GB2255251A - Colour anaglyph 3d television with field rate doubling - Google Patents

Abstract

Colour cameras 1 capture left and right views of a scene and relay them to time division multiplexer 2 which alternately outputs left view and right view representing fields. These may be stored in video recorder 3 or passed directly to a processor in which they are first demultiplexed 4 to form respective left view and right view signals each having only alternate fields present. The display of such a signal would lead to objectionable flicker and to prevent this the field rate of both left and right view signals is doubled 5, 6 after which they may be encoded into a 3D anaglyph signal 9-11 for display on suitable equipment with doubled field rate. The signal is observed through spectacles 13 having complementary coloured red/cyan filters. <IMAGE>

Description

FIELD OF THE INVENTION.

Description of the Prior Art.

There have been many attempts at presenting stereoscopic 3D television. Generally this is achieved by capturing two images with two cameras side by side, about eye distance apart. One camera is adapted to generate a red signal, the other a green or blue signal and the combination of both cameras viewed through corresponding coloured filters, generally worn as cardboard eye glasses. The 3D image is perceived as a monochrome image in the brain.

It is one intention of this invention to present, what is perceived by the brain to be, a natural colour 3D image or COLOUR ANAGLYPH TV image.

A major shortcoming regarding the recording of any anaglyph 3D signal is that it requires a high bandwidth to retain stereoscopic information. This facility is found in professional and semi-professional video formats, as these formats tend to separately process the Chromanance and Luminance signals through recording and playback. This kind of separate processing retains the more subtle colour characteristics required for good quality anaglyph 3D TV images.

A broadcast or live 3D anaglyph transmitted image is also found to contain an acceptable amount of depth when viewed on domestic equipment; but a VHS recording, for example, when played back would, destroy the stereoscopic information resulting in poor to no 3D. This is due to the low band width generally associated with domestic video recorders and their inability to process chromanance and luminance information separately.

More recently, a method has been employed called "time division multiplexing", where the two fields represented in a single television frame are each allocated a view from a pair of cameras. This is achieved by use of a multiplexer. FIG.1.(2) This halves the amount of frames or fields seen by the eyes.

25 fields per second if the standard rate is 50hz or 30 fields per second as in the NTSC 60hz TV standard. This alternating left-right image is viewed via liquid crystal shutter eye glasses synchronised to the television fields. This allows the left field to be seen by the left eye and right field only by the right eye. This 3D TV method is considered excellent for keeping the stereo images separate and can be seen in full colour: though it is known to suffer from severe flicker.

SUMMARY OF THE INVENTION.

It is the intention of this invention to overcome the problems associated with the recording and playing back of anaglyph 3D images using VHS and other domestic video tape formats. To present natural COLOUR ANAGLYPH 3D TV and/or the usual anaglyph 3D TV, particularly on, what is considered to be, domestic television equipment.

To realize these objectives a standard 3D video capture procedure is used as described above.

A video signal is time division multiplexed so that each field, of which there, for this example, are two, is allocated a view from a pair of gen-locked colour video cameras (See FIG.1.

(1)), at eye distance apart.

At this stage liquid crystal glasses can be employed to view a stereo 3D TV image, either live, from the cameras, or from a recorded tape or VCR. (3) For example, VHS.

The 3D image at this stage is not COLOUR ANAGLYPH but full colour, and sufferes from severe flicker. It is at this stage the video signal, which consists of left-right interlaced fields is fed to an external processor. That is to say from the output of the video recorder it is sent to a decoder unit. In some instances, the external processor or "decoder" could be built into the VCR or video monitor/projector.

A further option exists at the initial capture and recording stage. If each camera is adapted to record, left camera - red, and right camera - blue/green, but not as previously mentioned where they are mixed together and recorded on a professional tape format; but instead, each field is allocated a colour stripped version. For example, left camera, red only recorded on field one and right camera, blue/green recorded on field two. A substantial amount of stereoscopic definition is retained even if recorded/played back using a domestic video tape format. The image at this stage is viewable with LC glasses or red/cyan cardboard spectacles.

A flicker-less image can also be produced by appropriate field buffing as is explained in detail in the description of preferred embodiments.

This version is particularly preferable if a high quality 3D image is not essential and the deletion of colour splitters in the decoder unit is required.

DESCRIPTION OF THE DRAWINGS.

FIG.1 is a simplified block diagram depicting one example of the invention. It shows the processing systems employed, and some of the output stages from initial capture of two images to final viewing of a natural colour anaglyph 3D image.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.

The left-right interlacing signal is first sent to a demultiplexer, (4) within the "decoder", (See FIG.1. Elements contained within dashed line represent the decoder) dividing the left and right interlacing signal in two. This produces a left eye signal made up of an interlaced field containing left eye picture information and a black or neutral field. The right eye view is similarly made up of a picture field and a neutral field. Viewing the left or right image independently at this stage would appear course and suffer from flicker.

To smooth out the coarseness and reduce flicker, further processing is required. The left eye signal containing one picture information field and one neutral field is buffed using a field/frame store, (5) discarding the neutral field. The copy of the original picture field is interlaced with the newly created field resulting in a full, standard frame/signal. This is repeated 25 times a second (PAL rate), or 30 times a second (NTSC). The field buffing process is similarly taking place with the right eye picture carrying field, (6) copying it and then interlacing it with the original right eye picture field signal. The results at this stage are two full colour standard video signals. (7) (8).

Here, a number of possibilities occur. Firstly, the two "whole" video signals could be sent to a pair of standard video projectors or monitors, fitted with cross-polarising filters and the image viewed through corresponding polarised filters for a flicker-less, full colour 3D image.

Another variation is to directly connect the left image, for example, to the red gun of a CRT and the right eye view to the green and blue guns.

Viewing of the 3D image is achieved by each eye looking through coloured filters. eg. red and cyan, generally in the form of cardboard glasses. The 3D image can also be perceived without the use of spectacles by placing a colour coded lenticular screen or diffraction grating between the viewer and the image.

In addition to these autostereo methods a red/cyan polariser material (generally used with professional still camera equipment) could be placed over the image. This allowes the viewer to see the natural colour anaglyph 3D image whilst wearing cross polarising spectacles.

In another case, two totally different images from, let us say two TV tuners or satellite channels, representing different programmes on different channels, could have been recorded. On playback, the field representing programme one would be field buffed as previously described, so allowing a full video signal to be viewed or processed. Just as easily the other field could be buffered, allowing a second full standard video signal or programme to be accessed. This process would allow the recording of two channels off air, two cameras, two computers or any combination of video signal, to be recorded and played back as independent signals. (In the case of four fields being used, similar field buffing and processing could produce four "whole" signals from one tape recording.) A further 3D TV option exists at the two signal output stage.

By employing a simple form of store and delay interface, it would be possible to feed a high scanning monitor or projector with both video signals and view them using LC switching specs or a LC switching screen and passive polarised specs. This has the advantage of still being flicker-less, using a single monitor or projector.

The natural COLOUR ANAGLYPH 3D TV signal still needs to be extracted from the two full colour newly created signals. The left eye signal, for example is sent to a colour splitter which strips off the blue and green picture information allowing only the red picture information to pass through. (9) The right signal is divided in two and each part sent to two further colour splitters. (10) (11) This allows only the green and blue parts of the right eye view to pass through resulting in the extraction of red. The blue and green elements of the right eye signal could be mixed together to create cyan, and the cyan ultimately mixed together with the red picture information.

This results in a single RGB (red, green, blue) natural COLOUR 3D TV ANAGLYPH, non flicker image. This is due to all of the final 3D colour information being created in real-time after it has left the VCR. (Except in the case of the cameras being initially colour coded and allocated separate fields; as previously explained).

At this stage the picture could be viewed on RGB equipment (12) using red/cyan coloured spectacles, (13) though some further processing is required for viewing the 3D TV image on domestic television sets.

The final stages of processing required by the decoder unit are the conversion of the RGB signal into a video signal by employing, for example, a PAL or NTSC encoder, (14) and the conversion of this video signal into an RF signal. This is achieved by a using a video to RF modulator. (15) At both these video and RF output stages, the natural Colour Anaglyph, nonflicker, 3D image could be viewed with red/cyan (13) glasses on domestic television equipment.

Claims (20)

CLAIMS.

1. A method of recording two video signals as a single signal, compatible to any world television standard, the de-coding of this signal into two separate signals, the reinstating of these signals as two standard video signals, and the further "realtime" colour separation processing of these signals into a single 3D stereoscopic natural colour anaglyph image for viewing on standard television equipment.

2. A method of recording two video signals as a single signal, as in claim 1. with the intention of this invention overcoming the problems associated with the recording and playing back of anaglyph 3D images using VHS and other domestic video tape formats. To present natural COLOUR ANAGLYPH 3D TV and/or the usual anaglyph 3D TV, particularly on, what is considered to be, domestic television equipment.

3. A method of recording two video signals as a single signal, as in claim 1 and 2 where a video signal is time division multiplexed so that each field, of which there can be any number, is allocated independent signals from any combination of video sources for processing.

4. A method of recording two video signals as a single signal, as in claims 1, 2, and 3 which could be fed to an external processor. That is to say from the output of the video recorder a multiplexed signal could be sent to a an external device, for example, a decoder unit, or alternatively, the processing system could be built into a VCR, monitor, projector or other piece of equipment required in the system.

4. A method of recording two video signals as a single signal, as in claims 1, 2, 3 and 4 where at the initial capture and recording stage, each camera is adapted to record, left camera - red, and right camera - blue/green, where each field is allocated a colour stripped image. For example, left camera, red only recorded on field one and right camera, blue/green recorded on field two.

5. A method of recording two video signals as a single signal, as in claims 1, 2, 3, and 4 where a flicker-less image can be produced by appropriate field buffing with a red/cyan source tape being used instead of real-time colour separation processing.

6. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4 and 5 where the left-right interlacing signal is fed to the "decoder" unit, which buffs each field to produce two standard video signals.

7. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5 and 6 where further colour separation is introduced so that each signal is coloured red/cyan.

8. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, and 7 where each signal can be mixed together to be viewed as a single image via a single television viewing apparatus.

9. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, 7, and 8 where the two signals can be delayed and interlaced to form one signal operating at twice the usual television standard rate.

10. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, 7, 8, and 9 where the image is viewed through colour filters eg. red/cyan in the form of spectacles.

11. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 where dual channel colour separation is achieved by directly routing the left/right images to the CRT. eg. left-red/right-blue, green.

12. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 or independent signals off air or satellite are multiplexed and buffered using field/frame store.

13. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 with further processing of the RGB signals to video and RF for compatibility with domestic equipment.

14. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 where each eye receives a combination of red or cyan perceived as a natural colour anaglyph 3D image by use of coded lenticular screen, or other anaglyph to autostereo device.

Amern-rits to the clairns have been filed as follows

15. A method of recording two video signals as a single signal and displaying them as two separate non-flicker signals but without employing the use of field/frame buffers by outputting only the interlaced field/s to Liquid Crystal Television monitor/s.

16. A method of recording two video signals as a single signal and displaying them as two separate non-flicker signals but without employing the use of field/frame buffers as in claim 15. but using colour striped interlaced fields eg. one field red and one field cyan, and displaying this signal on a single Liquid Crystal Monitor.

17. A method of recording and playing back two independent video signals using a single VCR with modified play and record circuitry: so as one field can be in record mode while the other field is in play-back, with the result that one programme can be viewed while another is being recorded on the same tape.

18. A method of recording two video signals as a single signal, by dividing the full screen image into, for example, two half screen images, and in real-time, from the VCR, digitally re constituting these half frame signals into two full and separate video signals.

19. A method of recording two video signals as a single signal, by dividing the full screen image into, for example, two half screen images, and in real-time, from the VCR, digitally re constituting these half frame signals into two full and separate video signals as in claim 18. then colour splitting each of the re constituted signals as a red and a cyan signal respectively and mixing them, in real time, to form a single natural colour 3D non-flicker anaglyph signal.

20. A method of recording two video signals as a single signal, as in claims 1, 2, 3, 4 and 5 where the left-right interlacing signal is fed to the "decoder" unit, which buffs each field to produce two standard video signals as in claim 6., only, a single lens 3D video capture technique is used instead of the usual two camera rig, where the lens aperture is divided vertically by an alternating switching shutter synchronised to the TV field/frame rate. The two reinstated video signals leaving the decoder are fed to two polarised projectors and the image viewed in 3D with corresponding polarised glasses, or in 2D without polarising filters.