KR20140099180A - Method for encodig high resolution digital video and apparatus therefor - Google Patents

Abstract

Disclosed are a method for encoding/decoding a high-resolution digital video and an apparatus therefor. A method for encoding a digital video includes the steps of: dividing a picture into a plurality of divided frames; generating a plurality of element frames for each of the plural divided frames; extracting a lowest frequency element frame having the lowest frequency band among the element frames; and combining the lowest frequency element frames of each of the divided frames with each other to generate a low-resolution picture having a resolution lower than that of the picture.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for encoding a high-resolution digital image,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for encoding and decoding a high-resolution digital image, and more particularly, to a technology utilizing an JPEG-2000 standard and an image segmentation technique for an 8K-level digital cinema service.

Data compression is essential for the communication and storage of multimedia data in a multimedia society. In particular, in the case of image data having a large amount of data, a conversion process of representing original information in a different form is performed. Then, the amount of information is reduced by eliminating high frequency components that the human eye does not recognize or assigning fewer bits.

In this way, it is necessary to perform transform coding in order to compress the digital image. The conversion algorithm has no correlation between the data of the conversion area, it is possible to have dense data, reverse conversion is possible, Accuracy, and sufficient number of calculations to be calculated. Such transcoding includes discrete cosine transform (DCT), wavelet transform, Fourier transform, and the like.

However, discrete cosine transform has a disadvantage that blocking phenomenon occurs at low bit rate compression. On the other hand, the discrete wavelet transform is advantageous in that both the frequency information and the position information can be expressed by the transfer function because there is no blocking phenomenon because the transform is performed for the entire image.

As a processing technology for digital images, Digital Cinema standard adopts JPEG-2000 algorithm for high-capacity image compression. The JPEG-2000 algorithm is based on wavelet transform, unlike JPEG and MPEG based on discrete cosine transform.

Unlike the discrete cosine transform with 8x8 or 4x4 blocks as the basic unit, wavelet transform has the advantage that there is no blocking phenomenon as described above because the entire coding screen is used as a basic unit. On the other hand, when the screen becomes larger than 4K, There is also a limitation in that the input / output time for data movement also increases sharply.

In terms of technology, the Digital Cinema Theater will be screened at a resolution of 1.3K (1280 * 1024), 2K (2048 * 1080) and 4K (4096 * 2048) ) Will be screened with digital projectors of 1.3K or more. Currently, digital cinema technology for 2K and 4K resolutions has been commercialized and supports the international standard JPEG-2000 compression method and the Digital Cinema Initiative (DCI).

However, in order to provide 8K digital cinema services, it is necessary to provide backward compatibility for 2K and 4K digital cinema services. In other words, in a theater having a 2K or 4K projector, 8K contents should be able to be displayed at 2K or 4K. However, the conventional system can not provide such a function. In addition, a problem of complexity for coding and decoding and an increase in input / output time for moving data are also necessary.

It is an object of the present invention to overcome the above-mentioned problems by providing a JPEG-2000 encoding and decoding method for 8K digital cinema service.

Another object of the present invention is to provide a coding / decoding apparatus using the coding and decoding method.

According to one aspect of the present invention, there is provided a method of encoding a digital video, the method comprising: dividing a picture into a plurality of divided frames, ), Generating a plurality of element frames for each of the plurality of divided frames, extracting a lowest frequency element frame having the lowest frequency band among the plurality of elementary frames, Combining the lowest frequency element frames of each of the divided frames to generate a low-resolution picture having a lower resolution than the picture.

Here, the dividing step may divide a picture recursively or iteratively until a plurality of divided frames become lower than a predetermined resolution.

Here, the generating of the plurality of element frames may generate a plurality of element frames by performing transform coding on each of the plurality of divided frames.

Furthermore, the transcoding may be a wavelet transform.

Here, the digital image encoding method may further include a step of applying a deblocking filter to a boundary between the lowest frequency element frames constituting a picture having a lower resolution.

According to another aspect of the present invention, there is provided an apparatus for encoding a digital image, the apparatus comprising: a frame dividing unit dividing a picture into a plurality of divided frames; A lowest frequency element frame extracting unit for extracting a lowest frequency element frame having the lowest frequency band among the plurality of elementary frames; a minimum frequency element frame extracting unit for extracting a lowest frequency element frame of each of the plurality of divided frames, And an element frame combining unit for generating a low-resolution picture having a lower resolution than the picture.

Here, the frame dividing unit can divide the picture recursively or repeatedly until a plurality of divided frames become lower than a predetermined resolution.

Here, the element frame generation unit may generate a plurality of element frames, which are obtained by compressing and compressing each of the plurality of divided frames.

Furthermore, the transcoding may be a wavelet transform.

Here, the digital image encoding apparatus may further include a deblocking filter unit that applies a deblocking filter to the boundary between the lowest frequency element frames constituting the picture having the lower resolution.

By using the digital image encoding / decoding method and the configuration of the apparatus provided by the present invention, parallel processing is performed using a separate thread on a multi-GPU or multiple CPUs for each data area in order to divide a large- It is possible to carry out the present invention.

Furthermore, it is possible to construct an image processing system of 8K class resolution for high-speed digital cinema using the same.

In addition, since the data is divided, the complexity for wavelet transform performed in the JPEG-2000 encoding and decoding process can be reduced, and high-speed operation can be performed.

In addition, since the original data itself can be divided and stored due to the data division processing, the input / output time for the large-capacity data can be shortened.

1 is an exemplary diagram for explaining a result of applying a wavelet-based JPEG-2000 compression algorithm to an original image according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a data structure for a digital cinema 4K service according to an embodiment of the present invention.
3 is a flowchart illustrating a digital image encoding method and its detailed steps according to an embodiment of the present invention.
4 is an exemplary diagram for explaining a digital image encoding method according to an embodiment of the present invention.
5 is an exemplary diagram for explaining a result of applying a compression algorithm to each divided frame according to an embodiment of the present invention.
FIG. 6 is an exemplary diagram for explaining a result of application of a minimum frequency component frame extraction and deblocking filter according to an embodiment of the present invention. Referring to FIG.
7 is a conceptual diagram illustrating a data structure for a digital cinema 8K service according to an embodiment of the present invention.
8 is a block diagram for explaining a digital image encoding apparatus and its components according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

First, the terms used in the present application will be briefly described as follows.

A video may be composed of a series of pictures, and each picture may be divided into a predetermined area such as a block. It is to be understood that any person skilled in the art will recognize that the term picture may be replaced with another term having an equivalent meaning such as an image, You will understand.

However, in the present invention, a picture is an image which is not divided into a predetermined spatial region, and a frame is mainly used to mean a portion constituting the whole or part of a picture.

Digital cinema is a digital cinema system that processes and packs film taken by film or digital camera into digital files and sends the digital files to digital projectors and home systems through a process medium (hard disk), satellite, or broadband access network It is a movie that distributes through various media such as theater and mobile terminal, and provides high-quality digital image service to visitors and users.

On the technical side, the Digital Cinema Theater will be screened at a resolution of 1.3K (1280x1024), 2K (2048x1080), 4K (4096x2160) and encrypted compressed video (Wavelet, MPEG- 2000) as a digital projector with 1.3K or higher.

4K resolution (4K Ultra High Definition, 4K Ultra HD, 4K UHD) is a term referring to the next generation of high definition resolution with about 4 times the number of pixels (about 4000 width, about 2000 height) of Full HD (1920 * 1080). As of January 2012, there is no standard yet, and two products are available: 4096 * 2160 or 3840 * 2160.

The Consumer Electronics Association defines 3840 × 2160, twice the full HD for television, and 4096 * 2160, 4K, as defined by Digital Cinema Initiatives (DCI), the standard for digital cinema.

A deblocking filter is an image filter applied to a decoded in-picture block to improve sharpness and sharpness of sharp edges formed between macroblocks when a block coding technique is used. The deblocking filter is intended to improve the quality of the decoded image. This technology is included in the specifications of the Microsoft VC-1 codec and the H.264 codec.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is an exemplary diagram for explaining a result of applying a wavelet-based JPEG-2000 compression algorithm to an original image according to an embodiment of the present invention. The results of applying the JPEG-2000 compression algorithm with reference to FIG. 1 will be described below.

The present invention relates to a JPEG-2000 image compression used in an image compression algorithm in digital cinema, and relates to a tile structure and a coding / decoding method for an 8K-level digital cinema service. The present invention provides a method for an 8K digital cinema service compatible with existing 2K and 4K digital cinema services.

The present invention also provides a multiple file input method, a data compression method, and a data file format for large-capacity data processing. FIG. 1 shows a result of applying a wavelet-based JPEG-2000 compression algorithm to an original image. When a compression algorithm is applied to a 4K image, three 2K images (LL) and two 2K high frequency images (HL, LH, HH) do. As can be seen from FIG. 1, LL images differ only in size and size.

When the Haar wavelet transform is applied to separate the 4K image into low frequency components and high frequency components, LL (low-low) and 3 high-frequency regions LH (low-high), HL (high-low) and HH high-high element frame. Each element frame is reduced to one-quarter the size of the input image frame.

2 is a conceptual diagram illustrating a data structure for a digital cinema 4K service according to an embodiment of the present invention. The data structure for the digital cinema 4K service will now be described with reference to FIG.

Each compressed frame of the 2K distribution has three tile parts and each tile part can contain all the data of one color component. Each compressed frame for 4K distribution has six tile parts, and the first three tile parts may each contain all the data needed to decode one 2K color component. The next three tile parts may contain all the data needed to decode the 4K color component.

3 is a flowchart illustrating a digital image encoding method and its detailed steps according to an embodiment of the present invention. The digital image encoding method will be described with reference to FIG.

A digital image encoding method is a digital image encoding method comprising: a step (S310) of dividing a picture into a plurality of divided frames; a step (S310) of dividing a picture into a plurality of divided frames; A step S330 of extracting a lowest frequency element frame having the lowest frequency band among a plurality of elementary frames, a step S330 of generating a plurality of elementary frames, And combining the frames to generate a low-resolution picture having a lower resolution than the picture (S340).

The dividing step S310 can recursively or iteratively divide a picture until a plurality of divided frames become lower than a predetermined resolution. The step of generating a plurality of element frames (S320) may generate a plurality of element frames by performing transform coding on each of the plurality of divided frames. Furthermore, the transcoding may be a wavelet transform.

Here, recursive means to call its own routine again in a routine, or to use a routine that is called again by the subroutine that it calls to hold the progress. This type of processing method consists of several steps, which are related to the tree structure. On the other hand, iterative execution does not call itself, but continues to execute the same process until a certain condition is satisfied. The reason why it is repeated until it becomes lower than the predetermined resolution is to reduce the burden of the calculation due to the wavelet transformation.

4 is an exemplary diagram for explaining a digital image encoding method according to an embodiment of the present invention. The division of the 8K digital image will be described with reference to FIG.

To encode an 8K image, an 8K image can be first divided into four 4K images. Since 8K image is divided into 4 4K contents, it can be divided into four 4K images in DCDM (Digital Cinema Distribution Master) generation process instead of storing one 8K image.

5 is an exemplary diagram for explaining a result of applying a compression algorithm to each divided frame according to an embodiment of the present invention. The result of applying the compression algorithm will be described with reference to FIG.

According to the present invention, the Digital Cinema JPEG-2000 compression algorithm can be applied to each of the four divided frames. 5 shows a result image obtained by applying a compression algorithm to divided frame regions. The image after applying the JPEG-2000 compression algorithm to each of the four frame regions divided in FIG. 4 can be confirmed. Each image after applying the JPEG-2000 compression algorithm can be configured to include one LL element frame and three high frequency element frames.

FIG. 6 is an exemplary diagram for explaining a result of application of a minimum frequency component frame extraction and deblocking filter according to an embodiment of the present invention. Referring to FIG. Referring to FIG. 6, the result of application of the lowest frequency element frame extraction and deblocking filter will be described below.

The digital image encoding method may further include a step (S350) of applying a deblocking filter to the boundary between the lowest frequency element frames constituting the picture having the lower resolution.

6, a new 4K image can be constructed by extracting LL band data A_LL0, B_LL0, C_LL0, and D_LL0 in four divided frame regions converted using JPEG-2000 shown in FIG. 5 .

In addition, a deblocking filter can be selectively applied to prevent errors that may occur due to screen reconstruction after the screen division. Since the deblocking filter is applied, it is possible to eliminate noise such as a staircase that may occur at the interface. The JPEG-2000 algorithm applied in the existing digital cinema can be applied to the newly constructed 4K image.

7 is a conceptual diagram illustrating a data structure for a digital cinema 8K service according to an embodiment of the present invention. The data structure for Digital Cinema 8K service will be described with reference to FIG.

The compressed data for the 4K image generated by the method shown in FIG. 6 can be stored in the same format as the existing digital cinema. Referring to FIG. 7, each compressed frame for 8K distribution according to the present invention may have nine or more tile parts.

The first three tile parts may each contain all the data needed to decode one 2K color component. The next three tile parts may contain all the data needed to decode the 4K color component.

The last tile portion may contain all the data needed to decode the 8K color component. A_HL0, A_LH0, A_HH0, B_HL0, B_LH0, B_HH0, C_HL0, C_LH0, C_HH0, D_HL0, D_LH0, D_HH0 consist of one tile A tile composed of A_HL0, A_LH0, and A_HH0, a tile composed of B_HL0, B_LH0, and B_HH0, a tile consisting of C_HL0, C_LH0, and C_HH0, and a tile composed of D_HL0, D_LH0, and D_HH0 ≪ / RTI > tiles.

FIG. 8 is a block diagram for explaining a digital image encoding apparatus 10 and its components according to an embodiment of the present invention. The digital image encoding apparatus 10 will now be described with reference to FIG.

An apparatus for encoding a digital image, the apparatus comprising: a frame dividing unit (100) for dividing a picture into a plurality of divided frames; a plurality of element frames for each of a plurality of divided frames A lowest frequency element frame extracting unit 300 for extracting a lowest frequency element frame having the lowest frequency band among a plurality of elementary frames; And an element frame combining unit 400 for generating a low-resolution picture having a low resolution.

The frame dividing unit 100 can divide a picture recursively or repeatedly until a plurality of divided frames become lower than a predetermined resolution. The element frame generation unit 200 can generate a plurality of element frames in which each of the plurality of divided frames is transform-encoded and compressed. Furthermore, the transcoding may be a wavelet transform.

The digital image coding apparatus 10 may further include a deblocking filter unit 500 for applying a deblocking filter to a boundary between the lowest frequency element frames constituting a picture having a low resolution .

The description of the digital image coding apparatus 10 and the detailed constituent elements has been described in the description of the digital image coding method described above and is not described in duplicate. However, the digital image encoding apparatus 10 and its constituent elements are logically distinguishable elements, but do not mean that the physical positions are different from each other. That is, for example, the constituent elements of the digital image encoding apparatus 10 may be physically located at the same physical positions.

The decoding method according to the present invention for the 8K digital cinema service can be performed in the reverse order of the above-described encoding method. In summary, the present invention provides a coding method for 8K digital cinema services compatible with existing 2K and 4K digital cinema services.

The present invention also provides a multiple file input method, a data compression method, and a data file format for large capacity data processing. According to the configuration of the present invention as described above, since it supports backward compatibility with existing 2K and 4K digital cinema systems, 2K or 4K screening can be performed when reproducing the 8K contents presented in the existing system.

Although some aspects have been described in terms of a method, it is evident that these aspects represent a description of the corresponding apparatus, wherein the steps of the method correspond to the apparatus. According to certain implementation requirements, embodiments of the invention may be implemented in hardware or software. Embodiments of the present invention may be implemented as program code, a computer program product having program code that is operative for performing one of the methods.

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 intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

10: Digital image encoding apparatus 100: Frame division unit
200: Element frame generation unit
300: lowest frequency element frame extracting unit
400: element frame coupling unit 500: deblocking filter unit

Claims (1)

An encoding method for a digital video, the method comprising:
Comprising: dividing a picture into a plurality of divided frames;
Generating a plurality of element frames for each of the plurality of divided frames;
Extracting a lowest frequency element frame having the lowest frequency band among the plurality of elementary frames; And
And combining the lowest frequency element frames of each of the plurality of divided frames to generate a low-resolution picture having a lower resolution than the picture.

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