Apparatus and method for image pickup

• US 20070230932A1
• Filed: 03/29/2007
• Published: 10/04/2007
• Est. Priority Date: 04/03/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Techwin Corporation (Hanwha Vision Company Limited)
• Inventors: Hamamura, Toshihiro, Tanaka, Toshiyuki
• Granted Patent: US 7,856,174 B2
• Time in Patent Office: Days
• US Class Current: 396/55
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/684 performed by controlling the image sensor readout, e.g. by controlling the integration time
• CPC Class Codes: H04N 23/6845 by combination of a plurality of images sequentially taken
• CPC Class Codes: H04N 25/63 applied to dark current

Abstract

An apparatus and method for image pickup capable of reducing noise in the images to reduce the effect of shaking due to, for example, hand movement. The image pickup apparatus and method can employ an exposure photographing unit for photographing at least one exposure image at predetermined time intervals using time-division exposure in a light exposure state, a dark frame photographing unit for photographing at least one dark frame at predetermined time intervals using time-division exposure in a dark state, a subtracting processor for subtracting the dark frames from the exposure images to reduce noise in the exposure images, and an image combiner for combining the plurality of reduced noise exposure images.

Claims

1. An image pickup apparatus for electronically reducing an effect of shaking by combining a plurality of images that are photographed at predetermined time intervals using time-division exposure, the apparatus comprising:

an exposure photographing unit for photographing exposure images at predetermined time intervals using time-division exposure in a light exposure state;

a dark frame photographing unit for photographing at least one dark frame at at least one predetermined time interval using time-division exposure in a dark state;

a subtracting processor for subtracting the at least one dark frame from the exposure images to reduce noise in the exposure images and produce reduced noise exposure images; and

an image combiner for combining the reduced noise exposure images.

2. The apparatus of claim 1, wherein the dark frame photographing unit photographs one dark frame, and the subtracting processor subtracts the one dark frame from each of the exposure images that are photographed at predetermined time intervals using time-division exposure to reduce noise in the exposure images.

3. The apparatus of claim 1, wherein the exposure photographing unit and the dark frame photographing unit photograph the exposure images and the dark frames alternately, and the subtracting processor subtracts the corresponding dark frames, which are photographed immediately after their corresponding exposure images are photographed, from the corresponding exposure images to reduce the noise in the corresponding exposure images.

4. The apparatus of claim 1, further comprising:

a dark frame interpolating unit for performing an interpolation based on at least two dark frames, and generating a dark frame corresponding to at least one point in time between when the dark frames are photographed,

wherein the subtracting processor subtracts the dark frame obtained by the interpolation from the exposure images to reduce the noise in the exposure images.

5. The apparatus of claim 4, wherein:

the interpolation is a linear interpolation.

6. The apparatus of claim 4, wherein:

the interpolation is a non-linear interpolation.

7. The apparatus of claim 4, wherein:

the dark frame interpolating unit performs the interpolation based on brightness values of pixels of the at least two dark frames,

8. An image pickup apparatus electronically reducing an effect of shaking by combining a plurality of images that are photographed at predetermined time intervals using time-division exposure, the apparatus comprising:

an exposure photographing unit for photographing exposure images at predetermined time intervals using time-division exposure in a light exposure state;

a dark frame photographing unit for photographing at least one dark frame at at least one predetermined time intervals using the time-division exposure in a dark state;

a feature point detector for detecting each feature point of the exposure images;

a feature recording unit for recording positions of the feature point;

an image combiner for combining the exposure images after shifting the exposure images so as to form a combined exposure image having a coincided feature point, and combining the dark frames corresponding to the exposure images to form a combined dark frame after shifting the dark frames according to the shifted movements of the exposure images; and

a subtracting processor subtracting the combined dark frame from the combined exposure image to reduce noise in the combined exposure image.

9. The apparatus of claim 8, wherein:

the feature point detector detects the feature points based on differences in brightness between adjacent pixels in the exposure images.

10. The apparatus of claim 8, wherein:

the feature point detector detects edges of the exposure images as feature points of those images.

11. An image pickup method of electronically reducing an effect of shaking by combining a plurality of images photographed at predetermined time intervals using time-division exposure, the method comprising:

photographing exposure images at predetermined time intervals using time-division exposure in a light exposure state;

photographing at least one dark frame at least one predetermined time interval using time-division exposure in a dark state;

subtracting the at least one dark frame from the exposure images to reduce noise in the exposure images and produce reduced noise exposure images; and

combining the reduced noise exposure images.

12. The method of claim 11, wherein in the photographing of the at least one dark frame, one dark frame is photographed using time-division exposure, and in the subtracting of the images, the dark frame is subtracted from each of the exposure images photographed at predetermined time intervals using time-division exposure to reduce the noise in the exposure images.

13. The method of claim 11, wherein in the photographing of the exposure images and the photographing of the dark frames, the exposure images and the dark frames are photographed alternately, and in the subtracting of the images, for each exposure image, the corresponding dark frame that is photographed immediately after its corresponding exposure image is photographed is respectively subtracted from the corresponding exposure image.

14. The method of claim 11, further comprising:

performing an interpolation based on at least two dark frames, and generating a dark frame corresponding to at least one point in time between when the two dark frames are photographed,

wherein the subtracting of images, for each exposure image, is performed by subtracting, from an exposure image, a corresponding dark frame obtained by the interpolation to reduce the noise in the exposure image.

15. The method of claim 14, wherein:

the interpolation is a linear interpolation.

16. The method of claim 14, wherein:

the interpolation is a non-linear interpolation.

17. The method of claim 14, wherein:

the interpolation is performed based on brightness values of pixels of the at least two dark frames,

18. An image pickup method of electronically reducing an effect of shaking by combining a plurality of images photographed at predetermined time intervals using time-division exposure, the method comprising:

photographing exposure images at predetermined time intervals using time-division exposure in a light exposure state;

photographing one or more dark frames at least one predetermined time interval using the time-division exposure in a dark state;

detecting each feature point of the exposure images;

recording positions of the feature points of the exposure images;

combining exposure images by shifting the exposure images so that the feature points of the images can coincide to form a combined exposure image, and combining the dark frames corresponding to the exposure images by shifting the dark frames according to the shifted movements of the exposure images combined dark frame; and

subtracting the combined dark frame from the combined exposure image to reduce noise in the combined exposure image.

19. The method of claim 18, wherein:

the feature detecting detects the feature points based on differences in brightness between adjacent pixels in the exposure images.

20. The method of claim 18, wherein:

the feature detecting detects edges of the exposure images as feature points of those images.