Photographing apparatus and method for compensating brightness of an image

• US 20060228102A1
• Filed: 04/07/2006
• Published: 10/12/2006
• Est. Priority Date: 04/08/2005
• Status: Abandoned Application

• Current Assignee: BenQ Corporation (Qisda Corporation)
• Original Assignee: BenQ Corporation (Qisda Corporation)
• Inventors: Chang, Chun-Jung, Yang, Shih-Yang
• Application Number:
  US11/399,809
• Publication Number:
  US 20060228102A1
• Time in Patent Office: Days
• US Class Current: 396/213
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation

Abstract

A photographing apparatus includes an image sensor for capturing first and second images sequentially, the first image including a reference image part; a calculation module for calculating average brightness degree of the reference image part for serving as a reference brightness value, wherein a brightness difference between the reference image part and an adjacent part succeeding the reference image part is greater than a threshold, brightness of the first image and the reference brightness value cooperatively defining a compensation ratio; and a compensation module for compensating brightness of the second image according to the compensation ratio.

Claims

1. A photographing apparatus comprising:

an image sensor for capturing a first image and a second image sequentially, said first image including a reference image part;

a calculation module for calculating average brightness degree of said reference image part as a reference brightness value, wherein a brightness difference between said reference brightness value and average brightness degree of an adjacent part of said first image succeeding said reference image part is greater than a threshold value, brightness of said first image and said reference brightness value cooperatively defining a first compensation ratio; and

a compensation module for compensating brightness of said second image according to said first compensation ratio.

2. The photographing apparatus according to claim 1, wherein said first image includes a background formed by a plurality of first blocks, each of said first blocks having a set of pixel units, said calculation module further including:

a block calculation module for calculating average brightness levels for each of said first blocks according to brightness degree of each of said pixel units within said respective one of said first blocks; and

a comparison module for comparing average brightness degree of two adjacent said first blocks in order to select said reference image part.

3. The photographing apparatus according to claim 2, wherein said background is white.

4. The photographing apparatus according to claim 2, wherein said first image further includes a non-reference image part surrounding said reference image part, said reference brightness value and brightness value of one of said first blocks cooperatively defining a second compensation ratio, said compensation module selecting said one of said first blocks from said non-reference image part and compensating said one of said first blocks according to said second compensation ratio.

5. The photographing apparatus according to claim 4, wherein said second image includes a plurality of second blocks respectively correspond to said first blocks of said first image in positions, said compensation module selecting one of said second blocks from said non-reference image part of said second image and compensating said one of said second blocks the same as said one of said first blocks.

6. The photographing apparatus according to claim 2, wherein said calculation module selects a central first block, comparison module comparing said central first block with respect to an adjacent said first block along a predetermined path in order to obtain a first brightness difference therebetween, said calculation module equalizing total brightness value of said central first block and said adjacent first block in case said brightness difference does not exceed a predetermined value so as to obtain a temporary reference brightness value, said comparison module comparing said central first block with respect to said first block succeeding said adjacent first block along said predetermined path in order to obtain a second brightness difference therebetween, said calculation module equalizing total brightness value of said central first block and succeeding said first block in case said second brightness difference does not exceed said predetermined value so as to obtain a new temporary reference brightness value replacing said temporary reference brightness value, said comparison module stopping comparison operation once a final brightness difference between said central first block and one of said first block is greater than said predetermined value, thereby obtaining a final temporary reference brightness value, said final temporary reference brightness value defining said reference brightness value.

7. The photographing apparatus according to claim 6, wherein said predetermined path turns in a clockwise manner with respect to said central first block.

8. The photographing apparatus according to claim 6, wherein said predetermined path turns in a counter clockwise manner with respect to said central first block.

9. The photographing apparatus according to claim 6, wherein said predetermined path is defined by said first blocks within said reference image part, said reference image part including more than two numbers of said first blocks.

10. The photographing apparatus according to claim 6, wherein said predetermined path is defined by a plurality of said first blocks including a middle first block, and left and right first blocks sandwiching said middle first block, said middle first block defining said central first block in case said predetermined path is formed by odd number of said first blocks, said middle first block defining said central first block in case said predetermined path is formed by even number of said first blocks.

11. The photographing apparatus according to claim 2, wherein said calculation module further includes a median filter for eliminating varying brightness difference prior to permit calculating average brightness of said respective one of said first blocks according to pixel value of each of said pixel units of said respective one of said first blocks by said block calculation module.

12. The photographing apparatus according to claim 11, wherein said varying brightness difference is greater than said predetermined value.

13. The photographing apparatus according to claim 4, wherein under certain ambient light beams, said second compensation ratio being used for compensating said one of said first blocks within said non-reference image part of said first image, said second compensation ratio including a plurality of compensation values, the photographing apparatus further comprising:

a storage device for storing said ambient light beams corresponding to said compensation values;

a photo detector for detecting ambient brightness degree around the photographing apparatus; and

a selection module for selecting one of said ambient light beams corresponding to a respective one of said compensation values for compensating brightness to the photographing apparatus in operation under said one of said ambient light beams.

14. A method for compensating brightness of an image in a photographing apparatus, comprising the steps of:

(1) capturing a first image, said first image including a reference image part;

(2) calculating average brightness degree of said reference image part for serving as a reference brightness value, wherein a brightness difference between said reference image part and an adjacent part succeeding said reference image part is greater than a threshold, brightness of said first image and said reference brightness value cooperatively defining a first compensation ratio;

(3) capturing a second image; and

(4) compensating brightness of said second image according to said first compensation ratio.

15. The compensation method according to claim 14, the compensation method further comprising the steps;

(5) dividing said first image into a plurality of first blocks, each of said first blocks having a set of pixel units;

(6) calculating average brightness of a respective one of said first blocks according to pixel value of each of said pixel units within said respective one of said first blocks;

(7) comparing average brightness degree of two adjacent said first blocks in order to select said reference image part.

16. The compensation method according to claim 15, wherein said first image further includes a non-reference image part surrounding said reference image part, said reference brightness value and brightness value of one of said first blocks cooperatively defining a second compensation ratio, the compensation method further comprising the steps:

(8) selecting one of said first blocks from said non-reference image part and compensating said one of said first blocks according to said second compensation ratio.

17. The compensation method according to claim 16, wherein said second image includes a plurality of second blocks respectively correspond to said first blocks of said first image in positions, the compensation method further comprising the step:

(9) selecting one of said second blocks from said non-reference image part of said second image and compensating said one of said second blocks the same as said one of said first blocks.

18. The compensation method according to claim 15, further comprising the steps:

selecting a central first block;

comparing said central first blockwith respect to an adjacent said first block along a predetermined path in order to obtain a first brightness difference therebetween;

equalizing total brightness value of said central first block and said adjacent first block in case said brightness difference does not exceed a predetermined value so as to obtain a temporary reference brightness value;

comparing said central first block with respect to said first block succeeding said adjacent first block along said predetermined path in order to obtain a second brightness difference therebetween;

equalizing total brightness value of said central first block and succeeding said first block in case said second brightness difference does not exceed said predetermined value so as to obtain a new temporary reference brightness value for replacing said temporary reference brightness value; and

stopping comparison operation once a final brightness difference between said central first block and one of said first block is greater than said predetermined value, thereby obtaining a final temporary reference brightness value, said final temporary reference brightness value defining said reference brightness value.

19. The compensation method according to claim 18, wherein said predetermined path turns in a clockwise manner with respect to said central first block.

20. The compensation method according to claim 18, wherein said predetermined path turns in turns in a counter clockwise manner with respect to said central first block.