EP0797895A1 - Procede pour coder des images video - Google Patents

Procede pour coder des images video

Info

Publication number
EP0797895A1
EP0797895A1 EP96932760A EP96932760A EP0797895A1 EP 0797895 A1 EP0797895 A1 EP 0797895A1 EP 96932760 A EP96932760 A EP 96932760A EP 96932760 A EP96932760 A EP 96932760A EP 0797895 A1 EP0797895 A1 EP 0797895A1
Authority
EP
European Patent Office
Prior art keywords
blocks
transform
rate
coding
block
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP96932760A
Other languages
German (de)
English (en)
Inventor
Rob Anne Beuker
Hendrik Gemmualdus Jacobus Theunis
Richard Heusdens
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Philips Norden AB
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
Philips Norden AB
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 Koninklijke Philips Electronics NV, Philips Electronics NV, Philips Norden AB filed Critical Koninklijke Philips Electronics NV
Priority to EP96932760A priority Critical patent/EP0797895A1/fr
Publication of EP0797895A1 publication Critical patent/EP0797895A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/189—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding
    • H04N19/19—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding using optimisation based on Lagrange multipliers
    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/119—Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/124—Quantisation
    • H04N19/126—Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/146—Data rate or code amount at the encoder output
    • H04N19/147—Data rate or code amount at the encoder output according to rate distortion criteria
    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • 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
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/124—Quantisation
    • 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
    • H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
    • 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
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding

Definitions

  • the invention relates to a method of encoding video images, comprising the steps of dividing said images into blocks selecting one of a plurality of different coding methods for each of said blocks and encoding said blocks using the selected coding method to obtain coded data for each block.
  • the invention also relates to an arrangement for carrying out said encoding method.
  • a method of encoding Video images as described in the opening paragraph is disclosed in European Patent Application EP-A 0 220 706.
  • transform coding is applied to each block, the block size being variable in response to brightness changes.
  • the blocks are subdivided into smaller blocks so that the mean distortion inside each block does not exceed an allowable value.
  • the method according to the invention is characterized in that the step of selecting the encoding method comprises the determination of that coding method which is optimal in a rate-distortion sense. An optimal compromise between rate and distortion is thereby achieved.
  • the plurality of different coding methods is applied to pixel blocks of equal size.
  • different coding methods are transform coding and fractal coding.
  • the coding methods are all picture transforms, but they are applied to pixel blocks of different block sizes.
  • Transforms used in transform coding are the Discrete Cosine Transform (DCT), the Hadamard transform, the Lapped Orthogonal Transforms (LOT), in particular the Modified LOT (MLOT), all known in the art.
  • DCT Discrete Cosine Transform
  • LOT Lapped Orthogonal Transforms
  • MLOT Modified LOT
  • the statistics of the image to be coded are Gaussian, and that the transform coefficients are uncorrelated.
  • the rate and distortion, on which the selection of the optimal transform type is based can easily be calculated.
  • Fig.1 shows a diagram of a video encoding and transmitting station employing the method according to the invention.
  • Fig.2 shows examples of rate-distortion curves associated with different coding methods.
  • Fig.3 shows a flow chart of steps carried out by a segmentation circuit which is shown in Fig. l.
  • Fig.4 shows a segmentation map of an image indicating the different coding methods applied to different regions of the image.
  • Fig. l shows a diagram of a video encoding and transmitting station employing the method according to the invention.
  • the arrangement receives a video input signal X m .
  • a predicted video signal X pred is subtracted therefrom.
  • the encoder can thus operate in an intraframe mode or a (possibly motion- compensated) interframe mode.
  • the picture to be coded is applied to a segmentation circuit 2 and a transform circuit 3.
  • the segmentation circuit determines, for example in a pre-analysis phase, which transform for a given block is optimal in a rate-distortion sense.
  • the circuit further merges the contiguous blocks subjected to the same transform so as to form regions with the same transform.
  • a "segmentation map" thus created is encoded for transmission or storage by an encoding circuit 4.
  • the segmentation map is further applied to transform circuit 3 so as to indicate which transform is to be carried out during the actual coding phase.
  • the transform coefficients obtained from transform circuit 3 are quantized and lossless coded by a quantizer and entropy coder 5.
  • Quantization and entropy coding are well-known in the art. For example MPEG2-like coding can be used.
  • the coefficients for each transform block are zigzag-scanned.
  • the DC coefficients are quantized using a fixed step size, and encoded differentially.
  • the AC coefficients are adaptively quantized and entropy-coded using a combination of Huffman coding and run-length coding.
  • An end-of-block code is transmitted after the last non-zero AC coefficient of a block.
  • the coded data thus obtained is multiplexed with the encoded segmentation map by a multiplexer 6 and transmitted to a decoder or stored on a storage medium (not shown).
  • the segmentation circuit 2 determines the optimal coding method in a rate-distortion sense.
  • the rate-distortion curve of a given coding method is the collection of rate-distortion pairs (R,D) for different values of an encoding parameter t, e.g. the quantization step size of a transform coder.
  • Fig.2 shows a rate-distortion curve 201 associated with a first coding method Tl and a second rate-distortion curve 202 associated with a second coding method T2.
  • transform coding is applied to pixel blocks of non-equal size.
  • the segmentation circuit 2 determines the optimal block size.
  • c i k is the i-th coefficient of transform block k and t is an encoding parameter, e.g. representative of a quantizer step size.
  • Fig.3 shows a flow chart of steps carried out by segmentation circuit 2.
  • the circuit calculates the operating value of t in such a way that the global rate R(t) equals a required rate R rcf , i.e. such that:
  • Table I shows an example of such a bi-section algoritm in a pseudo-programming language.
  • more efficient algorithms such as Gradient methods, can be used.
  • a step 22 the circuit subjects each pixel block k to a given transform so as to obtain transform coefficients c i k , and calculates the rate R ⁇ t) and distortion D k (t) for said block in accordance with equations (1) and (2), using the value t which was found in step 21.
  • the step 22 is repeated for different block sizes. In the present example, four different transforms are considered: a 2*2 transform Tl , a 4*4 transform T2, an 8*8 transform T3, or a 16*16 transform T4.
  • a step 23 it is checked whether or not all these transforms have been processed.
  • the best transform is selected in a step 24.
  • L the "Lagrangian cost"
  • s the slope of the rate-distortion curve in accordance with equation (3).
  • the selected transform type is stored in the segmentation map, which defines a grid determined by the smallest block size.
  • Fig.4 shows an illustrative example of such a segmentation map.
  • the segmentation map is applied to transform circuit 3 so as to indicate which transform type is to be used during the phase of really encoding the image.
  • the rate R k (t) for block k as determined in step 22 may be applied to a bitrate regulation circuit (not shown in Fig. l) so as to actually achieve the rate as determined by the segmentation circuit 2.
  • Bitrate regulation circuits are known in the art.
  • the segmentation map is further applied to encoding circuit 4 for transmission to the decoder or storage on a storage medium.
  • a practical encoding strategy is to assign a unique number to the different transform types.
  • the transform number is lossless encoded, using DPCM.
  • the resultant differences are transmitted by a combination of Huffman coding and run-length coding.
  • An alternative embodiment for calculating the rate-distortion pairs is to actually encode (transform, quantize, Huffman and run-length coding) each potential image block k.
  • the above assumptions the statistics of the image to be coded are Gaussian, and the transform coefficients are uncorrelated are not applicable.
  • transforms with equal block sizes can be used in the automatic segmentation, for example Discrete Cosine Transforms, Hadamard transforms, or Lapped Transforms such as the Modified Lapped Orthogonal Transform.
  • a provision in the coding process is required to switch between the different transforms at the contour between regions, while maintaining (near) perfect reconstruction. For example, using linear phase transforms, this can be accomplished by mirroring at the region boundaries.
  • a method of encoding video images is disclosed in which different coding methods are applied to different regions of the image. The image is divided into blocks, and for each block the coding method is selected which is optimal in a rate- distortion sense.
  • transform coding such as DCT or LOT, is applied to all blocks. The block size is selected in accordance with a rate-distortion criterion.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

L'invention concerne un procédé pour coder des images vidéo, dans lequel différents procédés de codage sont appliqués à différentes régions de l'image. L'image est divisée en blocs et le procédé qui est optimal du point de vue débit/distorsion est choisi (2) pour chaque bloc. Dans une forme d'exécution, un codage par transformation (3), par exemple par DCT ou LOT, est appliqué à tous les blocs. La taille du bloc est choisie conformément au critère débit/distorsion.
EP96932760A 1995-10-18 1996-10-17 Procede pour coder des images video Withdrawn EP0797895A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP96932760A EP0797895A1 (fr) 1995-10-18 1996-10-17 Procede pour coder des images video

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP95202819 1995-10-18
EP95202819 1995-10-18
EP96932760A EP0797895A1 (fr) 1995-10-18 1996-10-17 Procede pour coder des images video
PCT/IB1996/001099 WO1997015146A1 (fr) 1995-10-18 1996-10-17 Procede pour coder des images video

Publications (1)

Publication Number Publication Date
EP0797895A1 true EP0797895A1 (fr) 1997-10-01

Family

ID=8220733

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96932760A Withdrawn EP0797895A1 (fr) 1995-10-18 1996-10-17 Procede pour coder des images video

Country Status (3)

Country Link
EP (1) EP0797895A1 (fr)
JP (1) JPH10511532A (fr)
WO (1) WO1997015146A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112203088A (zh) * 2015-09-14 2021-01-08 谷歌有限责任公司 用于非基带信号代码化的变换选择

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EP0938235A1 (fr) * 1998-02-20 1999-08-25 Canon Kabushiki Kaisha Codage et décodage de signal numérique
US6975742B2 (en) * 2000-11-29 2005-12-13 Xerox Corporation Rate-distortion optimization system and method for image compression
US7813473B2 (en) * 2002-07-23 2010-10-12 General Electric Company Method and apparatus for generating temporally interpolated projections
FR2846835B1 (fr) * 2002-11-05 2005-04-15 Canon Kk Codage de donnees numeriques combinant plusieurs modes de codage
EP1439712A1 (fr) 2002-12-17 2004-07-21 Visiowave S.A. Procédé pour la sélection du codec optimal entre des codecs vidéo spatiaux pour un même signal d'entrée
CN100387059C (zh) 2003-02-21 2008-05-07 松下电器产业株式会社 图像解码方法
WO2005013201A1 (fr) * 2003-08-05 2005-02-10 Koninklijke Philips Electronics N.V. Procedes de codage et de decodage video et dispositifs associes
WO2005015501A1 (fr) * 2003-08-12 2005-02-17 Koninklijke Philips Electronics N.V. Procedes de codage et de decodage video et dispositifs correspondants
FR2867327B1 (fr) * 2004-03-04 2006-09-01 Canon Kk Procede et dispositif de codage d'une image
JP4538724B2 (ja) * 2004-08-18 2010-09-08 富士ゼロックス株式会社 パラメータ決定装置、符号化装置、パラメータ決定方法及びそのプログラム
US8270736B2 (en) 2007-09-12 2012-09-18 Telefonaktiebolaget L M Ericsson (Publ) Depth buffer compression
PL2476255T3 (pl) 2009-09-10 2019-03-29 Guangdong Oppo Mobile Telecommunications Corp., Ltd. Techniki przyspieszenia dla zoptymalizowanej kwantyzacji współczynnik-zniekształcenie
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112203088A (zh) * 2015-09-14 2021-01-08 谷歌有限责任公司 用于非基带信号代码化的变换选择
CN112203088B (zh) * 2015-09-14 2023-08-25 谷歌有限责任公司 用于非基带信号代码化的变换选择

Also Published As

Publication number Publication date
WO1997015146A1 (fr) 1997-04-24
JPH10511532A (ja) 1998-11-04

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