WO2004093463A1 - Method of compressing moving pictures - Google Patents

Method of compressing moving pictures Download PDF

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Publication number
WO2004093463A1
WO2004093463A1 PCT/KR2004/000754 KR2004000754W WO2004093463A1 WO 2004093463 A1 WO2004093463 A1 WO 2004093463A1 KR 2004000754 W KR2004000754 W KR 2004000754W WO 2004093463 A1 WO2004093463 A1 WO 2004093463A1
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WO
WIPO (PCT)
Prior art keywords
block
sub
similar
error
blocks
Prior art date
Application number
PCT/KR2004/000754
Other languages
French (fr)
Inventor
Young-Cheul Wee
Original Assignee
I-Master Co., Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by I-Master Co., Ltd filed Critical I-Master Co., Ltd
Publication of WO2004093463A1 publication Critical patent/WO2004093463A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
    • H04N19/99—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals involving fractal coding

Definitions

  • the present invention relates, in general, to a method of compressing moving pictures and, more particularly, to a method of compressing moving pictures, which does not increase compression time though using fractal compressing, and considerably reduces the amount of data of a moving picture to be compressed.
  • DCT Compression Transform
  • an i-th frame to be compressed is divided into a plurality of blocks without overlapping, a previous (i-l)-th frame is searched for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of the blocks, the error between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n), that is, the difference between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n), is calculated, and DCT compression is performed based on the calculated difference.
  • an object of the present invention is to provide a method of compressing moving pictures, which compresses sub-blocks of a sufficiently small size using special fractal compression while storing the positions of similar blocks having small errors and having been searched for in a previous frame, and dividing each of blocks having large errors into four sub-blocks and calculating errors, so that compressing time is not considerably increased and the amount of data of a moving image to be compressed is considerably reduced, compared to general fractal compression.
  • the present invention provides a method of compressing moving pictures, including the first step of searching a previous (i-l)-th frame for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of blocks into which an i- th frame is divided without overlapping; the second step of determining whether the error between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n) falls within a critical range; the third step of storing only the position of the similar block(k, 1, n) without Discrete Cosine Transform (DCT) compression if the error falls within the critical range; the fourth step of dividing the block Ri(p, q, n) into four sub-blocks if the error deviates from the critical range, and setting an inherit flag to 1 if the error between each of the sub-blocks and a block of the previous frame most similar to the sub-block falls within the critical range, and searching for a sub-block
  • DCT Discrete Cosine
  • FIG. 1 is a view illustrating a conventional method of compressing moving pictures
  • FIG. 2 is a view illustrating fractal compression according to the present invention.
  • FIG. 3 is a flowchart illustrating a method of compressing moving pictures according to the present invention.
  • An i-th frame to be compressed is divided into a plurality of blocks without overlapping, and a previous (i-l)-th frame is searched for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of the blocks.
  • the position of the similar block is stored. If it is determined that the calculated error deviates from the critical error range, the block Ri(p, q, n) is divided into four sub- blocks. Thereafter, if the error between each of the sub-blocks and a block of the previous frame most similar to the sub-block falls within the critical range, an inherit flag is set to 1 ; whereas if the error between each of the sub-blocks and the block of the previous frame most similar to the sub-block deviates from the critical range, a sub- block most similar to the sub-block and the above-described steps are repeatedly performed based on an allowable error between the sub-block and the similar sub- block.
  • the sub-block is compressed using special fractal compression.
  • the reason why the fractal compression is used when the size of a sub- block is sufficiently small, like a 22 size, is to utilize the advantage of the fractal compression in which, in the case where the size of a block is sufficiently small, the quality of an image is sufficiently good in terms of visibility even though the values of variables used for a search range and conversion are considerably limited.
  • a high compression ratio can be maintained by limiting the range, in which a current frame is searched for a block most similar to a sub-block R of a 22 size, to a four 44 blocks including the sub-block R in a quadrant, limiting a contrast value to 0.75 and 0.5, and limiting a brightness value to four bits through quantization.
  • the total bits of an image compressed by the above-described fractal compression include two bits for the position thereof, one bit for the contrast thereof and four bits for the brightness thereof. Accordingly, a compression ratio of 32/7 always is guaranteed, and a higher compression ratio can be obtained if entropy coding is performed on compressed code.
  • an image block of a 44 size is directly compressed using fractal compression, 6 bits for the position thereof, 3 or more bits for the contrast thereof and 7 or more bits for the brightness thereof are required for the obtainment of a better restored image, so that at least 16 bits are required.
  • a block of a 44 size is divided into blocks of a 22 size and the blocks are compressed using fractal compression, blocks of a previous frame similar to about 2 blocks of a 22 size can be used, so that about 18 bits, including 27 bits for two 22 fractals and 4 bits for a flag, are used. If entropy coding is applied to this, the image can be compressed into 16 or less bits.
  • the present invention provides a method of compressing moving pictures, which compressing sub-blocks of a sufficiently small size using special fractal compression while storing the positions of similar blocks having small errors and having been searched for in a previous frame, and dividing each of blocks having large errors into four sub-blocks and calculating errors, so that the data of an image to be compressed can be considerably reduced and a compressing speed faster than that of general fractal-based compression can be achieved.
  • the compressing method of the present invention can improve a compression ratio and compressing time, compared to a conventional moving picture compressing method based on DCT compressing.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)
  • Compression Of Band Width Or Redundancy In Fax (AREA)

Abstract

A method of compressing moving pictures includes the first step of searching a previous (i-1)-th frame for block Ri-1(k,1, n) most similar to each Ri(p, q, n) of blocks into which an i-th frame is divided. Thereafter, it is determined whether the error between the block Ri(p, q, n) and the similar block Ri-1(k,1, n) falls within a critical range. If the error falls within the critical range, only the position of the similar block(k, 1, n) is stored without discrete cosine transform compression. If the error deviates from the critical range, the block Ri(p, q, n) is divided into four sub-blocks. If the error between each of the sub-blocks and a similar block falls within the critical range, an inherit flag is set to 1. If the error between the sub-block and the similar block deviates from the critical range, a sub-block most similar to the sub-block is searched for and the above-described steps are repeatedly performed based on the allowable error. If the sub-block is of a 22 size, the sub-block is compressed by fractal compression.

Description

Description
METHOD OF COMPRESSING MOVING PICTURES
Technical Field
[1] The present invention relates, in general, to a method of compressing moving pictures and, more particularly, to a method of compressing moving pictures, which does not increase compression time though using fractal compressing, and considerably reduces the amount of data of a moving picture to be compressed.
Background Art
[2] A conventional method of compressing moving pictures based on Discrete
Compression Transform (DCT) compression is described with reference to FIG. 1 below.
[3] In the conventional moving picture compressing method, an i-th frame to be compressed is divided into a plurality of blocks without overlapping, a previous (i-l)-th frame is searched for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of the blocks, the error between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n), that is, the difference between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n), is calculated, and DCT compression is performed based on the calculated difference.
[4] However, the conventional moving picture compressing method has the following disadvantages.
[5] In the case where the edges of an image frame to be compressed have movements other than a translation, many edges are exhibited in the difference Ri(p, q, n)-Ri-l(k, 1, n) between sampling block Ri(p, q, n) and similar block Ri-l(k, 1, n). Furthermore, the compression ratio of the DCT compression is reduced compared to those of other types of compressions (for example, wavelet compression, fractal compression, etc.) when many edges exist.
[6] Accordingly, moving picture compressing methods using DCT compression, such as MPEG2, MPEG4, H261 and H26L, are problematic in that the compression ratios thereof are reduced when there are many movements.
[7] There are the cases where general fractal compression is used to solve the above- described problems. The general fractal compression is problematic in that, in the case where complicated conversion is used to perform a search for a similar block, excessive time is required and a compression ratio is reduced by the amount of information required for the complicated conversion thereof. Disclosure of Invention Technical Problem
[8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of compressing moving pictures, which compresses sub-blocks of a sufficiently small size using special fractal compression while storing the positions of similar blocks having small errors and having been searched for in a previous frame, and dividing each of blocks having large errors into four sub-blocks and calculating errors, so that compressing time is not considerably increased and the amount of data of a moving image to be compressed is considerably reduced, compared to general fractal compression.
[9] In order to accomplish the above object, the present invention provides a method of compressing moving pictures, including the first step of searching a previous (i-l)-th frame for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of blocks into which an i- th frame is divided without overlapping; the second step of determining whether the error between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n) falls within a critical range; the third step of storing only the position of the similar block(k, 1, n) without Discrete Cosine Transform (DCT) compression if the error falls within the critical range; the fourth step of dividing the block Ri(p, q, n) into four sub-blocks if the error deviates from the critical range, and setting an inherit flag to 1 if the error between each of the sub-blocks and a block of the previous frame most similar to the sub-block falls within the critical range, and searching for a sub-block most similar to the sub-block and repeatedly performing the above-described steps based on the allowable error between the sub-block and the similar sub-block, if the error between each of the sub-blocks and the block of the previous frame most similar to the sub- block deviates from the critical range; and the fifth step of compressing the sub-block by fractal compression having a considerably limited search range and performing considerably limited conversion if the sub-block is of a 22 size. Brief Description of the Drawings
[10] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
[11] FIG. 1 is a view illustrating a conventional method of compressing moving pictures;
[12] FIG. 2 is a view illustrating fractal compression according to the present invention; and
[13] FIG. 3 is a flowchart illustrating a method of compressing moving pictures according to the present invention.
Mode for Invention
[14] Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.
[15] With reference to FIGs. 2 and 3, a preferred embodiment of the present invention is described below.
[16] An i-th frame to be compressed is divided into a plurality of blocks without overlapping, and a previous (i-l)-th frame is searched for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of the blocks.
[17] Thereafter, the error between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n) is calculated, and then it is determined whether the calculated error falls within a critical error range.
[18] If it is determined that the calculated error falls within the critical error range, the position of the similar block is stored. If it is determined that the calculated error deviates from the critical error range, the block Ri(p, q, n) is divided into four sub- blocks. Thereafter, if the error between each of the sub-blocks and a block of the previous frame most similar to the sub-block falls within the critical range, an inherit flag is set to 1 ; whereas if the error between each of the sub-blocks and the block of the previous frame most similar to the sub-block deviates from the critical range, a sub- block most similar to the sub-block and the above-described steps are repeatedly performed based on an allowable error between the sub-block and the similar sub- block.
[19] In the meantime, if a sub-block is of a sufficiently small size, more particularly, a
22 size, the sub-block is compressed using special fractal compression.
[20] In this case, the reason why the fractal compression is used when the size of a sub- block is sufficiently small, like a 22 size, is to utilize the advantage of the fractal compression in which, in the case where the size of a block is sufficiently small, the quality of an image is sufficiently good in terms of visibility even though the values of variables used for a search range and conversion are considerably limited.
[21] That is, a high compression ratio can be maintained by limiting the range, in which a current frame is searched for a block most similar to a sub-block R of a 22 size, to a four 44 blocks including the sub-block R in a quadrant, limiting a contrast value to 0.75 and 0.5, and limiting a brightness value to four bits through quantization.
[22] The total bits of an image compressed by the above-described fractal compression include two bits for the position thereof, one bit for the contrast thereof and four bits for the brightness thereof. Accordingly, a compression ratio of 32/7 always is guaranteed, and a higher compression ratio can be obtained if entropy coding is performed on compressed code.
[23] In accordance with the present invention, since only four domain blocks are searched and fractal compression is performed with respect to the sufficiently small sub-block of a 22 size, compression can be performed faster than fractal compression with respect to a block of the size larger than a 22 size.
[24] If an image block of a 44 size is directly compressed using fractal compression, 6 bits for the position thereof, 3 or more bits for the contrast thereof and 7 or more bits for the brightness thereof are required for the obtainment of a better restored image, so that at least 16 bits are required. If a block of a 44 size is divided into blocks of a 22 size and the blocks are compressed using fractal compression, blocks of a previous frame similar to about 2 blocks of a 22 size can be used, so that about 18 bits, including 27 bits for two 22 fractals and 4 bits for a flag, are used. If entropy coding is applied to this, the image can be compressed into 16 or less bits. Furthermore, if the similar block of a previous frame is used as the block of a 22 size or fractal compression is performed on a current frame, a better restored image can be obtained and compressing time can be considerably reduced, compared to the case where a block of a 44 size is directly compressed using fractal compression.
Industrial Applicability
[25] As described above, the present invention provides a method of compressing moving pictures, which compressing sub-blocks of a sufficiently small size using special fractal compression while storing the positions of similar blocks having small errors and having been searched for in a previous frame, and dividing each of blocks having large errors into four sub-blocks and calculating errors, so that the data of an image to be compressed can be considerably reduced and a compressing speed faster than that of general fractal-based compression can be achieved. Accordingly, the compressing method of the present invention can improve a compression ratio and compressing time, compared to a conventional moving picture compressing method based on DCT compressing.
[26] Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

Claims
[1] 1. A method of compressing moving pictures, comprising: the first step of searching a previous (i-l)-th frame for block Ri-l(k, 1, n) most similar to each Ri(p, q, n) of blocks into which an i-th frame is divided without overlapping; the second step of determining whether an error between the block Ri(p, q, n) and the similar block Ri-l(k, 1, n) falls within a critical range; the third step of storing only a position of the similar block(k, 1, n) without Discrete Cosine Transform (DCT) compression if the error falls within the critical range; the fourth step of dividing the block Ri(p, q, n) into four sub-blocks if the error deviates from the critical range, and setting an inherit flag to 1 if an error between each of the sub-blocks and a block of the previous frame most similar to the sub-block falls within the critical range, and searching for a sub-block most similar to the sub-block and repeatedly performing the above-described steps based on an allowable error between the sub-block and the similar sub-block, if the error between each of the sub-blocks and the block of the previous frame most similar to the sub-block deviates from the critical range; and the fifth step of compressing the sub-block by fractal compression having a considerably limited search range and performing considerably limited conversion if the sub-block is of a 22 size.
[2] 2. The method according to claim 1, wherein the fifth step is performed in such a way that a range, in which a current frame is searched for a block most similar to the sub-block of a 22 size, is limited to a four 44 blocks including the sub-block R in a quadrant, a contrast value is limited to 0.75 and 0.5, and a brightness value is limited to four bits though quantization.
PCT/KR2004/000754 2003-04-18 2004-03-31 Method of compressing moving pictures WO2004093463A1 (en)

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KR10-2003-0024677 2003-04-18
KR1020030024677A KR20040090743A (en) 2003-04-18 2003-04-18 Moving picture compression method

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KR102114390B1 (en) 2017-08-30 2020-05-25 이세희 Method to improve compression date for moving picture

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5923376A (en) * 1996-03-29 1999-07-13 Iterated Systems, Inc. Method and system for the fractal compression of data using an integrated circuit for discrete cosine transform compression/decompression

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5923376A (en) * 1996-03-29 1999-07-13 Iterated Systems, Inc. Method and system for the fractal compression of data using an integrated circuit for discrete cosine transform compression/decompression

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"A review of the fractal image coding literature", IEEE TRANS. ON IMAGE PROCESSING, vol. 8, no. 12, December 1999 (1999-12-01) *
"Adaptive approximative nearest neighbor search for fractal image compression", IEEE TRANS. ON IMAGE PROCESSING, vol. 11, no. 6, June 2002 (2002-06-01) *
"An efficient fractal image-coding method using interblock correlation search", IEEE TRANS. ON CSVT, vol. 11, no. 1, January 2001 (2001-01-01) *

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