WO2007085233A2 - Procédés de compression de données d'hologrammes vidéo produits par ordinateur - Google Patents

Procédés de compression de données d'hologrammes vidéo produits par ordinateur Download PDF

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Publication number
WO2007085233A2
WO2007085233A2 PCT/DE2007/000108 DE2007000108W WO2007085233A2 WO 2007085233 A2 WO2007085233 A2 WO 2007085233A2 DE 2007000108 W DE2007000108 W DE 2007000108W WO 2007085233 A2 WO2007085233 A2 WO 2007085233A2
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WO
WIPO (PCT)
Prior art keywords
scene
data compression
values
slm
points
Prior art date
Application number
PCT/DE2007/000108
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German (de)
English (en)
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WO2007085233A3 (fr
Inventor
Norbert Leister
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Seereal Technologies S.A.
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Publication date
Application filed by Seereal Technologies S.A. filed Critical Seereal Technologies S.A.
Publication of WO2007085233A2 publication Critical patent/WO2007085233A2/fr
Publication of WO2007085233A3 publication Critical patent/WO2007085233A3/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/08—Synthesising holograms, i.e. holograms synthesized from objects or objects from holograms
    • 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
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2294—Addressing the hologram to an active spatial light modulator
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H2210/00—Object characteristics
    • G03H2210/40—Synthetic representation, i.e. digital or optical object decomposition
    • G03H2210/45—Representation of the decomposed object
    • G03H2210/454—Representation of the decomposed object into planes

Definitions

  • the invention relates to a method for data compression of a sequence of computer-generated video holograms, CGVH.
  • CGVH In contrast to classical holograms, which are stored as interference patterns in a photographic or otherwise manner, CGVH exist as a result of calculating discrete hologram data from sequences of a three-dimensional scene and storing them with, for example, electronic means, an electronic storage medium of a computer, graphics processor, graphics adapter or in similar hardware components.
  • the modulated interference-capable light propagates in the space in front of the eyes of a beholder as a complex, two-dimensional, controllable by the amplitude values of the optical wavefront for the reconstruction of a three-dimensional scene.
  • the coding of a light modulator matrix with the complex hologram values of the computer-generated video holograms causes the pixel-modulated wave field emanating from the display screen to reconstruct the desired three-dimensional scene by interfering with the space.
  • Hardware components and computational methods can achieve application in key areas.
  • the calculated hologram data encode a light modulator matrix which influences interference-capable light in amplitude and phase, in short called complex-valued or simply amplitude-controlled electronically.
  • the light modulator matrix SLM is referred to as a means for controlling the intensity, color and / or phase by switching, blanking or modulating light beams of one or more independent light sources.
  • a holographic display usually contains a matrix of controllable pixels, wherein the pixels change the amplitude and / or phase of transmitted light and thus reconstruct the object points.
  • An SLM comprises such a matrix.
  • the SLM can be discretely listed as an acousto-optical modulator AOM or also continuously.
  • An embodiment for the reconstruction of the holograms by amplitude modulation can be achieved with a liquid crystal display (LCD).
  • the present invention also relates to other controllable devices for modulating sufficiently coherent light to a lightwave front or to a lightwave relief.
  • pixel includes a controllable hologram pixel of the SLM, represents a discrete value of the hologram point, and is individually addressed and controlled. Each pixel represents a hologram point of the hologram.
  • a pixel means an individually controllable display pixel.
  • a pixel is an individually controllable micromirror or a small group thereof.
  • a pixel includes an imaginary region that represents the hologram point.
  • a pixel is usually subdivided into several subpixels which represent the primary colors.
  • the encoded hologram is the transformation of the 3D scene.
  • a transformation becomes widespread in this document interprets and includes any mathematical or computer-aided method that represents or approximates a transformation and is based on Maxwell's wave equation.
  • the Fourier transformation which is used with particular preference, can be implemented simply in terms of programming technology and, moreover, can be realized very precisely by optical systems.
  • the holographic representation In contrast to the presentation of 2D video data, the holographic representation generates the lightwave front of 3D objects or 3D scenes through the interference and superposition of coherent lightwaves. In doing so, the hologram values required to contribute to the reconstruction of each point of the object are determined for each pixel. A single pixel thus contributes with the correspondingly modulated light to the representation of the entire scene. Conversely, the information about each scene point is distributed throughout the hologram.
  • Compression techniques store the digital hologram prior to application of a Burrows-Wheeler coding algorithm in intermediate coding of separate data streams for real and imaginary components.
  • Lossy compression techniques are based on subsampling, quantization, and discrete Fourier transform.
  • the amount of data required per video frame for storage or processing should be significantly reduced.
  • the resulting hologram data should allow the use of known, as simple as possible or standardized data compression method and thereby achieve such high compression rates that a resource-saving and economical application is possible.
  • the method is for data compression of a sequence of computer generated
  • Video holograms which, starting from an image content of image data with
  • Depth information is encoded as complex hologram values.
  • SLM provided with a variety of pixels.
  • a modulated wave field is generated by the SLM, which is controlled with complex hologram values, and the desired real or virtual three-dimensional scene is reconstructed by interferences in space.
  • observer windows are generated in truncated pyramidal reconstruction spaces.
  • the windows are close to the viewer's eye and can be tracked with known position detection and tracking the current viewer position.
  • the area in which a viewer sees a scene is given by a truncated pyramidal reconstruction space, the so-called frustrum, which extends from the SLM to the viewer window.
  • the truncated pyramid can be replaced by a pyramid in an approximation because the observer window is much smaller than the SLM.
  • the viewer windows are dimensioned so small that, in an inverse view, changes in restricted areas of the image content to be encoded only in limited areas the SLM, so in a few pixels, cause changes in the complex hologram values.
  • a phase matrix with defined phase values is defined.
  • the random values of the phases are chosen to be equally distributed, with further distributions possibly being conceivable for further image enhancement.
  • a phase matrix of the same dimension is defined.
  • the second method step involves determining the visibility of the scene.
  • the scene is structured into visible object points.
  • the object of the scene within the frustrum is structured with a three-axis discretization and, starting from the observer window, the visible object points of the scene are determined. In this calculation, the scene is cut into a plurality of virtual planes parallel to the SLM.
  • the cut planes are discretized into an equivalent screening with m object points per line and n object points per column.
  • the sectional planes lie within the pyramidal frustrum and are advantageously discretized into the same number of n * m points despite the different dimensions.
  • areas of the scene that are closer to the viewer are correspondingly finer discetized than areas that are far away from the viewer.
  • it is checked for all points whether they are already covered by a closer point to the viewer.
  • further embodiments are explained.
  • the method is based on the idea that a more efficient compression of a sequence can be achieved, provided object points whose amplitude does not change retain identical phase values in successive pictures of a sequence.
  • the phase matrix determined in the first step is used for each hologram of the sequence to be calculated.
  • the visible object points are based on the same defined phase value in a transformation to complex hologram values independently of the respective depth information of a respective object point and in each image of the sequence.
  • an object point remains the same in successive pictures, it automatically gets the same complex hologram value in each picture in the sequence. If an object point is omitted, another point in the next image of the sequence may get the phase value that the first object point previously had instead. The phase values once assigned to an object point are no longer changed. Unmodified object points imply unchanged complex hologram values.
  • the inventive method thus allows efficient data compression of the sequence and also allows the use of simple and faster compression methods, as they can be realized for example by the group of differential image methods. The application of further compression methods is also possible.
  • the examples are based on means for representing computer generated
  • the virtual observer windows cover the pupils of the observer and are tracked with known position detection and tracking devices of the current observer position.
  • a virtual truncated pyramid-shaped observer area is spanned, with the SLM forming the base area and the observer window forming the top.
  • the truncated pyramid can be regarded as a pyramid. The observer sees through the observer window in the direction of the SLM and, in the observer window, perceives the wavefront as true, which represents the scene, sees the object reconstructed in the observer area of the scene.
  • the computer-generated video holograms are reconstructed with a hologram display, which the applicant has already described in the publication PCT / EP 2005 009604 "Method and device for Encoding and Reconstructing Computer Generated Video Holograms ".
  • Viewer window that wave front is generated which would represent or represent the scene.
  • the observer windows are dimensioned so small that, in an inverse view, changes in restricted areas of the image content to be encoded cause changes in the complex hologram values only in restricted areas of the SLM, that is to say in a few pixels.
  • the following embodiment will be further explained with an SLM with m pixel rows and n pixel columns.
  • the SLM is here an LCD display, which modulates sufficiently modulated light in the amplitude values.
  • a phase matrix with phase values is determined.
  • the phase matrix comprises equal to the SLM m rows and n columns, with the phase values chosen to be equally distributed in the row and column directions.
  • a second method step relates to the discretization of the object of the scene and the determination of visible object points of the scene.
  • the determination of the visibility is carried out according to the position of the viewer, ie the viewing direction through the small observer window on the object of the scene and according to the depth information of the scene points.
  • the object is cut in planes parallel to the SLM.
  • the object is scanned into points within the observer area, analogous to the resolution of the SLM in n-rows and m-columns as well.
  • the points in the visibility level are now checked to see if a new point is already covered by a previous point.
  • the assigned area to the individual grid points changes in proportion to the distance from the viewer window.
  • the aim of the visibility determination is the determination or selection of m times n visible points that now discretize the visible object.
  • the step size between the cutting planes is equidistant in simple embodiments, but can be adjusted individually to the depth information of the scene.
  • the intersection with the object is determined in each section plane and the visibility of these boundary points is checked as to whether they are already obscured by a point closer to the viewer.
  • the visibility of the object points is determined by edge points, which are determined as a section of the plane with the edge of the object.
  • a sampled scene point in row i and column j of a more distant level lies hidden behind the element in row i and column j of a closer level for the eye in the center of the viewing window. In the calculation, it is thus checked whether a scene point i, j is already present in a plane closer to the eye and possibly eliminated.
  • the visible object points are based on the same defined phase value in a transformation to complex hologram values independently of the respective depth information of a respective object point and in each image of the sequence. If an object point remains the same in successive pictures, it automatically gets the same complex hologram value in each picture in the sequence.
  • An application of differential image compression allows efficient reduction of the data size of the sequence.
  • the viewer windows in a hologram display according to document WO 2004/044659 are generated by temporal multiplexing.
  • Video hologram and device for the reconstruction of video holograms are generated by temporal multiplexing.
  • the inventive method for data compression can be applied to both image views.
  • An additional reduction in the amount of data stored can be achieved if, for example, the different perspective for areas in the background of the scene is neglected and the views are assumed to be the same.
  • the obtained hologram values generated in the two embodiments are converted into Burckhardt coding or two-phase coding.
  • the complex value is represented by three gray levels discretized in the values 0 to 255, the one represented by 255
  • Value represents the maximum achievable component value.
  • the maximum value is selected and initialized at the beginning of data compression.
  • the maximum value occurring in a video sequence, or the corresponding quantile of a normal distribution, is not known at the beginning of the coding.
  • a simple solution is to cut off the peak values that exceed the maximum value and replace them with the maximum value.
  • the maximum value corresponds to a corresponding quantile of the normal distribution and allows a corresponding statistical description.
  • the compression device for carrying out the data compression comprises at least memory means for storing the phase matrix, arithmetic means for generating the phase values of the phase matrix, arithmetic means for structuring the scene into visible object points with corresponding storage means, arithmetic means for coding the visible object points on the basis of the phase values to complex hologram values and further storage means, which provides at least one subsequence as input data for the data compression.
  • Applicant's document DE 10 2004 063 838 describes a method for calculating computer-generated video holograms. It assigns objects with complex amplitude values of a three-dimensional scene in grid points of parallel, virtual cutting planes to define a separate object data set with discrete amplitude values in grid points for each cutting plane and to calculate a holographic coding for a light modulator matrix of a hologram display from the image data sets.
  • the document describes a signal processing device for carrying out the method. The method steps are implemented by the corresponding elements of the signaling device and include:
  • this signal device for coding is constructed in a simple embodiment.
  • the use of the cutting planes also offers the possibility of structuring the scene, as explained in the first exemplary embodiment, into visible object points.
  • the coding is extended by assigning the phase values of the phase matrix to the visible object points as explained in the preceding exemplary embodiments.
  • the generated complex holograms are separated into three- or two-phase components and efficiently compressed, for example, by a differential image method, which is also implemented with corresponding calculation means.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Holo Graphy (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)
  • Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)

Abstract

L'invention concerne des procédés de compression de données d'une séquence d'hologrammes vidéo produits par ordinateur, codés à partir de données d'images comportant des informations de profondeur en tant que valeurs d'hologrammes complexes d'une scène, pour la représentation sur un dispositif de reproduction comportant un modulateur de lumière spatial produisant un champ d'ondes modulé et reconstruisant la scène tridimensionnelle souhaitée, des changements dans des zones limitées du contenu d'images à coder ne provoquant des changements des valeurs d'hologrammes complexes que dans des zones limitées du modulateur de lumière spatial. Le procédé selon l'invention consiste (S1) à définir une matrice de phase comportant des valeurs de phase fixées f(i,j); (S2) à déterminer la visibilité de la scène selon la position d'un observateur et de l'information de profondeur du contenu d'images à coder, la scène étant structurée en points d'objets visibles; et (S3) à coder la scène, la même valeur de phase définie f(i,j) servant de base pour ces points d'objets visibles lors d'une transformation de valeurs d'hologrammes complexes, indépendamment de l'information de profondeur respective, et dans chaque image de la séquence, de telle manière que des points d'objets, inchangés dans des images consécutives, impliquent des valeurs d'hologrammes complexes inchangées et permettent une compression de données de la séquence efficace.
PCT/DE2007/000108 2006-01-24 2007-01-15 Procédés de compression de données d'hologrammes vidéo produits par ordinateur WO2007085233A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102006004299.9 2006-01-24
DE200610004299 DE102006004299A1 (de) 2006-01-24 2006-01-24 Verfahren zur Datenkompression computergenerierter Videohologramme

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WO2007085233A2 true WO2007085233A2 (fr) 2007-08-02
WO2007085233A3 WO2007085233A3 (fr) 2007-09-13

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006066906A1 (fr) * 2004-12-23 2006-06-29 Seereal Technologies Gmbh Procede et dispositif de traitement d'hologrammes video realises par ordinateur

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0880110B1 (fr) * 1997-05-22 2006-11-08 Nippon Telegraph And Telephone Corporation Système d'affichage d'hologrammes génerées par ordinateur
US6900904B1 (en) * 2000-02-04 2005-05-31 Zebra Imaging, Inc. Distributed system for producing holographic stereograms on-demand from various types of source material

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006066906A1 (fr) * 2004-12-23 2006-06-29 Seereal Technologies Gmbh Procede et dispositif de traitement d'hologrammes video realises par ordinateur

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
NAUGHTON T J ET AL: "Three-dimensional imaging, compression, and reconstruction of digital holograms" OPTO-IRELAND 2002: OPTICAL METROLOGY, IMAGING, AND MACHINE VISION 5-6 SEPT. 2002 GALWAY, IRELAND, Bd. 4877, 5. September 2002 (2002-09-05), - 6. September 2002 (2002-09-06) Seiten 104-114, XP002435814 Proceedings of the SPIE - The International Society for Optical Engineering SPIE-Int. Soc. Opt. Eng USA ISSN: 0277-786X *
YOSHIKAWA H ET AL: "HOLOGRAPHIC IMAGE COMPRESSION BY MOTION PICTURE CODING" PROCEEDINGS OF THE SPIE, SPIE, BELLINGHAM, VA, US, Bd. 2652, 29. Januar 1996 (1996-01-29), Seiten 2-9, XP008035887 ISSN: 0277-786X *

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DE102006004299A1 (de) 2007-07-26
TW200812393A (en) 2008-03-01
WO2007085233A3 (fr) 2007-09-13

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