Adjusting a softness region

• US 6,571,012 B1
• Filed: 03/31/1999
• Issued: 05/27/2003
• Est. Priority Date: 04/01/1998
• Status: Expired due to Term

• Current Assignee: Autodesk, Inc.
• Original Assignee: Autodesk, Inc.
• Inventors: Pettigrew, Daniel
• Primary Examiner(s): Wu, Jingge
• Application Number:
  US09/282,659
• Time in Patent Office: 1,518 Days
• Field of Search: 382/162-167, 358/500-540, 348/584-592
• US Class Current: 382/167
• CPC Class Codes: H04N 9/75 Chroma key

Abstract

Image data representing a matte, key or control signal is processed. A transitional portion or softness region of the matte in which undesirable transitions occur is identified. The position of the softness region in colour-space is adjusted so as to reduce relative amplitudes of variations within the identified portion.

Claims

1. A method of processing image data representing a matte, key or control signal, comprising the steps of:

identifying a tolerance region in a colour-space matte, wherein the tolerance region comprises a first geometric shape that defines a background colour, and wherein said matte is for utilization in compositing video images;

identifying a transitional portion of said matte in which undesirable transitions occur in a form displayed as noise artifacts, and

reducing the relative amplitudes of variations within said identified portion by modifying a softness region in said colour-space so as to reduce the presence of high frequency variations, wherein the softness region comprises a second geometric shape that defines a volume of said colour-space for the undesirable transitions, and wherein the softness region is modified by directly transforming the second geometric shape.

2. A method according to claim 1, wherein said matte is generated by a process of chroma-keying.

3. A method according to claim 1, comprising steps of perturbing the softness region iteratively, measuring frequency distributions and selecting a preferred perturbation.

4. A method according to claim 1, wherein frequency values are determined by performing a Fourier transform against softness values.

5. A method according to claim 1, wherein the second geometric shape of the softness region is an ellipsoid and the position of said softness region is modified by transforming the shapes of said ellipsoid.

6. A method according to claim 5, wherein a stretching operation is performed against said ellipsoid.

7. A method according to claim 5, wherein said ellipsoid is determined by defining a convex hull around a plurality of pixel colours defined in colour-space.

8. A method according to claim 5, wherein said ellipsoid is displayed to an operator.

9. A method according to claim 8, wherein the shape of said ellipsoid is modified in response to manual operation of an interface device.

10. Image data processing apparatus configured to process image data representing a matte, key or control signal, comprising

first identifying means for identifying a tolerance region in a colour-space for said matte, wherein the tolerance region comprises a first geometric shape that defines a background color, and wherein said matte is for utilization in compositing video images;

second identifying means for identifying a transitional portion of said matte in which undesirable transitions occur in a form displayed as noise artefacts; and

adjusting means configured to reduced the relative amplitudes of variations within said identified portion by modifying a softness region in said colour-space so as to reduce the presence of high frequency variations, wherein the softness region comprises a second geometric shape that defines a volume of said colour-shape for the undesirable transitions, and wherein the softness region is modified by directly transforming the second geometric shape.

11. Chroma-keying apparatus configured to composite image portions, including image data processing apparatus configured to process image data representing a key, according to claim 10.

12. Apparatus according to claim 10, wherein said adjusting means is configured to perturb the softness region iteratively, measure frequency distribution and select a preferred perturbation on the basis of said measurements.

13. Apparatus according to claim 10, including processing means configured to produce frequency values by performing a Fourier transform against softness values.

14. Apparatus according to claim 10, wherein said second geometric shape of the softness region is defined as an ellipsoid and the position of said softness region is modified by said adjusting means, configured to transform the shape of said ellipsoid.

15. Apparatus according to claim 14, wherein said adjusting means is configured to perform a stretch upon said ellipsoid.

16. Apparatus according to claim 14, including processing means configured to define a convex hull around a plurality of pixel colours defined in colour-space.

17. Apparatus according to claim 14, including display means for displaying an ellipsoid to an operator in colour-space.

18. Apparatus according to claim 17, wherein the shape of said displayed ellipsoid is modified in response to manual operation of a manually operable device.

19. A computer system programmed to process image data representing a matte, key or control signal, including the program steps of:

identifying a tolerance region in a colour-space for said matte, wherein the tolerance region comprises a first geometric shape that defines a background colour, and wherein said matte is for utilization in compositing video images;

identifying a transition portion of said matte in which undesirable transitions occur in a form displayable as noise artefacts; and

reducing the relative amplitudes of variations within said identifies portion by modifying a softness region in said colour-space so as to reduce the presence of high frequency variations, wherein the softness region comprises a second geometric shape that defines a volume of said colour-space for the undesirable transitions, and wherein the softness region is modified by directly transforming the second geometric shape.

20. A computer system programmed according to claim 19, further programmed to process image data representing a key as part of a chroma-keying process.

21. A computer system programmed according to claim 19, further programmed to perturb the softness region iteratively, measure frequency distribution and select a preferred perturbation on the basis of said measurements.

22. A computer system programmed according to claim 19, further programmed to produce frequency values by performing a Fourier transform against softness values.

23. A computer system programmed according to claim 19, wherein the second geometric shape comprises an ellipsoid.

24. A computer system programmed according to claim 23, further programmed to perform a stretch upon said ellipsoid.

25. A computer system programmed according to claim 23, further programmed to define a convex hull around a plurality of pixel colours defined in colour-space.

26. A computer system programmed according to claim 23, further programmed to supply data to a display means thereby allowing said display means to display the ellipsoid to an operator in colour-space.

27. A computer system programmed according to claim 26, further programmed to respond to manual operation of a manually operable device so as to modify the shape of the displayed ellipsoid.

28. A computer-readable medium having computer-readable instructions executable by a computer, such that said computer performs the steps of:

identifying a tolerance region in a colour-space for said matte, wherein the tolerance region comprises a first geometric shape that defines a background colour, and wherein said matte is for utilization in comprising video image;

identifying a transitional portion of a matte, key or control signal in image data in which undesirable transitions occur in a form displayed as noise artefacts, and

reducing the relative amplitudes of variations within said identified portion by modifying a softness region in said colour-space so as to reduce the presence of high frequency variations, wherein the softness region comprises a second geometric shape that defines a volume of said colour-space for the undesirable transitions, and wherein the softness region is modified by directly transforming the second geometric shape.

29. A computer-readable medium according to claim 28, having computer-readable instructions executed by a computer, such that said computer performs a further step of generating the matte by a chroma-keying process.

30. A Computer-readable medium according to claim 28, having computer-readable instructions executable by a computer, such that said computer performs a further step of perturbing the softness region iteratively, measuring frequency distributions and selecting a preferred perturbation.

31. A computer-readable medium according to claim 28, having computer-readable instructions executable by a computer, such that said computer performs the further step of determining frequency values by performing a Fourier transfer against softness values.

32. A computer-readable medium according to claim 28, wherein the second geometric shape is an ellipsoid.

33. A computer-readable medium according to claim 32, having computer-readable instructions executable by a computer, such that said computer performs a further step of performing a stretching operation against said ellipsoid.

34. A computer-readable medium according to claim 32, having computer-readable instructions executable by computer, such that said computer performs the further step of defining a convex hull around a plurality of pixel colours define in colour-space, so as to determine the position of the ellipsoid.

35. A computer-readable medium according to claim 32, having computer-readable instructions executable by a computer, such that said computer performs a further step of displaying the ellipsoid to an operator.

36. A computer-readable medium according to claim 35, having computer-readable instructions executable by a computer, such that said computer performs a further step of modifying said ellipsoid in response to manual operation of an interface device.