Image capturing apparatus with movement compensation function and method for movement compensation thereof

• US 20090087173A1
• Filed: 09/26/2008
• Published: 04/02/2009
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: Altek Corporation
• Original Assignee: Altek Corporation
• Inventors: Han, Shih-Chang, Yang, Chin-Lung, Li, Yun-Chin
• Granted Patent: US 8,018,495 B2
• Time in Patent Office: Days
• US Class Current: 396/55
• CPC Class Codes: G03B 2217/005 Blur detection
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations

Abstract

A method for compensating movement of an image capturing apparatus is applied in a photographing mode whose exposure time is greater than the safe shutter time. The method includes the steps of: capturing a long exposure image under the desired exposure time and a short exposure image with an exposure time smaller than or equal to the safe shutter time, and recording a camera motion signal in the exposure time of the long exposure image. The image-shift signal is used to reconstruct the short exposure image and form a reconstructed image, and an image analyzing algorithm is utilized to extract the reconstructed image and the short exposure image of a different frequency component. Finally, different frequency components of the image are fused according to the specific ratios to produce a clear output image.

Claims

1. An image capturing apparatus with a movement compensation function, applied in a photographing mode whose exposure time is greater than the safe shutter time for providing the movement compensation function, comprising:

an image capturing unit, for receiving a release signal to capture a first image under a desired exposure time and a second image with an exposure time smaller than or equal to the safe shutter time;

a motion sensor, for recording a camera motion signal of the image capturing apparatus during the exposure period of the first image; and

a processing unit, for outputting the release signal, and reconstruct the first image to form a reconstructed image according to the camera motion signal, and using an image analyzing algorithm to extract an image of different frequency components from the reconstructed image and the second image, and performing a fusing process to the image of different frequency components according to a specific ratio to generate an output image.

2. The image capturing apparatus with a movement compensation function as recited in claim 1, further comprising a press key unit coupled to the processing unit for generating a trigger signal to trigger the processing unit to output the release signal.

3. The image capturing apparatus with a movement compensation function as recited in claim 1, further comprising a buffer unit coupled between the image capturing unit and the processing unit for buffering the first image and the second image to be accessed by the processing unit.

4. The image capturing apparatus with a movement compensation function as recited in claim 1, further comprising a memory unit coupled to the processing unit for storing the output image.

5. The image capturing apparatus with a movement compensation function as recited in claim 1, wherein the first image is captured in a long exposure by the image capturing unit to form a non-focusing blurred image, the second image is captured in a short exposure by the image capturing unit to form a sharp clear image filled with noise.

6. The image capturing apparatus with a movement compensation function as recited in claim 1, wherein the processing unit uses a point spread function according to the camera motion signal to reconstruct the first image to recover the clarity of the first image to form the reconstructed image.

7. The image capturing apparatus with a movement compensation function as recited in claim 1, wherein the image analyzing algorithm extracts an image of low frequency components from the reconstructed image and an image of high frequency components of the second image, and performs a fusing process according to the specific ratio for the image of low frequency components from the reconstructed image and the image of high frequency components of the second image to generate the output image.

8. The image capturing apparatus with a movement compensation function as recited in claim 7, wherein the image analyzing algorithm further extracts an image of high frequency components from the reconstructed image, such that the image of high frequency components of the second image is fused with the image of high frequency components from the reconstructed image in advance.

9. The image capturing apparatus with a movement compensation function as recited in claim 7, wherein the specific ratio is adjusted by the processing unit according to the settings of the desired exposure time and an exposure time smaller than or equal to the safe shutter time.

10. The image capturing apparatus with a movement compensation function as recited in claim 7, wherein the fusing process is a summation fusion.

11. A method for compensating movement of an image capturing apparatus, applied in a photographing mode having an exposure time greater than the safe shutter time, comprising the steps of:

capturing a first image under a desired exposure time and a second image with an exposure time smaller than or equal to the safe shutter time;

recording a camera motion signal of the image capturing apparatus during the exposure period of the first image;

reconstructing the first image to form a reconstructed image according to the camera motion signal; and

using an image analyzing algorithm to extract images of different frequency components from the reconstructed image and the second image, and perform a fusing process to the images of different frequency components to generate an output image according to a specific ratio.

12. The method for compensating movement of an image capturing apparatus as recited in claim 11, wherein the first image is captured by a long exposure to form a non-focusing blurred image, and the second image is captured by a short exposure to form a sharp clear image filled with noise.

13. The method for compensating movement of an image capturing apparatus as recited in claim 11, further comprising the step of executing a noise reduction procedure to reduce the noise of the second image, after the second image is capture.

14. The method for compensating movement of an image capturing apparatus as recited in claim 11, wherein the reconstruction step executes a point spread function according to the camera motion signal to reconstruct the first image to recover the clarity of the first image to form the reconstructed image.

15. The method for compensating movement of an image capturing apparatus as recited in claim 14, further comprising the step of executing an artifact reduction procedure to reduce an artifact produced during the reconstruction from the reconstructed image after the reconstruction step.

16. The method for compensating movement of an image capturing apparatus as recited in claim 11, wherein the image analyzing algorithm extracts an image of low frequency components from the reconstructed image and an image of high frequency components of the second image, and performs a fusing process according to the specific ratio for the image of low frequency components from the reconstructed image and the image of high frequency components of the second image.

17. The method for compensating movement of an image capturing apparatus as recited in claim 16, wherein the image analyzing algorithm further extracts an image of high frequency components from the reconstructed image, and fuses an image of high frequency components of the second image.

18. The method for compensating movement of an image capturing apparatus as recited in claim 16, wherein the specific ratio is adjusted according to the settings of the desired exposure time and an exposure time smaller than or equal to the safe shutter time.

19. The method for compensating movement of an image capturing apparatus as recited in claim 16, wherein the fusing process is a summation fusion.