upper right to the lower left improves the coding efficiency . Referring to FIG. 18C, it is possible to select a coding method in the order of the right upper end, the lower right end, the upper left end, and the lower left end.

The coding order of the conversion blocks according to the mode area is not limited to the above example, but it is also possible to determine the coding order of the conversion blocks according to the mode area.

FIGS. 19A to 19C show the coding order of the transform blocks when the coding order of the transform blocks according to each mode region is alternately selected with reference to FIGS. 17A to 18C.

19A shows the coding order of the transform blocks for the current block when the intra-picture prediction mode of the current block belongs to the first mode area, FIG. 19B shows the coding order of the transform blocks for the current block when the intra- FIG. 19C shows the coding order of the transform blocks for the current block when the intra prediction mode of the current block is the third mode region.

In the case of the first mode area, the coding order of the transform blocks may be determined from the upper left corner to the lower right corner as described with reference to Figs. 17A and 18A. In the case of the second mode area, referring to FIG. 19B, conversion blocks can be coded in the order of the lower left, lower right, upper left, and upper right according to the coding order determined with reference to FIG. 17B, If the intra prediction mode of the current block is the third mode, the transform blocks may be coded in the order of the upper right, lower right, upper left, and lower left according to the coding order described with reference to FIG. 18C. In another embodiment, the coding order of the second mode area and the third mode area may be determined in the coding order described with reference to Figs. 18B and 17C. In this way, the conversion blocks for the current block can generate the prediction signal using a combination of various coding sequences determined according to the intra-picture prediction mode of the current block, thereby improving the coding efficiency.

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 invention as defined in the appended claims. It will be clear to those who have knowledge.

Claims (22)

Setting a structure of a coding block constituting a current image;
Setting a structure of transform blocks corresponding to the coding block; And
And generating a prediction signal using the transform blocks,
Wherein the coding block comprises at least one of a square block and a non-square block. The method according to claim 1,
Wherein the transform block comprises at least one of a square transform block and a non-square transform block of the same size or small size of the coding block. 3. The method of claim 2,
Wherein the square transform block is a transform block having a quadtree structure. 3. The method of claim 2,
Wherein the non-square transform block is a transform block having a non-square binary tree structure or a non-square quadtree structure. 3. The method of claim 2,
Wherein the transform block includes at least one of a non-square transform sub-block and a square transform sub-block. The method according to claim 1,
And receiving transform block division information indicating the shape and size of the transform block. The method according to claim 1,
Further comprising re-partitioning the transform block into sub-transform blocks,
Transformed into the sub-transform blocks, the prediction signal is generated for each sub-transform block. 8. The method of claim 7,
Wherein the sub-transform blocks include at least one of a non-square sub-transform block and a square sub-transform block. 3. The method of claim 2,
Wherein when the current block performs intra prediction, a direction of an intra prediction mode of the current block is a first mode area having an angle of 90 degrees or more and less than 180 degrees, a second mode area having an angle of 180 degrees or more and less than 225 degrees, A mode region, and a third region having an angle of 45 degrees or more and less than 90 degrees; And
Further comprising the step of variably determining a coding order of the transform block based on a mode area to which the intra prediction mode belongs. 10. The method of claim 9,
And when the direction of the intra-picture prediction mode is the second mode region, the transform block is coded in order from the lower left end to the upper right direction. 11. The method of claim 10,
And if the transform block is a square transform block, coding is performed in the order of the lower left, lower right, upper left, and upper right. 11. The method of claim 10,
And if the transform block is a square transform block, coding is performed in the order of the left lower end, the upper left end, the lower right end, and the upper right end. 11. The method of claim 10,
And if the transform block is a vertically-divided non-square transform block, coding is performed in order from left to right. 11. The method of claim 10,
And if the transform block is a horizontally divided non-square transform block, coded in order from bottom to top. 10. The method of claim 9,
When the direction of the intra prediction mode is the third region mode, the transform block is coded in order from the upper right end to the lower left end. 16. The method of claim 15,
And if the transform block is a square transform block, coding is performed in order of a right upper end, a left upper end, a lower right end, and a lower left end. 16. The method of claim 15,
And if the transform block is a square transform block, coding is performed in the order of the right upper end, the lower right end, the upper left end, and the lower left end. 16. The method of claim 15,
And if the transform block is a vertically-divided non-square transform block, coding is performed in a right-to-left order. 16. The method of claim 15,
And if the transform block is a horizontally divided non-square transform block, the transform block is coded in order from the top to the bottom. The method according to claim 1,
Wherein the coding block is set as a prediction block corresponding to the coding block. The method according to claim 1,
Wherein the coding block is set as a prediction block corresponding to the coding block and the transform block. A block setting unit setting a structure of a coding block constituting a current image and setting a structure of conversion blocks corresponding to the coding block; And
And a prediction signal generator for generating a prediction signal using the conversion blocks,
Wherein the coding block and the transform block comprise at least one of a square block and a non-square block,
Wherein the prediction signal generator encodes the transform blocks according to which mode region among the mode regions classified according to the prediction direction of the intra-frame prediction mode of the coding block according to a variable coding order.

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