KR101035455B1 - Apparatus for making thumbnail-image based on H.264 - Google Patents

Abstract

The present invention relates to an apparatus for generating a thumbnail image from a video image of the H.264 standard, and more particularly, to generate an intra prediction block according to an intra mode performed in a spatial domain in the transform domain, thereby generating an image of the H.264 standard. An apparatus for generating a thumbnail image of an image directly in a conversion area.

The thumbnail image generating apparatus according to the present invention generates a prediction block in the transform region, and thus, the sum of the prediction block of the transform region and the residual image of the transform region does not need to reconstruct all the image blocks of the spatial region constituting the image image. Thumbnail images for .264 based video images can be generated. In addition, the apparatus for generating a thumbnail image according to the present invention extracts the DC coefficients of the reconstructed block generated from the prediction block of the transform region and the residual image block of the transform region, and generates thumbnail images directly on the H.264 based image image. It is possible to quickly search for a specific video image from the multimedia terminal in which the video images of the.

H.264, thumbnail image, DCT, intra prediction mode, prediction block, residual image

Description

Apparatus for making thumbnail-image based on H.264}

The present invention relates to an apparatus for generating a thumbnail image from a video image of the H.264 standard, and more particularly, to generate an intra prediction block according to an intra mode performed in a spatial domain in the transform domain, thereby generating an image of the H.264 standard. An apparatus for generating a thumbnail image of an image directly in a conversion area.

So-called multimedia, which combines and stores or transmits various types of information around an image, is widely used. For example, high-speed optical cables can reach homes, allowing high-definition televisions with large screens and high-fidelity stereos to be viewed in high-definition televisions in movie theaters. You may talk face to face.

Various compression schemes have been developed and used to store and transmit image data transmitted and received in the various multimedia terminals. MPEG and H.26x are examples of video compression standards developed and published by international standards organizations such as ISO and ITU.

The H.264 standard is a video standard coding method that has been developed as the next generation video compression method under ITU-T (Telecommunication Standardization) since 1997. It is 2 ~ 3 times higher compression rate than conventional MPEG2 and 1.5 ~ 2 than MPEG4. It is proved to show a high compressibility of the ship. The range of data rates and picture sizes supported by the H.264 standard is very wide, which has the advantage of compressing video images from HDX and higher resolutions, from low data rates and low frame rates for mobile devices and dial-up devices. Therefore, the H.264 standard is expected to be widely used in various multimedia terminals in the future, and many improvements to the H.264 standard have been developed and proposed.

1 and 2 are functional block diagrams illustrating an example of an apparatus for encoding and decoding a video image according to the H.264 standard.

First, referring to FIG. 1, an apparatus for encoding an image image according to the H.264 standard, the prediction mode determiner 11 determines an intra prediction mode for an N × N image block of an input spatial region. The prediction block generator 12 generates a prediction block used to generate a residual image block of the N × N image block of the input spatial region according to the determined intra prediction mode.

The subtraction unit 13 subtracts the input N × N image block and the generated prediction block from the input spatial region to generate the N × N residual image block. The transform unit 14 converts the generated N × N residual image block to the N × N residual image block of the transform region using DCT, which is a block-based conversion algorithm.

In general, a block-based transformation algorithm is used to convert an image image of a spatial region into an image image of a transformation region. Block-based transformation algorithm is a technique that compresses image data by transforming the spatial domain image in block unit like N × N image or N × N residual image. Karhunen-Loeve Transform (KLT), Singular Value Decomposition (SVD) , Discrete Cosine Transform (DCT), Integer DCT, etc. are used. The image data of the transform region transformed by the block-based transform algorithm is not correlated with each other, and the image data is concentrated in low frequency components.

The quantization unit 15 quantizes the N × N residual image block of the transform region with a constant quantization coefficient, and the encoding unit 16 quantizes the quantized N according to one of encoding methods such as prediction encoding, variable length encoding, and arithmetic encoding. XN Generates a bitstream by encoding the residual picture block.

In the H.264 standard, a reference block of a spatial domain must be reconstructed to generate a spatial domain prediction block. In order to reconstruct the reference block of the spatial domain, the inverse quantization unit 16 inversely quantizes the quantized N × N residual image block, and the inverse transformer 17 inversely transforms the inverse quantized N × N residual image block to determine the transform region. N × N residual image blocks are converted to N × N residual image blocks in the spatial domain. The spatial domain reference block generator 18 generates a reference block by adding the residual image blocks and the prediction blocks of the spatial domain.

As described above, the H.264 standard stipulates the compression of N × N video images in the spatial domain using N × N residual video images. The prediction block used to generate is determined through the intra prediction mode. In the H.264 standard, nine intra prediction modes are defined for luminance 4x4 image blocks, four intra prediction modes are defined for luminance 16x16 image blocks, and four for 8x8 image blocks for chrominance images. Intra prediction modes are defined.

Referring to FIG. 3, the nine intra prediction modes used in the 4 × 4 block mode will be described in more detail as follows.

1) 0th prediction mode (vertical)

-Vertical mode is a mode for predicting using 4 pixels of the upper X image block of the block to be currently encoded.

A pixel is filled with 4 pixels of the first column part of the block, B pixel is filled with 4 pixels of the second column part of the block, and C and D pixels are also filled with 4 pixels corresponding to each block column.

2) first prediction mode (horizontal)

Horizontal mode is a prediction mode using 4 pixels of the left Z image block of a block to be currently encoded.

The I pixel is filled with four pixels of the first row part of the block, the J pixel is filled with four pixels of the second row part of the block, and the K and L pixels are also filled with four pixels corresponding to the block row.

3) second prediction mode (DC)

DC mode is a mode predicted by an average value of 4 pixels (I, J, K, L) of the left Z image block and 4 pixels of the upper X image block (A, B, C, D) of the current block to be encoded. .

4) third prediction mode (diagonal down-left)

-Diagonal down-left mode is a prediction mode using 4 pixels of the upper X image block and up / right Y image block of the current block to be encoded.

It is filled with a 45 degree angle between the lower left and the upper right of the block to be encoded.

5) fourth prediction mode (diagonal down-right)

-Diagonal down-right mode is a prediction mode using 4 pixels of the upper X image block, 1 pixel of the upper left S image block (Q) and 4 pixels of the left Z image block of the current block to be encoded.

-Filled in the 45 degree direction at the bottom right of the block to be encoded.

6) fifth prediction mode (vertical-right)

-Vertical-right mode is a prediction mode using 4 pixels of the upper X image block, 1 pixel (Q) of the upper left S image block and 4 pixels of the left Z image block of the current block to be encoded.

-Filled in the direction of about 26.6 degrees to the right of the vertical. (Width / height = 1/2)

7) sixth prediction mode (horizontal-down)

-Horizontal-down mode is a prediction mode using 4 pixels of the upper X image block, 1 pixel (Q) of the upper left S image block, and 4 pixels of the left Z image block of the block to be encoded.

-Filled in the direction of about 26.6 degrees below the horizontal.

8) seventh prediction mode (vertical-left)

-Vertical-left mode is a prediction mode using 4 pixels of the upper X image block of the block to be currently encoded and 1 pixel (E) of the upper right Y image block.

-The left side of the vertical is filled in about 26.6 degrees.

9) eighth prediction mode (horizontal-up)

Horizontal-up mode is a prediction mode using 4 pixels of the left Z image block of the block to be currently encoded.

-Interpolate in the direction of about 26.6 degrees above the horizontal.

Referring to FIG. 4, four intra prediction modes used in the 16 × 16 block mode will be described in more detail.

1) 0th prediction mode (Vertical)

The vertical mode is the same as the zeroth prediction mode of the luminance 4x4 prediction mode. The prediction encoding method is the same except for the difference between 4x4 block units and 16x16 block units.

2) First prediction mode (Horizontal)

The horizontal mode is the same as the first prediction mode of the luminance 4x4 prediction mode. The prediction encoding method is the same except for the difference between 4x4 block units and 16x16 block units.

3) second prediction mode (DC)

DC mode is the same as the second prediction mode of luminance 4x4 prediction mode. The prediction encoding method is the same except for the difference between 4x4 block units and 16x16 block units.

4) third prediction mode (Plane)

-Plan mode encodes the pixels of the upper block and the pixels of the left block by interpolating diagonally (45 degrees).

On the other hand, the four intra prediction modes for the 8x8 image block in the chrominance image are the same as the luminance 16x16 mode, except that the coding scheme is the same except for the difference of 8x8 block unit and 16x16 block unit.

Referring to FIG. 2, referring to an apparatus for decoding a video image according to the H.264 standard, the decoding unit 30 decodes a received bitstream, and the dequantization unit 31 inverts each residual image block in the decoded bitstream. Inverse quantization with quantization coefficients The inverse transformer 32 inversely transforms each dequantized residual image block and converts the residual image block of the transform region into the residual image block of the spatial domain. The prediction mode determiner 33 determines an intra prediction mode for each residual image block stored in the bitstream, and the prediction block generator 34 of the spatial domain generates a prediction block of the spatial domain from the determined intra prediction mode. do. The adder 36 reconstructs the image block by adding the generated prediction blocks of the spatial domain and the residual image blocks of the spatial domain. The reference block generator 37 generates a reference block used to generate a prediction block from the reconstructed image block.

On the other hand, multimedia terminals such as mobile phones and digital TVs are used to retrieve image data stored in the multimedia terminal through a small size image (hereinafter referred to as a thumbnail image) for previewing the stored image image. do.

5 illustrates an example of a thumbnail image used in a mobile phone. Referring to the thumbnail image illustrated in FIG. 5, a plurality of video or video images stored in the mobile phone are previously displayed as thumbnail images on the display unit. When the user searches for an image or a video to be played back through the displayed thumbnail image and selects a predetermined video from the searched video, the selected video is played in the original size image.

Conventional methods for generating thumbnail images from the original image can be divided into two broad categories. The first method is to generate a thumbnail image of the original image by down sampling the original image of the spatial domain. The second method is to generate a thumbnail image of the original image by extracting only DC coefficients from each image block of the transform region constituting the image. The DC coefficient at the top left of each image block in the transform region is the average value for each image block in the spatial domain. The image image generated by extracting only the DC coefficient is equivalent to downsampling the size of the original image image by 1 / N. same.

In order to generate a thumbnail image of the H.264 standard image image using the first method described above, an inverse transformed residual image block is inversely transformed, and an inverse transformed residual image block and a prediction block of the spatial domain are combined to generate a reconstruction block of the spatial domain. After that, the restoration block is down sampled again to generate a thumbnail image of the video image. Therefore, the first method has a problem in that complicated data processing is required to generate thumbnail images for video images of the H.264 standard.

In addition, in order to generate a thumbnail image of a video image of the H.264 standard by the second method described above, since the prediction block used in the H.264 base is generated using the neighboring video blocks, after each image block is restored, each image block Is orthogonally transformed to extract a DC coefficient present in the image block of the transform region to generate a thumbnail image.

Therefore, the second method also has to go through complicated data processing to generate thumbnail images for H.264-based image images, and it takes a long time to generate thumbnail images because thumbnail images can be generated after restoring all image blocks. Have

It is an object of the present invention to provide an apparatus for generating a thumbnail image for a video image of the above-mentioned H.264 standard by a simple data processing process.

More specifically, an object of the present invention is to create a prediction block according to the intra prediction mode performed in the spatial domain in the transform domain to generate a thumbnail image of the video image directly in the transform domain in the H.264 standard To provide.

Another object of the present invention is to provide an apparatus for generating a thumbnail image that helps to quickly search for a video image stored in a multimedia terminal through a thumbnail image.

In order to achieve the object of the present invention, a thumbnail image generating apparatus includes a prediction mode determination unit for determining a prediction mode of a spatial region for an N × N image block of a spatial region constituting an H.264 standard image image and a determined spatial region. A prediction block generator of the transform region for generating an N × N prediction block of the transform region from the reference frame reconstructed in the transform region based on the prediction mode of Thumbnail for generating a thumbnail image of a video image by extracting only DC coefficients from the reconstructed block generator and the generated reconstructed block by combining the residual image block with the N × N prediction block of the transform region to generate a reconstructed block of the transform region. It includes an image generator.

The thumbnail image generating apparatus according to the present invention has various effects as follows.

First, the thumbnail image generating apparatus according to the present invention generates a prediction block in the transform region, thereby reconstructing the prediction block of the transform region and the residual image block of the transform region without having to reconstruct all the image blocks of the spatial region constituting the image image. In sum, thumbnail images for video images of the H.264 standard can be generated.

Second, the thumbnail image generating apparatus according to the present invention extracts the DC coefficients of the reconstructed block generated from the prediction block of the transform region and the residual image block of the transform region to generate a thumbnail image directly on the H.264-based image image, In a multimedia terminal in which a plurality of video images are stored, a specific video image can be quickly searched through a thumbnail image.

Third, the thumbnail image generating apparatus according to the present invention extracts the DC coefficients of the reconstructed block generated from the prediction block of the transform region and the residual image block of the transform region, and generates a thumbnail image directly on the H.264 based image image. The memory saving effect can be achieved more than restoring image blocks in the spatial domain and generating thumbnail images.

Hereinafter, an apparatus for generating a thumbnail image from a video image of the H.264 standard according to the present invention will be described in detail with reference to the accompanying drawings.

6 is a functional block diagram of an H.264 standard encoding apparatus for generating thumbnail images according to an embodiment of the present invention.

Referring to FIG. 6, when the N × N image block of the spatial domain is input, the prediction mode determiner 110 determines an intra prediction mode for the input N × N image block and predicts the prediction block generator 120 of the spatial domain. ) Generates a prediction block for the N × N image block of the spatial domain from the reference block according to the determined intra prediction mode. The subtraction unit 130 generates N × N residual image blocks in the spatial domain by subtracting the input N × N image blocks in the spatial domain and the generated prediction blocks. The transform unit 140 converts the generated N × N residual image block to the transform region, the quantization unit 150 quantizes the N × N residual image block in the transform region, and the encoding unit 190 performs a predetermined encoding. The bitstream is generated by encoding the quantized N × N residual image block according to the scheme.

In the H.264 standard, a reference block of a spatial domain must be reconstructed to generate a spatial domain prediction block. In order to reconstruct the reference block of the spatial domain, the inverse quantization unit 160 inversely quantizes the quantized N × N residual image block, and the inverse transformer 170 inversely transforms the inverse quantized N × N residual image block to determine the transform region. N × N residual image blocks are converted to N × N residual image blocks in the spatial domain. The spatial domain reference block generator 180 generates a reference block by adding the residual image blocks and the prediction blocks of the spatial domain.

Meanwhile, in order to generate a thumbnail image from the H.264 standard image, the prediction block generation unit 200 of the transform region may reference the transform region based on the intra prediction mode of the spatial region determined by the prediction mode determiner 110. An N × N prediction block of the transform region is generated from the block. That is, the prediction block generation unit 200 of the transform region generates an N × N prediction block in the same transform region as the N × N residual image block of the transform region.

만족시켜주기 위한 행렬(Λ)과 이전에 생성되어 저장되어 있는 변환영역의 참조블록을 참조한다. When the N × N residual image block of the spatial domain is converted to the integer DCT by the transform unit 140, the prediction block generator 200 of the transform domain is N × in the same transform domain as the N × N residual image block of the transform domain. Orthogonal transformation properties, i.e., to generate N prediction blocks

Reference is made to the matrix Λ to satisfy and the reference block of the transform region previously generated and stored.

However, when the N × N residual image block of the spatial domain is transformed into the approximated DCT by the transform unit 140, the prediction block generator 200 of the transform domain satisfies the orthogonal transform property in the case of the approximated DCT, so that the orthogonal transform property is separately applied. There is no need to use a matrix Λ to satisfy.

For example, when a 4x4 residual image block of the transform region is converted to an integer DCT and the vertical mode is used as the intra prediction mode, a reference block used to generate a prediction block of the 4x4 residual image block of the transform region. Is the upper block of the 4x4 residual image block of the transform region, which is previously generated and stored, and defines the upper block T _D of the 4x4 residual image block of the transform region as shown in Equation (1) below. do.

[Equation 1]

Accordingly, the prediction block of the transform region according to the 0th prediction mode (Vertical) generated from the upper block of the 4 × 4 residual image block of the transform region previously reconstructed is represented by Equation (2) below.

[Equation 2]

=

는 H.264 표준의 복호화에 사용되는 정수 DCT의 역행렬로 T_inverse는 아래의 수학식(4)과 같다.Where the integer DCT is calculated as in Equation (3) below,

Is the inverse of the integer DCT used for decoding of the H.264 standard, and T _inverse is expressed by Equation (4) below.

&Quot; (3) "

&Quot; (4) "

는 공간영역 수직예측모드에 대한 예측모드선택행렬이며,

는 변환영역 수직예측모드에 대한 변환예측선택 행렬이며,

는 공간영역의 수직예측모드 에 대한 예측 블록을 변환영역의 예측 블록으로 생성해주기 위한 스케일링 행렬이다. 예측모드선택행렬, 변환예측선택행렬, 스케일링 행렬은 사용하는 정수 DCT 계수에 따라 다르게 계산된다.

Is the prediction mode selection matrix for the spatial domain vertical prediction mode.

Is the transform prediction selection matrix for the transform region vertical prediction mode.

Is a scaling matrix for generating the prediction block for the vertical prediction mode of the spatial domain as the prediction block of the transform domain. The prediction mode selection matrix, the transformation prediction selection matrix, and the scaling matrix are calculated differently according to the integer DCT coefficients used.

The reconstruction block generation unit 210 of the transform region combines the N × N residual image block Resi of the transform region and the N × N prediction block of the transform region to restore the N × N of the transform region as shown in Equation (5) below. Create a block Rec.

[Equation 5]

Where a is a constant scale factor to prevent rounding errors.

The thumbnail image generator 230 generates a thumbnail image by dividing only DC coefficients by a from the N × N reconstruction blocks of the generated transform region.

7 is a functional block diagram of a decoding apparatus of the H.264 standard for generating thumbnail images according to an embodiment of the present invention.

Referring to FIG. 7, the decoding unit 300 decodes the received bitstream, and the inverse quantization unit 310 dequantizes each residual image block in the decoded bitstream by inverse quantization coefficients. The inverse transformer 320 inversely transforms each inversely quantized residual image block and inversely transforms the residual image block of the transform region into the residual image block of the spatial domain. The prediction mode determiner 330 reads the intra prediction mode for each residual image block stored in the bitstream to determine an intra prediction mode for each residual image block, and the prediction block generator 340 of the spatial domain The prediction block of the spatial domain is generated from the determined intra prediction mode. The adder 360 generates a reconstructed block by adding the residual image blocks of the spatial domain generated by the inverse transform and the prediction blocks of the generated spatial domain.

The spatial domain reference block generator 370 generates a reference block for generating a spatial domain prediction block by storing a reconstructed block that is an output of the adder 360 as in the encoding apparatus.

Meanwhile, in order to generate a thumbnail image from the received bitstream, the prediction block generator 380 of the transform region is transformed from the reference block of the transform region based on the intra prediction mode of the spatial domain determined by the prediction mode determiner 330. Generate an N × N prediction block of the region. That is, the prediction block generation unit 380 of the transform region generates an N × N prediction block in the same transform region as the N × N residual image block of the transform region.

When the N × N residual video block of the bitstream received from the H.264 standard encoding device is converted to integer DCT, the prediction block generator 380 of the transform region is a matrix Λ for satisfying the orthogonal transformation property. The N × N prediction block is generated in the same transform region as the N × N residual image block of the transform region with reference to the reference frame of the transform region previously reconstructed.

The reconstruction block generation unit 400 of the transform region generates an N × N reconstruction block of the dequantized transform region by adding the N × N residual image block of the dequantized transform region and the N × N prediction block of the transform region.

Preferably, the N × N residual image block of the transform region and the N × N prediction block of the transform region correct an error occurring before the reconstruction block generator 400 adds up.

The vertical mode prediction block of the transform region, which is generated through the matrix multiplication of a block previously restored in the transform region and the transform prediction pixel selection matrix, generates a round error unlike generating a predictive block in the spatial region. This is because a part rounded by the inverse transform unit 320 excludes a part rounded by matrix multiplication in the transform region. Therefore, the error correction unit 390 of the prediction block corrects the round error of the N × N prediction block generated in the transform domain.

The following describes a method of correcting an error when a prediction block generated in a transform region has a value only in DC. When the prediction block generated in the transform domain has a value only in DC and the DC value of the prediction block is divided by 64, when the remainder is less than 32, the error is less than 0.5, so the round error generated in the inverse transform unit does not occur. On the other hand, when the DC value of the prediction block is divided by 64, if the remainder is greater than or equal to 32, the error is greater than or equal to 0.5, and when the round in the inverse transform unit increases the value by 1, the remainder is greater than 32 in the transform domain. If greater than or equal to, correct the error as shown in Equation (6) below.

&Quot; (6) "

Error correction value = a-(rest divided by a)

Corrected DC value = DC + error correction value

As shown in Equation (6), the prediction block in the corrected transform region is an input of the summation unit. In addition to the above embodiments, the round error may be corrected when the prediction block of the transform region has an AC value in addition to the DC value.

In addition, as in the prediction block error correction unit 390, the residual image block error correction unit 395 corrects an error as shown in Equation (6) when the residual signal has a value only in DC. It is an input.

The thumbnail image generator 420 extracts only DC coefficients from the N × N reconstructed blocks of the generated transform region to generate a thumbnail image.

8 is a flowchart illustrating a method of generating a thumbnail image in an H.264 standard image encoding apparatus according to an embodiment of the present invention.

을 만족시켜주기 위한 행렬(Λ)을 사용한다. Referring to FIG. 8, when the N × N image block of the spatial domain is input, an intra prediction mode of the spatial domain for the input N × N image block is determined (S1), and based on the determined intra prediction mode of the spatial domain. An N × N prediction block of the transform region is generated from the reference block reconstructed in the transform region (S3). When the N × N residual image block for the input N × N image block in the spatial domain is converted to an integer DCT, orthogonal to generate an N × N prediction block in the same transform domain as the N × N residual image block in the transform domain. Transformation properties, i.e.

Use a matrix (Λ) to satisfy.

delete

An example of a matrix Λ satisfying an orthogonal transformation property, which is used to generate an N × N prediction block in the same transform region as the N × N residual image block in the transform region in the integer DCT, is represented by the following equation (7). Is created in the same way.

[Equation 7]

인 경우, ∧는

이다.here

If is ∧

to be.

The reconstructed block of the transform region is generated by adding the generated prediction blocks of the transform region and the residual image blocks of the transform region (S5). Only DC coefficients are extracted from the reconstructed blocks of the generated transform region (S7), and a thumbnail image is generated from the DC coefficients of the extracted reconstructed blocks (S9).

9 is a flowchart illustrating a method of generating a thumbnail image in a decoding apparatus of an H.264 standard according to an embodiment of the present invention.

Referring to FIG. 9, the decoding apparatus receives a bitstream storing information about a residual image block and an intra prediction mode (S11), and intra-prediction of a spatial domain used to generate a residual image block from the received bitstream. The mode is determined (S13).

As described above, the N × N prediction block of the transform region is generated from the reference block of the transform region based on the determined intra prediction mode of the spatial region (S15). When the N × N residual image block for the input N × N image block in the spatial domain is converted to an integer DCT, orthogonal to generate an N × N prediction block in the same transform domain as the N × N residual image block in the transform domain. A matrix (Λ) is used to satisfy the conversion properties.

The prediction block of the transform region generated from the reference block in the transform region corrects an error occurring when the prediction block is generated from the reference block of the transform region (S16). In addition, an error occurring in the residual image block of the dequantized transform region is corrected (S17). The reconstructed block of the dequantized transform region is generated by adding the prediction block of the corrected transform region and the residual image block of the corrected dequantized transform region (S18). Only the DC coefficients are extracted from the reconstructed blocks of the inverse quantized transform region (S19) to generate thumbnail images (S20).

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.

The computer readable recording medium may include a magnetic storage medium (eg, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (eg, a CD-ROM, a DVD, etc.) and a carrier wave (eg, the Internet). Storage medium).

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a functional block diagram illustrating an apparatus for encoding a video image based on H.264.

2 is a functional block diagram illustrating an apparatus for decoding a video image based on H.264.

3 is a diagram for describing an intra prediction mode of a 4x4 luma block in a spatial domain.

4 is a diagram for describing a 16x16 luma block and an 8x8 chroma block prediction mode in a spatial domain.

5 illustrates an example of a thumbnail image used in a mobile phone.

6 is a functional block diagram of an encoding apparatus of the H.264 standard for generating thumbnail images according to an embodiment of the present invention.

7 is a functional block diagram of a decoding apparatus of the H.264 standard for generating thumbnail images according to an embodiment of the present invention.

8 is a flowchart illustrating a method of generating a thumbnail image in an H.264 standard image encoding apparatus according to an embodiment of the present invention.

9 is a flowchart illustrating a method of generating a thumbnail image in the H.264 standard image decoding apparatus according to an embodiment of the present invention.

Description of the main parts of the drawing

110: prediction mode determination unit 120: prediction block generation unit of the spatial domain

130: subtraction unit 140: conversion unit

150: quantization unit 160: inverse quantization unit

170: inverse transform unit 180: spatial domain reference block generation unit

190: encoder 200: prediction block generator of the transform region

210: restoration block generation unit of the conversion area 230: thumbnail image generation unit

300: decoding unit 310: inverse quantization unit

320: inverse transform unit 330: prediction mode determination unit

340: Spatial domain prediction block generation unit 360: Summing unit

370: spatial domain reference block generation unit

380: transform domain prediction block generation unit 390: prediction block error correction unit

400: reconstruction block generation unit 395: residual image block error correction unit

420: thumbnail image generator

Claims (8)

An apparatus for generating a thumbnail image from a video image of the H.264 standard, A prediction mode determination unit to determine a prediction mode of the spatial region of the N × N image block of the spatial region constituting the video image; A prediction block generator of the transform region for generating an N × N prediction block of the transform region from the reference block reconstructed in the transform region based on the determined prediction mode of the spatial region; A reconstruction block generation unit of the transform region for generating a reconstructed block of the transform region by adding the N × N residual image block of the transform region to the N × N image block of the spatial region with the N × N prediction block of the transform region; And A thumbnail image generator for extracting only a DC coefficient from the generated reconstruction block to generate a thumbnail image of the video image; The prediction block generator of the transform region When the residual image block of the transform region for the N × N image block of the spatial domain is transformed by integer DCT, the reference block and the scaling matrix of the transform region calculated by using a matrix satisfying an orthogonal transformation property in integer DCT And an N × N prediction block of the transform region directly from the image generator. delete delete delete An apparatus for receiving a bitstream storing H.264 based video image information and generating a thumbnail image of the video image from the received bitstream. A prediction mode determination unit that reads a prediction mode for the N × N residual image block of the transform region stored in the received bitstream to determine a prediction mode of the N × N residual image block of the transform region; A prediction block generator of the transform region for generating an N × N prediction block of the transform region from the reference block of the transform region based on the determined prediction mode; A reconstruction block generation unit of the transform region for generating a reconstruction block by adding the N × N residual image block of the transform region and the N × N prediction block of the transform region; And A thumbnail image generator for extracting only DC coefficients from the generated reconstruction block to generate thumbnail images of the video image; The prediction block generator of the transform region When the N × N residual image block of the transform region is block transformed through an integer DCT, N × of the transform region is calculated from a reference block and a scaling matrix of the transform region calculated using a matrix satisfying an orthogonal transformation property in integer DCT. An apparatus for generating a thumbnail image, characterized by directly generating N prediction blocks. delete delete delete

Images