KR101626449B1 - Method and apparatus for video encoding for compensating pixel value of pixel group, method and apparatus for video decoding for the same - Google Patents

Abstract

A reconstructed image is generated by performing loop filtering on the decoded image data by decoding the encoded image data and generating a reconstructed image by performing loop filtering on the reconstructed pixels of a predetermined group among the reconstructed images, Disclosed is a video encoding method for determining a group of pixels including a compensation value for an error between original pixels and a restored pixel to be compensated, and compensating a pixel value for transmitting a coded compensation value and a bit stream of the encoded input image.

Description

TECHNICAL FIELD The present invention relates to a video encoding method and apparatus for compensating pixel values for each pixel group, and a video decoding method and apparatus for compensating pixel values for each pixel group. decoding for the same}

The present invention relates to encoding and decoding of video.

Background of the Invention [0002] As the development and dissemination of hardware capable of playing back and storing high-resolution or high-definition video content increases the need for video codecs to effectively encode or decode high-definition or high-definition video content. According to the existing video codec, video is encoded according to a limited encoding method based on a macroblock of a predetermined size.

The image quality of the image may be distorted by the video decoding. In order to improve the quality of the restored image, a post-processing module may be added to the restored image at the decoding end.

The present invention relates to a video encoding method and apparatus, and a video decoding method and apparatus for compensating a pixel value of a predetermined pixel group.

According to another aspect of the present invention, there is provided a video encoding method for compensating a pixel value, comprising: encoding an input video sequence; Decoding the encoded image data and performing loop filtering on the decoded image data to generate a reconstructed image; Determining a pixel group including a compensation value for an error between each restored pixel and a corresponding original pixel and a restored pixel to be compensated for using the compensation value for restored pixels of a predetermined group among the restored images; And encoding the compensation value and transmitting the encoded compensation value and the bit stream of the encoded input image.

The compensation value and pixel group determination step may include comparing pixel values of neighboring restored pixels in the restored image and determining an extreme value level indicating a degree of approximation to a maximum value or a minimum value on a restored pixel basis; And determining a pixel group including a restored pixel to be compensated among the neighboring restored pixels based on the restored per-pixel level value. The pixel group determination step based on the extreme value level according to an exemplary embodiment may classify the neighboring restored pixels into pixel groups including restored pixels having the same extreme level based on the extreme value level for each restored pixel, The compensating value and the pixel group determining step determine a compensating value for the corresponding pixel group by at least one extremum level determined by the compensating pixels to be compensated And a step of deciding whether or not to perform a search.

The compensation value and the pixel group determination step may include a step of determining a compensation value and a pixel group based on bands in which a total interval of pixel values is divided into a plurality of bands, Grouping them into groups; And determining a compensation value for each band-by-band pixel group. According to an embodiment, the band-by-band pixel group classification step may classify the restored pixels into band-by-band pixel groups based on bands whose total interval of the pixel values is divided by the number of squares of 2. In one embodiment, the exponent of the power of 2 may be determined based on the number of most significant bits of the bit depth of the reconstructed pixel, and the total duration of the pixel value may be a range of extended bit depths.

The compensation value and pixel group determination step may include classifying the restored pixels of the restored image into line-by-line pixel groups including restored pixels located on the same line; And determining a compensation value for each line-by-line pixel group. The line-by-line pixel group classification step according to an exemplary embodiment may include a step of detecting restored pixels constituting a line in a horizontal direction, a vertical direction, and a boundary direction of a predetermined object among restored pixels of the restored image .

The compensation value and the restored pixel to be compensated may be determined using an average value of the errors of the predetermined restored pixels according to an exemplary embodiment. The compensation value and the reconstructed pixel to be compensated may be determined according to an embodiment of the present invention. The compensation value may be determined for all of the reconstructed pixels to be compensated or separately for each predetermined group of compensated reconstructed pixels.

The reconstructed image generation step according to an exemplary embodiment may use adaptive loop filtering using a plurality of continuous one-dimensional filters.

The compensation value and the reconstructed pixel to be compensated may be determined based on at least one of a video sequence, a slice, a frame, and a coding unit of the input video according to an exemplary embodiment of the present invention. have.

The bitstream transmission step may insert the encoded compensation value into a slice header and transmit the inserted compensation value.

The encoding of the input image sequence may include: dividing a picture of the input image sequence into an encoding unit of a predetermined maximum size; The encoding unit performs encoding for each of at least one depth-by-depth encoding unit for each of the maximum encoding units, the maximum encoding unit being hierarchically divided as the depth is deepened, Determining an encoding mode for the encoding unit of the encoding depth including information on at least one encoding depth for generating an error; And outputting encoded image data that is a result of encoding according to the determined encoding depth and encoding mode.

A video decoding method for pixel value compensation according to an embodiment of the present invention includes: receiving and parsing a bitstream of a coded image, extracting coded image data and a compensation value from the bitstream; Decoding the encoded image data and performing loop filtering on the decoded image data to generate a reconstructed image; Determining a pixel group including a restored pixel to be compensated for using the compensation value among restored pixels of the restored image; And compensating for an error between the restored pixel and the corresponding original pixel using the compensation value for the restored pixel of the determined pixel group.

The determining of the pixel group according to an exemplary embodiment may include comparing pixel values of neighboring restored pixels in the restored image to determine a maximum value level for each restored pixel; And determining a restored pixel to be compensated among the neighboring restored pixels based on the restored maximum value level. The pixel group determination step based on the extreme value level for each restoration pixel according to an exemplary embodiment classifies the neighboring restored pixels into pixel groups including restored pixels having the same extreme level based on the extrema level for each restored pixel ; And determining at least one pixel group of a predetermined maximum level as a pixel group to compensate for the pixel value. The pixel value compensating step may compensate the pixel value of the restored pixels of the pixel group for each extreme value level by using the compensation value for each extreme value level for compensating the pixel value for each pixel group for each extreme value level. can do.

The pixel group determination step according to an exemplary embodiment may include a step of classifying the restored pixels of the restored image into pixel groups per band. The pixel value compensating step may compensate the pixel value of the restored pixels of the pixel group for each extreme value level by using the compensation value for each extreme value level for compensating the pixel value for each pixel group for each extreme value level. can do.

The pixel group determination step may include classifying the restored pixels of the restored image into line-by-line pixel groups including restored pixels located on the same line. The step of compensating the pixel value according to an embodiment may compensate the pixel value of the restored pixel of the per-line pixel group by using the compensated value per line pixel group for the restored pixels of the per-line pixel group. The line-by-line pixel group classification step according to an exemplary embodiment may include a step of detecting restored pixels constituting a line in a horizontal direction, a vertical direction, and a boundary direction of a predetermined object among restored pixels of the restored image .

The compensation value may be determined by using an average value of the errors between the restored pixels and the corresponding original pixels in the encoding step. The compensated reconstructed pixel compensation step according to an exemplary embodiment may compensate all of the reconstructed pixels to be compensated using the compensation value. The compensated reconstructed pixel compensating step according to an embodiment may compensate the pixel values of the reconstructed pixels by using compensation values individually determined for a predetermined group of reconstructed pixels to be compensated.

In the reconstructed image generation step according to an embodiment, the loop filtering may include adaptive loop filtering using a plurality of continuous one-dimensional filters.

According to an embodiment of the present invention, in the encoding step of the received bitstream, a picture of an input video sequence is divided into coding units of a predetermined maximum size, and for each maximum coding unit, And at least one coding depth for coding at least one coding unit for each depth by dividing the maximum coding unit into hierarchically divided areas and generating a minimum coding error with the original image of the picture Wherein the reconstructed image generating step further extracts information on a coding mode for the coding unit of the coding depth from the bitstream, Mode and decoding the coded image data based on the loop filtering Can be performed.

According to an aspect of the present invention, there is provided a video encoding apparatus for compensating a pixel value, including: an encoding unit encoding an input video sequence; A reconstructed image generation unit for decoding the encoded image data and performing loop filtering on the decoded image data to generate a reconstructed image; A compensation value for determining a pixel group including a compensation value for an error between each restored pixel and a corresponding original pixel and a restored pixel to be compensated for using the compensation value, A pixel group determination unit; And a transmitter for encoding the compensation value and transmitting the encoded compensation value and the bitstream of the encoded input image.

An apparatus for decoding a video value for compensating a pixel value according to an exemplary embodiment of the present invention includes an extractor for receiving and parsing a bitstream of an encoded image and extracting encoded image data and a compensation value from the bitstream; A reconstructed image generation unit for reconstructing the reconstructed image by decoding the encoded image data and performing loop filtering on the decoded image data; A pixel group determination unit for determining a pixel group including a restored pixel to be compensated by using the compensation value among restored pixels in the restored image; And a reconstruction pixel compensator for compensating an error between the reconstructed pixel and the corresponding original pixel using the compensation value, with respect to the reconstructed pixel of the determined pixel group.

The present invention includes a computer-readable recording medium on which a program for implementing a video encoding method for compensating a pixel value according to an embodiment is recorded. The present invention also includes a computer-readable recording medium on which a program for implementing a video encoding method for compensating a pixel value according to an embodiment is recorded.

1 shows a block diagram of a video encoding apparatus for pixel value compensation according to an embodiment of the present invention.
2 shows a block diagram of a video decoding apparatus for pixel value compensation according to an embodiment of the present invention.
FIG. 3 illustrates neighboring reconstructed pixels to be compared to determine the extreme level of the reconstructed pixel, according to one embodiment.
4 illustrates a flow diagram of adaptive loop filtering in accordance with one embodiment.
5 shows a flow diagram of adaptive loop filtering according to another embodiment.
FIG. 6 shows a flowchart of a video encoding method for pixel value compensation according to an embodiment of the present invention.
FIG. 7 shows a flowchart of a video decoding method for pixel value compensation according to an embodiment of the present invention.
8 is a block diagram of a video encoding apparatus for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.
9 is a block diagram of a video decoding apparatus for compensating pixel values after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.
FIG. 10 illustrates a concept of an encoding unit according to an embodiment of the present invention.
11 is a block diagram of an image encoding unit based on an encoding unit according to an embodiment of the present invention.
12 is a block diagram of an image decoding unit based on an encoding unit according to an embodiment of the present invention.
FIG. 13 shows a coding unit and a prediction unit according to an embodiment of the present invention.
FIG. 14 shows a relationship between an encoding unit and a conversion unit according to an embodiment of the present invention.
FIG. 15 illustrates depth-specific encoding information, in accordance with an embodiment of the present invention.
FIG. 16 shows a depth encoding unit according to an embodiment of the present invention.
FIGS. 17, 18 and 19 illustrate the relationship between an encoding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention.
FIG. 20 shows encoding information for each encoding unit according to an embodiment of the present invention.
FIG. 21 shows a flowchart of a video encoding method for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.
FIG. 22 shows a flowchart of a video decoding method for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.

Hereinafter, with reference to Figs. 1 to 22, various embodiments of a video encoding method and apparatus, and a video decoding method and apparatus for compensating a pixel value of a predetermined pixel group are described in detail. Referring specifically to Figures 1 to 7, various embodiments of video encoding and decoding for pixel value compensation after loop filtering according to an embodiment of the present invention are disclosed and with reference to Figures 8 to 22, Various embodiments of video encoding and decoding for compensating pixel values after loop filtering based on domain-specific hierarchical data units according to an embodiment are disclosed.

1 to 7, video encoding and decoding for pixel value compensation after loop filtering according to an embodiment of the present invention will be described in detail.

1 shows a block diagram of a video encoding apparatus for pixel value compensation according to an embodiment of the present invention.

The video encoding apparatus 10 for compensating pixel values according to an embodiment includes a coding unit 12, a reconstructed image generating unit 14, a compensation value and pixel group determining unit 16, and a transmitting unit 18 do.

The encoding unit 12 according to the embodiment encodes an image in a picture unit in an input video sequence. The encoding unit 12 according to an exemplary embodiment may generate encoded image data through motion estimation, inter prediction, intraprediction, frequency conversion, and quantization on an input image.

The encoding unit 12 according to one embodiment may comply with various video encoding schemes such as MPEG 1, 2, 4, and H.26x. For example, the encoding unit 12 according to an embodiment may comply with a video encoding scheme based on a hierarchical data unit for each region according to an embodiment of the present invention, which will be described later with reference to FIGS. 8 to 22.

The reconstructed image generating unit 14 according to an embodiment receives the image data encoded by the encoding unit 12, decodes the encoded image data, performs loop filtering on the decoded image data, and generates a reconstructed image do.

The reconstructed image generating unit 14 according to an exemplary embodiment may generate decoded image data through inverse quantization, inverse frequency transform, inter prediction, motion compensation, and intra prediction on the encoded image data.

The decoding of the encoded image data performed by the reconstructed image generating unit 14 according to an embodiment may be performed as an inverse process to the video coding scheme followed by the encoding unit 12 according to the embodiment. For example, in the case where the encoding unit 12 and the reconstructed image generating unit 14 according to the embodiment comply with a video encoding method based on a hierarchical data unit for each region according to an embodiment of the present invention, A possible embodiment of a video encoding apparatus 10 for compensating a pixel value according to the present invention will be described later with reference to FIGS.

The reconstructed image generating unit 14 according to an embodiment may perform in-loop filtering on the decoded image data. In-loop filtering according to one embodiment may optionally include deblocking filtering and adaptive loop filtering. The adaptive loop filtering according to an embodiment may be performed using a plurality of continuous one-dimensional filters. Referring to Figures 4 and 5, adaptive loop filtering according to various embodiments are described in detail below.

The compensation value and pixel group determination unit 16 according to an exemplary embodiment receives the restored image and the input image output by the restored image generation unit 14, Determines a compensation value for an error between the original pixel of the restored pixel and the corresponding input image, and determines a group of pixels including the restored pixel to be compensated using the compensation value.

The compensation value and pixel group determination unit 16 according to the embodiment compares the pixel values between neighboring restored pixels among the restored pixels of the restored image to determine the extreme value level indicating the degree of approximation to the maximum value and the minimum value have. The compensation value and pixel group determination unit 16 according to the embodiment classifies the neighboring restored pixels into pixel groups including restored pixels having the same extreme level based on the extreme level of each of the neighboring restored pixels can do.

The compensation value and pixel group determination unit 16 according to the embodiment may determine at least one pixel group of the maximum level among the classified pixel groups as a pixel group to be a pixel value compensation target. For example, the compensation value and pixel group determination unit 16 according to an exemplary embodiment may determine that only the pixel groups of the maximum value and the minimum value of the minimum level are compensated for the pixel values, May be determined to compensate for the pixel value. A method of determining a compensation target based on an extremum level of neighboring restored pixels will be described later in detail with reference to FIG.

The compensation value and pixel group determination unit 16 according to the embodiment may determine to perform pixel value compensation on a group of pixels for each band according to the pixel value. The compensation value and pixel group determination unit 16 according to the embodiment may divide the total range of the pixel values of the restored pixel into a plurality of divided bands for group designation of restored pixels. The compensation value and pixel group determination unit 16 according to an exemplary embodiment may classify the reconstructed pixels into band-specific pixel groups including reconstructed pixels of the same band based on pixel values. In this case, the restored pixels of all the band-by-band pixel groups may be determined as the pixel value compensation target, and the compensation value and pixel group determining unit 16 according to the embodiment may separately determine the compensation value for each band-

For fast operation, the total range of pixel values is preferably divided into bands of the number of powers of two. Also, for faster computation, if the number of most significant bits of the bit depth of the bit stream of restored pixels is p, then the total range of pixel values may be divided into bands of number of p power of 2. The total range of pixel values of the restored pixel may also be the range of the extended bit depth of the restored pixel.

The compensation value and pixel group determination unit 16 according to the exemplary embodiment analyzes the restored image and detects lines in a predetermined direction and outputs the restored pixels to the pixel groups for each line including restored pixels located on the same line . When lines in various directions such as a horizontal direction, a vertical direction, and a line in the boundary direction of an object are detected, the pixels constituting each line can be classified into one pixel group. The compensation value and pixel group determination unit 16 according to the embodiment can individually determine the compensation value for each pixel group per line.

The compensation value and pixel group determination unit 16 according to the embodiment may determine an average value of the errors with the corresponding original pixel as a compensation value for each restored pixel to be compensated. The error between the restored pixel and the original pixel may include the difference value between the restored pixel and the original pixel, the absolute value of the difference, the squared value of the difference, and the like. The compensation value and pixel group determination unit 16 according to an exemplary embodiment may determine one compensation value to be applied to all of the restored pixels to be compensated at present or individually determine a compensation value for each pixel group classified according to the characteristic It is possible.

The compensation value and pixel group determination unit 16 according to an exemplary embodiment determines a restored pixel to be compensated for each data unit of at least one of a video sequence, a slice, a frame, and a coding unit of the input video, .

The transmission unit 18 according to an exemplary embodiment receives the compensation value and the compensation value determined by the pixel group determination unit 16, and encodes the compensation value. The transmitting unit 18 according to an embodiment receives the image data encoded by the encoding unit 12 and generates and outputs a bit stream including the encoded compensation value and the encoded image data. The image data encoded by the encoding unit 12 may be converted into a bit stream format through entropy encoding and then inserted into a bit stream for transmission.

The transmitting unit 18 according to an embodiment may receive the compensation value and the additional information on the pixel group determination method from the pixel group determination unit 16 and may encode the additional information and insert the additional information into the bitstream. For example, since the determination method of the pixel group to be compensated may be the above-described extremum level, the pixel value band, the directional line, and the like, the compensation value to be transmitted is a compensation value adopted according to which method, Or the like may be transmitted.

In addition, when adaptive loop filtering is performed in the reconstructed image generating unit 14, the transmitter 18 according to an embodiment receives information about coefficients of the loop filter for adaptive loop filtering, As shown in FIG.

The video encoding apparatus 80 for compensating for pixel values according to an exemplary embodiment may acquire a video encoding signal so that it can support post-processing processing that can be performed to reduce errors between the reconstructed video and the original video at the decoding terminal. It is possible to provide the decoding unit with information on an error compensation value. Also, since the compensation value is determined for each pixel group, only the information about the compensation value for each pixel group is encoded and transmitted without information on the individual pixel positions, thereby reducing the transmission bit amount.

2 shows a block diagram of a video decoding apparatus for pixel value compensation according to an embodiment of the present invention.

The video decoding apparatus 20 for compensating a pixel value according to an embodiment includes an extraction unit 22, a reconstructed image generation unit 24, a pixel group determination unit 26, and a reconstructed pixel compensation unit 28 .

The extracting unit 22 according to an embodiment receives and parses a bitstream of an encoded image and extracts encoded image data and compensation value related information from the bitstream. The compensation value related information may include compensation value information. When the compensation value related information further includes information on the determination method of the reconstruction pixel to be compensated using the compensation value, the extraction unit 22 extracts, from the bit stream, Information on the group determination method may be extracted. The extracting unit 22 according to an embodiment may extract compensation value or compensation value related information for each data unit of at least one of a video sequence, a slice, a frame, and a coding unit of the input video.

In addition, the extracting unit 22 according to an embodiment may extract encoding information such as a coding method and an encoding mode necessary for decoding the encoded image data. The extracting unit 22 according to an embodiment may extract information on a filter coefficient from a bitstream when information on a filter coefficient for adaptive loop filtering is embedded in the bitstream.

The reconstructed image generating unit 24 according to an embodiment receives the encoded image data extracted by the extracting unit 22, encoding information, information on loop filter coefficients, and the like, decodes the encoded image data, Filtering is performed to generate a reconstructed image.

The decoding of the encoded image data can be performed as an inverse process to the video encoding method according to the encoded image data. For example, when the encoded image data is encoded and transmitted according to a video encoding method based on a hierarchical data unit for each region according to an embodiment of the present invention, the reconstructed image generating unit 24 according to an embodiment And can be decoded according to a video decoding method based on a hierarchical data unit for each area.

The reconstructed image generating unit 24 may selectively perform in-loop filtering such as deblocking filtering or adaptive loop filtering on the decoded image data. The adaptive loop filtering according to an embodiment may be performed using a plurality of continuous one-dimensional filters.

The pixel group determining unit 26 according to an exemplary embodiment receives the restored image generated by the restored image generating unit 24 and the compensation value related information extracted by the extracting unit 22, A pixel group including a restored pixel to be compensated for using the compensation value for restored pixels of the pixel group. The reconstructed pixel compensator 28 according to an exemplary embodiment receives the compensation value extracted by the extractor 12 and the information about the reconstructed pixels determined by the pixel group determiner 26, Compensates the pixel value of the restored pixel, and outputs the restored image with the pixel value compensated.

When the extraction unit 22 extracts information on the pixel group determination method to be compensated by the extraction unit 22 according to the embodiment, the pixel group determination unit 26 according to the embodiment calculates the pixel value The pixel group to be compensated can be determined. For example, the pixel group determination unit 26 according to one embodiment determines whether to classify the restored pixels according to whether the restored pixels are configured at the extreme level, the pixel value band, or the directional line, Value compensation target pixel group.

The pixel group determination unit 26 according to an exemplary embodiment may compare the pixel values of neighboring restored pixels in the restored image to determine the extreme value level for each restored pixel. The pixel group determination unit 26 according to the embodiment classifies the neighboring restored pixels based on the extremum level and groups the group of pixels including the restored pixels of at least one predetermined maximum level into a pixel value As a group of pixels including reconstructed pixels to be compensated for. The reconstructed pixel compensator 28 according to the embodiment can compensate the pixel value using the compensation value for reconstructed pixels of the pixel group determined as the pixel value compensated object.

In addition, the pixel group determination unit 26 according to the exemplary embodiment may classify the restored pixels of the restored image into pixel groups of each band based on bands in which the total interval of pixel values is divided into a plurality of bands. The reconstructed pixel compensator 28 may compensate the pixel values of the reconstructed pixels of the per-band pixel group using the per-band compensation values for the reconstructed pixels of the per-band pixel group.

According to one embodiment, the total duration of the pixel values may be divided into bands of the number of powers of two. In this case, the exponent of the power of 2 can be determined based on the number of most significant bits of the bit depth of the reconstructed pixel. Also, the total duration of the pixel values of the reconstructed pixel may be the range of the extended bit depth of the reconstructed pixel.

The pixel group determination unit 26 according to an exemplary embodiment may classify the restored pixels of the restored image into pixel groups per directional line. The reconstructed pixel compensator 28 according to the embodiment can compensate the pixel value of the reconstructed pixel of the pixel group per line by using the compensated value per line pixel group. The pixel group determination unit 26 according to an exemplary embodiment may detect restored pixels constituting a line in a horizontal direction, a vertical direction, and a boundary direction of a predetermined object among the restored pixels of the restored image .

The compensation value according to an exemplary embodiment may be determined by using an average value of errors between the restored pixels and the corresponding original pixels in the encoding step and transmitted. The reconstructed pixel compensator 28 may compensate all of the reconstructed pixels to be compensated for using the received compensation value. When the compensation value extracted by the extracting unit 22 according to the embodiment is set for each pixel group, the reconstructed pixel compensating unit 28 according to an embodiment performs compensation for each pixel group, Using the determined compensation value, the pixel value of the restored pixels can be compensated.

The video encoding apparatus 10 for compensating for pixel values according to an embodiment and the video decoding apparatus 20 for compensating for pixel values according to an embodiment may be configured such that when a coded image is decoded and restored, The systematic error that occurs can be compensated.

As an example of the systematic error between the restored image and the original image, there occurs a case where the average value of the error of the pixel value is not 0 for the restored pixels of the predetermined group and the corresponding original pixels. Accordingly, the video encoding apparatus 10 for compensating for pixel values and the video decoding apparatus 20 for compensating for pixel values according to an embodiment of the present invention are intended to compensate for the error between the restored pixel and the original pixel .

The compensation value and pixel group determination unit 16 according to the embodiment can determine the compensation value according to Equation (1) below.

의 픽셀들을 포함하는 픽셀 그룹

에 대해, 원본 픽셀의 픽셀값

, 복원 픽셀의 픽셀값

간의 오차의 평균값

이 픽셀 그룹

에 대한 보상값으로 이용될 수 있다. m is an integer of 1, 2, ..., M-1, M,

Lt; RTI ID = 0.0 >

The pixel value of the original pixel

, The pixel value of the restored pixel

Mean value of error

This pixel group

Can be used as a compensation value.

The reconstructed pixel compensator 28 according to the embodiment can compensate the pixel values of the reconstructed pixels of the pixel group according to Equation (2) below.

를 보상값

을 이용하여 보상함으로써, 픽셀 그룹

에 대해 픽셀값이 보상된 결과 픽셀값

을 픽셀별로 출력할 수 있다. The reconstructed pixel compensator 28 according to one embodiment reconstructs the reconstructed pixel value

The compensation value

The pixel group < RTI ID = 0.0 >

The resulting pixel value < RTI ID = 0.0 >

Can be outputted for each pixel.

The video encoding apparatus 10 for compensating for pixel values according to an embodiment and the video decoding apparatus 20 for compensating for pixel values according to an embodiment are arranged in accordance with a predetermined criterion It is possible to classify the restored pixels.

As a first embodiment of pixel group determination, pixel groups can be classified according to the extremum level. The local extreme has a local minimum and a local maximum. The local minimum value f ( _xmin , _ymin ) and the local maximum value f (x, y) of the neighboring coordinates (x, y) within the predetermined range epsilon are calculated for the quadratic function f (x _max , y _max ) are mathematically defined, respectively.

A local minimum value f ( _xmin , _ymin ) and a local maximum value f ( _xmax , _ymax ) can be defined for the discrete signal pixel (x, y) according to the following equations (5) and (6).

The video encoding apparatus 10 for compensating a pixel value according to an embodiment and the video decoding apparatus 20 for compensating a pixel value according to an embodiment may be arranged such that, in accordance with Equations 5 and 6, Pixels corresponding to the extreme values can be determined.

A flattening phenomenon may occur by a general video decoding system. Accordingly, the local minimum value of the restored image is larger than the pixel value of the original image, and the error between the restored image and the original image is positive with respect to the local minimum value. Also, the local maximum value of the restored image is smaller than the pixel value of the original image, and the error between the local maximum value and the restored image is negative.

Accordingly, the video encoding apparatus 10 for compensating for pixel values according to an embodiment and the video decoding apparatus 20 for compensating for pixel values according to an embodiment are capable of correcting An average error between the minimum value and the maximum value may be respectively determined to compensate the pixel values of the restored pixels of the corresponding pixel group. 3, the compensation value of the video coding apparatus 10 for pixel value compensation according to an embodiment and the compensation value of the pixel group deciding unit 16 and the video decoding apparatus 20 ) Determines the extreme level of the restored pixel of the predetermined pixel group is described in detail.

FIG. 3 illustrates neighboring reconstructed pixels to be compared to determine the extreme level of the reconstructed pixel, according to one embodiment.

The compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to an exemplary embodiment of the present invention may be configured such that the reconstructed pixels 32, 34, 35, 37) to determine the extreme level of the current reconstructed pixel 30. [ The pixel value Rec [x] [y] of the current reconstructed pixel 30, the pixel value of the neighboring reconstructed pixels 32, 34, 35, and 37, In the case of Rec [x] [y-1], Rec [x-1] [y], Rec [x + 1] [y] and Rec [x] [y + 1]

ExtremeType = 0;

if (Rec [x] [y]> Rec [x-1] [y]) ExtremeType ++;

if (Rec [x] [y] <Rec [x-1] [y]) ExtremeType--;

if (Rec [x] [y]> Rec [x + 1] [y]) ExtremeType ++;

if (Rec [x] [y] <Rec [x + 1] [y]) ExtremeType--;

if (Rec [x] [y]> Rec [x] [y-1]) ExtremeType ++;

if (Rec [x] [y] <Rec [x] [y-1]) ExtremeType--;

if (Rec [x] [y]> Rec [x] [y + 1]) ExtremeType ++;

if (Rec [x] [y] <Rec [x] [y + 1]) ExtremeType--;

That is, the pixel value is compared with neighboring restored pixels 32, 34, 35, 37 of a predetermined range of the restored pixel 30 to determine the extreme value 'ExtremeType'. If the extreme level ExtremeType of the current restoration pixel 30 is the maximum extreme value level 4, the current restoration pixel 30 is determined as the local maximum pixel, and if the extreme level ExtremeType of the current restoration pixel 30 is the minimum extreme level -4, The reconstruction pixel 30 may be determined to be a local minimum pixel. The compensation value and pixel group determination unit 16 according to the embodiment and the pixel group determination unit 26 according to an embodiment can determine a restored pixel determined as a local maximum pixel and a local minimum pixel as a pixel to be compensated.

In this manner, the compensation value and pixel group determination unit 16 according to the embodiment and the pixel group determination unit 26 according to the embodiment determine the extremum level for the restored pixels of the current data unit, A pixel group including the four restored pixels and a pixel group including the extreme level of -4 can be determined. In addition, the compensation value and pixel group determination unit 16 according to an exemplary embodiment may determine an average value of pixel value errors between the restored pixels and each original pixel on a pixel group basis, and determine a compensation value based on the error . The pixel group determining unit 26 and the reconstructed pixel compensating unit 28 according to the embodiment can compensate the pixel values of the reconstructed pixels for each pixel group using the compensation value extracted from the received compensation value information.

In addition, the compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to the embodiment according to the embodiment may be configured to determine the pixel group including the restoration pixels neighboring the local maximum pixel and the local minimum pixel, The pixel value compensation target may be determined. To this end, the compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to an exemplary embodiment of the present invention may be configured to determine a compensation value and pixel group determination unit 26 for a predetermined range of extremum levels including a maximum extremum level and a minimum extremum level The compensation value can be determined. For example, since the maximum peak level illustrated above is 4, restored pixels having an extremum level of 3 may indicate neighboring a local maximum pixel.

Therefore, the compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to the embodiment of the present invention are capable of determining the restoration pixels of the corresponding extremum level when the extremum level is greater than a predetermined positive value The pixel groups including the pixel groups are determined as a group of neighboring pixels of the maximum extreme level, and when the extreme level is smaller than a predetermined negative value, the restoration pixels of the extreme level may be determined as a group of neighboring pixels of the minimum extreme level. For example, when the extremum level is greater than 1 or less than -1, that is, when the extremum levels are -4, -3, -2, 3, 4, the compensation value for each extremum level can be determined.

In addition, the compensation value and pixel group determination unit 16 according to an exemplary embodiment calculates an average value of the error between the restored pixel and the original pixel for each pixel group for each neighboring pixel group of the maximum extreme level, Value can be determined. The pixel group determining unit 26 and the reconstructed pixel compensating unit 28 according to the exemplary embodiment may use the compensated values for each pixel group extracted from the received compensation value information to calculate the pixel values of the reconstructed pixels for each pixel group You can compensate.

The extreme level is determined using four reconstructed pixels 32, 34, 35, and 37 neighboring up, down, left, and right with respect to the current reconstructed pixel 30. However, The extreme level of the current reconstruction pixel 30 may be determined using the eight reconstructed pixels 31, 32, 33, 34, 35, 36, 37, 38 surrounding the pixel 30 as neighboring reconstructed pixels.

As a second embodiment of pixel group determination, a video encoding apparatus 10 for compensating for pixel values according to an embodiment and a video decoding apparatus 20 for compensating for pixel values according to an embodiment, Band.

For example, when the bit depth of the restored pixel is N, the total range of the pixel value Rec [x] [y] of the restored pixel is ≤ Rec [x] [y] ≤ 2 ^N -1. That is, the maximum value Max of the pixel value Rec [x] [y] of the restored pixel is 2 ^N -1, and the interval of the restored pixel is [0, Max]. The compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to an exemplary embodiment may divide the segment of the restored pixel into L bands. That is, the bands of the restored pixels are [0, (Max + 1) / L -1], [Max / L, 2 * (Max + 1) / L -1], ..., [(L-1) * Max / L, L * (Max + 1) / L -1].

The number of divided bands [0, Max] of the restored pixel is preferably determined to be a square of 2 and more than 16 for fast calculation. Also, for quick calculation, it is preferable that the number L of divided bands is determined within a number in which the number p of the most significant bits of the reconstructed pixel value is an exponent of 2. For example, when the most significant bit of the restored pixel is 4 bits (p = 4) and the extended bit depth of the restored pixel is 12 bits, the number L of divided bands may be determined as L = 2 ^p = 16. Therefore, in this case, the bandwidth of the reconstructed pixel of the extended bit depth can be divided as shown in Table 1 below.

Band number 0 One 2 ... 16 The pixel value band of the reconstructed pixel. [0, 255] [256, 511] [512, 767] ... [3840, 4095] Hexadecimal representation of pixel values [0x0000, 0x00FF] [0x0100, 0x01FF] [0x0200, 0x02FF] ... [0x0F00, 0x0FFF]

Since the pixel value band is divided based on the number of the most significant bits of the restored pixel, the calculation for the pixel band determination of the pixel group determination unit 26 according to the embodiment, which is a decoding end, is performed very efficiently .

The compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to an exemplary embodiment may determine the restored pixels included in the same band as a group of pixels for each band.

The average of the pixel value error with the original pixel for the restored pixels included in the band-by-band pixel group is not zero. Accordingly, the compensation value and the pixel group determination unit 16 according to the embodiment can determine the compensation value using the average of the pixel value errors for each band. The pixel group determining unit 26 and the reconstructed pixel compensating unit 28 according to an exemplary embodiment use the band-specific compensation values extracted from the received compensation value information to calculate the pixel values Can be compensated.

As a third embodiment of pixel group determination, a video encoding apparatus 10 for compensating for pixel values according to an embodiment and a video decoding apparatus 20 for compensating for pixel values according to an embodiment, It is possible to classify the pixel group including the restored pixels constituting the line.

The compensation value and pixel group determination unit 16 according to the embodiment and the pixel group determination unit 26 according to an embodiment analyze the image characteristic of the restored image to detect the vertical line, It is possible to detect a line in a predetermined direction such as a line constituting a boundary line. The compensation value and pixel group determination unit 16 according to the embodiment and the pixel group determination unit 26 according to the embodiment can determine the restored pixels constituting the same line as a pixel group per line.

The average of the pixel value errors with the original pixels for the restored pixels included in the line-by-line pixel group is also not zero. Accordingly, the compensation value and pixel group determination unit 16 according to the embodiment can determine the compensation value using an average of the pixel value errors per line. The pixel group determining unit 26 and the reconstructed pixel compensating unit 28 according to an exemplary embodiment may use the compensation value for each line extracted from the received compensation value information to calculate a pixel value Can be compensated.

The compensation value and pixel group determination unit 16 and the pixel group determination unit 26 according to the embodiment of the present invention calculate the compensation value for each extremum level for each data unit such as video sequence, You can decide. The transmitting unit 18 according to an embodiment can transmit the compensation value related information including the compensation value as overhead information and transmit it. The smaller the data unit for determining the compensation value for each extremum level, the better the accuracy of the compensation value. However, since the additional information for coding and transmitting the compensation value-related information including the compensation value can be increased, can do.

In addition, the extracting unit 22 may extract the compensation value related information from the overhead information or the slice header information, and compensate the pixel value of the restored pixel by using the compensation value.

The reconstructed image generating unit 14 and the reconstructed image generating unit 24 according to an embodiment may selectively perform adaptive loop filtering on the image data decoded into the spatial domain. The reconstructed image generating unit 14 and the reconstructed image generating unit 24 according to an embodiment continuously perform one-dimensional filtering in the horizontal direction and one-dimensional filtering in the vertical direction according to the adaptive loop filtering And the current picture can be restored.

The transmitter 18 of the video encoding apparatus 10 for pixel value compensation according to an exemplary embodiment may encode and output a filter coefficient used for adaptive loop filtering. In addition, for adaptive loop filtering according to an embodiment, the type, number, size, quantization bit, coefficient, filtering direction, whether to perform filtering, and whether to perform running filtering can be set for each one- Information about a one-dimensional filter set of filtering may be encoded and transmitted.

The reconstructed image generating unit 24 may derive the filter coefficients of each one-dimensional filter using the residual information of the filter coefficients extracted from the extracting unit 22. [

For example, for each one-dimensional filter, the current filter coefficient may be derived by adding the difference between the current filter coefficient and the previous filter coefficient to the previous filter coefficient. Using the filter coefficients of each derived one-dimensional filter, continuous one-dimensional filtering can be performed on the deblocked data. Deblocking reduces the block effect of the decoded data, and loop filtering minimizes the error between the reconstructed image and the original image.

For a specific understanding of the invention, loop filtering by continuous one-dimensional filtering in the horizontal and vertical directions will be described below with reference to the mathematical expression.

The current filter coefficient may be derived according to equation (7).

Where i represents the index of the one-dimensional filter and j represents the index of the filter coefficient of each one-dimensional filter. c [i] [j] denotes the current filter coefficient, adaptive_loop_filter_prev [i] [j] denotes the previous filter coefficient, and adaptive_loop_filter [i] [j] denotes the residual component of the filter coefficient transmitted as the filter coefficient information.

That is, the current filter coefficient may be derived as the sum of the previous filter coefficient and the residual component. The current filter coefficient c [i] [j] is updated to adaptive_loop_filter_prev [i] [j] to derive the next filter coefficient after deriving the current filter coefficient.

Loop filtering by continuous one-dimensional filtering can be performed according to equations (2) and (3). In Equations (8) and (9), i represents the width direction index of the current picture, and j represents the height direction index of the current picture.

p _{i , j} represents the deblocked data of the current picture, and q _{i , j} represents the one-dimensional filtered data in the horizontal direction with respect to the deblocked data. Using the filter coefficient c of the symmetric filter, it is symmetrically filtered using five filter coefficients for the nine deblocked data.

f _{i , j} represents one-dimensional filtered data in the vertical direction with respect to q _{i , j} . Since the filter coefficient c follows the running filtering method, vertical one-dimensional filtering is continuously performed on the one-dimensional filtered data in the horizontal direction.

In the case of a symmetric filter, the advantage is that the coefficients of all filters can be set even if only a small number of coefficients are required for a one-dimensional filter compared to a two-dimensional filter. Thus, there is a relatively small number of bits associated with the filter characteristics that a plurality of one-dimensional filter sets should be inserted into the transmitted bitstream than a two-dimensional filter.

Also, the capacity of the memory for storing the temporary data during the filtering is smaller than that of the two-dimensional filter. The amount of computation of filtering by the two-dimensional filter is considerably larger than that of the one-dimensional filtering. In the case of running filtering, it is impossible to perform concurrent processing by multiple filtering which is impossible in two dimensions, but it is possible to perform concurrent processing by a one-dimensional filter.

However, loop filtering according to an embodiment is not limited to continuous one-dimensional filtering in the horizontal direction and the vertical direction. The loop filtering according to one embodiment can be implemented with continuous filtering of any number of one-dimensional filters, and each one-dimensional filtering can be performed in any direction.

In addition to the filter coefficient information, the video decoding apparatus 20 for pixel value compensation according to an exemplary embodiment receives information on a one-dimensional filter set of loop filtering, and determines the type, number, size, quantization bit, Coefficient, direction of filtering, whether to perform filtering, and whether to perform running filtering. Accordingly, the reconstructed image generating unit 24 according to an exemplary embodiment can perform loop filtering by combining various one-dimensional filters.

4 and 5, the adaptive loop filtering of the reconstructed image generating unit 14 and the reconstructed image generating unit 24 according to an embodiment will be described in detail.

4 illustrates a flow diagram of adaptive loop filtering in accordance with one embodiment.

Loop filtering can be performed by successively filtering a plurality of one-dimensional filters. In step 41, the decoded image data can be input. Image data on which deblocking filtering has been performed may be input. In step 42, it is determined whether or not all the filters of the first filter, the second filter, and the Nth filter are used. If it is determined that all the filters are not used, the process proceeds directly to the storing or reproducing step (step 46). If it is determined in step 42 that it is determined to perform filtering by all the filters, the one-dimensional filtering of the first filtering direction using the first filter in step 43, the second filtering using the second filter in step 44, The one-dimensional filtering of the filtering direction, and the one-dimensional filtering of the Nth filtering direction using the Nth filter in step 45, in that order.

In step 46, the decoded image data, deblocked image data, or successively one-dimensional filtered data is stored in a buffer or reproduced in a reproducing apparatus.

The filtering direction of the one-dimensional filter of one embodiment can be adaptively determined to the characteristics of the local image through analysis of the image characteristic. For example, the filtering direction may be adaptively determined in the edge direction of the local image to preserve the edge of the image.

5 shows a flow diagram of adaptive loop filtering according to another embodiment.

When the decoded image data or deblocked image data is input in step 51, an edge is detected for each pixel of the decoded image data in step 52. [ In step 53, one-dimensional filtering is performed according to the detected edge direction, and the filtered data in step 54 is stored or reproduced on the reproducing apparatus.

Information regarding the first-order filter set including the filtering direction determined according to the edge direction in the video encoding process is encoded and provided to the decoding end. In the video decoding process, information about the loop filter is read from the received data, and one-dimensional filtering according to a filtering direction such as an edge direction of a predetermined one-dimensional filter can be performed.

The post-processing by loop filtering can reduce the distortion between the original image and the reconstructed image caused by complicated loss compression. Further, by using the loop-filtered image as a reference image, the image quality of a resultant image of prediction or motion compensation can be improved.

Accordingly, the reconstructed image generating unit 14 and the reconstructed image generating unit 24 according to an embodiment selectively perform adaptive loop filtering to generate a reconstructed image using a combination of one- The loop filter can be performed in consideration of the characteristics of the system, the system environment, or the user demand. By adaptive loop filtering according to an embodiment, a continuous one-dimensional filter is used instead of a two-dimensional filter, so that it can be advantageous in various aspects such as memory, calculation amount, and transmission bit compared with a two-dimensional filter. In addition, when the reconstructed image generating unit 14 and the reconstructed image generating unit 24 according to an embodiment perform adaptive loop filtering, the transmitting unit 18 and the one- The extraction unit 22 according to the example transmits and receives the encoded information of the residual components of the coded filter coefficients, so that the burden of the information amount required for the adaptive loop filtering can be reduced.

FIG. 6 shows a flowchart of a video encoding method for pixel value compensation according to an embodiment of the present invention.

In step 62, the input video sequence is coded. In step 64, the encoded image data is decoded and loop-filtered on the decoded image data to generate a reconstructed image. According to one embodiment, a reconstructed image may be generated by performing adaptive loop filtering that performs one or more one-dimensional filtering operations on the decoded image data or deblocked image data one after another.

In step 66, for the restored pixels of the predetermined group among the restored images, a group of pixels including the compensation value for the error between each restored pixel and the original pixel and the pixel to be compensated is determined. The pixel group including the restored pixels to be compensated for the pixel value may be determined according to the extreme level of the pixel value, the pixel value band, or whether the line is composed. The compensation value for each pixel group can be determined based on an average value of the errors between the corresponding restored pixels and respective corresponding original pixels.

In step 68, the compensation value is encoded, and the bit stream of the encoded compensation value and the encoded input image is transmitted. If a compensation value is determined for a more refined pixel group, more accurate pixel value compensation is possible, but overhead can be increased.

FIG. 7 shows a flowchart of a video decoding method for pixel value compensation according to an embodiment of the present invention.

In step 72, a bitstream for the encoded image is received and parsed, and the encoded image data and the compensation value are extracted from the bitstream.

In step 74, the encoded image data is decoded and loop-filtered on the decoded image data to generate a reconstructed image. The reconstructed image can be generated by performing adaptive loop filtering on the decoded image data or deblocked image data, in which one or more one-dimensional filtering operations are continuously performed according to an embodiment.

In step 76, among the restored pixels of the restored image, a group of pixels including the restored pixel to be compensated using the compensation value is determined. Based on the extracted compensation value related information, in accordance with the pixel group determination method, according to the extreme value level of the pixel value of the restored pixel, the pixel value band, or the configuration of the line, The group of pixels including the pixel can be determined. In step 78, for the restored pixel of the determined pixel group, the error between the restored pixel and the original pixel is compensated by using the compensation value, and a restored image in which the error is compensated can be outputted.

According to the video encoding method for pixel value compensation according to an embodiment of the present invention or the video decoding method for compensating pixel values according to an embodiment, the systematic error of the reconstructed image is compensated, Only compensation value information for each pixel group is encoded and transmitted and received and information on the position of a pixel to be compensated for pixel value need not be transmitted and received so that the transmission bit amount of the additional information for improving the picture quality of the restored image can be reduced have.

8 to 22, video encoding and decoding for compensating pixel values after loop filtering based on the hierarchical data units for each region according to an embodiment of the present invention will be described in detail.

8 is a block diagram of a video encoding apparatus for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.

The video coding apparatus 80 for performing pixel filtering after loop filtering based on the hierarchical data units according to an embodiment includes a coding unit 81, a reconstructed image generating unit 84, A portion 87 and a transfer portion 88. [ The encoding unit 81 according to an embodiment includes a maximum encoding unit division unit 82 and a coding depth and encoding mode determination unit 83. The reconstructed image generation unit 84 according to an embodiment includes a decoding unit (85) and a loop filtering performing unit (86).

The encoding unit 81 according to an embodiment encodes an input video sequence. The encoding unit 81 according to an exemplary embodiment may encode an input image sequence based on a hierarchical data unit for each region. For this, the maximum encoding unit division unit 82 according to an embodiment can divide the current picture based on the maximum encoding unit, which is a maximum-size encoding unit for the current picture of the image. If the current picture is larger than the maximum encoding unit, the image data of the current picture may be divided into at least one maximum encoding unit. The image data may be output to the coding depth and coding mode determination unit 83 for each of at least one maximum coding unit.

An encoding unit according to an embodiment may be characterized by a maximum size and a depth. Depth indicates a stage in which coding units are hierarchically divided. As the depth increases, the depth coding units can be divided from the maximum coding unit to the minimum coding unit. The depth of the maximum encoding unit is the highest depth and the minimum encoding unit can be defined as the least significant encoding unit. As the depth of the maximum encoding unit increases, the size of the depth-dependent encoding unit decreases, so that the encoding unit of the higher depth may include a plurality of lower-depth encoding units.

As described above, according to the maximum size of an encoding unit, the image data of the current picture is divided into a maximum encoding unit, and each maximum encoding unit may include encoding units divided by depth. Since the maximum encoding unit according to an embodiment is divided by depth, image data of a spatial domain included in the maximum encoding unit can be hierarchically classified according to depth.

The maximum depth for limiting the total number of times the height and width of the maximum encoding unit can be hierarchically divided and the maximum size of the encoding unit may be preset.

The coding depth and coding mode determining unit 83 codes at least one divided area in which the area of the maximum coding unit is divided for each depth, and determines the depth at which the final coding result is output for each of at least one of the divided areas. That is, the coding depth and coding mode determining unit 83 selects the depth at which the smallest coding error occurs, and determines the coding depth as the coding depth by coding the image data in units of depth coding for each maximum coding unit of the current picture. The determined encoding depth and the image data per encoding unit are output to the transmitter 88.

The image data in the maximum encoding unit is encoded based on the depth encoding unit according to at least one depth below the maximum depth, and the encoding results based on the respective depth encoding units are compared. As a result of the comparison of the encoding error of the depth-dependent encoding unit, the depth with the smallest encoding error can be selected. At least one coding depth may be determined for each maximum coding unit.

As the depth of the maximum encoding unit increases, the encoding unit is hierarchically divided and divided, and the number of encoding units increases. In addition, even if encoding units of the same depth included in one maximum encoding unit, the encoding error of each data is measured and it is determined whether or not the encoding unit is divided into lower depths. Therefore, even if the data included in one maximum coding unit has a different coding error according to the position, the coding depth can be determined depending on the position. Accordingly, one or more coding depths may be set for one maximum coding unit, and data of the maximum coding unit may be divided according to one or more coding depth encoding units.

The predictive encoding and frequency conversion of the maximum encoding unit can be performed. Likewise, predictive coding and frequency conversion are performed on the basis of the depth coding unit for each maximum coding unit and for each depth below the maximum depth.

Since the number of coding units per depth is increased every time the maximum coding unit is divided by the depth, the coding including the predictive coding and the frequency conversion should be performed for every depth coding unit as the depth increases. For convenience of explanation, predictive coding and frequency conversion will be described based on a coding unit of a current depth among at least one maximum coding unit.

The video encoding apparatus 80 according to the embodiment may select various sizes or types of data units for encoding image data. To encode the image data, a step such as predictive encoding, frequency conversion, and entropy encoding is performed. The same data unit may be used for all steps, and the data unit may be changed step by step.

For example, the video coding apparatus 80 can select a coding unit and a data unit different from the coding unit in order to perform predictive coding of the video data of the coding unit as well as the coding unit for coding the video data.

For predictive coding of the maximum coding unit, predictive coding may be performed based on the partial data unit of the coding unit for each depth of the maximum coding unit. The partial data unit of the encoding unit may include a data unit in which at least one of the height and the width of the encoding unit and the depth encoding unit is divided.

For example, when the size of the encoding unit is 2Nx2N (where N is a positive integer), the size of the partial data unit may be 2Nx2N, 2NxN, Nx2N, NxN, and the like. Prediction coding may be performed based on data units of various types, in addition to data units of a type in which at least one of the height and the width of an encoding unit is divided by half. Hereinafter, a data unit on which prediction encoding is based may be referred to as a 'prediction unit'.

The prediction mode of the encoding unit may be at least one of an intra mode, an inter mode, and a skip mode. For example, the intra mode and the inter mode can be performed for prediction units of 2Nx2N, 2NxN, Nx2N, and NxN sizes. In addition, the skip mode can be performed only for a prediction unit of 2Nx2N size. Encoding is performed independently for each prediction unit within an encoding unit, and a prediction mode having the smallest encoding error can be selected.

In addition, the video encoding apparatus 80 according to an exemplary embodiment may perform frequency conversion of image data of an encoding unit based on not only an encoding unit for encoding image data but also a data unit different from the encoding unit.

For frequency conversion of a coding unit, frequency conversion may be performed based on a data unit having a size smaller than or equal to the coding unit. For example, a data unit for frequency conversion may include a data unit for intra mode and a data unit for inter mode. Hereinafter, the data unit on which the frequency conversion is based may be referred to as a 'conversion unit'.

The coding information according to the coding depth needs not only the coding depth but also prediction related information and frequency conversion related information. Therefore, the coding depth and coding mode determining section 83 determines not only the coding depth at which the minimum coding error is generated, but also the partition type in which the coding unit of the coding depth is divided into prediction units, the prediction mode for each prediction unit, And the like can be determined.

The coding depth and coding mode decision unit 83 according to the embodiment can measure the coding error of the coding units of depth by using a Lagrangian Multiplier based Rate-Distortion Optimization have.

The reconstructed image generation unit 84 according to an embodiment decodes the encoded image data and performs loop filtering on the decoded image data to generate a reconstructed image. The decoding unit 85 of the reconstructed image generating unit 84 according to an embodiment decodes the image data encoded based on the hierarchical data unit for each region by the encoding unit 81. [ The decoding unit 85 according to the embodiment decodes the encoded image data based on the encoding depth and the encoding mode determined by the encoding depth and encoding mode deciding unit 830, Data can be output.

The loop filtering performing unit 86 of the reconstructed image generating unit 84 according to an exemplary embodiment may perform in-loop filtering on the decoded image data. The same technique as the adaptive loop filtering selectively performed by the reconstructed image generating unit 14 according to the embodiment may be applied to the loop filtering performing unit 86 according to the embodiment of the present invention. Accordingly, the loop filtering performing unit 86 according to the embodiment of the present invention can continuously perform one-dimensional filtering in the horizontal direction and one-dimensional filtering in the vertical direction to restore the current picture. The loop filtering performing unit 86 according to an embodiment outputs a reconstructed image and the reconstructed image may be input to the compensation value and pixel group determination unit 87. [

The compensation value and pixel group determination unit 87 according to an exemplary embodiment of the present invention determines a compensation value for an error between each restored pixel and a corresponding original pixel, And determines a group of pixels including the pixels. The compensation value and pixel group determination unit 87 and the compensation value and pixel group determination unit 16 according to the embodiment according to the embodiment are corresponding technical components.

Accordingly, the compensation value and pixel group determination unit 87 according to an embodiment determines the extreme level of each reconstructed pixel of neighboring reconstructed pixels of the reconstructed image and classifies neighboring reconstructed pixels into pixel groups of the extreme level . In addition, the compensation value and pixel group determination unit 87 according to an exemplary embodiment may classify the restored pixels into pixel groups for each band based on pixel values. In addition, the compensation value and pixel group determination unit 87 according to an exemplary embodiment analyzes the restored image, detects lines in a predetermined direction, and restores the restored pixels to a line-by-line pixel group . &Lt; / RTI &gt;

The compensation value and pixel group determination unit 87 according to the embodiment can determine the compensation value using the average value of the errors between the restored pixel and the original pixel separately for each pixel group. The compensation value and pixel group determination unit 87 according to an exemplary embodiment determines a restored pixel to be compensated for each data unit of at least one of a video sequence, a slice, a frame, and an encoding unit of the input video, . The compensation value according to the embodiment and the compensation value or information about the pixel group determined by the pixel group determination unit 87 may be output to the transmission unit 88. [

The transmitting unit 88 according to an embodiment transmits the video data of the maximum coding unit encoded based on at least one coding depth determined by the coding depth and coding mode deciding unit 83 and information on the coding mode per depth And outputs it in stream form. The image data encoded by the encoding unit 81 may be converted into a bit stream format through entropy encoding and then inserted into a bit stream for transmission.

In addition, the transmission unit 88 according to an exemplary embodiment may encode the compensation value and the compensation value determined by the pixel group determination unit 16, and may be inserted into the transmission bitstream. The transmitting unit 88 according to an embodiment may receive the compensation value and the additional information on the pixel group determination method from the pixel group determining unit 87, and may encode the added information and insert it into the bitstream.

The encoded image data may be a result of encoding residual data of the image.

The information on the depth-dependent coding mode may include coding depth information, partition type information of a prediction unit of a coding unit of coding depth, prediction mode information per prediction unit, size information of a conversion unit, and the like.

The coding depth information can be defined using depth division information indicating whether or not coding is performed at the lower depth coding unit without coding at the current depth. If the current depth of the current encoding unit is the encoding depth, the current encoding unit is encoded in the current depth encoding unit, so that the division information of the current depth can be defined so as not to be further divided into lower depths. On the other hand, if the current depth of the current encoding unit is not the encoding depth, the encoding using the lower depth encoding unit should be tried. Therefore, the division information of the current depth may be defined to be divided into the lower depth encoding units.

If the current depth is not the encoding depth, encoding is performed on the encoding unit divided into lower-depth encoding units. Since there are one or more lower-level coding units in the current-depth coding unit, the coding is repeatedly performed for each lower-level coding unit so that recursive coding can be performed for each coding unit of the same depth.

At least one coding depth is determined in one maximum coding unit and at least one coding mode information is determined for each coding depth so that information on at least one coding mode can be determined for one maximum coding unit. Since the data of the maximum encoding unit is hierarchically divided according to the depth and the depth of encoding may be different for each position, information on the encoding depth and the encoding mode may be set for the data.

Therefore, the transmitting unit 88 according to the embodiment can set the corresponding encoding information for each minimum encoding unit included in the maximum encoding unit. That is, the coding unit of the coding depth includes at least one minimum coding unit that holds the same coding information. By using this, if the neighboring minimum encoding units have the same depth encoding information, it can be the minimum encoding unit included in the same maximum encoding unit.

For example, the encoding information output through the transmission unit 88 can be classified into encoding information for each depth unit and encoding information for each prediction unit. The under-coding-by-depth coding unit information may include prediction mode information and partition size information. The encoding information to be transmitted for each prediction unit includes information about the estimation direction of the inter mode, information about the reference picture index of the inter mode, information on the motion vector, information on the chroma component of the intra mode, information on the interpolation mode of the intra mode And the like. Information on the maximum size of a coding unit defined for each picture, slice or GOP, and information on the maximum depth can be inserted into the header of the bitstream.

The transmitter 88 according to an exemplary embodiment may encode and output a filter coefficient used for adaptive loop filtering. In addition, for adaptive loop filtering according to an embodiment, the type, number, size, quantization bit, coefficient, filtering direction, whether to perform filtering, and whether to perform running filtering can be set for each one- Information about a one-dimensional filter set of filtering may be encoded and transmitted.

According to an embodiment of the simplest form of the video coding apparatus 80 according to the embodiment, the coding unit for depth is a coding unit which is half the height and width of the coding unit of one layer higher depth. That is, if the size of the current depth encoding unit is 2Nx2N, the size of the lower depth encoding unit is NxN. In addition, the current encoding unit of 2Nx2N size can include a maximum of 4 sub-depth encoding units of NxN size.

Therefore, the video decoding apparatus 80 according to the embodiment determines the encoding unit of the optimal form and size for each maximum encoding unit based on the size and the maximum depth of the maximum encoding unit determined in consideration of the characteristics of the current picture . In addition, since each encoding unit can be encoded by various prediction modes, frequency conversion methods, and the like, an optimal encoding mode can be determined in consideration of image characteristics of encoding units of various image sizes.

Therefore, if an image having a very high image resolution or a very large data amount is encoded in units of existing macroblocks, the number of macroblocks per picture becomes excessively large. This increases the amount of compression information generated for each macroblock, so that the burden of transmission of compressed information increases and the data compression efficiency tends to decrease. Therefore, the video encoding apparatus according to an embodiment can increase the maximum size of the encoding unit in consideration of the image size, and adjust the encoding unit in consideration of the image characteristic, so that the image compression efficiency can be increased.

In addition, since the compensation value information for compensating the pixel value between the restored image and the original image necessary for improving the image quality of the restored image at the decoding end is coded and transmitted without information about the pixel position, .

9 is a block diagram of a video decoding apparatus for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.

The video decoding apparatus 90 for performing pixel filtering after loop filtering based on the hierarchical data units according to an embodiment includes an extracting unit 91, a restored image generating unit 94, a pixel group determining unit 97, And a restored pixel compensation unit 98. [ The extraction unit 91 according to an embodiment includes a receiver 92 and image data, encoding mode information, loop filter coefficient information and a compensation value information extraction unit 93. The reconstruction image generation unit 94 includes a decoding unit (95) and a loop filtering performing unit (96).

Depth unit, prediction unit, conversion unit, and various encoding modes for various processing of the video decoding apparatus 90 for pixel value compensation after loop filtering based on the hierarchical data units for each region according to an embodiment And the like are the same as those described above with reference to the video encoding apparatus 80 for pixel value compensation after loop filtering based on the hierarchical data units for each region according to FIG. 8 and one embodiment.

The extracting unit 91 according to an embodiment receives and parses a bitstream of the encoded image, and extracts the encoded image data and the compensation value from the bitstream. The receiving unit 92 of the extracting unit 91 according to the embodiment receives and parses the bitstream of the encoded video. The image data, encoding mode information, loop filter coefficient information, and compensation value information extraction unit 93 (hereinafter referred to as 'information extraction unit') according to an exemplary embodiment extracts image data by a maximum encoding unit from a parsed bitstream And outputs it to the decoding unit 95. The information extracting unit 93 may extract information on the maximum size of the encoding unit of the current picture from the header of the current picture.

In addition, the information extracting unit 93 extracts information on a coding depth and a coding mode for each maximum coding unit from the parsed bitstream. The information on the extracted coding depth and coding mode is output to the decoding unit 95. That is, the video data of the bit stream can be divided into a maximum encoding unit, and the decoding unit 95 can decode video data per maximum encoding unit.

Information on the coding depth and the coding mode per coding unit can be set for one or more coding depth information, and the information on the coding mode for each coding depth includes information on partition type information, prediction mode information, Size information of the conversion unit, and the like. In addition, as the encoding depth information, depth-based segmentation information may be extracted.

The information on the coding depth and the coding mode for each maximum coding unit extracted by the information extracting unit 93 according to an exemplary embodiment is similar to that of the video coding apparatus 80 according to the embodiment, And information on a coding depth and a coding mode determined to repeatedly perform coding for each coding unit to generate a minimum coding error. Accordingly, the video decoding apparatus 90 according to an exemplary embodiment can decode data according to a coding scheme that generates a minimum coding error to recover an image.

The information extracting unit 93 may extract information on the coding depth and coding mode for each minimum coding unit. If information on the coding depth and the coding mode of the corresponding maximum coding unit is recorded for each minimum coding unit, the minimum coding units having the same coding depth and information on the coding mode are estimated as data units included in the same maximum coding unit . That is, if the minimum coding units of the same information are collected and decoded, it is possible to decode based on the coding units of the coding depth with the smallest coding error.

The decoding unit 95 according to an embodiment decodes the image data of each maximum encoding unit based on information on the encoding depth and the encoding mode for each maximum encoding unit to reconstruct the current picture. Based on the coding depth information for each maximum coding unit, the decoding unit 95 according to an embodiment can decode the video data for each coding unit of at least one coding depth. The decoding process may include a prediction process including intra prediction and motion compensation, and an inverse frequency conversion process.

The decoding unit 95 according to one embodiment decodes each prediction unit and prediction mode for each coding unit on the basis of the partition type information and the prediction mode information of the prediction unit of the coding unit for each coding depth, To perform intra prediction or motion compensation.

In addition, the image data decoding unit 95 according to an exemplary embodiment may perform frequency inverse transform (inverse transform) on the basis of the size information of the transform unit of the coding unit for each coding depth, Can be performed.

The decoding unit 95 according to an exemplary embodiment can determine the coding depth of the current maximum coding unit using the division information by depth. If the partition information indicates that the current depth is to be decoded, the current depth is the depth of the encoding. Therefore, the decoding unit 95 according to the embodiment can decode the current depth encoding unit with respect to the image data of the current maximum encoding unit using the partition type, the prediction mode, and the conversion unit size information of the prediction unit.

That is, it is possible to observe the encoding information set for the minimum encoding unit and to decode the minimum encoding units that hold the encoding information including the same division information, into one data unit.

The information extracting unit 93 may extract information on a filter coefficient from a bitstream when information on a filter coefficient for adaptive loop filtering is embedded in the bitstream. The loop filtering performing unit 96 according to the embodiment receives information on the loop filter coefficient extracted by the information extracting unit 93 and the like and performs loop filtering on the image data decoded by the decoding unit 95 So that a reconstructed image can be generated.

For the loop filtering performing unit 96 according to the embodiment, the technical components of the reconstructed image generating unit 24 according to the embodiment may be applied equally. Accordingly, the loop filtering performing unit 96 according to an exemplary embodiment may selectively perform deblocking filtering and adaptive loop filtering on the decoded image data. The adaptive loop filtering according to an embodiment may be performed using a plurality of continuous one-dimensional filters.

The reconstructed image generation unit 94 may derive the filter coefficients of each one-dimensional filter using the residual information of the filter coefficients extracted from the information extraction unit 93. [ For example, for each one-dimensional filter, the current filter coefficient may be derived by adding the difference between the current filter coefficient and the previous filter coefficient to the previous filter coefficient. Using the filter coefficients of each derived one-dimensional filter, continuous one-dimensional filtering can be performed on the deblocked data. Deblocking reduces the block effect of the decoded data, and loop filtering minimizes the error between the reconstructed image and the original image.

The information extracting unit 93 extracts the encoded image data and the compensation value related information from the bit stream. The compensation value related information may include compensation value information. When the compensation value related information includes information on the determination method of the reconstructed pixel to be compensated using the compensation value, the information extracting unit 93 extracts, from the bit stream, Information on the group determination method may be extracted. The information extracting unit 93 according to an exemplary embodiment may extract compensation value or compensation value related information for each data unit of at least one of a video sequence, a slice, a frame, and a coding unit of the input video.

The pixel group determining unit 97 according to an exemplary embodiment receives the compensation value information extracted by the restored image and information extracting unit 93 generated by the restored image generating unit 94, A pixel group including a restored pixel to be compensated for using the compensation value for restored pixels of the pixel group. The reconstruction pixel compensating unit 98 according to the embodiment receives the compensation value extracted by the information extracting unit 93 and the information about the reconstructed pixels determined by the pixel group deciding unit 97, And compensates the pixel value of the reconstructed pixel to output the reconstructed image with the compensated pixel value.

When information on the pixel group determining method to be compensated by the information extracting unit 93 according to the embodiment is extracted, the pixel group determining unit 97 according to an embodiment selects the pixel group determining method based on the pixel group determining method, Value compensation target pixel group. For example, the pixel group determination unit 97 according to one embodiment determines whether to classify the restored pixels according to the above-mentioned extremum level, the pixel value band or the directional line based on the pixel group determination method, The pixel group to be compensated may be determined. In this case, the restored pixel compensator 98 compensates the pixel values of the restored pixels of the pixel group using the compensation value for the pixel group for each extreme level, the group for each band, or the group for each line .

The video decoding apparatus 90 according to an exemplary embodiment recursively performs encoding for each maximum encoding unit in the encoding process to obtain information on the encoding unit that has generated the minimum encoding error and can use it for decoding the current picture have. That is, it is possible to decode video data in the optimal encoding unit for each maximum encoding unit.

Accordingly, even if an image with a high resolution or an excessively large amount of data is used, the information on the optimal encoding mode transmitted from the encoding end is used, and the image data is efficiently encoded according to the encoding unit size and encoding mode, Can be decoded and restored.

In addition, a video coding apparatus 80 for compensating for pixel values based on hierarchical data units according to an embodiment and a video decoding apparatus for compensating pixel values based on hierarchical data units for each region according to an embodiment The decoding unit 90 can compensate for a systematic error occurring between the original images when the encoded image is decoded and restored.

10 to 20, video encoding and decoding based on area-specific hierarchical data units according to an embodiment will be described in detail.

FIG. 10 illustrates a concept of an encoding unit according to an embodiment of the present invention.

An example of an encoding unit may include 32x32, 16x16, 8x8, and 4x4 from an encoding unit with a width x height of 64x64. In addition to the square-shaped encoding units, there may be encoding units whose width x height is 64x32, 32x64, 32x16, 16x32, 16x8, 8x16, 8x4, 4x8.

With respect to the video data 310, the resolution is set to 1920 x 1080, the maximum size of the encoding unit is set to 64, and the maximum depth is set to 2. With respect to the video data 320, the resolution is set to 1920 x 1080, the maximum size of the encoding unit is set to 64, and the maximum depth is set to 4. With respect to the video data 330, the resolution is set to 352 x 288, the maximum size of the encoding unit is set to 16, and the maximum depth is set to 2.

It is preferable that the maximum size of the coding size is relatively large in order to improve the coding efficiency as well as to accurately characterize the image characteristics when the resolution or the data amount is large. Therefore, the maximum size of the video data 310 and 320 having the higher resolution than the video data 330 can be selected to be 64. FIG.

The maximum depth indicates the total number of layers in the hierarchical encoding unit. Therefore, since the maximum depth of the video data 310 is 2, the encoding unit 315 of the video data 310 is encoded from a maximum encoding unit having a major axis size of 64, Units. On the other hand, since the maximum depth of the video data 330 is 2, the encoding unit 335 of the video data 330 has a depth of two layers from the encoding units having the major axis size of 16, Units.

Since the maximum depth of the video data 320 is 4, the encoding unit 325 of the video data 320 has a depth of four layers from 32 to 16, 8, and 4 Encoding units. The deeper the depth, the better the ability to express detail.

11 is a block diagram of an image encoding unit based on an encoding unit according to an embodiment of the present invention.

The image encoding unit 400 according to an exemplary embodiment includes operations to encode image data in the encoding depth and encoding mode determination unit 83 of the video encoding device 80. [ That is, the intraprediction unit 410 performs intraprediction on the intra-mode encoding unit of the current frame 405, and the motion estimation unit 420 and the motion compensation unit 425 perform intraprediction on the current frame 405 of the inter- And a reference frame 495. The inter-frame estimation and the motion compensation are performed using the reference frame and the reference frame.

The data output from the intraprediction unit 410, the motion estimation unit 420 and the motion compensation unit 425 is output as a quantized transform coefficient through the frequency transform unit 430 and the quantization unit 440. The quantized transform coefficients are reconstructed into spatial domain data through the inverse quantization unit 460 and the frequency inverse transform unit 470 and the data of the reconstructed spatial domain is passed through the deblocking unit 480 and the loop filtering unit 490 Processed and output to the reference frame 495. [ The quantized transform coefficient may be output to the bitstream 455 via the entropy encoding unit 450.

The motion estimation unit 420, the motion compensation unit 425, and the frequency transformation unit 420, which are the components of the image encoding unit 400, are applied to the video encoding apparatus 80 according to one embodiment. The quantization unit 440, the entropy encoding unit 450, the inverse quantization unit 460, the frequency inverse transform unit 470, the deblocking unit 480, and the loop filtering unit 490, The work should be performed based on the depth encoding unit considering the maximum depth.

In particular, the intra prediction unit 410, the motion estimation unit 420, and the motion compensation unit 425 determine the prediction unit and the prediction mode in the coding unit in consideration of the maximum size and depth of the coding unit, and the frequency conversion unit 430 ) Should consider the size of the conversion unit considering the maximum size and depth of the encoding unit.

12 is a block diagram of an image decoding unit based on an encoding unit according to an embodiment of the present invention.

The bit stream 505 passes through the parsing unit 510 and the encoded video data to be decoded and the encoding-related information necessary for decoding are parsed. The encoded video data is output as inverse quantized data through the entropy decoding unit 520 and the inverse quantization unit 530, and the image data in the spatial domain is restored through the frequency inverse transform unit 540.

The intra-prediction unit 550 performs intraprediction on the intra-mode encoding unit for the video data in the spatial domain, and the motion compensating unit 560 performs intra-prediction on the intra-mode encoding unit using the reference frame 585 And performs motion compensation for the motion compensation.

The data in the spatial domain that has passed through the intra prediction unit 550 and the motion compensation unit 560 may be post-processed through the deblocking unit 570 and the loop filtering unit 580 and output to the reconstruction frame 595. Further, the post-processed data via deblocking unit 570 and loop filtering unit 580 may be output as reference frame 585.

In order to decode the image data in the decoding unit 95 of the video decoding apparatus 90 according to the embodiment, operations after the parsing unit 510 of the image decoding unit 500 according to the embodiment may be performed have.

The entropy decoding unit 520, the inverse quantization unit 530, and the frequency inverse transform unit (not shown), which are components of the video decoding unit 500, to be applied to the video decoding apparatus 90 according to one embodiment. The intraprediction unit 550, the motion compensation unit 560, the deblocking unit 570 and the loop filtering unit 580 all have to perform an operation based on the encoding unit of the encoding depth for each maximum encoding unit .

In particular, the intra prediction unit 550 and the motion compensation unit 560 determine a coding unit and a prediction mode in consideration of the maximum size and depth of a coding unit, and the frequency inverse transform unit 540 sets the maximum size and depth of the coding unit The size of the conversion unit should be considered.

FIG. 13 shows a coding unit and a prediction unit according to an embodiment of the present invention.

The video encoding apparatus 80 and the video decoding apparatus 90 according to an embodiment use a hierarchical encoding unit to consider the image characteristics. The maximum height, width, and maximum depth of the encoding unit may be adaptively determined according to the characteristics of the image, or may be variously set according to the demand of the user. The size of each coding unit may be determined according to the maximum size of a predetermined coding unit.

The hierarchical structure 600 of the encoding unit according to an embodiment shows a case where the maximum height and width of the encoding unit is 64 and the maximum depth is 4. Since the depth is deeper along the vertical axis of the hierarchical structure 600 of the encoding unit according to the embodiment, the height and width of the encoding unit for each depth are divided. In addition, along the horizontal axis of the hierarchical structure 600 of the coding unit, a prediction unit which is a partial data unit on which prediction coding of each depth coding unit is based is shown.

That is, the coding unit 610 is the largest coding unit among the hierarchical structures 600 of the coding units and has a depth of 0, and the size of the coding units, that is, the height and the width, is 64x64. A depth-1 encoding unit 620 having a size of 32x32, a depth-2 encoding unit 620 having a size 16x16, a depth-3 encoding unit 640 having a size 8x8, a depth 4x4 having a size 4x4, There is an encoding unit 650. An encoding unit 650 of depth 4 of size 4x4 is the minimum encoding unit.

The partial data units are arranged as a prediction unit of the encoding unit along the horizontal axis for each depth. That is, the prediction unit of the encoding unit 610 having a size of 64x64 with a depth of 0 is a partial data unit 610 having a size of 64x64, partial data units 612 having a size of 64x32 included in the encoding unit 610 of size 64x64, Partial data units 614 of size 32x64, and partial data units 616 of size 32x32. Conversely, the encoding unit may be a minimum-sized square data unit including the conversion units 610, 612, 614, and 616.

Likewise, the prediction unit of the encoding unit 620 of the size 32x32 of the depth 1 is the partial data unit 620 of the size 32x32, the partial data units 622 of the size 32x16, and the partial data unit 620 of the size 32x32 included in the encoding unit 620 of the size 32x32, Partial data units 624 of size 16x32, partial data units 626 of size 16x16.

Likewise, the prediction unit of a 16x16 size 16x16 encoding unit is a 16x16 partial data unit 630, a 16x8 partial data unit 632, and a 16x16 partial data unit 630 included in the 16x16 encoding unit 630, Partial data units 634 of size 8x16, and partial data units 636 of size 8x8.

Likewise, the prediction unit of the encoding unit 640 of the size 8x8 of the depth 3 includes the partial data unit 640 of the size 8x8, the partial data units 642 of the size 8x4, and the partial data units 640 of the size 8x8 included in the encoding unit 640 of the size 8x8, Partial data units 644 of size 4x8, and partial data units 646 of size 4x4.

Finally, a coding unit 650 of size 4x4 is the minimum coding unit and the coding unit of the lowest depth, and the prediction unit is a data unit 650 of size 4x4.

The encoding depth and encoding mode determination unit 83 of the video encoding apparatus 80 according to an embodiment determines the encoding depth of the maximum encoding unit 610 based on the respective depths included in the maximum encoding unit 610 Encoding is performed for each encoding unit of the encoder.

The number of coding units per depth to include data of the same range and size increases as the depth of the coding unit increases. For example, for data containing one coding unit at depth 1, four coding units at depth 2 are required. Therefore, in order to compare the encoding results of the same data by depth, they should be encoded using a single depth 1 encoding unit and four depth 2 encoding units, respectively.

For each depth-of-field coding, encoding is performed for each prediction unit of the depth-dependent coding unit along the horizontal axis of the hierarchical structure 600 of the coding unit, and a representative coding error, which is the smallest coding error at the corresponding depth, is selected . In addition, depths are deepened along the vertical axis of the hierarchical structure 600 of encoding units, and the minimum encoding errors can be retrieved by comparing the representative encoding errors per depth by performing encoding for each depth. The depth at which the minimum coding error occurs among the maximum coding units 610 can be selected as the coding depth and the partition type of the maximum coding unit 610. [

FIG. 14 shows a relationship between an encoding unit and a conversion unit according to an embodiment of the present invention.

The video coding apparatus 80 or the video decoding apparatus 90 according to an embodiment encodes or decodes an image in units of coding units smaller than or equal to the maximum coding unit for each maximum coding unit. The size of the conversion unit for frequency conversion during encoding can be selected based on data units that are not larger than the respective encoding units.

For example, in the video coding apparatus 80 according to the embodiment or the video coding apparatus 90 according to the embodiment, when the current coding unit 710 is 64x64 size, the 32x32 conversion unit 720 The frequency conversion can be performed.

In addition, the data of the encoding unit 710 of 64x64 size is encoded by performing the frequency conversion with the conversion units of 32x32, 16x16, 8x8, and 4x4 size of 64x64 or smaller, respectively, and then the conversion unit having the smallest error with the original Can be selected.

FIG. 15 illustrates depth-specific encoding information, in accordance with an embodiment of the present invention.

The encoding information encoding unit of the video encoding device 80 according to the embodiment is information on the encoding mode, and includes information on the partition type 800, information on the prediction mode 810, Information 820 on the unit size can be encoded and transmitted.

The partition type information 800 indicates information on a type in which the current encoding unit is divided as a prediction unit for predictive encoding of the current encoding unit. For example, the current encoding unit CU_0 of depth 0 and size 2Nx2N includes a prediction unit 802 of size 2Nx2N, a prediction unit 804 of size 2NxN, a prediction unit 806 of size Nx2N, a prediction unit 808 of size NxN ) And can be used as a prediction unit. In this case, information 800 regarding the partition type of the current encoding unit includes a prediction unit 802 of size 2Nx2N, a prediction unit 804 of size 2NxN, a prediction unit 806 of size Nx2N, and a prediction unit 808 of size NxN. Lt; / RTI &gt;

The information 810 on the prediction mode indicates the prediction mode of each prediction unit. The prediction unit indicated by the information 800 relating to the partition type is predicted to be one of the intra mode 812, the inter mode 814 and the skip mode 816 through the prediction mode information 810, for example. Can be set.

In addition, the information 820 on the conversion unit size indicates whether to perform frequency conversion on the basis of which conversion unit the current encoding unit is performed. For example, the conversion unit may be one of a first intra-conversion unit size 822, a second intra-conversion unit size 824, a first inter-conversion unit size 826, have.

The encoding information extracting unit of the video decoding apparatus 90 according to the embodiment extracts the information 800 about the partition type, the information 810 about the prediction mode, the information 820 about the conversion unit size ) Can be extracted and used for decoding.

FIG. 16 shows a depth encoding unit according to an embodiment of the present invention.

Partition information may be used to indicate changes in depth. The division information indicates whether the current-depth encoding unit is divided into lower-depth encoding units.

The prediction unit 910 for the prediction encoding of the coding units of depth 0 and 2N_0x2N_0 has a partition type 912 of 2N_0x2N_0 size, a partition type 914 of 2N_0xN_0 size, a partition type 916 of N_0x2N_0 size, a partition of size N_0xN_0 Type &lt; / RTI &gt;

For each partition type, predictive encoding should be repeatedly performed for each prediction unit of 2N_0x2N_0 size, two 2N_0xN_0 size prediction units, two N_0x2N_0 size prediction units, and four N_0xN_0 size prediction units. For a prediction unit of size 2N_0x2N_0, size N_0x2N_0, size 2N_0xN_0, and size N_0xN_0, predictive coding may be performed in intra mode and inter mode. The skip mode can be performed only for predictive encoding in a prediction unit of size 2N_0x2N_0.

If the coding error by the partition type 918 of the size N_0xN_0 is the smallest, the depth 0 is changed to 1 (920), and the coding units 922, 924, 926 and 928 of the partition type of the depth 2 and the size N_0xN_0 are changed The minimum coding error can be repeatedly searched for.

Since encoding is repeatedly performed on the encoding units 922, 924, 926, and 928 of the same depth, encoding of only one of the encoding units of depth 1, for example, will be described. The prediction unit 930 for predicting the coding unit of the depth 1 and the size 2N_1x2N_1 (= N_0xN_0) includes a partition type 932 of size 2N_1x2N_1, a partition type 934 of size 2N_1xN_1, a partition type 936 of size N_1x2N_1, , And a partition type 938 of size N_1xN_1. For each partition type, predictive coding should be repeatedly performed for each prediction unit of a size 2N_1x2N_1, a prediction unit of two sizes 2N_1xN_1, a prediction unit of two sizes N_1x2N_1, and a prediction unit of four sizes N_1xN_1.

If the coding error by the partition type 938 of the size N_1xN_1 is the smallest, the coding units 942, 944, 946 and 948 of the depth 2 and the size N_2xN_2 are changed while changing the depth 1 to the depth 2 (940) The minimum coding error can be repeatedly searched for.

If the maximum depth is d, the depth-based segmentation information can be set until the depth d-1. That is, the prediction unit 950 for predictive coding of the coding unit of the depth d-1 and the size 2N_ (d-1) x2N_ (d-1) A partition type 954 of size 2N_ (d-1) xN_ (d-1), a partition type 956 of size N_ (d-1) x2N_ 1) xN_ (d-1) &lt; / RTI &gt;

(D-1) x2N_ (d-1), two predicted units of two sizes 2N_ (d-1) (d-1) x2N_ (d-1), four sizes N_ (d-1) xN_ (d-1). Since the maximum depth is d, the coding unit 952 of depth d-1 no longer undergoes the division process.

The video coding apparatus 80 according to an exemplary embodiment compares depth-dependent coding errors to determine the depth of coding for the coding unit 912 to select the depth at which the smallest coding error occurs.

For example, a coding error for a coding unit of depth 0 is predicted for each partition type 912, 914, 916, and 918, and a prediction unit in which the smallest coding error occurs is determined. Similarly, a prediction unit having the smallest coding error can be searched for every depth 0, 1, ..., d-1. At the depth d, the coding error can be determined through predictive coding based on the prediction unit 960, which is a coding unit of size 2N_dx2N_d.

In this way, the minimum coding error of each of the depths 0, 1, ..., d-1, and d is compared and the depth with the smallest error is selected to be determined as the coding depth. The coding depth and the prediction unit of the corresponding depth can be encoded and transmitted as information on the coding mode. In addition, since the coding unit must be divided from the depth 0 to the coding depth, only the division information of the coding depth is set to '0', and the division information by depth is set to '1' except for the coding depth.

The extracting unit 91 of the video decoding apparatus 90 according to the embodiment may extract the information on the coding depth and the prediction unit for the coding unit 912 and use it to decode the coding unit 912. [ The video decoding apparatus 90 according to an embodiment grasps the depth with the division information of '0' as the coding depth using the division information according to the depth, and uses the information about the coding mode for the corresponding depth to use it for decoding have.

FIGS. 17, 18 and 19 illustrate the relationship between an encoding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention.

The coding unit 1010 is coding units for coding depth determined by the video coding apparatus 80 according to the embodiment with respect to the maximum coding unit. The prediction unit 1060 is a prediction unit of each coding depth unit among the coding units 1010 and the conversion unit 1070 is a conversion unit of each coding depth unit.

When the depth of the maximum encoding unit is 0, the depth of the encoding units 1012 and 1054 is 1 and the depth of the encoding units 1014, 1016, 1018, 1028, 1050, The coding units 1020, 1022, 1024, 1026, 1030, 1032 and 1048 have a depth of 3 and the coding units 1040, 1042, 1044 and 1046 have a depth of 4.

A portion (1014, 1016, 1022, 1032, 1048, 1050, 1052, 1054) of the prediction units 1060 is a type in which the coding unit is divided. That is, the prediction units 1014, 1022, 1050 and 1054 are partition types of 2NxN, the prediction units 1016, 1048 and 1052 are partition types of Nx2N, and the prediction units 1032 are partition types of NxN. That is, the prediction unit of the depth-dependent coding units 1010 is smaller than or equal to each coding unit.

The image data of a part 1052 of the conversion units 1070 is subjected to frequency conversion or frequency inverse conversion in units of data smaller in size than the encoding unit. The conversion units 1014, 1016, 1022, 1032, 1048, 1050, 1052, and 1054 are data units of different sizes or types when compared with the prediction units of the prediction units 1060. That is, the video coding apparatus 80 according to the embodiment and the video coding apparatus 90 according to the embodiment can perform the intra prediction / motion estimation / motion compensation operation for the same coding unit and the frequency conversion / , Each based on a separate data unit.

FIG. 20 shows encoding information for each encoding unit according to an embodiment of the present invention.

The transmitting unit 80 of the video encoding apparatus 80 according to an embodiment outputs encoding information for each encoding unit and the encoding information extracting unit 91 of the video decoding apparatus 90 according to the embodiment extracts encoding information for each encoding unit It is possible to extract the encoding information.

The encoding information may include division information for the encoding unit, partition type information, prediction mode information, and conversion unit size information. The encoding information shown in FIG. 11 is an example that can be set in the video encoding apparatus 80 according to the embodiment and the video encoding apparatus 90 according to the embodiment.

The division information may indicate the coding depth of the corresponding encoding unit. That is, since depths that are no longer divided according to the division information are coding depths, partition type information, prediction mode, and conversion unit size information can be defined with respect to the coding depth. When it is necessary to further divide by one division according to the division information, encoding should be performed independently for each of four divided sub-depth coding units.

As the partition type information, the partition type of the conversion unit of the coding unit of the coding depth can be represented by 2Nx2N, 2NxN, Nx2N and NxN. The prediction mode may be represented by one of an intra mode, an inter mode, and a skip mode. The intra mode and the inter mode can be defined in the partition types 2Nx2N, 2NxN, Nx2N and NxN, and the skip mode can be defined only in the partition type 2Nx2N. The conversion unit size can be set to two kinds of sizes in the intra mode and two kinds of sizes in the inter mode.

The encoding unit-specific encoding information of the belonging encoding depth may be stored for each minimum encoding unit in the encoding unit. Therefore, if encoding information held in each of the adjacent minimum encoding units is checked, it can be confirmed whether or not the encoding information is included in the encoding unit of the same encoding depth. In addition, since the encoding unit of the encoding depth can be identified by using the encoding information held in the minimum encoding unit, the distribution of encoding depths in the maximum encoding unit can be inferred.

In this case, when the current encoding unit is predicted with reference to the neighboring data unit, the encoding information of the minimum encoding unit in the depth encoding unit adjacent to the current encoding unit is directly used, so that the data of the minimum encoding unit can be referred to.

In yet another embodiment, the encoding information of the depth encoding unit may be stored only for the minimum encoding unit represented in the depth encoding unit. In this case, when the current encoding unit is predicted by referring to the surrounding encoding unit, the data adjacent to the current encoding unit in the depth encoding unit may be retrieved using the encoding information of the adjacent depth encoding unit.

FIG. 21 shows a flowchart of a video encoding method for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.

In step 2110, the current picture is divided into at least one maximum coding unit, and the coding unit is coded in at least one divided area in which the area of the maximum coding unit is divided for each depth, The coding depth is determined. In addition, the coding modes such as the coding depth or the number of times of division, the partition type of the coding depth, the prediction mode, and the size of the conversion unit are determined for each depth-by-depth coding unit.

The maximum depth indicating the possible total number of divisions may be set in advance. The maximum encoding unit is divided into stages, and each time the depth is deepened, it is necessary to repeatedly perform encoding for each lower-depth encoding unit. In order to determine the coding depth that causes the minimum coding error of the coding unit, the coding error should be measured and compared for each coding unit of each depth.

In step 2120, the encoded image data is decoded based on the encoding depth and encoding mode, and the decoded image data is subjected to loop filtering to generate a reconstructed image. According to one embodiment, a reconstructed image may be generated by performing adaptive loop filtering that performs one or more one-dimensional filtering operations on the decoded image data or deblocked image data one after another.

In step 2130, for the restored pixels of the predetermined group among the restored images, a group of pixels including the compensation value for the error between each restored pixel and the original pixel and the pixel to be compensated is determined. The pixel group including the restored pixels to be compensated for the pixel value may be determined according to the extreme level of the pixel value, the pixel value band, or whether the line is composed. The compensation value for each pixel group can be determined based on an average value of the errors between the corresponding restored pixels and respective corresponding original pixels.

In step 2140, video data as a final encoding result for each of at least one divided area, information on the coding depth and encoding mode, loop filtering coefficient information, and compensation value related information are outputted for each maximum encoding unit. The information on the encoding mode may include information on the encoding depth or division information, partition type information of the encoding depth, prediction mode information, and conversion unit size information.

The compensation value-related information for each pixel group between the restored image and the original image is coded together with the information on the encoding mode, the encoded video data, and the loop filtering coefficient information encoded by the video encoding method based on the hierarchical data unit for each region , And can be transmitted to the decoding end.

FIG. 22 shows a flowchart of a video decoding method for pixel value compensation after loop filtering based on hierarchical data units for each region according to an embodiment of the present invention.

In step 2210, a bitstream for video encoded by the video encoding method is received and parsed based on the hierarchical data unit for each region, and the image data of the current picture allocated to the maximum encoding unit of the maximum size from the parsed bitstream Information on coding depth and coding mode for each coding unit, loop filtering coefficient information, and compensation value related information are extracted.

The coding depth for each maximum coding unit is the depth selected with the smallest coding error for each maximum coding unit in the process of coding the current picture. The encoding of the maximum encoding unit is the image data encoded based on at least one data unit obtained by dividing the maximum encoding unit hierarchically by depth. Accordingly, the decoding efficiency of the image can be improved by decoding each image data after grasping the coding depth for each coding unit.

In step 2220, the image data of each maximum encoding unit is decoded based on the information on the encoding depth and the encoding mode for each maximum encoding unit, and the decoded image data is subjected to loop filtering to generate a reconstructed image. The reconstructed image can be generated by performing adaptive loop filtering on the decoded image data or deblocked image data, in which one or more one-dimensional filtering is continuously performed according to an embodiment.

In step 2230, among the restored pixels of the restored image, a group of pixels including the restored pixel to be compensated by using the compensation value is determined. Based on the extracted compensation value related information, in accordance with the pixel group determination method, according to the extreme value level of the pixel value of the restored pixel, the pixel value band, or the configuration of the line, The group of pixels including the pixel can be determined.

In step 2240, for the restored pixel of the determined pixel group, the error between the restored pixel and the original pixel is compensated using the compensation value, and the restored image with the error compensated can be output.

A video encoding method for compensating a pixel value based on a hierarchical data unit for each region according to an embodiment and a video decoding method for compensating a pixel value based on a hierarchical data unit for each region according to an embodiment The systematic error of the reconstructed image is compensated to improve the image quality of the reconstructed image and only the compensation value information per pixel group is coded and transmitted so that it is necessary to transmit and receive information on the position of the pixel to be compensated for the pixel value The transmission bit rate of the additional information for improving the image quality of the reconstructed image can be reduced.

The above-described embodiments of the present invention can be embodied in a general-purpose digital computer that can be embodied as a program that can be executed by a computer and operates the program using a computer-readable recording medium. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (e.g., ROM, floppy disk, hard disk, etc.) and an optical reading medium (e.g., CD-ROM, DVD, etc.).

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (4)

Obtaining type information for pixel value compensation from a bitstream;
Obtaining a plurality of offsets from the bitstream when the type information indicates at least one of a first type and a second type;
Applying one of the plurality of offsets to one pixel of the pixels of the current block corresponding to one pixel value band when the type information indicates the first type; And
Applying one of the plurality of offsets to a pixel corresponding to one level of pixels of the current block when the type information indicates the second type,
Wherein the pixel value band is one of a plurality of pixel value bands,
Wherein said level is one of a plurality of levels, said level being determined by comparing a magnitude of sample values of said pixel with neighboring pixels of said pixel,
When the type information indicates the first type, the plurality of offsets correspond to the plurality of pixel value bands,
And when the type information indicates the second type, the plurality of offsets correspond to the plurality of levels. delete delete A processor for obtaining type information for pixel value compensation from a bitstream and obtaining a plurality of offsets from the bitstream when the type information indicates at least one of a first type and a second type; And
And a compensator for applying the plurality of offsets to pixels of a current block,
When the type information indicates the first type, the compensation unit applies one of the plurality of offsets to one pixel corresponding to one pixel value band among the pixels of the current block,
When the type information indicates the second type, the compensation unit applies one of the plurality of offsets to one pixel corresponding to one level among the pixels of the current block,
Wherein the pixel value band is one of a plurality of pixel value bands,
Wherein said level is one of a plurality of levels, said level being determined by comparing a magnitude of sample values of said pixel with neighboring pixels of said pixel,
When the type information indicates the first type, the plurality of offsets correspond to the plurality of pixel value bands,
And when the type information indicates the second type, the plurality of offsets correspond to the plurality of levels.

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