Method of controlling digital photographing apparatus to increase brightness detectable range and digital photographing apparatus adopting the method

• US 7,538,802 B2
• Filed: 03/21/2005
• Issued: 05/26/2009
• Est. Priority Date: 09/09/2004
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Techwin Corporation (Hanwha Vision Company Limited)
• Inventors: Lee, Seok-goun
• Primary Examiner(s): Hannett; James M
• Application Number:
  US11/085,689
• Publication Number:
  US 20060050171A1
• Time in Patent Office: 1,527 Days
• Field of Search: 348/229.1, 348/218.1
• US Class Current: 348/229.1
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene

Abstract

Provided is a method of controlling a digital photographing apparatus that performs exposure in response to a photographing command signal and captures an image. The method includes (a) capturing an image of at least a first field using a smaller amount of exposure than a reference amount of exposure; (b) capturing an image of at least a second field using a larger amount of exposure than the reference amount of exposure; and (c) synthesizing the images of the at least first and second fields.

Claims

1. A method of controlling a digital photographing apparatus that performs exposure in response to a photographing command signal and captures an image, the method comprising:

(a) capturing an image of a first field using a first exposure

(b) capturing an image of a second field using a second exposure, wherein the level of the second exposure is different from the level of the first exposure; and

(c) synthesizing the images of the first and second fields,

wherein the first exposure is executed for a first exposure duration shorter than a reference exposure duration and the second exposure is executed for a second exposure duration that adds the first exposure duration to a predetermined duration to be longer than the reference exposure duration, and

wherein the first exposure duration and the second exposure duration are started together.

2. The method of claim 1 wherein the first exposure level is less than a reference exposure level.

3. The method of claim 1 wherein the second exposure level is greater than a reference exposure level.

4. The method of claim 2 wherein the second exposure level is greater than both of the first exposure level and the reference exposure level.

5. The method of claim 1 wherein step (a) comprises:

generating a first synchronization pulse relative to the photographing command signal;

generating a first group of sequential shutter pulses by the first synchronization pulse;

generating a second synchronization pulse at a predetermined time after the first synchronization pulse; and

capturing the image of the first field having the first exposure level corresponding to the first exposure duration after the second synchronization pulse.

6. The method of claim 5 wherein step (b) comprises:

generating a third synchronization pulse at a predetermined time after the second synchronization pulse; and

capturing the image of the second field having the second exposure level corresponding to the second exposure duration after generating the third synchronization pulse,

wherein the first exposure duration and the second exposure duration are started together at the time of stopping the generating the first group of sequential shutter pulses.

7. The method of claim 1 wherein the synthesizing step comprises:

normalizing an average brightness value of the image of the first field to an average brightness value of a reference image; and

normalizing an average brightness value of the image of the second field to the average brightness value of the reference image.

8. The method of claim 7 wherein the normalizing steps are performed relative to a correction lookup table that is stored in a memory of the digital photographing apparatus.

9. A method of controlling a digital photographing apparatus that performs exposure in response to a photographing command signal and captures an image, the method comprising:

(a) capturing an image of a first field using a smaller exposure than a reference exposure;

(b) capturing an image of a second field using a larger exposure than the reference exposure;

(c) adjusting an average brightness of the image of the first field and an average brightness of the image of the second field; and

(d) synthesizing the images of the first and second fields,

wherein the smaller exposure is executed for a first exposure duration shorter than a reference exposure duration and the larger exposure is executed for a second exposure duration that adds the first exposure duration to a predetermined duration to be longer than the reference exposure duration, and

wherein the first exposure duration and the second exposure duration are started together.

10. The method of claim 9 wherein step (a) comprises:

generating a first synchronization pulse relative to the photographing command signal;

generating a first group of sequential shutter pulses by the first synchronization pulse;

generating a second synchronization pulse at a predetermined time after the first synchronization pulse;

capturing the image of the first field having the smaller exposure corresponding to a first exposure duration shorter than a reference exposure duration.

11. The method of claim 10 wherein step (b) comprises:

generating a third synchronization pulse at a predetermined time after the second synchronization pulse; and

capturing the image of the second field having the larger exposure corresponding to a second exposure duration longer than the reference exposure duration,

wherein the first exposure duration and the second exposure duration are started together at the time of stopping the generating the first group of sequential shutter pulses.

12. The method of claim 9 wherein the adjusting step comprises:

normalizing an average brightness value of the image of the first field to an average brightness value of a reference image; and

normalizing an average brightness value of the image of the second field to the average brightness value of the reference image.

13. The method of claim 12 wherein the normalizing steps are performed relative to a correction lookup table that is stored in a memory of the digital photographing apparatus.

14. The method of claim 9 wherein the adjusting step comprises:

compensating for the image of the first field such that a first brightness characteristic relative to the first field becomes generally linear; and

compensating for the image of the second field such that a second brightness characteristic relative to the second field becomes substantially collinear with the first brightness characteristic.

15. A digital photographing apparatus comprising:

an optical system including an aperture;

a photoelectric conversion unit in optical communication with the aperture for receiving a light reflected from a subject and creating an image signal according to the light;

a processor linked with the aperture and the photoelectric conversion unit for controlling opening and closing of the aperture and for storing an image file based on the image signal; and

a memory linked with the processor, wherein the memory stores at least one lookup table for increasing a brightness detectable range of the photoelectric conversion unit,

wherein the processor controls the aperture and the photoelectric conversion unit by the method comprising;

(a) capturing an image of a first field using a first exposure;

(b) capturing an image of a second field using a second exposure, wherein the level of the second exposure is different from the level of the first exposure; and

(c) synthesizing the images of the first and second fields,

wherein the first exposure is executed for a first exposure duration shorter than a reference exposure duration and the second exposure is executed for a second exposure duration that adds the first exposure duration to a predetermined duration to be longer than the reference exposure duration, and

wherein the first exposure duration and the second exposure duration are started together.

16. The digital photographing apparatus of claim 15 wherein the processor further comprises a means for timing first and second exposure durations during which the aperture is opened, wherein the first exposure duration is shorter than a reference exposure duration for providing an underexposed image of the subject and the second exposure is longer than the reference exposure duration for providing an overexposed image of the subject.

17. The digital photographing apparatus of claim 16 wherein the processor further comprises a synthesizing means for combining the underexposed image and the overexposed image relative to the lookup table.

18. The digital photographing apparatus of claim 15 wherein the processor comprises at least one of a digital camera processor and a micro-controller.

19. The digital photographing apparatus of claim 18 wherein the memory comprises an EEPROM.

20. The digital photographing apparatus of claim 19 wherein the photoelectric converter comprises one of a charge coupled device and a CMOS semiconductor.