KR20100044333A - Video encoding apparatus, and apparatus and method of 2 dimensional ordering transform for image signal, and recording medium therefor - Google Patents

Abstract

The present invention relates to a video encoding apparatus and a device and method for two-dimensional alignment conversion of an image signal, and a recording medium therefor. The apparatus for two-dimensional alignment conversion of an image signal according to the present invention is provided with respect to pixels of an image block. A horizontal alignment unit for horizontal alignment in the order of size in the horizontal direction; A vertical alignment unit for vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And an index map generator for generating an index map of original positions of the horizontally and vertically aligned pixels, and may rearrange an arbitrary image signal into two-dimensionally aligned image signals in size order. Since the video signal effectively removes the discontinuities of the existing video, the coding efficiency can be maximized by increasing the energy concentration effect of block-based transform techniques such as DCT.

Description

Apparatus and method for converting video signal and two-dimensional alignment conversion of image signal therefor, and recording medium therefor {Video encoding apparatus, and Apparatus and Method of 2 dimensional ordering transform for image signal, and Recording Medium therefor}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for efficiently compressing image data in order to efficiently use a storage medium and a communication medium in the field of video data compression technology. Particularly, the present invention is used as a preprocessing technique of a block unit transformation technique such as a conventional DCT transformation. A video encoding apparatus and a 2D alignment conversion apparatus and method thereof, which perform 2D alignment transformation on an image signal in order to increase compression efficiency while maintaining correlation with the 2D image signal, and the same It relates to a recording medium for.

Generally, JPEG, JPEG2000, MPEG-2, MPEG-4, and H.26L are typical compression techniques of image data, and most of these techniques are DCT transform, Wavelet transform, Burrows-wheeler transform, and variants of these techniques. An image compression technique based on a transformation technique (hereinafter, referred to as a conventional transformation technique) using a transformation or the like.

The conversion efficiency of the conventional conversion technique lies in how well the original signal can be represented by a limited amount of conversion coefficients. Therefore, the better the original signal is represented with the smallest possible transform coefficient, the higher the conversion efficiency of the conversion scheme.

Conventional conversion schemes based on DCT or Wavelet are designed to provide the original signal when the input signal is not smooth due to noise, or when there are discontinuities such as points or edges due to abrupt changes in values between pixels. A large amount of transform coefficients is needed to represent.

Pre-processing techniques to improve the conversion efficiency of conventional conversion techniques include noise reduction filters for removing noise in an image, techniques for converting the size of an image into an appropriate size for encoding, designing a directional interpolation filter for accurate motion prediction, and directionality. There are a number of techniques, such as the conversion technique considered, and the technique through alignment of signals is described in Zhihai He (“Peak Transform for Efficient Image Representation and coding”, IEEE Trans. Image Processing, vol. 16, No. 7, Jul. 2007). )] Is the typical peak transform.

However, the Peak Transform of Document 1 improves the compression efficiency of image data by converting a hard-to-compress signal into an easier-to-compress signal form. Due to the alignment of the dimensional signals, there are problems in that the correlation of the 2D video signals cannot be effectively utilized and the inverse conversion process is not guaranteed for the discrete signals. In addition, there is a problem in that a proper signal alignment cannot be provided for a conventional conversion technique such as DCT performed in block units.

In order to solve the above-described problems, the present invention can be utilized as a preprocessing technique of a block unit conversion technique such as a conventional DCT transform to achieve a conversion efficiency of the conventional block unit transformation technique by two-dimensional alignment of arbitrary image signals. An object of the present invention is to provide a video encoding apparatus, an apparatus and method for two-dimensional alignment conversion of an image signal, and a recording medium for maximizing the same.

According to an aspect of the present invention to achieve the above object, a horizontal alignment unit for horizontally aligned in the order of the size of the horizontal direction with respect to the pixels of the image block; A vertical alignment unit for vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And an index map generator for generating an index map of original positions of the horizontally and vertically aligned pixels.

According to another aspect of the present invention to achieve the above object, a horizontal alignment step of horizontally aligning the pixels of the image block in the order of the size of the horizontal direction; A vertical alignment step of vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And an index map generation step of generating an index map for the original positions of the horizontally and vertically aligned pixels.

According to yet another aspect of the present invention, a subtraction unit for generating a residual signal by calculating a difference value between the original pixel value of each pixel of the current block and the predicted pixel value of each pixel of the current block. ; The pixels of the image block of the residual signal are arranged in a horizontal order, the pixels are arranged in a vertical direction with respect to the pixels of the image block, and the indexes of the horizontal and vertically aligned pixels are indicative of original positions. An alignment conversion unit generating a map; A converter for converting the horizontally and vertically aligned pixels into frequency coefficients; A quantizer for quantizing the transformed frequency coefficients; And an encoder which encodes the quantized frequency coefficients into a bitstream.

According to another aspect of the present invention to achieve the above object, a horizontal alignment function for horizontally aligning the pixels of the image block in the order of the size of the horizontal direction; A vertical alignment function of vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And an index map generation function for generating an index map for the original positions of the horizontally and vertically aligned pixels, a computer-readable recording medium having recorded thereon a two-dimensional alignment conversion program of an image signal.

According to the present invention, since the pixels are arranged in descending order with respect to the matrix, when the conversion technique such as the conventional DCT is performed, the energy concentration effect is large so that the original signal can be represented with a small number of coefficients. .

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to that other component, but there may be another configuration between each component. It is to be understood that the elements may be "connected", "coupled" or "connected".

Since the video screen is composed of 30 frames in one second, the difference is small between one frame and neighboring frames, and thus cannot be distinguished by the human eye. For this reason, when 30 frames are sprayed in one second, the human eye recognizes the frames as continuous.

As such, when the previous frame is similar to the current frame, the pixel value of the next frame can be predicted from the known pixel values constituting the previous frame (this is called interprediction).

The encoding and decoding of such video data is performed based on a motion prediction technique. The motion prediction is performed by referring to past frames or referring to both past and future frames based on the time axis. The frame referred to to encode or decode the current frame is called a reference frame. In block-based video encoding, one still image (frame) constituting a video is divided into macroblocks and subblocks constituting the macroblock, and motion is predicted in units of blocks and encoding is performed.

It is also possible to predict the next pixel using the correlation of the pixel signals in the same frame and to encode the prediction error (this is called intraprediction).

FIG. 1 is a diagram illustrating video frames constituting a video used for inter prediction.

Referring to Fig. 1, video data is composed of a series of still images. These still images are divided into GOP (Group of Picture) units. Each still image is called a frame. One GOP includes an I frame 110, a P frame 120, and a B 130 frame. The I frame 110 is a frame that is encoded by itself without using a reference frame, and the P frame 120 and the B frame 130 are frames that are encoded by performing motion estimation and compensation using the reference frame. In particular, the B frame 130 is a frame that is encoded by predicting the frame of the past and the frame of the future in the forward and reverse directions (bidirectional), respectively.

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

Referring to FIG. 2, the video encoding apparatus 200 according to an embodiment of the present invention may include a motion estimation / compensation unit 210, a subtraction unit 220, an alignment transformer 230, a transformer 240, and quantization. The unit 250 and the encoder 260 are included.

The video encoding apparatus 200 may be a personal computer (PC), a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), or a PlayStation Portable (PSP). ), A communication device such as a communication modem for communicating with various devices or a wired / wireless communication network, a memory for storing various programs and data for encoding an image, and executing a program. Means a variety of devices including a microprocessor for operation and control.

As described above, the motion estimator / compensator 210 performs any one or a combination of intra prediction based on motion prediction or intra prediction that predicts the next pixel using correlation of pixel signals in the same frame. It can be used to predict the current block (or macroblock).

For example, the motion estimator / compensator 210 may be divided into a motion estimator (not shown) and a motion compensator (not shown). The motion estimator finds the motion prediction value of the macroblock of the current frame in the reference frame and outputs the difference of the motion as a motion vector. That is, the macroblock to be searched is searched within a predetermined search area of the reference frame to find the most similar macroblock and the degree of movement thereof is output as a motion vector. The motion compensation unit obtains a prediction macro block corresponding to the obtained motion vector from the reference frame.

As another example, the motion estimator / compensator 210 is an intra predictor that predicts a current macroblock of a current frame using a neighboring macroblock of a current macroblock in an image, and includes one or more pixel values of one or more neighboring macroblocks ( The predicted macro block is predicted by calculating a predicted pixel value of each pixel of the current macro block using the pixel value. Here, the peripheral macroblock may be one or more peripheral macroblocks that are compressed before the current macroblock and located around the current macroblock.

The subtraction unit 220 generates a residual signal by subtracting the prediction macro block from the macro block of the original image frame and calculating the difference value.

The alignment converter 230 arranges the pixels of the image block of the residual signal in the horizontal order and in the vertical direction, and generates an index map of the original positions of the horizontal and vertical aligned pixels. do. The alignment conversion unit 230 according to the present invention will be described later in more detail with reference to FIG. 3.

The converter 240 converts the horizontally and vertically aligned pixels (residual signals) by the alignment converter 230 into a frequency domain to obtain frequency coefficients. Here, the transform unit 240 uses various transformation techniques for transforming an image signal on a time axis such as Discrete Cosine Transform (DCT) or Wavelet Transform into a frequency axis. To convert the residual signal into the frequency domain. In the case of the I frame described with reference to FIG. 1, the converter 240 converts the macroblock of the original image frame into the frequency domain.

The quantizer 250 quantizes the frequency coefficients transformed into the frequency domain by the transformer 230.

Subtracting the predictive macroblock from the macroblock of the original picture frame is called a residual signal, and the residual signal value is encoded to reduce the amount of data during encoding. Since an error occurs during the quantization process, the video data generated in the bitstream includes an error generated during the transformation and quantization process.

In addition, the video encoding apparatus 200 may further include an inverse quantizer 270 and an inverse transform unit 280 to obtain a reference frame.

In order to obtain a reference frame, the quantized residual signal is combined with an image predicted by the motion estimation / compensator 210 through an inverse quantizer 270 and an inverse transformer 280 and stored in a reference frame storage unit (not shown). . In the case of an I frame, it is stored in the reference frame storage of the motion estimation / compensation unit 210 through the inverse quantization unit 270 and the inverse transform unit 280. That is, when the original image is called A and the predicted image is called B, the conversion unit 240 receives the A-B, which is a difference between the original image and the predicted image, and performs conversion.

The encoder 260 encodes the frequency coefficients quantized by the quantizer 250 into a bitstream. An entropy encoding technique may be used as the encoding technique, but various encoding techniques may be used without being limited thereto.

3 is a block diagram of a two-dimensional alignment conversion apparatus for a video signal according to an embodiment of the present invention, and corresponds to the alignment conversion unit 230 of FIG. 2.

As shown in FIG. 3, the 2D alignment conversion apparatus 230 of an image signal according to an exemplary embodiment of the present invention may include a horizontal alignment unit 231, a vertical alignment unit 233, and an index map generator 235. It includes. In addition, the converter 240 may further include.

The horizontal alignment unit 231 horizontally aligns pixels of the image block in the order of the size of the horizontal direction. That is, the horizontal alignment unit 231 arranges the pixels in the same row of the image block in order of decreasing pixel value from left to right.

The vertical alignment unit 233 vertically aligns pixels of the image block in the order of the size of the vertical direction. That is, the vertical alignment unit 233 sorts the pixels in the same column of the image block in order of decreasing size of pixel values from the top to the bottom.

The index map generator 235 generates an index map with respect to the original position (the original position before sorting) of pixels of the image block horizontally aligned by the horizontal alignment unit 231 and vertically aligned by the vertical alignment unit 233. do.

The transform unit 240 converts an image signal of a time axis into a frequency axis by using a discrete cosine transform (DCT) as an example, or converts an image signal of a time axis into a frequency axis by using a wavelet transform. To convert. Such a conversion unit 240 refers to the description of FIG. 2. However, the conversion unit 240 according to the present invention is not limited to the above example and may represent all existing configurations for performing the necessary transformation (or inverse transformation) process in the encoding (or decoding) process.

FIG. 4 is a flowchart illustrating a two-dimensional alignment conversion method of an image signal according to an embodiment of the present invention. Since the present invention is applied to the apparatus of FIG. 3, it will be described together with the operation of the apparatus.

First, the image block signal as shown in FIG. 5 is input to the 2D alignment conversion apparatus 230 of the image signal (S420). 5 is an example of an image signal having a 4x4 block size, and pixel values of the image are represented as f (x, y) as an arbitrary function on the x and y axes.

Subsequently, the horizontal alignment unit 231 horizontally aligns the input image block signal of FIG. 5 in the horizontal order based on the row of the corresponding image block as shown in FIG. 6. That is, as shown in FIG. 6, the horizontal alignment unit 231 arranges the pixels in the same row of the image block in order of decreasing size of pixel values from left to right (S420).

Subsequently, the vertical alignment unit 233 vertically aligns the pixels of the image block horizontally aligned by the horizontal alignment unit 231 in the vertical direction based on the column size as shown in FIG. 7. do. That is, as shown in FIG. 7, the vertical alignment unit 233 arranges the pixels in the same column of the image block in order of decreasing size of pixel values from the top to the bottom (S430).

Through the horizontal alignment step S420 of FIG. 6 and the vertical alignment step S430 of FIG. 7, the pixel having the highest pixel value is disposed at the upper left as shown in FIG. 8, and the pixel having the lowest pixel value is located at the lower right. The two-dimensional alignment transformation may be performed such that is arranged.

This sorting method is such that the pixels are arranged in descending order with respect to the matrix, and when the conversion technique such as the conventional DCT is performed, the energy concentration effect is large, and the original signal can be represented with a small number of coefficients.

Next, an inverse transformation for rearranging the aligned pixels to their original positions as shown in FIG. 8 requires an index map containing information about the original positions of the pixels. 9 illustrates an example of a change of an index map according to pixel alignment transformation. The upper left corner of the image block signal is defined as 1, and the raster scan is defined as 16 by increasing the number to the lower right corner. The series of numbers according to the defined video signal is called an index map, and the position of the original signal can be recorded before alignment through the index map (S440).

The bit amount of the index map generated after the alignment conversion can be obtained through the following equation (1) when the number of given pixels is N.

Formula (1)

Finally, the block image signals arranged as shown in FIG. 8 and the index map generated as shown in FIG. 9 are output (S450).

In addition, the converter 240 converts the aligned block image signal into frequency coefficients as shown in FIG. 8. The transform unit 240 may convert a time axis image signal to a frequency axis using a discrete cosine transform (DCT), or convert a time signal image signal to a frequency axis using a wavelet transform. have.

Through the method of the present invention, an arbitrary video signal can be rearranged into a two-dimensional aligned video signal. Since the aligned video signal efficiently removes discontinuities of the existing video, block-based conversion techniques such as DCT The energy concentration effect can be maximized, resulting in high coding efficiency.

The 2D alignment conversion method of an image signal according to an embodiment of the present invention may be implemented as computer readable codes on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

In the above description, all elements constituting the embodiments of the present invention are described as being operated in combination, and the present invention is necessarily limited to these embodiments. In other words, within the scope of the present invention, all of the components may be selectively operated in combination with one or more. In addition, although all of the components may be implemented in one independent hardware, each or all of the components may be selectively combined to perform some or all functions combined in one or a plurality of hardware. It may be implemented as a computer program having a. Codes and code segments constituting the computer program may be easily inferred by those skilled in the art. Such a computer program may be stored in a computer readable storage medium and read and executed by a computer, thereby implementing embodiments of the present invention. The storage medium of the computer program may include a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like.

In addition, the terms "comprise", "comprise" or "having" described above mean that the corresponding component may be included, unless otherwise stated, and thus excludes other components. It should be construed that it may further include other components instead. All terms, including technical and scientific terms, have the same meanings as commonly understood by one of ordinary skill in the art unless otherwise defined. Terms commonly used, such as terms defined in a dictionary, should be interpreted to coincide with the contextual meaning of the related art, and shall not be construed in an ideal or excessively formal sense unless explicitly defined in the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, the present invention can be applied to the field of video encoding and decoding technology to rearrange an arbitrary video signal into a two-dimensional aligned video signal, and the aligned video signal efficiently discontinues the discontinuous points of the existing video. Because it eliminates, the energy-intensive effect of block-based transformation techniques such as DCT is maximized, resulting in the effect of maximizing the coding.

1 is a view showing video frames constituting a video, used for inter prediction;

2 is a block diagram of a video encoding apparatus according to an embodiment of the present invention;

3 is a block diagram of a two-dimensional alignment conversion apparatus of an image signal according to an embodiment of the present invention;

4 is a flowchart of a 2D alignment conversion method of an image signal according to an embodiment of the present invention;

5 is a diagram illustrating an example of a video signal having a 4x4 block size;

6 is a view illustrating a horizontal alignment process according to the present invention;

7 is a view illustrating a vertical alignment process according to the present invention;

8 illustrates an example of an image block signal after horizontal and vertical alignment processes according to the present invention;

9 illustrates a process of generating an index map according to the present invention.

<Description of Symbols for Main Parts of Drawings>

200: encoding device (or coder)

210: motion estimation / compensation unit, adaptive overlap block motion compensation device

220: subtraction unit 230: alignment conversion unit

231: horizontal alignment portion 233: vertical alignment portion

235: index map generation unit 240: conversion unit

250: quantizer 260: encoder

270: inverse quantization unit 280: inverse transform unit

Claims (20)

A horizontal alignment unit that horizontally aligns the pixels of the image block in an order of magnitude in a horizontal direction; A vertical alignment unit for vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And Index map generator for generating an index map of the original position of the horizontally and vertically aligned pixels Device for two-dimensional alignment conversion of the video signal, characterized in that it comprises a. The method of claim 1, And the horizontal alignment unit arranges the pixels in the same row in order of decreasing pixel value from left to right. The method of claim 1, And the vertical alignment unit aligns the pixels in the same column in order of decreasing size of pixel values from top to bottom. The method of claim 1, And a converter for converting the horizontally and vertically aligned pixels into frequency coefficients. The method of claim 4, wherein And the transform unit converts an image signal on a time axis into a frequency axis by using a discrete cosine transform (DCT). The method of claim 4, wherein And the transform unit converts an image signal of a time axis into a frequency axis using a wavelet transform. A horizontal alignment step of horizontally aligning the pixels of the image block in an order of magnitude in a horizontal direction; A vertical alignment step of vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And An index map generation step of generating an index map for the original position of the horizontally and vertically aligned pixels 2D alignment conversion method of an image signal comprising a. The method of claim 7, wherein The horizontally aligning step of the two-dimensional alignment conversion method of the image signal, characterized in that in order from the left to the right of the pixels in the same row size of the pixel value is smaller. The method of claim 7, wherein The vertical alignment step of the two-dimensional alignment conversion method of the image signal, characterized in that the order of the pixels in the same column in order of decreasing size of the pixel value from the top to the bottom. The method of claim 7, wherein And converting the horizontally and vertically aligned pixels into frequency coefficients. The method of claim 10, The transforming step is a two-dimensional alignment transformation method of an image signal, characterized in that for transforming the image signal on the time axis to the frequency axis using a discrete cosine transform (DCT). The method of claim 10, And the transforming step converts an image signal of a time axis into a frequency axis using a wavelet transform. A subtraction unit configured to generate a residual signal by calculating a difference value between an original pixel value of each pixel of the current block and a predicted pixel value of each pixel of the current block; The pixels of the image block of the residual signal are arranged in a horizontal order, the pixels are arranged in a vertical direction with respect to the pixels of the image block, and the indexes of the horizontal and vertically aligned pixels are indicative of original positions. An alignment conversion unit generating a map; A converter for converting the horizontally and vertically aligned pixels into frequency coefficients; A quantizer for quantizing the transformed frequency coefficients; And An encoder that encodes the quantized frequency coefficients into a bitstream Video encoding apparatus comprising a. The method of claim 13, The sorting converting unit sorts the pixels in the same row in order of decreasing pixel size from left to right, and arranges the pixels in the same column in decreasing order of size from top to bottom. Video encoding device. The method of claim 13, And the transform unit converts an image signal on a time axis into a frequency axis by using a discrete cosine transform (DCT). The method of claim 13, And the transform unit converts an image signal on a time axis into a frequency axis using a wavelet transform. A horizontal alignment function of horizontally aligning the pixels of the image block in an order of magnitude in a horizontal direction; A vertical alignment function of vertically aligning the pixels of the image block in an order of magnitude in a vertical direction; And Index map generation function for generating an index map for the original position of the horizontally and vertically aligned pixels And a computer-readable recording medium having recorded thereon a two-dimensional alignment conversion program of an image signal. The method of claim 17, And the horizontal alignment function arranges the pixels in the same row in order of decreasing pixel value from left to right. The method of claim 17, And the vertical alignment function aligns the pixels in the same column in order of decreasing pixel value from top to bottom. The method of claim 17, And a conversion function for converting the horizontally and vertically aligned pixels into frequency coefficients.

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