WO2007087142A2

WO2007087142A2 - Video conference system with parallax correction and background reduction

Info

Publication number: WO2007087142A2
Application number: PCT/US2007/000303
Authority: WO
Inventors: David Hunter; Gordon Massey
Original assignee: Children's Medical Center Corporation
Priority date: 2006-01-12
Filing date: 2007-01-08
Publication date: 2007-08-02
Also published as: WO2007087142A3

Abstract

Generally, the present invention relates to a video teleconference system which is amenable to the mobile and stationery/desktop environment with concurrent parallax correction and background suppression for privacy. An embodiment of the invention is directed to a video teleconference system for allowing a first conferee to maintain direct eye contact with a second conferee, the system including an image display emanating a linearly polarized image output of the second conferee. A partially reflecting, partially transparent beam splitter is interposed between the first conferee and the image display, the beam splitter disposed at an angle relative to the line of sight of the first conferee and the image display, the splitter being hingeably attached to display. A video camera is oriented to receive the reflected image of the first conferee as projected off the beam splitter. An optical (linear) polarizer is oriented orthogonally to the polarized light from the display disposed between the beam splitter and the video camera thereby minimizing eye contact parallax between the first and second conferees.

Description

VIDEO CONFERENCE SYSTEM WITH PARALLAX CORRECTION AND

BACKGROUND REDUCTION

Field of the Invention

The present invention is directed generally to visual display systems and more particularly to a video teleconference system which is amenable to both the mobile and desktop environment with concurrent parallax correction and background suppression for privacy.

Background

Typical videoconference systems include, at each remote site, at least one monitor and at least one camera to project visual presence of the conferees. A persistent problem that arises from the standard placement of the camera on top of the monitor or elsewhere is the so-called parallax effect, wherein it appears that the conferees are not making direct eye contact. In this configuration with a conferee looking directly into the monitor, would give the visual image to their counterpart that they are looking downward or away, any and may give the unwanted impression that they are disinterested or non attentive. This effect is highly distracting and is a key reason why video conferencing is disliked and/or undervalued by many users.

Prior art approaches to eliminate this parallax effect have typically been concerned with the case where the monitor is a cathode ray tube (CRT) type device and/or the environment is office based only and non mobile. These solutions typically involve interposing a beamsplitter or partial mirror type device between the monitor and the conferee (most have the beamsplitter at 45° and the camera vertical looking down), such that an image of the conferee is reflected to the camera while the conferee is simultaneously looking directly at their monitor.

Alternative prior art approaches to eliminate parallax for the flat screen user have focused on a modified configuration as explained above for the CRT monitor, wherein the screen is placed horizontal (flat) facing upwards with a beamsplitter or partial mirror oriented at 45° to reflect an image of the LCD screen to the teleconference participant. In this configuration, the camera is placed behind the beamsplitter and centered on the reflected image off the beamsplitter. Also, to reflect the entire image generated by the LCD screen, the beamsplitter needs to be at least as large in physical dimensions as the LCD screen. Given this geometry, the teleconference participant is looking directly at the camera while simultaneously viewing the reflected image off the beamsplitter, thereby eliminating the parallax offset. Although this configuration may be adapted to accommodate the laptop user it suffers from at least two practical drawbacks for the mobile. First, the hardware configuration consisting of free standing mounts for both the beamsplitter and camera would be awkward to assemble while on business or personal travel (difficult in the car or airport, and near impossible on the airplane). And secondly, the configuration suffers from an annoying artifact of the background being visible. For example, with the camera aimed at the conferee (through the beamsplitter), the field of view of the camera also includes whatever is behind and/or adjacent the participant. Given that the mobile traveler may be in a coffee shop or at an airport restaurant, there is every reason to believe the background environment may be full of dynamic movement. More important, the conferee on the other end may have the unwanted impression that other passers bye may easily be viewing the visual content of the teleconference. Furthermore, there are drawbacks to prior art desktop videoconference systems that may include impractically oversized equipment, dominance of desktop space, and burdensome complexity in set-up needs, all of which may be eliminated or reduced by the present invention. Given the above, there is a need for a teleconference system which is amenable to both the desktop and the mobile environment with concurrent parallax correction and suppression of unwanted competing images.

Summary of the Invention

Generally, the present invention relates to a video teleconference system which is amenable to the mobile and stationery/desktop environment with concurrent parallax correction and background suppression for privacy.

One particular embodiment of the invention is directed to a video teleconference system for allowing a first conferee to maintain direct eye contact with a second conferee, the system including an image display emanating a linearly polarized image output of the second conferee. A partially reflecting, partially transparent beam splitter is interposed between the first conferee and the image display, the beam splitter disposed at an angle relative to the line of sight of the first conferee and the image display, the splitter being hingeably attached to display. A video camera is oriented to receive the reflected image of the first conferee as projected off the beam splitter. An optical (linear) polarizer is oriented orthogonally to the polarized light from the display disposed between the beam splitter and the video camera thereby minimizing eye contact parallax between the first and second conferees.

Another embodiment of the invention is directed to a video teleconference system for allowing a first conferee to maintain direct eye contact with a second conferee while simultaneously reducing unwanted background clutter, the system including an image display emanating a linearly polarized image output of the second conferee. A partially reflecting partially transparent beam splitter is interposed between the first conferee and the image display, the beam splitter disposed at an angle relative to the line of sight of the first conferee and the image display. A video camera is disposed orthogonally to the reflected image of the first conferee as projected off the beam splitter, the angular field of view of the video camera being substantially limited to viewing to only polarized light emanating from the image display and the image of the conferee. An optical (linear) polarizer is oriented orthogonally to the polarized light from the display and disposed between the partially reflecting transparent device and the video camera, thereby minimizing parallax and minimizing the image from the image display from reaching the video camera.

Another embodiment of the invention is directed to a method of providing substantially parallax free eye to eye contact of conferees in a video teleconferencing system including the steps of linearly polarizing the image output of a display, interposing a beam splitter in front of the display, positioning a video camera to capture an image of one of the conferees off the beam splitter, and interposing a linear polarizer in the image field of the camera, the polarizer being oriented to block images emanating from the display while passing the image of the conferee.

The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments.

Brief Description of the Drawings

The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:

FIG. 1 shows a schematic representation of a video conference system in session with conferees A and B each utilizing an LCD or other display system with a camera, beam splitter, and polarizer in accordance with the present invention.

FIG. 2 shows a schematic representation a video conference system with the addition of a spatial filter to limit the angular field of view of the camera depicted in FIG. 1.

FIG. 3 shows a schematic representation of a video conference system employing the prior art depicting the image of conferee A's face superimposed upon the image of conferee A's hand.

Figure 4 shows a schematic representation of a video conference system employing a partial beam splitter and video camera which are attached to the video display device on a flexible swing-out mounting device

Figure 5 shows a schematic representation of a video display device employing a partial beam splitter and video camera which are attached to the top portion of the video display by a hinged mounting device. Figure 6A.and 6B (side view) show a schematic representation of a video display device wherein the video conference hardware is configured to only utilize a fraction of the video display screen, thereby allowing the conferee to multi-task if desired.

Figure 7 shows a schematic representation of a video display device with a ledge unit.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Detailed Description

In general, the present invention is directed to a video teleconference system which is amenable to the mobile and stationery/desktop environment with concurrent parallax correction and background suppression for privacy. Figure 1 is a schematic representation of such a video teleconference system 100 with conferees A and B in session. With reference to conferee A's hardware configuration, liquid crystal display 0-CD) 110 is shown at an oblique angle Θ (theta) relative to the line of sight of camera 120. Partial beam splitter 130 is shown interposed between conferee A and LCD 110, and oriented at oblique angle Φ (phi) relative to the line of sight of camera 120. The relative placement of camera A, liquid crystal display 110, and partial beam splitter 130 may be such that the line of sight of camera A views through beam splitter 130 onto the lower portion 140 of the liquid crystal display 110. In this configuration the camera would capture a superposition of the reflected image of conferee A's face off beam splitter 110 along with an image of the lower portion 140 of the LCD display 110. The above configuration may be designed to take advantage of the polarizing effects typically associated with liquid crystal displays as explained later.

In contrast to the present invention described above, Figure 3 highlights one embodiment of the prior art with inherent artifacts the present invention may reduce or possibly eliminate. With reference to conferee A's alternative hardware configuration (a typical set-up used in a mobile environment wherein the camera may be mounted/clipped directly to the LCD display), LCD display 310 is shown position upright (vertical) with camera A looking downward. Partial beam splitter 330 is shown interposed between conferee A and LCD 310, and oriented at approximately 45° relative to the line of sight of camera 320. Given this geometry, the camera 320 would transmit an image to conferee B which would be the superposition of conferee A's face (reflected off partial beamsplittter 330) and the image captured by the camera viewing conferees A's hand (as seen by the camera looking directly through partial beamsplittter 330). Given that conferee A may be talking notes during the videoconference, there may be dynamic movement in the superimposed image on conferee B's LCD screen which may be annoying and/or confusing. To reduce or possibly eliminate the annoying effects described above, the present invention may take advantage of the optical polarizing characteristics associated with liquid crystal displays. Liquid crystal displays are internally designed with a 90° optical polarization rotating component (the liquid crystal) sandwiched between two linear polarizers which are oriented orthogonal to one another. In this configuration, non-polarized backlighting is typically vertically polarized by a first polarizer and with no voltage applied to the liquid crystal (i.e., no polarization rotation) the vertically polarized light is blocked from exiting the display by the second horizontally aligned polarizer (passes horizontal & blocks vertical). However, when an appropriate voltage is applied to the liquid crystal, the input vertically polarized light is rotated 90° to the horizontal by the liquid crystal and now passes out, exiting the horizontal polarizer, and illuminating the LCD.

Referring again to figure 1 , given that the light emanating from the

LCD display 110 may be horizontally polarized (along the x axis), by placing a linear polarizer 150 at the entrance of the camera 120 oriented orthogonal to the x axis (i.e., passes light polarized in the y direction and blocks light polarized in the x direction), this may filter out the image from the lower portion 140 of the LCD screen that would otherwise make its way into the image viewed by conferee B. However, given that natural sunlight or artificial room light is partially or completely depolarized, the light reflected off/emanating from conferee A's face will have optical energy both along the x and y axis — the energy aligned along the y axis passing through the polarizer 150 enroute to the camera 120, ultimately generating a visual image of conferee A's face on conferee B's LCD screen. This selective spatial filtering may eliminate unwanted background signals from being superimposed upon the image of the conferee's face. For example, in the configuration described above with no polarization filter 150 at the input to the camera 120, the LCD screen 110 may have scrolling text or dynamic imagery emanating from the screen in region 140 which would otherwise be superimposed on the image of conferee's A face and may be annoying or distracting to conferee B. The above scenario is easily adaptable to alternative LCD displays which may have their output optical polarization vector oriented in any arbitrary linear direction. In this scenario, conferee A may simply rotate the polarizer 150 until the unwanted image generated from region 140 is extinguished.

The above hardware configuration may also be adapted to eliminate a second source of unwanted background signal. Figure 2 shows a similar hardware configuration as shown in figure 1 with the addition of a spatial filter 160 attached to the camera assembly 120. The spatial filter 160 may be designed to limit the angular field of view of the camera to eliminate unwanted background imagery from behind or adjacent to conferee A from making its' way into conferee B's screen. Jn one embodiment the spatial filter 160 may be cylindrical in shape and the angular field of view of the camera 120 may be determined by the length, L, of the cylindrical tube. In this configuration, the angular field of view of the camera 120 decreases as the length, L, of the cylindrical tube increases. The cylindrical tube may be designed to have an adjustable length so that conferee A can adjust the camera 120 angular field of view appropriate to the environment as necessary. An alternative approach to eliminate unwanted background imagery from behind or adjacent to conferee A may consist of limiting or tailoring the physical size of the partial beam splitter 130 to reflect only an image of the head and shoulder region of conferee A.

The hardware architecture shown in figures 1 and figure 2 can be configured for both the mobile and office-based user. Figure 4 shows an embodiment of the present invention wherein the partial beam splitter 330 and video camera 320 are attached to the video display device 310 on a flexible swing-out or hinged mounting device 340. Other structures may be used, such as a "snake" tube of flexible metal. Device 340, in this configuration is a multi pivoted arm which allows one to move the camera 320 to the precise position required. A phantom line device is also shown to illustrate movement. Note that the camera 320 and splitter 330 are kept in alignment at all times by rigid arm 460. The angle required for splitter 330 relative the camera does not vary regardless of other movement of the arm 340.

Thus the mounting device may contain both the partial beam splitter 330 and video camera 320 pre-aligned for immediate use when rotated (hinge approach) or manually maneuvered (flex arm). The mounting device may also allow for relative adjustments in the location of the partial beam splitter 330 and video camera 320 to accommodate different geometries in the video display device 310. The mounting device 340 may be temporarily attached to the video display device 310 by way of snap-on clamps, mounting clips, magnetic attachments, or any such devices for ease of storage while in transit.

Figure 5 shows an embodiment of the present invention wherein the partial beam splitter 530 is attached to the LCD 510 display by an adjustable hinge unit 511. In this embodiment the partial beam splitter 530 may be sufficiently large to reflect not only an image of conferee A, but also project an image of conferee A's background and surrounding environment. (See Fig. 3). This may be important in cases where conferee B may seek visual confirmation that there are no unintended onlookers viewing the contents of the video teleconference at conferee A's location. In this embodiment, camera 520 may also be attached to the LCD display 510 by the same hinge unit 511 as the partial beam splitter 530 or may have a separate hinge unit 512 to allow differential adjustment in the placement of the camera 520 relative to the partial beam splitter 530. Again, it is advantageous that hinge 510 and the arm connecting it to the camera be rigid so that the angle between the camera and the beam splitter are always kept constant and aligned. And, similar to figure 1 , the direct line of sight of camera 520 through partial beam splitter 530 is centered on region 540 in the lower portion of the LCD display 510, wherein the linear polarizer (not shown in figure 5) attached to camera 520's input blocks the optical energy emanating from region 540. Figure 6A shows another embodiment of the present invention wherein the video conference hardware is configured to only utilize a fraction of the LCD screen 610. As depicted in figures 6A and 6B (side view), the partial beam splitter 630 and camera 620 are mounted to the LCD display 610 by hinged attachment arm 612. In this configuration, the camera 620 line of sight may be centered on LCD display region 640 and the camera angular field of view may be adjusted (limited) to coincide within the physical dimensions of the partial beam splitter 630. For ease of set-up and repeatable alignment, the partial beam splitter 630 may have support legs/standoff(s) 631 from the LCD display 610 which may be designed to maintain alignment of the partial beam splitter 630 at a desired predetermined angle relative to the LCD display 610. The standoffs 631 may also be designed to be adjustable in length to modify the angular offset of the partial beam splitter 630 relative to the LCD display 610. This embodiment has particular benefit in mobile configurations.

Figure 7 shows another embodiment of the present invention wherein the video conference hardware is configured with the partial beam splitter 730 overlaying a majority of the surface area of the LCD display 710 because the camera line of sight through the partial beam splitter may overspill the LCD display and capture and transmit unwanted background images to the conferee's counterpart a modification has been made in this embodiment. Figure 7 shows a ledge unit attached to the lower portion of the LCD or other display and covered with a non-reflective black felt like material or equivalent to eliminate or greatly reduce specular reflection from the ledge surface from generating an unwanted background image to the camera.

In this embodiment, camera 720 may also be attached to the LCD display 710 by the same hinge unit 711 as the partial beam splitter 730 or may have a separate hinge unit 712 to allow differential adjustment in the placement of the camera 720 relative to the partial beam splitter 730. In this configuration, the camera 720 line of sight 740 through partial beam splitter 730 may overspill the LCD display 710 and capture and transmit unwanted background images to the conferee's counterpart. To counter this, the conferee may attach ledge unit 760 to the lower portion of the LCD display 710 and cover the top surface of the ledge 760 with a substantially non- reflecting non glare material 770 (black felt like material for example) or equivalent to eliminate or greatly reduce specular reflection from the ledge surface 760 from generating an unwanted background image to the camera.

The user's hands, documents, etc, should be place below the surface 760 so that it is not visible by the camera. Otherwise distracting images such as those shown in Figure 3 will result.

As noted above, the present invention is applicable to video teleconference systems in a mobile environment and is believed to be particularly useful for eliminating parallax effects and suppressing unwanted background for privacy. The present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims.

Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification. The claims are intended to cover such modifications and devices.

Claims

I CLAIM:

1. A video teleconference system for allowing a first conferee to maintain direct eye contact with a second conferee comprising: an image display emanating a linearly polarized image output of the second conferee; a partially reflecting partially transparent beam splitter interposed between the first conferee and the image display, the beam splitter disposed at an angle relative to the line of sight of the first conferee and the image display, said splitter being hingeably attached to display; a video camera oriented to receive the reflected image of the first conferee as projected off the beam splitter; an optical (linear) polarizer oriented orthogonally to the polarized light from the display disposed between the beam splitter and the video camera; thereby minimizing eye contact parallax between the first and second conferees.

2. A video teleconference system for allowing a first conferee to maintain direct eye contact with a second conferee while simultaneously reducing unwanted background clutter, the system comprising: an image display emanating a linearly polarized image output of the second conferee; a partially reflecting partially transparent beam splitter interposed between the first conferee and the image display, the beam splitter disposed at an angle relative to the line of sight of the first conferee and the image display; a video camera disposed orthogonally to the reflected image of the first conferee as projected off the beam splitter, the angular field of view of the video camera being substantially limited to viewing to only polarized light emanating from the image display and the image of the conferee; an optical (linear) polarizer oriented orthogonally to the polarized light from the display and disposed between the partially reflecting transparent device and the video camera; and thereby minimizing parallax and minimizing the image from the image display from reaching the video camera.

3. The system of claim 2 wherein the image of the conferee reaching the polarizer is non-polarized.

4. The system of claim 2 wherein the display has an upper and lower end and wherein the field of view of the video camera is substantially limited at its lower end.

5. The system of claim 2 wherein said display includes a linear polarizing filter.

6. The system of claim 2 wherein said display is inherently emitting linearly polarized light.

7. The video teleconference system of claim 2 wherein the partially reflecting transparent device and the image display device are disposed at oblique angles such that the video camera field of view images the lower portion of the image display device through the partially reflecting transparent device.

8. The video teleconference system of claim 3 wherein the image display device radiates linearly polarized light.

9. The video teleconference system of claim 2 wherein the optical filtering device is a linear polarizer oriented orthogonal to the polarized light emanating form the image display device.

10. The video teleconference system of claim 2 wherein an angular field of view limiting device is attachably connected to the video camera to eliminate unwanted images.

5.

11. A method of providing substantially parallax free eye to eye contact of conferees in a video teleconferencing system comprising the steps of : a. linearly polarizing the image output of a display: b. interposing a beam splitter in front of the display; c. positioning a video camera to capture an image of one of the 0 conferees off the beam splitter; d. interposing a linear polarizer in the image field of the camera, said polarizer being oriented to block images emanating from said display while passing the image of said conferee.

5 12. The method of claim 12 further including the step of: a. positioning the camera such that its field view is limited to polarized light emanating from the display.

13. The method of claim 12 further including the step of: 0 a. hinging the beamsplitter to the display to permit removal and insertion of the splitter into the field of view.

14. The method of claim 12 further including the step of interposing a linear polarizer between the display and the beam splitter. 5

15. The method of claim 13 wherein the limiting step includes titling said display at an angle sufficient to prevent the camera from viewing unpolarized light adjacent the display

0