EP1245121A2 - Procedes et appareils pour coder et afficher des stereogrammes - Google Patents

Procedes et appareils pour coder et afficher des stereogrammes

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Publication number
EP1245121A2
EP1245121A2 EP00951279A EP00951279A EP1245121A2 EP 1245121 A2 EP1245121 A2 EP 1245121A2 EP 00951279 A EP00951279 A EP 00951279A EP 00951279 A EP00951279 A EP 00951279A EP 1245121 A2 EP1245121 A2 EP 1245121A2
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EP
European Patent Office
Prior art keywords
image
colour
stereogram
component
filter
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Withdrawn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
EP00951279A
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German (de)
English (en)
Inventor
Per Skafte Hansen
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Individual
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Individual
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Publication date
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Publication of EP1245121A2 publication Critical patent/EP1245121A2/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/324—Colour aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/20—Image signal generators
    • H04N13/204—Image signal generators using stereoscopic image cameras
    • H04N13/239—Image signal generators using stereoscopic image cameras using two 2D image sensors having a relative position equal to or related to the interocular distance
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/20—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
    • G02B30/22—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the stereoscopic type
    • G02B30/23—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes of the stereoscopic type using wavelength separation, e.g. using anaglyph techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/20—Image signal generators
    • H04N13/204—Image signal generators using stereoscopic image cameras
    • H04N13/243—Image signal generators using stereoscopic image cameras using three or more 2D image sensors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/332—Displays for viewing with the aid of special glasses or head-mounted displays [HMD]
    • H04N13/334—Displays for viewing with the aid of special glasses or head-mounted displays [HMD] using spectral multiplexing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/363—Image reproducers using image projection screens
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/10—Processing, recording or transmission of stereoscopic or multi-view image signals
    • H04N13/106—Processing image signals
    • H04N13/15—Processing image signals for colour aspects of image signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/10—Processing, recording or transmission of stereoscopic or multi-view image signals
    • H04N13/189—Recording image signals; Reproducing recorded image signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/20—Image signal generators
    • H04N13/257—Colour aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/20—Image signal generators
    • H04N13/286—Image signal generators having separate monoscopic and stereoscopic modes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/332—Displays for viewing with the aid of special glasses or head-mounted displays [HMD]
    • H04N13/337—Displays for viewing with the aid of special glasses or head-mounted displays [HMD] using polarisation multiplexing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/332—Displays for viewing with the aid of special glasses or head-mounted displays [HMD]
    • H04N13/341—Displays for viewing with the aid of special glasses or head-mounted displays [HMD] using temporal multiplexing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/361—Reproducing mixed stereoscopic images; Reproducing mixed monoscopic and stereoscopic images, e.g. a stereoscopic image overlay window on a monoscopic image background
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/365—Image reproducers using digital micromirror devices [DMD]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/398—Synchronisation thereof; Control thereof
    • 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
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/597—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding specially adapted for multi-view video sequence encoding

Definitions

  • the present invention relates to the encoding, or recording, and subsequent displaying and viewing of a stereogram as one colour image for viewing through a pair of filters, the filters transmitting light m the visible spectral range, each with a different transmission profile.
  • Colour encoded stereograms are conventionally known as anaglyphs, although this term m the present context will be reserved for a sub-class of colour-encoded stereograms. This subclass of images contains the vast ma ority of images made with the prior art and will be more precisely defined shortly.
  • the viewing filters must be separating. This word is here chosen to mean that there must be a first range of the visible spectrum transmitted by a first filter and excluded by a second; and a second range of the visible spectrum, not overlapping the first range and transmitted by the second filter and excluded by the first.
  • luminance level dm- age will be used, whenever the intended meaning is that only one channel or colour variable is represented (m the image) .
  • the visual appearance of a luminance level image may or may not be gray. If it is not gray, only one nameable colour (i.e. one hue) is present m it, m varying intensities.
  • the fil- ters will m the present context be called "disjoint" (although the word may have other connotations). Also for convenience, the full range of the visible light can be divided into three: visible light of wavelengths less than 500 nanometers, light m the range from 500 nanome- ters to 600 nanometers, and visible light having wavelengths greater than 600 nanometers.
  • a filter pair for anaglyph viewing can be termed a (1,1) -pair, if each filter transmits light from only one of these three ranges, and a (1,2) -pair if one filter transmits light from only one range, the other from the remaining two.
  • a red-green filter pair is then denoted as a ([1 0 0], [0 1 0])-pa ⁇ r, a red- cyan filter pair as a ([1 0 0], [0 1 l])-pa ⁇ r etc.
  • cyan is complementary to red, the word "cyan” being here used to denote an ideal mixture of green and blue.
  • a red-cyan filter pair is disjoint
  • the numbers 1 and 0 do not literally mean “all” and “none”, respectively, as no physical filter transmits all light m one spectral range and no light m another. Also, where the need arises to balance filters for complementarity m the narrower sense mentioned above, exact numbers would yield ratios appreciable different from 1:1.
  • a stereogram will be said to consist of two part-images, a left and a right. Terms such as “half images” are some- times seen, but it must be kept m mind that the two constituents of a (colour) stereogram are full two- dimensional (colour) images m themselves.
  • the aim of the art is to present a stereogram m such a fashion as to allow the eye-brain system to per- form fusion of colours as well as stereoscopic interpretation, and to eliminate or at least reduce rivalry where it should not appear.
  • the lustre of smooth fabrics, the gloss of polished metals and the glimmer of gems are all perceptive phenomena, produced by rivalry. These, of course, should not be suppressed.
  • a special form of stereoscopic rivalry can only be reduced, not removed: when a specific colour is transmitted by only one of the viewing filters, it may be perceived as having the right or nearly the right hue (the nameable quality, such as "pink”, “lavender”, “moss green”), but being materially different from other colours in the image.
  • the nameable quality such as "pink”, “lavender”, “moss green”
  • reflection prints it may e.g. seem translucent, on emissive screens it may e.g. take on a perceived luminance m excess of what the display can otherwise deliver.
  • Stereopsis is usually achieved, except when the original stereogram relies on, say, texture perspective as a support of parallactic differences, and this texture perspective happens to suffer from the colour loss.
  • Large areas of a pure colour can loose their stereoscopic ef ⁇ fect, if the colour is only transmitted by one of the viewing filters.
  • Rivalry, over and above the "sheen" is typically seen where strong contrasts exist m the stereogram, or where the surrounds of the display are not sufficiently dimmed, and may m some individuals lead to discomfort (nausea, headaches etc.), sometimes ascribed to "colour bombardment". Diplopia can occur, over and above what is caused by transgression of stereoscopic parameter limits, when the recording medium, the display or the filters, or any combination of these, fail to separate the part-images of the stereogram.
  • Patent US 5491646 diplopia caused by insufficient separation is subjected to the countermeasure of subtracting a scaled copy of the colour values extracted from one part-image from those extracted from the other "so that said first image is entirely, or almost entirely removed from said second image", a digital counterpart of the masking technique used m printing.
  • the prescriptions m Patent US 5491646 otherwise address the use of (1,2)- fliters .
  • Patent US 4217602 use is made, not of two part- images, but three.
  • the purpose is to allow non- stereoscopic, full-colour viewing, the stereoscopic ef- feet being obtained by the use of ( 1 , 1 ) -filters and thus giving a "monochrome" stereo image m the sense described above and discarding the third image.
  • the tnree lenses or lens systems of Patent US 4217602 are identical.
  • Patent US 4620770 use is made of two outline images ana a colour filling, rather than two definite images.
  • the method as described pertains to hand-drawn a anaglyphs, the viewing filters are referred to simply as "3- D glasses" and appear to be intended as (1,2) -pairs, and no procedure is given for the production of specific col- ours .
  • One of the filters m the pair still transmits from only one of the tnree colour ranges, though; there is a small amount of "ghost imaging"; and at least m the blue-amber combination here given as an example, the blue filter transmits only a small portion of the actual light.
  • Valyus (op. cit.) p. 109, describes the use by L. Lumiere of a blue-yellow filter pair which m fact, according to the few spectral data cited, must have been a violet- yellow ([1 0 1/2], [0 1/2 l/2])-pa ⁇ r. Obviously, L. Lumiere can not have attempted to display full-colour lm- ages - m fact, Valyus writes: "One of his [L. Lumiere's] images was coloured yellow, the other blue", suggesting "monochrome” anaglyphs - and there is no explicit record of further attempts with filters of this kind.
  • a “channel” is here a single valued function, such as a luminance level function, defined on the image area.
  • the function may take values m a circular domain, as with the hue, cp . the expression “hue circle”) .
  • a further two channels are required, typically representing the hue and saturation, respectively, of each scene point.
  • a minimum of four colour channels is required to produce a full- colour stereogram.
  • m a viewing filter pair designed as prescribed by the invention, both of the filters must transmit light m two of the ranges red, green or blue; to avoid double imaging and allow the use of optimisation and colour management, recording and encodings are no longer pomt-to- point; and display, even of existing stereograms, is colour-balanced, as far as the pertinent choice of media allows .
  • the present invention offers m its different aspects
  • a filter pair as prescribed by the invention must then be a "(3/2, 3/2) -pair" m the sense that the filters must be separating with respect to the carrier colour ranges; but both filters must transmit the mediant colour range.
  • This latter can take the form of a joint transmission m the entire mediant colour range; or each filter can transmit a part of this range.
  • Transmission m the mediant colour range may involve some reduction, relative to transmission m the pertinent carrier colour range.
  • the phrase "colour range” will be replaced by the simpler "colour”.
  • three separate images can then be recognized: one m each of the carrier colours and one in the mediant colour.
  • the same filters can be used as barrier fil- ters m a display device. If this device is a conventional stereoscopic projector, the filters can thus take the place of polarizing barrier filters. In a digital projector, the filters can again take the place of polar- lzing filters, but there is the further advantage that m the left part-image, no constituent corresponding to the carrier colour of the right part-image need ever be formed (or it can be suppressed); and vice versa.
  • Such a digital projector therefore, m a sense, projects four colour channels: the carrier colour associated with the left part-image and transmitted by the left-image filter; the mediant colour associated with the left part-image, but projected only m the sub-range transmitted by the left-image filter; the mediant colour associated with the right part-image, but projected only m the sub-range transmitted by the right-image filter; and the carrier colour associated with the right part-image and transmitted by the right-image filter.
  • the requirement of four perceptual colour channels is met directly and can be fully utilized by an optimising encoding of the stereogram, while m the remaining encodings described below, primarily aimed at conventional three- channel displays, the impression of a four-channel display is created by colour management.
  • the two carrier colour images considered as images m themselves, must, at least to some extent, compensate for any loss of sharpness caused by this blurring of the mediant colour image.
  • the amplitudes of the left carrier colour image will be enhanced, wherever the amplitude of the mediant colour image is smaller than that of the mediant colour component of the original left part-image; and it will be dampened, wherever the amplitude of the mediant colour image is larger than that of the mediant colour component of the original right part- image.
  • the right carrier colour image mutatis mutandis
  • an optimisation process will, when it is operating on a so-called "cost function" that also takes into account the final per- ceived colours, select those that cause the smallest changes (and hence, if possible: no changes) m the fused colours, compared with the fused colours perceived m the original stereogram, when this is stereoscopically viewed.
  • the encoding must replace some amount of one or both carrier colour with mediant colour, and vice versa, and this replacement can not be performed on a pomt-by-point basis, as this would create visible dis- continuities that would give rise to both diplopia and abrupt colour casts.
  • the simplest instantiation of the encoding is obtained by first photographically recording, along three parallel lines of sight, three (luminance level) images, the middle one having a restricted depth of field m the sense of being visually sharp only m the distance range m- tended for zero parallax m the final stereogram, then encoding the outermost two m the respective carrier colours and the middle one in the mediant colour, and finally mounting the three m register, i.e. with the zero parallax motif parts coalescent and homologous points horizontally aligned, to form a full-colour image.
  • colour separation filtered images can be recorded.
  • a re- cording process of this kind can be accomplished by an optical apparatus, but it should be noted that such an apparatus performs no amplitude enhancements of the carrier colour constituents.
  • the process can also be accomplished by an electronic filter, forming part of e.g. an electronic camera or image recorder.
  • Digital image recorders can avoid the double imaging caused by spectral separation failures; and an electronic filter can perform enhancements of the carrier colour constituents and indeed other cross-constituent operations, as they are described m the following.
  • the description of the image encoding as prescribed by the invention can proceed m steps, each resulting instantiation being a variation over or an improvement of this theme:
  • the middle image need not be directly recorded, but can be computed as an average of the mediant colour "planes" of the two outer images, each of which must then be recorded in at least two colours, the mediant colour and the relevant carrier colour.
  • the averaging can be simple (half the sum), weighted using pre-determmed weights, or adap- tively weighted, taking into account the fact that areas which are low in one of the carrier colours provide less room for subsequent colour manipulations.
  • the optical blurring can be simulated by a smoothing process.
  • the smoothing operator can be a simple "sliding strip” technique, one or two-dimensional, or a genuine approximation to the point spread function of a lens with finite (as opposed to point-shaped) aperture.
  • the local strength of the smoothing can vary according to any measure of local parallactic separation. Assuming that the stereo registration has been decided, this can be put m simpler terms: if there is very little difference between the mediant colour contents (or, alternatively, the gray scale contents) of the left and right images m and around a given position, the mediant colour should be only gently smoothed, in and around that position.
  • Such a replacement may also be used to remedy double image phenomena: if, owing to the spectral imperfections of recording media, display media or filters, an "echo" of the left part-image is visible to the right eye or vice versa, the one carrier colour image may be modified by subtraction of a scaled version of the other carrier colour image. (Lest it may seem that this procedure leads to an infinite regress, it should be noted that the problem can be stated as two simultaneous equations m two unknowns; that the repeated procedure, if m fact performed, has the character of a "relaxation solution" of this problem; and that the smallness of the scaling factors implies a rapid convergence) .
  • a correspondence map of the stereogram is a representation, typically m the form of a gray scale image, of the separation at any location, of the point at that location m one of the part-images and its homologous point m the other part-image.
  • Homologous points are images of one and the same scene point. Their separation is geometrically related to the depth of the scene point. Algorithms for solving the correspondence problem exist m great number m the arts of photogram- metry and machine vision.
  • the stereogram can be artificially de- saturated with little loss of image quality: if the saturation of colours of distant areas is reduced, they will be more easily encoded without causing artefacts of dis- continuities m, or mis-coloration of, areas closer to the foreground. As with the adaptive averaging, this is again a question of providing room for colour re ⁇ distribution .
  • any given image area serves two purposes simultaneously: it is the representation of an area m the original left part-image - and a representation of a different area m the original right part-image.
  • a colour-encoded stereogram considered as seen by the left eye
  • a homologous area can be found.
  • the stereogram is assumed to be an endo- stereogram (all scene points are perceived as lying behind the image plane), so the homologous area lies to the right of the given area.
  • a new homologous area can be found further to the right, etc.
  • a model for what is actually perceived m a colour encoded stereogram must represent such chains of homologous areas, typically m the form of lists of selected representative homologous point pairs and their surroundings. Colour fusion will be between the colours seen m an area and its homologous counterpart. The areas must be found m (and referred back to) the original stereogram.
  • a norm or metric on a device-independent col ⁇ our space an algorithm to solve the correspondence problem; a model for colour fusion; spectral measurements and models to convert device and image colour values into de- vice-independent values; an algorithm for numerical opti ⁇ misation; a viewing filter pair chosen as prescribed by the invention; and a stereogram - the image encoding pre ⁇ scribed by the invention: solves the correspondence problem for the original stereogram, representing the solution as a list or lists of homologous areas; - computes the perceived fused colours m these areas, according to the fusion model; sets up the optimisation problem of encoding the stereogram m such a fashion as to express that what is actually perceived (as fused colours m the same areas) m the encoded stereogram, when this is observed through the viewing filters, has the smallest deviation m terms of the norm or metric on the colour space from the fused colours m the original stereogram;
  • display of the recorded or encoded images can be made using any conventional (colour) display medium, including the media of prints or colour photos. If circumstances allow, though, use can advantageously be made of special stereoscopic projectors (designed as prescribed by the invention) accommodating coloured filters, which must then be functionally matched by the viewing filters.
  • the transmittance over a range shall mean the area under the transmission rate function graph divided by the width the range; and a filter will be said to "transmit a range", if its transmittance over that range is larger than 0.06 (6 C ), and to "exclude a range” if its transmittance over that range is less than 0.06. (This value corresponds to a damping of four photographic "stops” and marks a practical limit at which e.g. the presence of "ghost images” begins to cause diplopia) . Two filters will be said to have a "significant common transmission" of a range, if the common area of their transmission rate functions restricted to that range is no less than 10 of either area.
  • a "correspondence map” is defined elsewhere m the text and it remains only to note, that it is understood that homologous point pairs are at least approximately brought to lie on parallel lines ("horizontal lines"), and that such a map may take on negative values (negative parallaxes , if part of the scene depicted lies front of the image plane used in the depiction. If the left and right part-images of an alleged stereogram are actually identical, the scene depicted is a flat object, parallel to the image plane, and its correspondence map is constant, possibly everywhere zero.
  • an image can be considered a two-dimensional signal, and concepts such as discrete Fourier transforms applied to it. Using such a transform one may define frequency ranges and their energy contents. Reference is made to the literature on the subject. Only the idea of “smoothing" an image by removing or reducing some of its “energy” m the “high frequency range” is needed m the following. Such a description is valid, even if the actual smoothing is carried out by other means.
  • Figure 1 is a diagram showing the signal routes and operational units of an apparatus that performs the encoding of a stereogram as prescribed by the invention
  • figure 2 is a diagram showing the functional elements an optical apparatus that performs the encoding of a stereogram as prescribed by the invention
  • figure 3 is a diagram showing the signal routes and operational units of an apparatus that performs the encoding of a stereogram as prescribed by the invention
  • figures 4 to 6 show idealized transmission rates of viewing filter pairs as prescribed by the invention
  • FIGS 7 to 9 show transmission rates of physical view- mg filter pairs designed as prescribed by the invention.
  • figures 10 to 12 show idealized transmission rates of filter pairs for use, as viewing filters, and, m the projection apparatuses prescribed by the invention, si- multaneously as barrier filters;
  • figure 13 is a diagram showing the application of a filter pair with spectral properties derived from the ideal transmission rates of one of figures 10 to 12 as barrier filters a conventional stereo projector;
  • figure 14 shows one light ray path and a possible positioning of one of the filters of figure 10 to 12, jointly with a colour separation filter, m a projector as pre- scribed by the invention.
  • a stereogram is given as two part-images digital form, represented by their "RGB" value arrays (as is customary m e.g. computer graphics).
  • RGB RGB value arrays
  • the left carrier colour is exemplified by B (blue)
  • the right carrier colour by G green
  • the mediant colour by R red
  • the R components of the left and right images are then halved, added up and subjected to a smoothing m the form of a "sliding strip” averaging with a weight function m the form of a "Gaussian bell" (both terms defined and described detail m standard refer- ences on numerical analysis and image analysis) .
  • the encoded image is obtained as the combination of this averaged R component with the B component from the left image and the G component of the right image.
  • the simplicity of this embodiment is evident, but it is only truly applica- ble to stereograms with low contrasts and restricted depth .
  • an approximate correspondence map is first obtained, for example by simply computing the point-wise differences m luminance levels everywhere over the two part-images of the stereogram (this is crude, but remarkably effective for its present use) .
  • An adaptive averaging of the two R- components of the part-images is then computed: First, a point-wise sum is formed of the minimum of the two R- values with a weighted sum of the two differences between the minimum and the actual values (thus, m any given point, one or the other of the contributions is zero) .
  • the weights are so chosen, relative to the luminances of re ⁇ , green and blue the ⁇ isplay medium and to a selec- tion of test images, so that colour casts m the test images are found acceptable by visual inspection.
  • the choice of weights is thus empirical (psycho- physiological ) .
  • the result is smoothed, as described with reference to the first embodiment, with the smoothing strength now coupled to the values of the correspondence map.
  • the coupling is again determined by visual inspection, m order to avoid diplopia.
  • the encoded image is obtained as the combination of this averaged R component with the B component from the left image and the G component of the right image.
  • encoding proceeds as m the second embodiment, but the B and G components are further corrected to eliminate or nearly eliminate luminance variations ("ghost images") caused by the failure of the recording medium or of the viewing filters relative to the display medium or both to preserve ideal spectral separation.
  • G images luminance variations
  • a genuine, if not exact, correspondence map is first obtained (by any method of choice) and the saturation of colours m the part-images of the stereogram reduced, m- creas gly with increasing depth, colours of the nearest points remaining unreduced.
  • Encoding proceeds as m the third embodiment, except that the degree of smoothing is now more precisely controllable, a more precise corre ⁇ spondence map being available.
  • an exact correspondence map can be generated m the course of the rendering process, either directly by the expedient of monitoring the projection of scene points, or indirectly from the so-called depth buffers of the part-images.
  • - a device-independent colour space with a metric (colour distance) defined on it (several such are described colour science) ; - an extension of the metric, such as an integration or weighted summation of point-wise values of the metric, to an error measure allowing comparison of colours of fused homologous areas, as these are seen m the original stereogram, and m the encoding, respectively; - a model for colour fusion (with additive mixture as the very simplest); and
  • the encoding is then found as the solution to the optimisation problem of reducing the error, as determined by the error measure, of the fused colours seen m the encoded image, compared with the fused colours m the stereogram, as these are determined according to the colour fusion model, acting over homologous areas m the chains partitioning the stereogram.
  • the form of apparatuses aiding the recording of stereograms m the form of apparatuses aiding the recording of stereograms :
  • a sixth preferred embodiment of the invention takes the form of an electronic filter converting three incoming full-colour (or: a two- colour, a one-colour and a two-colour) image signals to one outgoing full-colour image signal.
  • This embodiment comprises, as shown m figure 1:
  • - a component, 101 for separating the partial signal representing the first carrier colour and the mediant colour from the first image signal
  • - a component, 102 for separating the partial signal representing the mediant colour from the second image signal
  • a component, 130 for the combination of a modified first carrier colour image signal, a smoothed second mediant colour image signal (optionally modified) and a modified third carrier colour image signal, modifications being controlled by the outcome of the comparisons m the component 120.
  • Through 150 runs the signal representing the second mediant colour image.
  • Through 160 runs the signal representing the smoothed second mediant colour image.
  • Through 170 runs the (optionally modified) smoothed mediant colour image signal and signals representing the outcome of the com- pa ⁇ sons made m 120.
  • Through 180 runs the signal repre ⁇ senting the final, encoded image.
  • a seventh preferred embodiment of the invention takes the form of an optical adaptor converting three visual image signals to one outgoing visual image signal.
  • the embodiment comprises, as shown m figure 2 :
  • - optical colour separation filters 201, 202 and 203 can for instance be the filters most frequently used other photographic colour separation work, Kodak Wratten 25 (red) , Kodak Wratten 58 (green) and Kodak Wratten 47B (blue) m some order. (The spectral properties of these filters are described m Kodak's technical references, and also elsewhere) ; - lenses or lens systems, 210, 211 and 212, with 211 having a reduced depth of field relative to 210 and 212 (which are identical);
  • - prismatic mirrors 230 allowing passage of an lmage- forming light ray (bundle) from 211 and reflecting an image-forming light ray (bundle) from each of 220 and 221 such a fashion as to produce a combined image.
  • the device would be of fixed stereo- scopic registration.
  • a coupling (not shown separately in the drawing) between the lens system of the camera, on which the adaptor is mounted, and e.g. the lenses or lens systems 210 and 212 can be added to allow variable stereoscopic registration.
  • An eighth preferred embodiment of the invention takes the form of an elec- tronic filter to be mounted m a three-lens camera, m which colour separation is carried out by means of e.g. optical filters, i.e. externally to the filter. Also, the conversion from optical signals to one-channel (essen- tially: luminance level) signals takes place externally to the apparatus. The available signals thus represent a reduced amount of information about the three images, but the modus operandi otherwise resembles that of the sixth embodiment.
  • the eighth embodiment comprises, as shown figure 3:
  • a component, 320 for the comparison of the smoothed second (mediant colour) image signal with the signals representing the first and third (carrier colour) images and optionally modifying the mediant colour image signal m accordance with the outcome of the comparison, the modification taking the form of a further smoothing or change of amplitude or both;
  • a component, 330 for the combination of a modified first carrier colour image signal, a smoothed second (mediant colour) image signal, optionally modified, and a modified third (carrier colour) image signal, modifica- tions being controlled by the outcome of the comparisons m the component 320.
  • the following signal routes are identified by numbers: Through 340 runs the signal representing the first carrier colour image. At the branching point 391, a copy of the signal is directed towards 320. Through 341 runs the signal representing the third carrier colour and mediant colour images. At the branching point 392, a copy of the signal is directed towards 320. Through 350 runs the signal representing the second mediant colour image. Through 360 runs the signal representing the smoothed second mediant colour image. Through 370 runs the (op- tionally modified) smoothed mediant colour image signal and signals representing the outcome of the comparisons made in 320. Through 380 runs the signal representing the final, encoded image. Electronically variable stereoscopic registration can be added; but no component ef- fecting this operation is shown the figure.
  • the first embodiment of the viewing filters the range of visual light from 400nm to 700nm (light outside this range being ignored) is divided into three: the range from 400nm to 500nm (blue light) , the range from 500nm to 600nm (green light) and the range from 600nm to 700nm (red light); and a unit function, i.e. a function of constant value 1, over the full range is partitioned into three, defined as taking the value 1 on the respective sub-ranges and 0 outside.
  • the unit "block” On one of the three ranges, which will act as the mediant colour, the unit "block” is divided "horizontally", as it were; and ideal transmission rates are obtained as functions of unit value over one range, zero value over another range and a constant ("partial") value over a third range. If complementarity is not required, the partial blocks need not add up to a constant unit function; but the zeros and ones must always do ust this.
  • Figures 4, 5 and 6 show examples of idealized filter pairs obtained this way. When such ide- alized transmission functions are approximated by practical filters, the block curves will be replaced by more irregular shapes.
  • Figures 7, 8 and 9 show examples of practical filter pairs.
  • figures 4 and 7 display ([0 1/2 1], [1 1/2 0]) -pairs
  • figures 5 and 8 display ([1/2 1 0], [1/2 0 1]) -pairs
  • figures 6 and 9 display ([1 0 1/2], [0 1 l/2])-pa ⁇ rs.
  • the second embodiment of the viewing filters the division of the mediant block is "vertical".
  • Idealized transmission curves are shown figures 10, displaying a ([0 1/2 1], [1 1/2 0])-pa ⁇ r; 11, displaying a ([1/2 1 0, [1/2 0 1])- pair; and 12, displaying a ([1 0 1/2], [0 1 1/2]) -pair, respectively.
  • the first embodiment of the viewing filters allows the better colour balance of the two. Both preserve the sepa- ration property m regards to certain conventional "monochrome" stereograms (replace the "1/2" by a "0" the descriptions to obtain the corresponding non- complementary "monochrome” viewing filter descriptions) .
  • the second embodiment alongside with its use with opti- mally encoded stereograms, also allows use as barrier filters m a stereo projector:
  • stereo projectors there are two preferred embodiments of stereo projectors, as they are prescribed by the invention:
  • the filters of the tenth embodiment are mounted m a conventional stereo projector, where they replace polarizing filters.
  • Figure 13 is a schematic diagram of a conventional stereo projector, such as a slide projector or a twin digital projector system, equipped with barrier filters functionally identical to a pair of viewing filters, as these are described m the tenth preferred embodiment above.
  • Elements 1301 and 1302 represent projector units, elements 1310 and 1311 lenses or lens systems, and elements 1320 and 1321 two filters of a pair, e.g. 1320 a [0 1/2 l]-f ⁇ lter, 1321 a [1 1/2 0]-f ⁇ lter, where the "l/2"s are disjoint parts of the visible spectrum.
  • the second embodiment of a stereo projector the filters of the tenth embodiment are mounted m the light paths of a four-channel digital projector.
  • the projector is constructed like any other digital projector, be it based on LCDs, digital mirror devices (rapidly adjustable micro- mirrors) or any other technique that allows projection of full-colour images.
  • the only difference between the projector, as it is prescribed by the invention, and its conventional counterpart is that four, not three, image forming elements are required. (With projectors based on digital mirror devices (DMDs) only the time-multiplexed partitioning of the projection light need changing from a cycle of three to a cycle of four) .
  • DMDs digital mirror devices
  • the diagram figure 14 shows a light path inside part of such an apparatus, with a possible positioning of one of the filters prescribed by the invention, here thought of as a distinct from the colour separation filter employed.
  • Component 1401 illustrates a timer unit, 1410 a unit controlling intensity of light, 1420 a light source, 1430 a primary separation filter (R, G or B) , 1431 one of the filters prescribed by the invention, and 1440 a component for controlling the exit direction of the light.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Stereoscopic And Panoramic Photography (AREA)
  • Color Television Systems (AREA)

Abstract

Cette invention se rapporte à des procédés et à des moyens améliorés permettant d'enregistrer ou de coder et afficher des stéréogrammes sous la forme d'images en une seule couleur destinées à être visualisées à travers des filtres optiques multichromes. On utilise à cet effet, d'une part, une combinaison de filtres de visualisation à équilibrage des couleurs et, d'autre part, des codages d'images basés sur des techniques d'optimisation numériques et sur la science des couleurs. En outre les filtres et les codages peuvent être sélectionnés et réalisés pour que leur application permette l'utilisation simultanée de certaines des réalisation de l'état actuel de la technique.
EP00951279A 1999-08-10 2000-08-10 Procedes et appareils pour coder et afficher des stereogrammes Withdrawn EP1245121A2 (fr)

Applications Claiming Priority (5)

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DK111599 1999-08-10
DKPA199901115 1999-08-10
DKPA200000748 2000-05-05
DK200000748 2000-05-05
PCT/DK2000/000448 WO2001011894A2 (fr) 1999-08-10 2000-08-10 Procedes et appareils pour coder et afficher des stereogrammes

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EP1252756B1 (fr) 2000-01-25 2006-05-31 NewSight GmbH Procede et dispositif de representation en trois dimensions
NZ505513A (en) * 2000-06-30 2002-05-31 Marc Dawson Anaglyphic 3-D colour imaging with selective colour filtering
US20070236809A1 (en) 2006-04-05 2007-10-11 Barret Lippey Forming spectral filters
US7784938B2 (en) 2007-05-09 2010-08-31 Dolby Laboratories Licensing Corporation Method and system for shaped glasses and viewing 3D images
US7959295B2 (en) 2007-05-18 2011-06-14 Dolby Laboratories Licensing Corporation Spectral separation filters for 3D stereoscopic D-cinema presentation
TWI539230B (zh) 2007-05-09 2016-06-21 杜比實驗室特許公司 三維影像之投影與觀看系統（一）
FR2917845B1 (fr) * 2007-06-19 2011-08-19 Christophe Brossier Procede de visualisation d'une sequence d'images produisant une sensation de relief
DE102010024666A1 (de) 2010-06-18 2011-12-22 Hella Kgaa Hueck & Co. Verfahren zur optischen Selbstdiagnose eines Kamerasystems und Vorrichtung zur Durchführung eines solchen Verfahrens
EP2605519A1 (fr) * 2011-12-15 2013-06-19 Thomson Licensing Dispositif de capture d'images stéréoscopiques anaglyphiques
EP2611172A1 (fr) * 2011-12-28 2013-07-03 Thomson Licensing Procédé de génération d'une image anaglyphe
DE102013226654A1 (de) * 2013-12-19 2015-06-25 Robert Bosch Gmbh Optisches Stereo-System
US10809543B2 (en) 2017-01-23 2020-10-20 Dolby Laboratories Licensing Corporation Glasses for spectral and 3D imaging
CN113674371B (zh) * 2021-08-06 2023-11-03 吉林大学 一种基于五维二次核建模的立体元图像阵列编码方法

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JPS61253993A (ja) * 1985-05-07 1986-11-11 Nippon Hoso Kyokai <Nhk> 立体テレビジョン画像信号の伝送方法
JP2002528746A (ja) * 1998-10-20 2002-09-03 エリク ベーレ ソーレンセン，スベン マルチクローム・フィルタを使って立体画像をカラーで記録および視覚するための方法

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WO2001011894A3 (fr) 2002-07-25
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WO2001011894A8 (fr) 2004-05-21

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