Video processing method and apparatus for use with a sequence of stereoscopic images

1. A method of processing a stereoscopic image sequence to generate a warning that the stereoscopic image sequence has been derived from a 2D image sequence, the method comprising the steps in a video processor of:

receiving left-eye image data and right-eye image data from a sequence of stereoscopic images;

performing a correlation process upon said left-eye image data and right-eye image data to identify any temporal offset where left-eye image data is substantially equal to delayed right-eye image data or right-eye image data is substantially equal to delayed left-eye image data; and

performing an analysis of said temporal offset to generate a warning signal that the said stereoscopic image sequence has been derived from a 2D image sequence where said temporal offset is constant at one value for a first set of said images and constant at a different value for a second set of said images.

2. A method according to claim 1 , wherein left-eye image data is compared with right-eye image data delayed by one image and with right-eye image data delayed by two images and right-eye image data is compared with left-eye image data delayed by one image and with left-eye image data delayed by two images.

3. A method according to claim 1 , wherein said first set and second set of images each comprise at least ten images.

4. A method according to claim 1 , wherein said left-eye image data and said right-eye image data are vertically filtered prior to performing of said correlation process.

5. A method according to claim 4 , wherein columns in said left-eye image data and said right-eye image data are vertically averaged.

6. A method according to claim 1 , wherein said analysis includes a determination that there is sufficient variation in pixel values over the image to make correlation meaningful.

7. A method according to claim 1 , wherein said warning signal is temporally filtered.

8. A method according to claim 7 , wherein said warning signal is temporally filtered in a non-linear temporal filter.

9. Video processing apparatus comprising:

an input for receiving left-eye image data and right-eye image data from a sequence of stereoscopic images;

a correlator for performing a correlation process upon said left-eye image data and right-eye image data to identify any temporal offset where left-eye image data is substantially equal to delayed right-eye image data or right-eye image data is substantially equal to delayed left-eye image data; and

a logic block for performing an analysis to generate a warning signal that the said stereoscopic image sequence has been derived from a 2D image sequence where said temporal offset is constant at one value for a first set of said images and constant at a different value for a second set of said images.

10. Apparatus according to claim 9 , wherein said correlator is adapted to compare left-eye image data with right-eye image data delayed by one image and with right-eye image data delayed by two images and to compare right-eye image data with left-eye image data delayed by one image and with left-eye image data delayed by two images.

11. Apparatus according to claim 9 , wherein said first set and second set of images each comprise at least ten images.

12. Apparatus according to claim 9 , comprising a vertical filter operating on said left-eye image data and said right-eye image data prior to performing of said correlation process.

13. Apparatus according to claim 12 , wherein said vertical filter comprises a vertical averager operating on columns in said left-eye image data and said right-eye image data.

14. Apparatus according to claim 9 , comprising an activity detector enabling said logic block to make a determination that there is sufficient variation in pixel values over the image to make correlation meaningful.

15. Apparatus according to claim 9 , comprising a temporal filter operating on said warning signal.

16. Apparatus according to claim 15 , wherein said temporal filter is non-linear.

17. A non-transitory computer program product containing instructions adapted to cause programmable apparatus to implement a method of processing a stereoscopic image sequence to generate a warning that the stereoscopic image sequence has been derived from a 2D image sequence, the method comprising the steps in a video processor of:

receiving left-eye image data and right-eye image data from a sequence of stereoscopic images; performing a correlation process upon said left-eye image data and right-eye image data to identify any temporal offset where left-eye image data is substantially equal to delayed right-eye image data or right-eye image data is substantially equal to delayed left-eye image data; and

performing an analysis of said temporal offset to generate a warning signal that the said stereoscopic image sequence has been derived from a 2D image sequence where said temporal offset is constant at one value for a first set of said images and constant at a different value for a second set of said images.

18. A computer program product according to claim 17 , wherein left-eye image data is compared with right-eye image data delayed by one image and with right-eye image data delayed by two images and right-eye image data is compared with left-eye image data delayed by one image and with left-eye image data delayed by two images.

19. A computer program product according to claim 17 , wherein said left-eye image data and said right-eye image data are vertically filtered prior to performing of said correlation process.

20. A computer program product according to claim 17 , wherein said analysis includes a determination that there is sufficient variation in pixel values over the image to make correlation meaningful.