Apparatus and method for correcting backlight of camera

• US 8,199,234 B2
• Filed: 07/01/2008
• Issued: 06/12/2012
• Est. Priority Date: 02/25/2008
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Seo, Sungha, Ahn, Namkyu, Min, Chol
• Primary Examiner(s): Laballe, Clayton E
• Assistant Examiner(s): Rhodes, Jr., Leon W.
• Application Number:
  US12/166,097
• Publication Number:
  US 20090213244A1
• Time in Patent Office: 1,442 Days
• Field of Search: 348/297, 348/362
• US Class Current: 348/297
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene

Abstract

An apparatus and method for correcting the backlight of a camera are disclosed. When the camera for photographing a moving image by a photographing device, such as a general-purpose CCD or a general-purpose CMOS, enters into a backlight shooting state for simultaneously photographing an object with a very high luminance level and an object with a very low luminance level, as the shutter speed of the photographing device is varied to a long shutter speed and a short shutter speed, an image shot with the long shutter speed and an image shot with the short shutter speed are synthesized and outputted, thereby enabling a proper luminance level object photographing operation for each of the objects. Accordingly, it is possible to efficiently prevent the phenomenon that the object with the low luminance level looks dark due to the object with the high luminance level.

Claims

1. A method for correcting the backlight of a camera having a shutter configured to operate in a backlight shooting mode, comprising:

varying a speed of the shutter between a long shutter speed and a short shutter speed;

synthesizing an image shot with the long shutter speed with an image shot with the short shutter speed to produce a final image by increasing a digital gain on the image shot with the long shutter speed and reducing a digital gain on the image shot with the short shutter speed; and

outputting the final image.

2. The method according to claim 1, the step of varying comprising:

varying the shutter speed so that the long shutter speed image and the short shutter speed image are shot at least once in a cycle of one field.

3. The method according to claim 1, wherein the steps of increasing and reducing are selectively performed in response to a user input.

4. The method according to claim 1, wherein the camera comprises a CCD or a CMOS device.

5. A method for correcting the backlight of a camera having a shutter configured to operate in a backlight shooting mode, comprising:

varying a speed of the shutter over a plurality of fields so that a long shutter speed operation and a short shutter speed operation are performed once respectively per field, the short shutter speed operation being performed at a starting portion of a corresponding field;

increasing a digital gain of images shot with the long shutter speed;

reducing a digital gain of images shot with a short shutter speed;

synthesizing long and short shutter speed images into a final image; and

outputting the final image.

6. The method according to claim 5, the step of synthesizing comprising:

synthesizing a short shutter speed image of one field with a long shutter speed image of a previous field.

7. The method according to claim 5, wherein the steps of increasing and reducing are selectively performed in response to a user input.

8. The method according to claim 5, wherein the photographing device comprises a CCD or a CMOS device.

9. A method for correcting the backlight of a camera having a shutter configured to operate in a backlight shooting mode, comprising:

varying a speed of the shutter over a plurality of fields so that a long shutter speed operation and a short shutter speed operation are performed once respectively per field, the short shutter speed operation being performed at an end portion of a corresponding field;

increasing a digital gain for images shot with the long shutter speed;

decreasing a digital gain for images shot with the short shutter speed;

synthesizing long and short shutter speed images into a final image; and

outputting the final image.

10. The method according to claim 9, the step of synthesizing comprising:

synthesizing a short shutter speed image of one field with a long shutter speed image of a subsequent field.

11. The method according to claim 9, wherein the steps of increasing and reducing are selectively performed in response to a user input.

12. The method according to claim 9, wherein the camera comprises a CCD or a CMOS device.

13. A method for correcting the backlight of a camera having a shutter configured to operate in a backlight shooting mode, comprising:

varying a speed of the shutter over a plurality of fields so that a long shutter speed operation is performed once and a short shutter speed operation is performed twice respectively per field;

increasing a digital gain for images shot with the long shutter speed;

decreasing a digital gain for images shot with the short shutter speed;

synthesizing long and short shutter speed images into final images; and

outputting the final images.

14. The method according to claim 13, the step of varying comprising:

varying the speed of the shutter over the plurality of fields so that the short shutter speed operation is performed at a start portion and an end portion of a respective field.

15. The method according to claim 14, the step of synthesizing comprising:

synthesizing a long shutter speed image of a cycle with a short shutter speed image of a start portion of the cycle to produce a first final image; and

synthesizing the long shutter speed image of the cycle with a short shutter speed image of an end portion of the cycle to produce a second final image.

16. The method according to claim 13, wherein the steps of increasing and reducing are selectively performed in response to a user input.

17. The method according to claim 13, wherein the camera comprises a CCD or a CMOS device.

18. An apparatus for correcting the backlight of a camera, comprising:

a shutter;

a controller configured to vary a speed of the shutter between a long shutter speed and a short shutter speed; and

a signal processor configured to synthesize an image shot with the long shutter speed with an image shot with the short shutter speed to produce a final image by increasing a digital gain on the image shot with the long shutter speed and reducing a digital gain on the image shot with the short shutter speed, and to output the final image.

19. The apparatus according to claim 18, wherein

the controller is configured to vary the shutter speed so that the long shutter speed image and the short shutter speed image are shot at least once in a cycle of one field.

20. The apparatus according to claim 18, wherein the signal processor is configured to increase or reduce the digital gain in response to a user input.

21. The apparatus according to claim 18, further comprising one of a CCD or CMOS.

22. An apparatus for correcting the backlight of a camera, comprising:

a shutter;

a controller configured to vary a speed of the shutter over a plurality of fields so that a long shutter speed operation and a short shutter speed operation are performed once respectively per field, the short shutter speed operation being performed at a start portion of a corresponding field; and

a signal processor configured to

increase a digital gain of images shot with the long shutter speed;

reduce a digital gain of images shot with a short shutter speed;

synthesize long and short shutter speed images into a final image; and

output the final image.

23. The apparatus according to claim 22, wherein the signal processor is configured to synthesize a short shutter speed image of one field with a long shutter speed image of a previous field.

24. The apparatus according to claim 22, wherein the signal processor is configured to increase or reduce the digital gain in response to a user input.

25. The apparatus according to claim 22, further comprising one of a CCD or CMOS.

26. An apparatus for correcting the backlight of a camera, comprising:

a shutter;

a controller configured to vary a speed of the shutter over a plurality of fields so that a long shutter speed operation and a short shutter speed operation are performed once respectively per field, the short shutter speed operation being performed at an end portion of a corresponding field; and

a signal processor configured to

increase a digital gain of images shot with the long shutter speed;

reduce a digital gain of images shot with a short shutter speed;

synthesize long and short shutter speed images into a final image; and

output the final image.

27. The apparatus according to claim 26, wherein the signal processor is configured to synthesize a short shutter speed image of one field with a long shutter speed image of a subsequent field.

28. The apparatus according to claim 26, wherein the signal processor is configured to increase or reduce the digital gain in response to a user input.

29. The apparatus according to claim 26, further comprising one of a CCD or CMOS.

30. An apparatus for correcting the backlight of a camera, comprising:

a shutter;

a controller configured to vary a speed of the shutter over a plurality of fields so that a long shutter speed operation is performed once and a short shutter speed operation is performed twice respectively per field; and

a signal processor configured to

increase a digital gain for images shot with the long shutter speed;

decrease a digital gain for images shot with the short shutter speed;

synthesize long and short shutter speed images into final images; and

output the final images.

31. The apparatus according to claim 30, wherein the controller is configured to vary the speed of the shutter over the plurality of fields so that the short shutter speed operation is performed at a start portion and an end portion of a respective field.

32. The apparatus according to claim 30, wherein the signal processor is configured to

synthesize a long shutter speed image of a cycle with a short shutter speed image of a start portion of the cycle to produce a first final image;

and

synthesize the long shutter speed image of the cycle with a short shutter speed image of an end portion of the cycle to produce a second final image.

33. The apparatus according to claim 30, wherein the signal processor is configured to increase or reduce the digital gain in response to a user input.

34. The apparatus according to claim 30, further comprising one of a CCD or CMOS.