METHOD FOR REDUCING SMEAR EFFECT OF DYNAMIC IMAGE

• US 20110032394A1
• Filed: 10/29/2009
• Published: 02/10/2011
• Est. Priority Date: 08/10/2009
• Status: Active Grant

• Current Assignee: Altek Corporation
• Original Assignee: Altek Corporation
• Inventors: Peng, Shih Yuan, Wang, Hsin Te
• Granted Patent: US 8,189,077 B2
• Time in Patent Office: Days
• US Class Current: 348/248
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/625 for the control of smear

Abstract

A method for reducing smear effects of a dynamic image is for an image sensor. The image sensor converts a shot image picture into image data, and the image data is divided into an effective region, an upper optical black region (UOB), and a lower optical black region (LOB). The method includes capturing two continuous image data to serve as a first frame image and a second frame image; calculating brightness difference values between individual pixels at corresponding pixel positions of the LOB of the first frame image and the UOB of the second frame image; comparing the brightness difference values with a threshold; obtaining positions to be compensated in the UOB of the second frame image, when the UOB of the second frame image requires brightness compensation; and compensating brightness values of pixels in the effective region of the second frame image corresponding to the positions to be compensated.

Claims

1. A method for reducing a smear effect of a dynamic image, applicable to an image sensor, wherein the image sensor converts a shot image picture into image data through a color filter array (CFA), and the image data has a plurality of pixels and comprises an effective region, an upper optical black region located above the effective region, and a lower optical black region located below the effective region, the method comprising:

capturing two continuous image data from the image sensor in sequence to serve as a first frame image and a second frame image;

individually calculating a brightness difference value of a plurality of corresponding pixels between an upper optical black region of the second frame image and one of two optical black regions of the first frame image, so as to obtain a plurality of brightness difference values;

comparing the brightness difference values with a threshold to obtain information to be compensated; and

compensating pixels in an effective region of the second frame image corresponding to the information to be compensated, according to the information to be compensated.

2. The method for reducing a smear effect of a dynamic image according to claim 1, wherein the step of calculating the brightness difference values is performed by using a formula as follows:

Li=|L(Ai)−

L(Bi)|,

wherein i is an i^th pixel position, Li is a brightness difference value of the i^th pixel position, L(Ai) is a brightness value of the i^th pixel position of one of the optical black regions of the first frame image, L(Bi) is a brightness value of the i^th pixel position of the upper optical black region of the second frame image, and i is a positive integer.

3. The method for reducing a smear effect of a dynamic image according to claim 2, wherein the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

recording pixel positions respectively corresponding to brightness difference values smaller than a first threshold as the information to be compensated.

4. The method for reducing a smear effect of a dynamic image according to claim 2, wherein the CFA satisfies a Bayer pattern, and the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

recording pixel positions respectively corresponding to brightness difference values smaller than a first threshold as candidate positions; and

by taking one Bayer pattern as a unit, when pixels corresponding to the same Bayer pattern position are all candidate positions, recording the Bayer pattern position as the information to be compensated.

5. The method for reducing a smear effect of a dynamic image according to claim 2, wherein the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

summing up the brightness difference values as a difference sum; and

recording all pixel positions as the information to be compensated, when the difference sum is smaller than a second threshold.

6. The method for reducing a smear effect of a dynamic image according to claim 5, further comprising:

recording no pixel position as the information to be compensated, when the difference sum is not smaller than the second threshold.

7. A method for reducing a smear effect of a dynamic image, applicable to an image sensor, wherein the image sensor converts a shot image picture into image data through a color filter array (CFA), and the image data has a plurality of pixels and comprises an effective region and a lower optical black region located below the effective region, the method comprising:

capturing three continuous image data from the image sensor in sequence to serve as a first frame image, a second frame image, and a third frame image;

individually calculating a brightness difference value of a plurality of corresponding pixels between a lower optical black region of the second frame image and a lower optical black region of the first frame image, so as to obtain a plurality of brightness difference values;

comparing the brightness difference values with a threshold to obtain information to be compensated; and

compensating pixels in an effective region of the third frame image corresponding to the information to be compensated, according to the information to be compensated.

8. The method for reducing a smear effect of a dynamic image according to claim 7, wherein the step of calculating the brightness difference values is performed by using a formula as follows:

Li=|L(Ai)−

L(Bi)|,

wherein i is an i^th pixel position, Li is a brightness difference value of the i^th pixel position, L(Ai) is a brightness value of the i^th pixel position of the lower optical black region of the first frame image, L(Bi) is a brightness value of the i^th pixel position of the lower optical black region of the second frame image, and i is a positive integer.

9. The method for reducing a smear effect of a dynamic image according to claim 8, wherein the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

recording pixel positions respectively corresponding to brightness difference values smaller than a first threshold as the information to be compensated.

10. The method for reducing a smear effect of a dynamic image according to claim 8, wherein the CFA satisfies a Bayer pattern, and the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

recording pixel positions respectively corresponding to brightness difference values smaller than a first threshold as candidate positions; and

by taking one Bayer pattern as a unit, when pixels corresponding to the same Bayer pattern position are all candidate positions, recording the Bayer pattern position as the information to be compensated.

11. The method for reducing a smear effect of a dynamic image according to claim 8, wherein the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

summing up the brightness difference values as a difference sum; and

recording all pixel positions as the information to be compensated, when the difference sum is smaller than a second threshold.

12. The method for reducing a smear effect of a dynamic image according to claim 11, further comprising:

recording no pixel position as the information to be compensated, when the difference sum is not smaller than the second threshold.

13. A method for reducing a smear effect of a dynamic image, applicable to an image sensor, wherein the image sensor converts a shot image picture into image data through a color filter array (CFA), and the image data has a plurality of pixels and comprises an effective region and an upper optical black region located above the effective region, the method comprising:

capturing two continuous image data from the image sensor in sequence to serve as a first frame image and a second frame image;

individually calculating a brightness difference value of a plurality of corresponding pixels between an upper optical black region of the second frame image and an upper optical black region of the first frame image, so as to obtain a plurality of brightness difference values;

comparing the brightness difference values with a threshold to obtain information to be compensated; and

compensating pixels in an effective region of the second frame image corresponding to the information to be compensated, according to the information to be compensated.

14. The method for reducing a smear effect of a dynamic image according to claim 13, wherein the step of calculating the brightness difference values is performed by using a formula as follows:

Li=|L(Ai)−

L(Bi)|,

wherein i is an i^th pixel position, Li is a brightness difference value of the i^th pixel position, L(Ai) is a brightness value of the i^th pixel position of the upper optical black region of the first frame image, L(Bi) is a brightness value of the i^th pixel position of the upper optical black region of the second frame image, and i is a positive integer.

15. The method for reducing a smear effect of a dynamic image according to claim 14, wherein the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

recording pixel positions respectively corresponding to brightness difference values smaller than a first threshold as the information to be compensated.

16. The method for reducing a smear effect of a dynamic image according to claim 14, wherein the CFA satisfies a Bayer pattern, and the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

recording pixel positions respectively corresponding to brightness difference values smaller than a first threshold as candidate positions; and

by taking one Bayer pattern as a unit, when pixels corresponding to the same Bayer pattern position are all candidate positions, recording the Bayer pattern position as the information to be compensated.

17. The method for reducing a smear effect of a dynamic image according to claim 14, wherein the step of comparing the brightness difference values with the threshold to obtain the information to be compensated comprises:

summing up the brightness difference values as a difference sum; and

recording all pixel positions as the information to be compensated, when the difference sum is smaller than a second threshold.

18. The method for reducing a smear effect of a dynamic image according to claim 17, further comprising:

recording no pixel position as the information to be compensated, when the difference sum is greater than or equal to the second threshold.