KR100476386B1 - Scan Interleaving Method for Stretched Object Images and MPEG-4 Shape-Encoding Information Coding Method - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Scan Interleaving Method

2. The technical problem to be solved by the invention

When scanning interleaving, the coding method is applied differently depending on the presence of ESD

3. Summary of Solution to Invention

When encoding an image of a low resolution base layer into an image of a high resolution enhancement layer using a scan interleaving method, and encoding an enhancement layer using a scan interleaving method, the transitional sample data of the target image The presence or absence of a signal is detected, and a coding method is applied differently according to the presence or absence of the signal.

Description

Scan Interleaving Method of Stretched Object Image and MPEG-4 Stretch Shape Coding Method

The present invention relates to a shape information encoding method (SHAPE INFORMATION CODING METHOD) that separates and processes a video applied through an image input device into each object image and background image having arbitrary shape information. In case of encoding ENHANCEMANT LAYER using SCAN INTERLEAVING method during SCALABLE SHAPE CODING process, it detects the presence of transitional sample data of the target image. The purpose of the present invention is to improve the coding efficiency by varying the coding method depending on the presence or absence thereof.

As is well known, the recent video processing technology is a method of compressing and encoding an image corresponding to one frame (FRAME) as a whole, so that a predetermined unit block having arbitrary shape information (or VOP (VIDEO OBJECT PLANE: VOP), and each of them flows in the direction of compression encoding and transmission for each of them.

That is, the applied image is separated into each object image and the background image, and the compression efficiency and the encoding efficiency are intended by transmitting only the change of the object image, thereby preparing an international standard.

For example, WG11 under ISO / IEC, the world's standardization organization, has arbitrary shape information unlike MPEG-1 (MPEG) -1 and MPEG-2 (MOVING PICTURE EXPERTS GROUP). MPEG-4, which is a standardization method for encoding an object, is performed. MPEG-4, which is being standardized, is based on the concept of VOP.

Here, the VOP is defined as a quadrangle that divides the applied image into a background image and each object image, and includes the separated background image and the object image. In MPEG-4, a predetermined object or a predetermined object is included in the image. If there is a region of the object consisting of the region of, the video of the object is divided into respective VOPs, and the separated VOPs are encoded respectively.

The VOP has the advantage of freely synthesizing or decomposing a natural image or an artificial image as a unit of an object image, and is fundamental to processing images of an object in the field of computer graphics and multimedia.

Fig. 1 shows the configuration of an encoder (ENCODER) 10, which is primarily determined by the International Standards Organization (ISO / IEC JTC1 / SC29 / WG11 MPEG96 / N1172 JANUARY). A block diagram is shown.

Here, the VOP formation unit 11 divides the image into the object image unit to form different VOPs when the image sequence (SEQUENCE) to be transmitted or stored is input.

2 shows an example in which one VOP is formed by setting an image of a cat as an object image.

Here, the horizontal size of the VOP is defined by the width of the VOP, the vertical size is defined by the height of the VOP, the formed VOP is M and N respectively in the X-axis and Y-axis with the upper left as the grid (GRID) starting point. It is partitioned into an M x N macroblock having two pixels. For example, it is divided into 16 x 16 macroblocks each having 16 pixels on the X and Y axes.

In this case, when there are not M and N pixels of the X and Y axes of the macroblock formed on the right and the bottom of the VOP, the size of the VOP is extended to M and both of the X and Y axes pixels of each macro block are expanded. And N.

In addition, M and N are set to an even number in order to perform encoding in units of sub-blocks in an object coding unit (TEXTURE CODING) to be described later.

On the other hand, each VOP formed in the VOP forming unit 11 is input to the VOP encoders 12A, 12B, ..., 12N, respectively, encoded by VOP, and multiplexed by the multiplexer 13 to form a bit string (BIT STREAM). Is sent.

FIG. 4 is a block diagram showing the configuration of the VOP encoders 12A, 12B, ..., 12N of the VM encoder 10, which is determined primarily by the international standard subdivision.

First, when a VOP for each object image formed by the VOP forming unit 11 is input to a motion estimation unit 31, the motion estimation unit 31 moves in units of macro blocks from an applied VOP. Will be estimated.

In addition, motion information estimated by the motion estimation unit 31 is input to a motion compensation unit 32 to compensate for motion.

In addition, the VOP whose motion is compensated by the motion compensator 32 is input to the subtractor 33 together with the VOP formed by the VOP forming unit 11 to detect a difference value, and the difference detected by the subtractor 33. The value is input to the object internal encoding unit 34 so that the internal information of the object is encoded in units of sub blocks of the macro block.

For example, after the X and Y axes of the macroblock are subdivided into 8 × 8 subblocks having 8 pixels each with M / 2 × N / 2, the object internal information is encoded.

On the other hand, the VOP whose motion is compensated by the motion compensator 32 and the internal information of the object encoded by the object internal encoding unit 34 are added to the adder 35 and added, and the output of the adder 35 is added. The signal is input to a PREVIOUS RECONSTRUCTED VOP 36 to detect a previous VOP which is a VOP of the image immediately before the current image.

In addition, the previous VOP detected by the previous VOP detector 36 is input to the motion estimation unit 31 and the motion compensation unit 32 and used for motion estimation and motion compensation.

The VOP formed by the VOP forming unit 11 is inputted to a SHAPE CODING BLOCK 37 to encode shape information.

Here, the output signal of the shape coding unit 37 varies depending on whether the VOP coders 12A, 12B, ..., 12N are applied, and as shown by a dotted line, the shape coding unit ( The output signal from 37 may be input to the motion estimation unit 31, the motion compensator 32, and the object internal encoding unit 34, and used to encode motion estimation, motion compensation, and internal information of the object.

In addition, motion information estimated by the motion estimation unit 31, object internal information encoded by the object internal encoding unit 34, and shape information encoded by the shape encoding unit 37 are applied to the multiplexer 38. After multiplexing, the data is output to the multiplexer 13 of FIG. 1 through the buffer 39 and transmitted in a bit string.

Fig. 3 is a block diagram showing the configuration of a VM decoder (DECODER) 20 which is determined primarily by an international standard subdivision.

The encoded signal of the VOP, which is encoded by the VM encoder 10 and transmitted in a bit string, is separated for each VOP in the demultiplexer 21 of the VM decoder 20.

In addition, each of the separated VOP coded signals is decoded by the VOP decoders 22A, 22B, ..., 22N, respectively, and the decoded signals output from the VOP decoders 22A, 22B, ..., 22N are synthesized. ) Is synthesized and output as the original image.

In such MPEG-4, as a technique applied to the shape encoding unit 37 for encoding each VOP transmitted from the VOP forming unit 11, there are N × N blocks (N = 16, 8, 4). MMR SHAPE CODING TECHNIQUE, which encodes shape information based on the VERIFEX-BASED SHAPE CODING TECHNIQUE, which encodes shape information based on the vertices, and the baseline. BASELINE-BASED SHAPE CODING TECHNIQUE and CONTEXT-BASED ARITHMETIC CODING.

On the other hand, the flexible shape information encoding is a function for transmitting and decoding a plurality of layers (BASE LAYER, enhancement layer) having different resolutions, which MPEG-4 supports.

As is well known, in order to transmit information having a plurality of different resolutions, a large amount of information needs to be transmitted. However, a large amount of information has a problem in that the transmission efficiency is reduced.

Accordingly, in order to reduce the amount of information to be transmitted in MPEG-4, as shown in FIG. 5, a method of estimating a high resolution enhancement using a low resolution base layer is applied.

Encoding the enhancement layer using the base layer includes a method using an I-VOP (INTRA VIDEO OBJECT PLANE: hereinafter referred to as I-VOP) of the base layer, and a P-VOP (PREDICTED VIDEO OBJECT PLANE: hereinafter). It is called P-VOP.)

When the base layer is encoded into the enhancement layer using the I-VOP of the base layer, a scan interleaving method is used.

In order to encode the enhancement layer, the pixel values of neighboring base layers existing below and above, left and right of the pixel to be encoded are used.

FIG. 6 illustrates a horizontal scanning in the process of encoding an enhancement layer from a base layer, using pixel values of a base layer existing below and above a pixel to be encoded.

That is, when the values of the two neighboring pixels below and above are the same, the pixel values of the current position to be encoded may have the same value. Therefore, the two neighboring pixel values are the same and the pixel values of the current position are also the two neighboring pixel values. If it is equal to, no encoding

However, if two neighboring pixel values are different, the pixel values of the current position are likely to be different. Therefore, the pixel values of the current position to be encoded should be encoded. This is called a transitional sample.

In addition, when two neighboring pixel values are the same but the pixel values of the current position are different, the encoding should be performed. This case is called an exceptional sample.

Therefore, two types of data are encoded for the enhancement layer, that is, the transient sample data (TSD) and the exceptional sample data (EXCEPTIONAL SAMPLE DATA). May exist.

Hereinafter, as illustrated in FIG. 7, a process of encoding and transmitting an image of a 4 × 4 enhancement layer as an image of a base layer and then encoding the image by a scan interleaving method will be described in detail.

First, as shown in FIG. 7A, the VOP encoder 10 divides an image of a 4 × 4 enhancement layer into four equal parts, and then selects pixels A5, A7, A13, and A15 at the lower right. A base layer image as shown in FIG. 7B is generated and transmitted to the VOP decoder 20. In this case, the reason for dividing the image of the enhancement layer into four parts is that the image of the base layer is one-fourth the size of the enhancement image.

Thereafter, the VOP decoder 20 encodes and reconstructs an enhancement image from the transmitted base layer. Referring to FIG. 8, the horizontal search method and the vertical search method will be described below.

FIG. 8A is a diagram for describing a horizontal search method, and it is time to encode a pixel of a current X point.

Then, the pixels adjacent to the X point are "A5, A6, A7, A13, A14, A15, and B0". In this case, the values of A5, A6, A7, A13, A14, A15, and B0 pixels are obtained by the scan interleaving method of the previous step, and the pixels of X 'points to be obtained are A5, A6, A7, A13, The values of A14, A15 and B0 are obtained by the arithmetic encoding method.

Similarly, in the vertical search method, as shown in Fig. 8B, the pixel value of Y point to be obtained is obtained from the pixel values of C0, C1, C2, A5, A7, A13, and A15.

Here, the pixels B0, C0, and C2 represent values obtained by the horizontal search method, the C1 pixels represent values obtained by the vertical search method, and the hatched pixels represent pixels to be obtained next.

Therefore, horizontal search doubles the pixels in the vertical direction, and vertical search doubles the pixels in the horizontal direction, resulting in a 2 × 2 base layer image reconstructed into a 4 × 4 enhancement layer image. Will be.

That is, in order to encode an image of a base layer into an image of an enhancement layer, a horizontal direction search and a vertical direction search must be performed, respectively. The search order is defined to perform a vertical direction search after a horizontal direction search.

In other words, in order to encode the enhancement layer, as shown in FIG. 9, two search in the vertical direction and the horizontal direction must be performed. We need to search about twice as many pixels as the number of bits.

Therefore, a difference occurs in the number of occurrences of the TSD and the ESD depending on whether the vertical direction search is performed first or the horizontal direction search first, and thus the number of bits to be searched is changed.

On the other hand, in the process of encoding the shape information, the block unit encoding. That is, in encoding the block for the previous shape information (hereinafter referred to as BINARY ALPHA BLOCK: BAB), transmission of information indicating the presence or absence of ESD is required to encode TSD and ESD when scan interleaving in flexible shape information coding. .

Therefore, when the ESD in the BAB is more than one pixel, it transmits information indicating that the ESD exists, and subsequently transmits information indicating the location of the ESD. If there is no ESD, only the information that there is no ESD is transmitted and the encoding for the ESD is terminated. .

That is, the conventional method for transmitting information indicating the presence or absence of ESD is represented by one bit of a flag and transmitted or by performing arithmetic encoding.

However, the conventional method as described above has a problem in that when the number of BABs is large, a large number of bits are required to reduce the coding efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems. In particular, when encoding an enhancement layer using a scan interleaving method, the presence or absence of transitional sample data of an object image is detected. The present invention provides a scan interleaving method for a stretchable target image which can improve encoding efficiency by varying an encoding method depending on the presence or absence thereof.

Another object of the present invention is to provide a method for encoding stretched shape information of MPEG-4 using a scan interleaving method for a stretched target image in which the scan interleaving method for the stretched target image is applied to MPEG-4.

In order to achieve the above object, the scan interleaving method of the stretchable target image of the present invention separates the moving image applied through the image input apparatus into each target image and the background image having arbitrary shape information, and then the resolution is different. In the flexible coding method for transmitting and decoding to a plurality of layers,

The BAB examines the base layer of the BAB, encodes using different probability distributions with and without TSDs, and then transmits arithmetic coding of information indicating whether ESD is present in BAB. It is done.

In addition, the method of encoding using different probability distributions is characterized in that when generating a probability distribution, if there is a TSD in the BAB, a probability distribution is generated with a probability that ESD exists among BABs in which the TSD exists.

In addition, the encoding method using the different probability distributions, when generating a probability distribution when the TSD in the BAB when generating the probability distribution with the probability of the presence of the ESD among the BAB in the TSD and when encoding the ESD If there is a TSD, it is characterized by transmitting presence information about ESD as an encoding table made of this probability distribution.

In addition, the method of encoding using the different probability distributions is characterized in that when generating a probability distribution, if there is no TSD in the BAB, a probability distribution is generated with a probability that ESD exists among BABs in which the TSD does not exist. do.

In addition, the method of encoding using the different probability distributions, when generating a probability distribution, if there is no TSD in the BAB, the device and ESD that create the probability distribution with the probability of ESD exists among the BABs without TSD If the TSD does not exist when encoding, the presence or absence of ESD information is transmitted as an encoding table made of this probability distribution.

In addition, the method of encoding using the different probability distributions is characterized in that the probability distribution is transmitted using a fixed arithmetic coding method.

In addition, the method of encoding using the different probability distributions is characterized in that the probability distribution is transmitted using an adaptive arithmetic coding method.

Meanwhile, according to the present invention, the MPEG-4 stretched shape information encoding method using the scan interleaving method of the stretchable object image transmits and decodes an object image included in a VOP composed of a predetermined number of macroblocks to a plurality of layers having different resolutions. In the MPEG-4 elastic shape information encoding method,

Detects whether there is ESD per VOP, and if there is ESD in VOP, it sends ESD presence information for each BAB, and if there is no ESD in VOP, ESD is present for each BAB in the VOP. It is characterized by the methodological configuration that the presence information is not transmitted to use different probability distributions for the presence or absence of the ESD.

In addition, the method of encoding using different probability distributions is characterized in that when generating a probability distribution, if there is a TSD in the BAB, a probability distribution is generated with a probability that ESD exists among BABs in which the TSD exists.

In addition, the encoding method using the different probability distributions, when generating a probability distribution when the TSD in the BAB when generating the probability distribution with the probability of the presence of the ESD among the BAB in the TSD and when encoding the ESD If there is a TSD, it is characterized by transmitting presence information about ESD as an encoding table made of this probability distribution.

In addition, the method of encoding using the different probability distributions is characterized in that when generating a probability distribution, if there is no TSD in the BAB, a probability distribution is generated with a probability that ESD exists among BABs in which the TSD does not exist. do.

In addition, the method of encoding using the different probability distributions, when generating a probability distribution, if there is no TSD in the BAB, the device and ESD that create the probability distribution with the probability of ESD exists among the BABs without TSD If the TSD does not exist when encoding, the presence or absence of ESD information is transmitted as an encoding table made of this probability distribution.

The method of encoding using the different probability distributions may be transmitted using an arithmetic coding method having a fixed probability distribution.

In addition, the method of encoding using different probability distributions is characterized by transmitting using an arithmetic coding method in which the probability distribution is adaptive.

In addition, the method of encoding using different probability distributions may include additional information on the presence or absence of ESD per VOP in the VOP layer syntax.

In addition, the method of encoding using the different probability distributions is characterized by placing additional information on the presence or absence of ESD per VOP in the VOL layer syntax.

The scan interleaving method of the stretchable object image of the present invention and the stretched shape information encoding method of MPEG-4 using the same are obtained by using the transitional interpolation of the transitional sample data of the object image when encoding the enhancement layer using the scan interleaving method. By detecting the presence or absence and changing the encoding method according to the presence or absence, the encoding efficiency can be improved.

Hereinafter, the configuration and operation of the present invention according to the technical concept of the scan interleaving method of the stretchable object image and the stretch shape information encoding method of MPEG-4 using the same will be described in detail with reference to the accompanying drawings. same.

The information transmitted in flexible shape information coding is divided into TSD, ESD, and additional information. In this case, the probability of occurrence of ESD in any BAB depends on whether a TSD exists in the BAB. In other words, the probability of the presence of ESD is higher in the case of a BAB in which a TSD exists than in a BAB in which a TSD does not exist. Therefore, if a different probability distribution is used depending on whether or not a TSD exists in the BAB, the entropy of information is reduced and the occurrence data is reduced.

9 is a flowchart illustrating an embodiment according to the spirit of the present invention. As the encoding of the enhancement layer is a process of shape information encoding as described above, it is first checked whether BAB exists. Thereafter, as shown in FIG. 9, the presence of ESD is checked, the base layer is examined, and the TSD is checked. Then, the probability distribution when the TSD is present and the probability distribution when the TSD does not exist is then transmitted by performing arithmetic encoding on information indicating whether ESD is generated in the BAB. That is, in FIG. 9, encoding method A performs fixed arithmetic encoding by using a probability table for a case where a TSD exists and an ESD, and the encoding method B further illustrates a case where an ESD exists and a TSD does not exist. Means to perform fixed arithmetic encoding using another probability table.

In this case, arithmetic encoding can be performed either by arithmetic coding having a fixed probability distribution or by adaptive arithmetic coding that changes the probability distribution at each transmission of information. Since the presence or absence of the TSD can be determined by examining the base layer transmitted in advance, information on the TSD need not be transmitted.

On the other hand, in another embodiment, it is determined whether the current ESD per BAB to transmit the presence of ESD information. However, after checking whether there is ESD per VOP, if ESD exists in the VOP, ESD presence information per BAB is sent, and if there is no ESD per VOP, one ESD presence information is sent to the VOP. By not sending ESD presence information for each BAB that does not exist, unnecessary information is reduced.

That is, when encoding the image of the enhancement layer by using the scan interleaving method, it is necessary to send information on whether ESD information exists. In this case, the TSD information has a high probability that the ESD information exists in the block in which the TSD information exists. By using the information to determine the probability distribution of the presence of ESD, the coding efficiency is improved.

In other words, the probability distribution (encoding method) applied differently depending on the presence of ESD improves coding efficiency.

For example, the coding efficiency is reduced by reducing the number of bits generated by different coding methods depending on the presence of ESD and TSD.

As described above, the scan interleaving method of the stretchable target image of the present invention and the stretched shape information encoding method of MPEG-4 using the same are particularly applicable to encoding the enhancement layer using the scan interleaving method. By detecting the presence or absence of the transitional sample data and changing the encoding method according to the presence or absence of the transition sample data, the coding efficiency can be improved.

1 is a block diagram showing the configuration of a VM encoder primarily determined by an international standard subdivision;

2 is a diagram illustrating a VOP having shape information divided into macro blocks;

3 is a block diagram showing the configuration of a VM decoder primarily determined by an international standard subdivision;

4 is a block diagram showing the configuration of a VOP encoding unit determined primarily by an international standard subdivision;

5 is a conceptual diagram of spatial stretch coding;

6 is a diagram illustrating a scan interleaving process for flexible coding;

7 and 8 illustrate a method of encoding an enhancement layer image;

9 is a block diagram showing a scan interleaving method of a stretchable object image of the present invention and a method of encoding stretched shape information of MPEG-4 using the same.

<Explanation of symbols for main parts of drawing>

10: VM encoder 11: VOP forming unit

12A, 12B,... , 12N: VOP encoding unit 13, 38: multiplexer

20: VM decoder 21: demultiplexer

22A, 22B,... , 22N: VOP decoder 23: synthesis section

31: motion estimation 32: motion compensation

33: subtractor 34: internal coded object

35: adder 36: previous VOP detector

37: shape coding unit

Claims (16)

In the flexible encoding method for separating a video applied through the image input device into each object image having a certain shape information and a background image, and then transmitted to a plurality of layers having different resolutions, decoding A telescopic object characterized in that the BAB examines the base layer of the BAB, encodes using different probability distributions with and without a TSD, and then transmits arithmetic coding of information indicating whether ESD is present in the BAB. Method of scan interleaving of images. The method of claim 1, wherein the encoding method using the different probability distributions generates a probability distribution with a probability that ESD is present among BABs in which a TSD exists when a TSD exists in a BAB when generating a probability distribution. Scan interleaving method of a stretchable target image. The apparatus of claim 1, wherein the encoding method using the different probability distributions includes an apparatus for generating a probability distribution with a probability that ESD exists among BABs in which a TSD exists when a TSD is present in a BAB when generating a probability distribution. If the TSD is present when encoding, scan interleaving method for a stretchable object image, characterized by transmitting presence or absence information about ESD as an encoding table created by the probability distribution. The method of claim 1, wherein the encoding method using the different probability distributions generates a probability distribution with a probability that ESD exists among BABs in which a TSD does not exist when a TSD is not present in a BAB when a probability distribution is generated. Scan interleaving method for a stretchable object image, characterized in that. The method of claim 1, wherein the encoding method using the different probability distributions generates a probability distribution with a probability that ESD is present among BABs in which a TSD does not exist when a TSD is not present in a BAB. If the TSD does not exist when encoding the device and ESD, the interleaving method of the stretchable object image, characterized by transmitting presence or absence information about the ESD as an encoding table created by the probability distribution. The method of claim 1, wherein the encoding using different probability distributions comprises: transmitting a probability distribution using a fixed arithmetic coding method. The method of claim 1, wherein the encoding using different probability distributions comprises: transmitting the probability distributions using an adaptive arithmetic coding method. In the MPEG-4 elastic shape information encoding method for transmitting and decoding an object image included in a VOP composed of a predetermined number of macroblocks to a plurality of layers having different resolutions, Detects whether there is ESD per VOP, and if there is ESD in the VOP, ESD presence information is sent for each BAB, and if there is no ESD in the VOP, ESD exists for each BAB in the VOP. The method for encoding stretched shape information of MPEG-4 using a scan interleaving method of a stretchable object image, by transmitting presence or absence information, and using different probability distributions for the presence or absence of the ESD. The method of claim 8, wherein the encoding method using the different probability distributions generates a probability distribution with a probability that ESD exists among BABs in which a TSD exists when a TSD exists in a BAB when generating a probability distribution. An MPEG-4 stretched shape information encoding method using a scan interleaving method of stretched object images. The apparatus of claim 8, wherein the encoding method using the different probability distributions includes an apparatus for generating a probability distribution with a probability that ESD exists among BABs in which a TSD exists when a TSD exists in a BAB when generating a probability distribution. And a shape information encoding method of MPEG-4 using a scan interleaving method of a stretchable object image, wherein the presence or absence information of ESD is transmitted as a coding table formed by the probability distribution when a TSD exists when encoding the PSP. The method of claim 8, wherein the encoding method using the different probability distributions generates a probability distribution with a probability that ESD is present among BABs in which a TSD does not exist when a TSD is not present in a BAB. MPEG-4 elastic shape information encoding method using a scan interleaving method of a stretchable object image. The method of claim 8, wherein the encoding method using the different probability distributions generates a probability distribution with a probability that ESD is present among BABs in which a TSD does not exist when a TSD is not present in a BAB. When the device and the ESD are encoded, if the TSD does not exist, the shape of the MPEG-4 using the scan interleaving method of the stretched object image is transmitted using the probability distribution information of the ESD as an encoding table made of this probability distribution. Information coding method. The method of claim 8, wherein the encoding using different probability distributions is performed by using an arithmetic encoding method with a fixed probability distribution. Flexible shape information coding method. The method of claim 8, wherein the encoding using different probability distributions is performed by using an arithmetic encoding method with adaptive probability distributions. Flexible shape information coding method. 10. The method of claim 8, wherein the encoding method using different probability distributions comprises: additional information on the presence or absence of ESD per VOP is placed in a VOP layer syntax. 4 shape information coding method. 9. The method of claim 8, wherein the encoding method using different probability distributions comprises: additional information on the presence or absence of ESD per VOP is placed in a VOL layer syntax. 4 shape information coding method.

Images