Foreground/background detector

• US 20020085096A1
• Filed: 05/15/2001
• Published: 07/04/2002
• Est. Priority Date: 05/18/2000
• Status: Active Grant

• Current Assignee: Dynamic Data Technologies LLC
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: De Haan, Gerard, Mertens, Mark Jozef Willem
• Granted Patent: US 6,771,799 B2
• Time in Patent Office: Days
• US Class Current: 348/161
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/223 using block-matching
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109

Abstract

A detector for detecting the foreground or background vector near a discontinuity in a vector field has a covering-uncovering detector (3)for determining whether covering or uncovering situation exists. The detector further has calculating means (1,2,4) for calculating at the position {right arrow over (x)}₁ of the discontinuity:

a first position {right arrow over (x)}_a in the previous (covering) or next (uncovering) vector field by shifting {right arrow over (x)}₁ over the first vector at one side of the discontinuity,

a second position {right arrow over (x)}_b in the previous (covering) or next (uncovering) vector field by shifting {right arrow over (x)}₁ over the second vector at the other side of the discontinuity

and a third intermediate position between {right arrow over (x)}_a and {right arrow over (x)}_b. Furthermore, the detector has means (5) for fetching the background vector with v_{{right arrow over (a)}v} at the third position in the previous (covering) or next (uncovering) vector field.

Claims

1. Method for detecting the foreground or background vector near a discontinuity in a vector field, characterised in that it is determined whether covering or uncovering situation exists, that at the position {right arrow over (x)}₁ of the discontinuity

a first position {right arrow over (x)}_a in the previous (covering) or next (uncovering) vector field is calculated by shifting {right arrow over (x)}₁ over the first vector at one side of the discontinuity,

a second position {right arrow over (x)}_b in the previous (covering) or next (uncovering) vector field is calculated by shifting {right arrow over (x)}₁ over the second vector at the other side of the discontinuity

and a third intermediate position between {right arrow over (x)}_a and {right arrow over (x)}_b is calculated,

in which the vector fetched with v_{{right arrow over (a)}v} at the third position in the previous (covering) or next (uncovering) vector field is the background vector.

2. Method according to claim 1, characterised in that the intermediate position is ({right arrow over (x)}_a+{right arrow over (x)}_b)/2.

7. Method according to claim 1, characterised in that the vector fetched with v_{{right arrow over (a)}v} at the first position in the previous (covering) or next (uncovering) image is filled in those regions of the image in the environment of the edge, to which no vector is projected, in case the background vector v_{{right arrow over (F)}G} should be filled in and the vector chosen between

3. Method for detecting the foreground or background vector near a discontinuity in a vector field, characterised in that it is determined whether covering or uncovering situation exists, and that two positions on either side of the discontinuity are projected to the previous (uncovering) or next (covering) vector field, in which a background velocity is identified as a velocity which crosses the velocity discontinuity and projects to a foreground velocity in the previous picture, whereas a foreground velocity projects to itself.

4. Method according to claim 3, characterised in that the determination is certain if the two projections yield the same vector.

6. Method according to claim 3, wherein the crossing from a background region to a foreground region in the previous image is verified by the match error of the vector in that block.

5. Method for detecting the foreground or background vector near a discontinuity in a vector field, characterised in that it is determined whether covering or uncovering situation exists, that the discontinuity is projected to the previous vector field in the covering situation and to the future vector field in the uncovering situation, near discontinuities it is tested whether the mentioned edge has moved over the first vector on one side of the discontinuity, or over the second vector on the other side of the discontinuity, and that in case the discontinuity moves with the first (second) vector, the second (first) vector is the background vector v_{{right arrow over (B)}G}.

8. Method according to claim 5, characterised in that the mentioned edge has moved over the first vector on one side of the edge, or over the second vector on the other side of the edge, in case the edge moves with the first vector with which the discontinuity moves, is filled in those regions of the projected vector field in the environment of the discontinuity, to which no vector is projected, in case a foreground vector v_{{right arrow over (F)}G} should be filled in, and the other vector is filled in, in case a background vector v_{{right arrow over (B)}G} should be filled.

9. Detector for detecting the foreground or background vector near a discontinuity in a vector field, characterised by a covering-uncovering detector (3)for determining whether covering or uncovering situation exists, calculating means (1, 2, 4) for calculating at the position {right arrow over (x)}₁ of the discontinuity

a first position {right arrow over (x)}_a in the previous (covering) or next (uncovering) vector field by shifting {right arrow over (x)}₁ over the first vector at one side of the discontinuity,

a second position {right arrow over (x)}_b in the previous (covering) or next (uncovering) vector field by shifting {right arrow over (x)}₁ over the second vector at the other side of the discontinuity

and a third intermediate position between {right arrow over (x)}_a and {right arrow over (x)}_b,

and means (5) for fetching the background vector with v_{{right arrow over (a)}v} at the third position in the previous (covering) or next (uncovering) vector field.

10. Detector according to claim 9, characterised in that the intermediate position is ({right arrow over (x)}_a+{right arrow over (x)}_b)/2.

15. Detector according to claim 9, characterised in that the vector fetched with v_{{right arrow over (a)}v} at the first position in the previous (covering) or next (uncovering) image is filled in those regions of the image in the environment of the edge, to which no vector is projected, in case the background vector v_{{right arrow over (F)}G} should be filled in and the vector chosen between

17. Image display apparatus comprising a foreground/background detector (16) according to one of the claims 9-16, a filling means (17) for filling the foreground/background vector detected by the detector (16) and a display device (18) connected to the filling means (17).

11. Detector for detecting the foreground or background vector near a discontinuity in a vector field, characterised by a covering-uncovering detector (8) for determining whether covering or uncovering situation exists, and means (6,7) for projecting two positions on either side of the discontinuity to the previous (uncovering) or next (covering) vector field, in which a background velocity is identified (10) as a velocity which crosses the velocity discontinuity and projects to a foreground velocity in the previous picture, whereas a foreground velocity projects to itself.

12. Detector according to claim 11, characterised in that the identification is certain if the two projections yield the same vector.

14. Detector according to claim 11, wherein the crossing from a background region to a foreground region in the previous image is verified by the match error of the vector in that block.

16. Detector according to claim 13, characterised in that the mentioned edge has moved over the first vector on one side of the edge, or over the second vector on the other side of the edge, in case the edge moves with the first (second) vector with which the discontinuity moves, the second (first) vector is filled in those regions of the projected vector field in the environment of the discontinuity, to which no vector is projected, in case a foreground vector v_{{right arrow over (F)}G} should be filled in, and the other vector is filled in, in case a background vector v_{{right arrow over (B)}G} should be filled.

13. Detector for detecting the foreground or background vector near a discontinuity in a vector field, characterised by a covering-uncovering detector (12) for determining whether covering or uncovering situation exists, means (11) for projecting the discontinuity to the previous vector field in the covering situation and to the future vector field in the uncovering situation, and testing means (15) for testing near discontinuities whether the mentioned edge has moved over the first vector on one side of the discontinuity, or over the second vector on the other side of the discontinuity, in which in case the discontinuity moves with the first (second) vector, the second (first) vector is the background vector v_{{right arrow over (B)}G}.