KR20190065994A - Apparatus and method for encoding and decoding to image of ultra high definition resoutltion - Google Patents

Abstract

Provided are a device and a method for encoding by using intra-prediction encoding, and a device and a method for decoding. The device for encoding can generate a prediction block of a current block according to any one of methods for generating a plurality of predetermined prediction blocks, and can output at least one of encoding information and a differential block as a bit stream through entropy-encoding according to whether the differential block is encoded.

Description

[0001] APPARATUS AND METHOD FOR ENCODING AND DECODING TO IMAGE OF ULTRA HIGH DEFINITION RESOUT [0002]

The present invention relates to a technique for reducing computation complexity and improving coding efficiency in intra-picture prediction coding in an ultrahigh-resolution image.

A broadcasting service having a HD (High Definition) resolution such as 1280 x 1024 or 1920 x 1080 is expanding not only in the domestic market but also in the world. Accordingly, users are demanding larger resolution and better picture quality contents such as 4K (3840 × 2160), 8K (7680 × 4320), etc. in order to watch more realistic images.

The number of pixels in a 4K image is four times that of an HD image, and the number of pixels in an 8K (7680x4320) image is 16 times that of an HD image. As a result, 4K and 8K images can display more detailed and natural images than HD resolution images. In general, H.264 / AVC (MPEG-4 Part 10 Advanced Video Coding) is used to encode 4K or 8K video.

As the resolution of the image increases, the spatial correlation between the pixels can be greatly increased.

FIG. 1 is a diagram for comparing the number of pixels used for representing a part of an image for each resolution.

In FIG. 1, when the number of pixels used to represent a portion of an image is 4 at a resolution of 480 x 270 at a resolution of QVGA (352 x 288) or more, a portion of an image is represented at 960x540 resolution and Full HDTV (1920x1080) The number of pixels used is 9 and 25, respectively. In the 4K (3840x2160) resolution, the number of pixels is 100, and in the 8K (7680x420) resolution, a part of the image is represented by 361 pixels. As described above, in the case of 4K and 8K resolution images, the number of pixels used for expressing a part of a specific image is excessively increased. In other words, 4K and 8K resolution images have a much higher correlation between pixels than HD resolution images. Particularly, the degree of correlation between pixels is further increased in a part of an image or an image having a complicated and flat characteristic.

As described above, when intra prediction is performed on an ultrahigh resolution image having a very high correlation between pixels, such as 4K or 8K, the pixel value of the current block can be almost predicted using only the pixel values of the neighboring blocks. Accordingly, when the degree of correlation between pixels is high, the process of encoding and decoding the differential block increases the computational complexity and causes a decrease in the coding efficiency.

Therefore, in the case of encoding and decoding an ultrahigh-resolution image having a high degree of correlation between pixels, there is a need for a coding and decoding technique capable of improving coding efficiency while reducing computational complexity.

The present invention provides an encoding apparatus and method, a decoding apparatus, and a method capable of reducing computational complexity due to intraprediction encoding for an ultrahigh-resolution image having high correlation between pixels.

Also, the present invention provides an encoding apparatus and method, a decoding apparatus, and a method capable of improving encoding efficiency by performing encoding and decoding using a prediction block having the best encoding efficiency among a plurality of prediction blocks.

An encoding apparatus according to an embodiment of the present invention includes an intra picture prediction unit for generating a prediction block of a current block based on a reference picture, a subtraction unit for generating a difference block through a difference between the current block and the generated prediction block, An encoding information generation unit for generating encoding information indicating whether or not the difference block is encoded based on whether or not the difference block is encoded; and an entropy encoding unit for entropy encoding at least one of the difference block and the encoding information based on the encoding information And an entropy encoding unit.

In addition, when the encoding information includes information indicating that the differential block is not encoded, the entropy encoding unit may generate a bitstream by encoding only the encoding information.

In addition, the intra-picture prediction unit may generate the prediction block using any one of a plurality of prediction block generation methods.

In addition, the intra-picture prediction unit may generate a plurality of prediction blocks of the current block according to a plurality of prediction block generation methods.

In addition, the intra-picture prediction unit may generate at least one prediction block of the current block based on a prediction block generation method used when generating a prediction block for each of the reconstructed neighboring blocks.

The apparatus may further include a prediction block selector for selecting any one of the generated prediction blocks of the plurality of current blocks.

A coding method according to an embodiment of the present invention includes generating a prediction block of a current block based on a reference image, generating a difference block through a difference between the current block and the generated prediction block, Generating encoded information indicating whether or not the difference block is encoded based on whether or not the difference block is coded; transforming and quantizing the difference block based on the encoded information; And entropy encoding at least one of the encoding information.

The entropy encoding step may include generating a bitstream by encoding only the encoding information, as the encoding information includes information indicating that the difference block is not encoded.

The generating of the prediction block may generate a plurality of prediction blocks of the current block according to a plurality of prediction block generating methods.

The generating of the prediction block may generate at least one prediction block of the current block based on the prediction block generating method used when generating the prediction block of each of the reconstructed neighboring blocks.

The method may further include selecting one of the prediction blocks of the generated current block having the best coding efficiency.

The decoding apparatus according to an embodiment of the present invention includes an entropy decoding unit for extracting encoded encoding information from a bitstream and decoding the encoded encoding information, a screen for generating a prediction block of a current block using the reconstructed neighboring blocks, And an adder for reconstructing a current block using at least one of a prediction block, a reconstructed differential block based on the decoded encoded information, and a predictive block of the generated current block.

The adding unit may include information indicating that the encoding information does not encode the difference block, and may restore the current block using only the prediction block of the current block.

A decoding method according to an embodiment of the present invention includes extracting at least one of encoded information and predictive block selection information encoded from a bitstream, decoding the extracted encoding information and prediction block selection information, Selecting one of prediction blocks of the generated current block on the basis of the decoded prediction block selection information, and selecting, based on the decoded encoding information, And reconstructing the current block using at least one of the reconstructed differential block and the predictive block of the selected current block.

According to the present invention, when intra-picture prediction coding is performed on an ultrahigh-resolution image having a high correlation between pixels, the calculation complexity can be reduced by outputting a bitstream using only the prediction block of the current block.

According to the present invention, encoding and decoding are performed using a prediction block having the best coding efficiency among a plurality of prediction blocks, thereby improving the coding efficiency.

FIG. 1 is a diagram for comparing the number of pixels used for representing a part of an image for each resolution.
2 is a block diagram of a coding apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram showing the overall configuration of an encoding apparatus according to an embodiment of the present invention.
4 is a flowchart illustrating an operation of the encoding apparatus according to an embodiment of the present invention.
5 is a block diagram illustrating a configuration of a decoding apparatus according to an embodiment of the present invention.
FIG. 6 is a diagram showing the overall configuration of an encoding apparatus according to an embodiment of the present invention.
FIG. 7 is a flowchart illustrating an operation of a decoding apparatus according to an embodiment of the present invention. Referring to FIG.
8 is a diagram illustrating a configuration of an encoding apparatus according to an embodiment of the present invention.
9 is a flowchart illustrating an operation of the encoding apparatus according to an embodiment of the present invention.
10 is a block diagram illustrating the configuration of a decoding apparatus according to an embodiment of the present invention.
11 is a flowchart illustrating an operation of a decoding apparatus according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. In addition, the same reference numerals shown in the drawings denote the same members.

2 is a block diagram of a coding apparatus according to an embodiment of the present invention.

In Fig. 2, the input image can be processed in units of coding having a size of 16 x 16 pixels in the horizontal and vertical directions. At this time, the encoding apparatus can output the bitstream generated through intra-picture prediction coding or inter-picture prediction coding. The intra picture prediction coding process will be described with reference to FIG. 2, and the inter picture prediction coding process will be described later with reference to FIG.

2, the encoding apparatus 200 includes an intra-picture prediction unit 210, a reference picture buffer 220, a subtractor 230, an encoding information generator 240, a transform and quantization unit 250, A dequantizer 260, an inverse quantization and inverse transformer 270, and an adder 280.

The intra prediction unit 210 may generate a prediction block of the current block based on the reference image stored in the reference image buffer 220. [ In this case, in the case of using the neighboring blocks restored to the reference image, the intra-frame prediction unit 210 uses the pixel values of neighboring blocks spatially adjacent to any one of the predetermined plurality of prediction block generation methods and the current block, A prediction block of a block can be generated.

For example, (1) the intra prediction unit 210 can generate a prediction block of a current block by directly copying (padding) pixels of neighboring blocks adjacent to the current block. At this time, the pixels to be copied (padded) to the current block may be changed according to the predicted direction, and the predicted direction information may be encoded and included in the bitstream. In other words, the intra prediction unit 210 can generate a prediction block of the current block by using the intra prediction method of H.264 / AVC.

(2) The intra-picture prediction unit 210 determines a prediction direction based on the degree of similarity between the current block and the neighboring blocks, and copies pixels of neighboring blocks according to the determined prediction direction to generate a prediction block of the current block . In other words, the intra-frame prediction unit 210 selects a neighboring block located in a prediction direction determined from among a plurality of neighboring blocks adjacent to the current block, and copies pixels of the selected neighboring block to generate a prediction block of the current block .

As another example, (3) the intra prediction unit 210 can extract the block most similar to the current block through matching in the current screen area in which coding has already been performed. The intra prediction unit 210 can generate a prediction block of the current block using the extracted block. At this time, the difference information about the position between the current block and the prediction block of the current block can be included in the bitstream.

As another example, (4) the intra prediction unit 210 finds the shape most similar to the neighboring block in the current screen area in which coding has already been performed, and generates a block surrounded by the found shape as a prediction block of the current block.

As another example, (5) the intra prediction unit 210 may generate a prediction block of the current block by mixing a plurality of predetermined prediction block generation methods. In this case, the intra prediction unit 210 may generate a prediction block using an average value of prediction blocks generated using a plurality of prediction block generation methods. In addition, a prediction block can be generated by summing weights according to each of the plurality of prediction block generating methods.

The subtraction unit 230 may generate a residual block by subtracting the current block from the current block.

The encoding information generation unit 240 can generate encoding information based on whether or not the difference block is encoded. For example, similarity between the current block and the prediction block of the current block or the like can be used to decide whether to code or not to difference block.

When the similarity between the current block and the prediction block of the current block is used, the encoding information generator 240 may use a Sum of Absolute Differences ( SAD ), Sum of Absolute Transformed Differences ( SATD ), or sum of squared differences The similarity between the current block and the prediction block of the current block can be calculated. Then, the encoding information generator 240 can generate encoding information based on the calculated similarity. Here, the encoding information may include information indicating whether the difference block is encoded or not.

For example, when the similarity between the current block and the prediction block of the current block is equal to or greater than a predetermined reference similarity, the encoding information generator 240 may generate encoding information including information indicating that the difference block is not encoded.

As another example, when the similarity between the current block and the prediction block of the current block is less than the reference similarity, the encoding information generator 240 may generate encoding information including information indicating that the difference block is encoded.

Then, the transform and quantization unit 250 can transform and quantize the difference block based on the encoding information. The entropy encoding unit 260 can generate a bitstream by entropy encoding at least one of the encoding information and the difference block based on the encoding information.

For example, when the encoded information includes information indicating that the difference block is not encoded, the transform and quantization unit 250 may not transform and quantize the difference block. Then, the entropy encoding unit 260 can generate a bitstream by entropy encoding only the encoding information without using a difference block. Accordingly, the computational complexity and the encoding time for converting and quantizing the difference block can be reduced. As described above, when the encoded information includes information indicating that the difference block is not encoded, the generated bitstream may include encoded encoded information.

As another example, when the encoded information includes information indicating that the differential block is encoded, the transform and quantization unit 250 may transform and quantize the differential block. Then, the entropy encoding unit 260 entropy-codes the transformed and quantized difference block, and entropy-encodes the encoded information. The entropy encoding unit 260 may generate a bit stream by mixing the encoded difference block and the encoded encoding information. As described above, when the encoded information includes information indicating that the difference block is encoded, the generated bitstream may include both the encoded difference block and the encoded encoded information.

At this time, the transform and quantization unit 250 may perform the transform and quantization on the difference block differently according to the intra prediction encoding mode.

For example, when 16 × 16 intra prediction encoding is used, the transform and quantization unit 250 transforms the difference block to generate a transform coefficient, and only the DC coefficient is collected from the generated transform coefficients, Can be performed. Then, the entropy encoding unit 260 can entropy-encode only the Hadamard transformed DC coefficient and output it as a bitstream.

As another example, when 8 × 8 and 4 × 4 intra prediction encoding modes other than 16 × 16 are used, the transform and quantization unit 250 transforms the difference block to generate a transform coefficient, The coefficient can be quantized according to the quantization parameter to generate a quantized coefficient. Then, the entropy encoding unit 260 can entropy-encode the generated quantization coefficient according to the probability distribution and output it as a bitstream.

The inverse quantization and inverse transform unit 270 may inverse quantize and inverse transform the quantized coefficients output from the transform and quantization unit 250 to decode the difference block.

Then, the adding unit 280 may add the decoded difference block to the prediction block of the current block to restore the current block. Then, the reference image buffer 220 can store the restored current block.

As the restored current block is stored in the reference image buffer 220, the restored neighboring block may be stored in the reference image buffer 220 as a reference image. If the encoded information includes information indicating that the difference block is not encoded, the reconstructed neighboring block stored in the reference image buffer 220 is reconstructed using only the prediction block of the neighboring block. When the encoded information includes information indicating that the differential block is to be coded, the reconstructed neighboring block stored in the reference image buffer 220 is a reconstructed block using the prediction block of the differential block and the neighboring block. Accordingly, the intra-picture prediction unit 210 uses the neighboring blocks reconstructed using only the prediction blocks of the neighboring blocks or the neighboring blocks reconstructed using the reconstructed differential blocks and the neighboring blocks, according to the encoding information, A prediction block of a block can be generated.

In FIG. 2, the intra-picture prediction coding is performed on the input picture for convenience of explanation. Hereinafter, a description will be given of a configuration for performing both intra-picture prediction coding and inter picture prediction coding with reference to FIG. .

FIG. 3 is a diagram showing the overall configuration of an encoding apparatus according to an embodiment of the present invention.

3, the elements mentioned in the description of the operation of FIG. 2 are substantially the same, and a duplicate description will be omitted. 3 may further include a motion predicting unit 310, a motion compensating unit 320, and a deblocking unit 350 in the encoding apparatus 200 of FIG.

The motion predicting unit 310 may calculate a motion vector by searching for an area having the best match with the current block among the reference pictures using various motion estimation algorithms such as BMA (Block Matching Algorithm), Phase Correlation, HSBMA have

Then, the motion compensation unit 320 may perform motion compensation using the calculated motion vector to generate a prediction block of the current block. As described above, the coding apparatus according to an embodiment of the present invention can perform inter picture prediction coding through motion prediction and compensation. Then, the subtraction unit 330 can generate a difference block by subtracting the current block from the prediction block of the current block generated through inter-picture prediction coding or intra-picture prediction coding.

The adder 340 may recover the current block using at least one of the prediction block and the reconstructed differential block of the current block. The restored difference block may be stored in the reference image buffer.

For example, when the difference block is not transformed and quantized in the transform and quantization unit, the adder 304 can restore the current block with only the prediction block of the current block. As another example, when the difference block is transformed and quantized in the transform and quantization unit, the adder 304 can restore the current block by adding the predicted block of the current block and the restored difference block.

Then, the deblocking unit 340 may remove the blocking artifact from the restored current block using the deblocking filter, and store the blocking artifact in the reference image buffer.

3, the inter picture prediction coding is divided into 16 × 16, 16 × 8, 8 × 16 and 8 × 8 inter picture prediction coding modes, and the 8 × 8 inter picture prediction coding mode is divided into 8 × 8, , 4x8, and 4x4 sub-picture prediction modes.

4 is a flowchart illustrating an operation of the encoding apparatus according to an embodiment of the present invention.

First, in step 410, the intra prediction unit 210 may generate a prediction block of the current block based on the reference image.

For example, the intra prediction unit 210 may generate a prediction block of a current block using any one of a plurality of predefined prediction block generation methods. Here, the restored neighboring block may be used as the reference image. At this time, the reconstructed neighboring block may be reconstructed using only the prediction block of the neighboring block, or may be reconstructed using the predicted block and the decoded differential block of the neighboring block. Then, the intra prediction unit 210 can generate a prediction block of the current block using the reconstructed neighboring block.

Subsequently, in step 420, the subtractor 230 may generate a difference block by subtracting the current block and the prediction block of the current block.

Then, in step 430, the encoding information generator 240 can generate encoding information based on whether or not the difference block is encoded. At this time, whether or not the difference block is coded can be determined based on the similarity degree between the current block and the prediction block of the current block.

For example, when the similarity is used, the encoding information generator 240 may generate a current block and a current block using a Sum of Absolute Differences (SAD), Sum of Absolute Transformed Differences (SATD), and Sum of Squared Difference The degree of similarity between prediction blocks can be calculated. Then, the encoding information generator 240 can generate the encoding information based on the calculated similarity.

At this time, if the calculated similarity is equal to or greater than the reference similarity, the encoding information generator 240 may generate encoding information to include information indicating that the difference block is not encoded. If the calculated similarity is less than the reference similarity, the encoding information generator 240 may generate the encoding information so as to include information indicating that the difference block is to be encoded.

Then, in step 440, the transform and quantization unit 250 may transform and quantize the difference block based on the encoding information.

In this case, when the encoded information includes information indicating that the differential block is to be coded, the transform and quantization unit 250 may transform and quantize the differential block.

If the encoding information includes information indicating that the difference block is not encoded, the conversion and quantization unit 250 may not convert and quantize the difference block.

Then, in step 450, the entropy encoding unit 260 entropy-codes at least one of the transformed and quantized difference block and the encoded information, and outputs the entropy-encoded result as a bitstream.

For example, when the difference block is transformed and quantized based on the encoding information, the entropy encoding unit 260 can entropy-encode the transformed and quantized difference block and entropy-encode the encoded information. The entropy encoding unit 260 may transmit the bit stream generated by mixing the encoded difference block and the encoding information to the decoding apparatus.

As another example, when the difference block is not transformed or quantized based on the encoding information, the entropy encoding unit 260 can entropy-encode only the encoded information without a difference block and output it as a bitstream.

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

5, the decoding apparatus 500 includes an intra-picture prediction unit 510, a reference picture buffer 520, an entropy decoding unit 530, an inverse quantization and inverse transform unit 540, and an addition unit 550 can do.

The intra prediction unit 510 can generate a prediction block of the current block based on the reference image. At this time, the intra prediction unit 520 can generate a prediction block of the current block using any one of the predefined plurality of prediction block generating methods. Here, the predefined plurality of prediction block generation methods have already been described in the intra prediction unit 210 of FIG. 2, and a duplicated description will be omitted.

For example, the intra-frame prediction unit 510 may generate a prediction block of a current block using the reconstructed neighboring block stored in the reference image buffer 520. At this time, the reconstructed neighboring block may be reconstructed using only the prediction block of the neighboring block, or may be reconstructed using the predicted block and the decoded difference block of the neighboring block, depending on whether the differential block is coded.

The entropy decoding unit 530 can demultiplex the bitstream to extract the encoded information, and entropy-decode the encoded information.

In this case, when the encoded information includes information indicating that the difference block is to be encoded, the entropy decoding unit 530 can extract the encoded difference block as well as the encoded information while demultiplexing the bitstream. Then, the entropy decoding unit 530 can decode the encoded information and decode the encoded difference block.

If the encoded information includes information indicating that the difference block is not encoded, the entropy decoding unit 530 can extract the encoded information while demultiplexing the bitstream. That is, when the encoded information includes information indicating that the difference block is not encoded, the encoded difference block may not be included in the bitstream. Accordingly, the entropy decoding unit 530 can entropy-decode only the encoded information.

The inverse quantization and inverse transform unit 540 can decode the difference block by inverse-quantizing and inverse transforming the difference block based on the decoded encoded information.

For example, when the encoded information includes information indicating that the differential block is to be coded, the inverse quantization and inverse transform unit 540 inversely quantizes the coded differential block using variable length decoding according to the probability distribution, Can be output. At this time, the output quantization coefficient may include only DC coefficient information or both DC coefficient information and AC coefficient information.

As another example, when the encoded information includes information indicating that the difference block is not encoded, the inverse quantization and inverse transform unit 540 may not operate because there is no coded difference block extracted from the bitstream. In other words, the inverse quantization and inverse transform unit 540 can operate only when the bit stream includes the encoded difference block.

The adder 550 can restore the current block using at least one of the differential block decoded based on the encoding information and the prediction block of the current block.

For example, when the encoded information includes information indicating that the differential block is to be coded, the adder 550 may restore the current block by adding the reconstructed difference block and the predicted block of the current block.

As another example, when the encoded information includes information indicating that the differential block is not encoded, the adder 550 can restore the current block using only the prediction block of the current block generated by the intra prediction unit 510 .

The reference image buffer 520 may store the restored current block.

FIG. 6 is a diagram showing the overall configuration of an encoding apparatus according to an embodiment of the present invention.

In FIG. 6, the components mentioned in the description of the operation of FIG. 5 are substantially the same, and a duplicate description will be omitted. The decoding apparatus 600 of FIG. 6 may further include a motion compensating unit 610 and a deblocking unit 620 in the encoding apparatus 500 of FIG.

The motion compensation unit 610 may perform motion compensation on the reference image using a motion vector extracted from the bitstream through entropy decoding. The motion compensation unit 610 can generate a prediction block of the current block through motion compensation.

The deblocking unit 620 may remove the blocking phenomenon from the restored current block and output the restored image. The restored image may be stored in the reference image buffer.

FIG. 7 is a flowchart illustrating an operation of a decoding apparatus according to an embodiment of the present invention. Referring to FIG.

First, in step 710, the intra prediction unit 510 may generate a prediction block of a current block using a reference image.

For example, the intra-frame prediction unit 510 may generate a prediction block of a current block using the reconstructed neighboring block stored in the reference image buffer 520. 2, the intra-picture prediction unit 510 may generate a prediction block of the current block according to any one of the predefined plurality of prediction block generation methods have.

Then, in step 720, the entropy decoding unit 530 may demultiplex the bitstream to extract the encoded information.

Then, in step 730, the entropy decoding unit 530 can entropy decode the encoded information. Here, the encoding information may include information indicating that the difference block is encoded, or information indicating that the difference block is not encoded.

In this case, if the encoded information includes information indicating that the difference block is to be encoded, the entropy decoding unit 530 may extract the encoded difference block from the bitstream and perform entropy decoding.

Then, in step 740, the inverse quantization and inverse transform unit 540 may dequantize and inverse transform the differential block based on the decoded encoded information.

For example, when the encoded information includes information indicating that the differential block is encoded, the inverse quantization and inverse transform unit 540 may inversely quantize the encoded difference block and then invert the inverse transformed block to restore the differential block.

As another example, when the encoded information includes information indicating that the difference block is not encoded, the inverse quantization and inverse transform unit 540 may skip the operation since there is no difference block extracted from the bitstream. In other words, the inverse quantization and inverse transform unit 540 can operate only when the bitstream includes encoded differential blocks. This reduces the computational complexity of the decoding apparatus and shortens the decoding time.

In step 750, the addition unit 550 may restore the current block based on at least one of the prediction block of the current block and the reconstructed differential block.

For example, when the encoded information includes information indicating that the differential block is to be coded, the adder 550 may add the prediction block and the reconstructed differential block of the current block to reconstruct the current block. Then, the current block, which is the original image, can be displayed.

As another example, when the encoded information includes information indicating that the differential block is not encoded, the adder 550 can restore the current block using only the prediction block of the current block. In other words, the reconstructed image can be composed of only the prediction block of the current block.

The above description has been made with reference to Figs. 2 to 7 on the construction of generating the prediction block of the current block by using any one of the plurality of predetermined prediction block generations. In particular, the encoding and decoding apparatus according to an embodiment of the present invention has described a configuration for restoring a current block using only the prediction block of the current block based on whether or not the difference block is encoded.

Hereinafter, a plurality of prediction blocks of the current block are generated according to a prediction block generation method used for generating a prediction block of a neighboring block or a predetermined plurality of prediction block generation methods, and one of the prediction blocks of the current block is selected A description will be given of a configuration for performing encoding and decoding.

8 is a diagram illustrating a configuration of an encoding apparatus according to an embodiment of the present invention.

FIG. 8 further includes a prediction block selector in the encoding apparatus of FIG. 2, and the operation of the intra prediction unit is different from that of FIG. Therefore, description of the components in FIG. 8 that are the same as those in FIG. 2 will be omitted, and a description will be made mainly of a prediction block selection unit and an intra prediction unit.

8, the encoding apparatus 800 includes an intra-picture prediction unit 810, a reference picture buffer 820, a prediction block selection unit 830, a subtraction unit 840, an encoding information generation unit 850, A quantization unit 860, an entropy encoding unit 870, an inverse quantization and inverse transformation unit 880, and an addition unit 890.

The intra prediction unit 810 may generate one or more prediction blocks of the current block using the reference image stored in the reference image buffer 820. [ In this case, the intra-picture prediction unit 810 generates a plurality of predefined prediction block generation methods based on the number of prediction block generation methods used when generating prediction blocks of neighboring blocks, A prediction block of the current block can be generated according to the generated prediction block generation method.

For example, if all of the prediction block generation methods used in generating prediction blocks of neighboring blocks are the same, the intra prediction unit 810 generates prediction blocks of the current block according to the prediction block generation method of neighboring blocks using the same . In other words, when the prediction block of the neighboring blocks is generated according to the intra-picture prediction 1, the intra-picture prediction unit 810 can generate a prediction block of the current block using the reference picture according to the intra-picture prediction 1. [ Then, the prediction block selector 830 can output the generated prediction block of the current block as it is because there is only one prediction block of the generated current block.

As another example, when there are two or less prediction block generation methods used in the generation of prediction blocks of neighboring blocks, the intra prediction unit 810 generates two current blocks according to two prediction block generation methods used when generating prediction blocks of neighboring blocks. A prediction block of a block can be generated.

Then, the prediction block selector 830 can select a prediction block having a good coding efficiency from the prediction blocks of two current blocks. For example, the prediction block selector 830 can select a prediction block having a good coding efficiency using the similarity between the prediction block of the current block and the current block, rate-distortion cost, and the like. The prediction block selection unit 830 may generate prediction block selection information including information indicating a prediction block generation method used when generating a prediction block of the selected current block. At this time, the prediction block selector 830 may calculate the degree of similarity using SAD, SSD, SATD, or the like.

As another example, when there are three or more prediction block generation methods used in generating prediction blocks of neighboring blocks, the intra prediction unit 810 may generate prediction blocks of a current block in accordance with a predetermined plurality of prediction block generation methods Can be generated. For example, when the prediction block generation methods (1) to (5) described in the intra prediction unit 210 of FIG. 2 are set as default, the intra prediction unit 810 generates five predefined prediction block generation Methods can be used to generate five prediction blocks of the current block. In other words, when there are three or more blocks, the intra prediction unit 810 generates prediction blocks of the current block using a predetermined plurality of prediction block generation methods instead of the prediction block generation method used when generating prediction blocks of neighboring blocks .

Then, the prediction block selector 830 can select one of the prediction blocks of the current block having the best coding efficiency. The prediction block selection unit 830 may generate prediction block selection information including information indicating a prediction block generation method used when generating a prediction block of the selected current block.

The adding unit 840 may generate a difference block by subtracting the current block from the prediction block of the selected current block.

The encoding information generation unit 850 can generate the encoding information based on whether or not the difference block is encoded. For example, similarity between the current block and the prediction block of the current block or the like can be used to decide whether to code or not to difference block. Here, the encoding information may include information indicating whether the difference block is encoded or not.

The transform and quantization unit 860 can transform and quantize the difference block based on the encoding information.

The entropy encoding unit 870 may entropy-encode at least one of the encoding information, the prediction block selection information, and the difference block, and output the result as a bitstream. For example, if the difference block is not coded, the entropy encoding unit 870 can entropy-encode the encoding information and the prediction block selection information and output it as a bitstream. When the difference block is coded, the encoding information, the prediction block selection information, and the difference block can be entropy-encoded and output as a bitstream.

The inverse quantization and inverse transform unit 880 can restore the difference block by inverse-quantizing and inverse transforming the transformed and quantized difference block.

The adder 890 can restore the current block by adding the reconstructed difference block and the selected current block prediction block based on the encoding information. Then, the reference image buffer 820 can store the restored current block. At this time, if the difference block is not coded, the adder 890 can restore the current block using only the prediction block of the selected current block.

9 is a flowchart illustrating an operation of the encoding apparatus according to an embodiment of the present invention.

In step 910, the prediction block generator 810 may generate one or more prediction blocks of the current block using the reference image.

For example, the intra prediction unit 810 may generate a prediction block of a current block according to a prediction block generation method used when generating a prediction block for each of the reconstructed neighboring blocks.

As another example, the intra-frame prediction unit 810 may generate a plurality of prediction blocks of the current block according to a predetermined plurality of prediction block generation methods based on the number of prediction block generation methods used in generation of prediction blocks of neighboring blocks .

In step 920, the prediction block selector 820 may select one of the prediction blocks of the current block as the prediction blocks of the plurality of current blocks are generated. At this time, the prediction block selector 820 can select a prediction block having the best coding efficiency among the prediction blocks of the plurality of current blocks.

For example, when the similarity between the current block and the generated current block is used, the prediction block selector 820 can determine that the higher the similarity, the better the encoding efficiency. Accordingly, the prediction block selector 820 can select a prediction block having the highest similarity among the prediction blocks of the current block.

As another example, the prediction block selector 820 may select the prediction block having the best coding efficiency using the rate-distortion cost.

In step 930, the subtraction unit 840 may subtract the prediction block and the current block of the selected current block to generate a difference block.

Next, in step 940, the encoding information generator 850 can generate the encoding information based on whether or not the difference block is encoded.

Then, in step 950, the transform and quantization unit 860 can transform and quantize the difference block based on the encoding information.

Next, in step 960, the entropy encoding unit 870 can entropy-encode at least one of the encoding information, the prediction block selection information, and the difference block based on the encoding information.

For example, when the difference block is coded, the entropy encoding unit 870 entropy-codes each of the encoding information, the prediction block selection information, and the transformed and quantized difference block, and outputs the encoded information, the encoded prediction block selection information, The encoded differential blocks can be mixed and output as a bit stream.

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

The decoding apparatus 1000 of FIG. 10 may further include a prediction block selection unit 1050 in the coding apparatus 400 of FIG. Accordingly, the components mentioned in the description of the operation of FIG. 10 through FIG. 4 are substantially the same, and a duplicate description will be omitted.

10, the decoding apparatus 1000 includes an intra-picture prediction unit 1010, a reference picture buffer 1020, an entropy decoding unit 1030, an inverse quantization and inverse transform unit 1040, and an addition unit 1060 can do.

The intra prediction unit 1010 can generate a prediction block of the current block based on the reference image stored in the reference image buffer 1020. [

For example, the intra prediction unit 810 may generate a prediction block of a current block according to a prediction block generation method used when generating a prediction block for each of the reconstructed neighboring blocks.

As another example, the intra-frame prediction unit 810 may generate a plurality of prediction blocks of the current block according to a predetermined plurality of prediction block generation methods based on the number of prediction block generation methods used in generation of prediction blocks of neighboring blocks . Here, as the plurality of prediction block generating methods, the predefined (1) to (5) prediction block generating methods described in the intra prediction block 210 of FIG. 2 can be used.

The entropy decoding unit 1030 can extract at least one of the encoded information, the encoded difference block, and the encoded prediction block selection information by demultiplexing the bitstream. The entropy decoding unit 1030 can entropy decode the encoded information, the encoded difference block, and the encoded prediction block selection information.

For example, the encoding information includes information indicating that the difference block is not encoded, so that the entropy decoding unit 1030 can entropy-decode only the encoded information and the encoded prediction block selection information.

As another example, as the encoding information includes information indicating that the difference block is to be encoded, the entropy decoding unit 1030 can entropy decode both the encoded information, the encoded difference block, and the encoded prediction block selection information .

The prediction block selection unit 1050 can select any one of the one or more prediction blocks generated based on the prediction block selection information.

The inverse quantization and inverse transform unit 1040 can dequantize and inverse transform the differential block encoded based on the encoding information.

For example, the encoding information includes information indicating that the difference block is encoded, the inverse quantization and inverse transformation unit 1040 can inverse-quantize the encoded difference block and then invert the inverse transformed block to restore the difference block. At this time, since the encoding information includes information indicating that the difference block is not encoded, the inverse quantization and inverse transformation unit 1040 may omit the operation.

The adder 1060 can restore the current block using at least one of the reconstructed differential block and the selected prediction block of the current block.

For example, when the difference information includes information indicating that the difference information is encoded, the adder 1060 adds the restored difference block and the selected current block to the current block to restore the current block. have.

As another example, when the encoding information includes information indicating that the difference block is not encoded, if the inverse quantization and inverse transform operation are omitted, the adder 1060 can restore the current block using only the prediction block of the selected current block . Then, a restored image composed of only a predicted block of the current block can be displayed.

The reference image buffer 1020 may store the restored current block.

11 is a flowchart illustrating an operation of a decoding apparatus according to an embodiment of the present invention.

First, in step 1110, the intra prediction unit 1030 may generate one or more prediction blocks of the current block.

For example, the intra prediction unit 810 may generate a prediction block of a current block according to a prediction block generation method used when generating a prediction block for each of the reconstructed neighboring blocks.

As another example, the intra-frame prediction unit 810 may generate a plurality of prediction blocks of the current block according to a predetermined plurality of prediction block generation methods based on the number of prediction block generation methods used in generation of prediction blocks of neighboring blocks .

Next, in step 1120, the entropy decoding unit 1030 demultiplexes the bitstream to extract the encoded information and the encoded prediction block selection information, and entropy-encodes the encoded information and the encoded prediction block selection information have.

In this case, when the encoded information includes information indicating that the difference block is to be encoded, the entropy decoding unit 1030 can extract the encoded difference block from the bitstream through demultiplexing and perform entropy decoding.

Then, in step 1130, the inverse quantization and inverse transform unit 1040 can restore the difference block by inverse-quantizing and inverse transforming the encoded difference block.

In step 1140, the prediction block selector 1050 may select one of the prediction blocks of one or more current blocks based on the prediction block selection information.

In step 1150, the addition unit 1060 may restore the current block using at least one of the prediction block and the reconstructed differential block of the selected current block. Then, the reference image buffer 1020 can store the restored current block.

For example, when the operation of the inverse quantization and inverse transform unit 1040 is omitted as the encoding information includes information indicating that the difference block is not encoded, the adder 1060 adds the current block to the prediction block of the selected current block only Can be restored. In other words, since the encoded difference block is not included in the bitstream, there is no restored difference block. Accordingly, the reconstructed image can be composed of only the prediction block of the current block selected based on the prediction block selection information.

As another example, when the difference information includes information indicating that the encoded information includes the difference block, the adder 1060 may add the predicted block and the restored difference block of the selected current block to restore the current block have.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill 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. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

210: intra picture prediction unit
220: reference picture buffer
230:
240:
250: Transform and quantization unit
260: Entropy coding unit
270: Inverse quantization and inverse transform unit
280:

Claims (19)

Performing a prediction on a current block; And
Generating a bitstream including selection information based on the prediction;
Lt; / RTI >
Wherein the bitstream includes information of a transformed and quantized difference block generated based on a difference block that is a difference between the current block and the prediction block,
In decoding the current block using the bitstream, a prediction block for the current block is generated according to a prediction block generation method for the current block, and a prediction block generation method for the current block includes Determining a plurality of prediction block generation methods of the plurality of neighboring blocks,
In the decoding of the current block, a plurality of prediction block generation methods of the plurality of neighboring blocks are prediction block generation methods used respectively in generating a plurality of prediction blocks of the plurality of neighboring blocks,
Wherein in the decoding of the current block, a prediction block generation method for the current block is determined based on the selection information. The method according to claim 1,
Wherein the selection information indicates a prediction block generation method used for generating a prediction block of the current block. The method according to claim 1,
Wherein the selection information indicates a prediction block generation method used for generating a prediction block of the current block among the plurality of prediction block generation methods. The method according to claim 1,
In the decoding of the current block, as the selection information indicates one of the plurality of prediction block generation methods, a prediction block of the current block is generated by the one prediction block generation method Encoding method. The method according to claim 1,
Wherein in decoding the current block, a prediction block generation method of a neighboring block of the current block specified by the selection information is used as a prediction block generation method for the current block. The method according to claim 1,
Wherein in the decoding of the current block, a prediction block generation method for the current block is determined based on the number of different prediction block generation methods used for predictions for the neighboring blocks. A computer-readable recording medium storing the bitstream generated by the encoding method of claim 1. Extracting selection information from a bitstream;
Generating a prediction block by performing prediction on a current block; And
Generating a reconstructed block for a current block using a difference block and the prediction block,
Lt; / RTI >
Wherein the prediction block is generated according to a prediction block generation method for the current block and a prediction block generation method for the current block is determined based on a plurality of prediction block generation methods of a plurality of neighboring blocks of the current block,
Wherein the plurality of prediction block generation methods of the plurality of neighboring blocks are prediction block generation methods used respectively in generating a plurality of prediction blocks of the plurality of neighboring blocks,
Wherein the prediction block generation method for the current block is determined based on the selection information. 9. The method of claim 8,
Wherein the selection information indicates a prediction block generation method used for generating the prediction block of the current block. 9. The method of claim 8,
Wherein the selection information indicates a prediction block generation method used for generating the prediction block of the current block among the plurality of prediction block generation methods. 9. The method of claim 8,
Wherein in decoding the current block, as the selection information indicates one of the plurality of prediction block generation methods, the prediction block of the current block is generated by the one prediction block generation method Lt; / RTI > 9. The method of claim 8,
Wherein in decoding the current block, a prediction block generation method of a neighboring block of the current block specified by the selection information is used as a prediction block generation method for the current block. 9. The method of claim 8,
Wherein the prediction block generation method for the current block is determined based on the number of different prediction block generation methods used for the predictions for the neighboring blocks. A computer-readable recording medium storing a bitstream for decoding an image,
The bitstream may include:
Information of transformed and quantized difference blocks; And
Optional Information
Lt; / RTI >
In the decoding, a difference block is generated based on the transformed and quantized difference block, and a reconstructed block for the current block is generated based on the difference block and a prediction block for the current block, Wherein a prediction block generation method for the current block is generated based on a plurality of prediction block generation methods of a plurality of neighboring blocks of the current block,
In the decoding, a plurality of prediction block generation methods of the plurality of neighboring blocks are prediction block generation methods used respectively for generating a plurality of prediction blocks of the plurality of neighboring blocks,
Wherein in the decoding, a prediction block generation method for the current block is determined based on the selection information. 15. The method of claim 14,
Wherein the selection information is used for generating a prediction block of the current block. 15. The method of claim 14,
Wherein the selection information is used for generating a prediction block of the current block among the plurality of prediction block generation methods. 15. The method of claim 14,
Wherein in the decoding, the selection information indicates one of the plurality of prediction block generation methods, and a computer-readable method of generating a prediction block of the current block by the one prediction block generation method Recording medium. 15. The method of claim 14,
Wherein in the decoding, a prediction block generation method of a neighboring block of the current block specified by the selection information is used as a prediction block generation method for the current block. 15. The method of claim 14,
Wherein in the decoding, a prediction block generation method for the current block is determined based on a number of different prediction block generation methods used for predictions for the neighboring blocks.

Images