Image processing apparatus, camera apparatus, image output apparatus, image processing method, color correction processing program and computer readable recording medium

• US 7,668,368 B2
• Filed: 12/22/2005
• Issued: 02/23/2010
• Est. Priority Date: 12/24/2004
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kimura, Katsuji
• Primary Examiner(s): Bali; Vikkram
• Assistant Examiner(s): YEH, EUENG NAN
• Application Number:
  US11/317,452
• Publication Number:
  US 20060139707A1
• Time in Patent Office: 1,524 Days
• Field of Search: 382/167, 358/518
• US Class Current: 382/167
• CPC Class Codes: H04N 1/62 Retouching, i.e. modification of isolated colours only or in isolated picture areas only
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 5/772 the recording apparatus and the television camera being placed in the same enclosure
• CPC Class Codes: H04N 9/643 Hue control means, e.g. flesh tone control

Abstract

A correction processing section 1 performs a color correction such that a movement amount indicating how much input values of image signals should be moved for the purpose of color correction becomes smaller as the distance between the input values and the coordinates of the center of region to be corrected becomes larger in the region to be corrected, based on the input values of the input signals (L signal, *a signal, *b signal), conditional data (such as radius r) defining a local region to be corrected, the coordinates (Lc, *ac, *bc) of the center of the region to be corrected and the coordinates (Lm, *am, *bm) of the center of an ideal color region to be targeted.

Claims

1. An image processing apparatus for performing color correction on input values of input signals in a predetermined region to be corrected in a color coordinate system, comprising:

a movement amount calculating section for calculating movement amounts indicating how much the input values should be moved, in accordance with a voltage corresponding to a distance between the input values and the center of the region to be corrected; and

a color correction section coupled to the movement amount calculating section, for performing color correction on the input values, by moving the input values based on the calculated-movement amounts,

wherein the movement amount calculating section calculates the movement amounts such that the movement amounts become smaller as the distance between the input values and the center of the region to be corrected becomes larger, and

wherein the movement amount calculating section calculates the movement amounts in accordance with an equation having a distribution with a kurtosis greater than that of the distribution defined by the equation;

(1−

(the distance between the input values and the center of the region to be corrected)/(conditional data which defines the region to be corrected))×

(a maximum distance of the movement amounts).

2. An image processing apparatus according to claim 1, wherein the movement amount calculating section calculates the movement amounts such that the movement amounts become close to “

0”

as the input values approach an outer peripheral boarder of the region to be corrected.

3. An image processing apparatus according to claim 1, wherein the movement amount calculating section calculates the movement amounts such that the movement amounts become “

0”

when the input values are located at an outer peripheral boarder of the region to be corrected.

4. An image processing apparatus according to claim 1, wherein changing amounts of the movement amounts are set to be equal between the center of the region to be corrected and an outer peripheral border of the region to be corrected.

5. An image processing apparatus according to claim 1, wherein the maximum distance of the movement amounts is a distance between the center of the region to be corrected and the center of an ideal color region.

6. An image processing apparatus according to claim 1, wherein the movement amount calculating section and the color correction section are implemented by hardware.

7. An image processing apparatus according to claim 1, further comprising:

an input value determining section for determining whether or not the input values are located within the region to be corrected, in accordance with the distance between the input values and the center of the region to be corrected,

wherein, when it is determined that the input values are located within the region to be corrected, the movement amount calculating section calculates the movement amounts, and the color correction section performs the color correction.

8. An image processing apparatus according to claim 7, further comprising:

a distance calculating section for calculating a distance between the input values and the center of the region to be corrected.

9. An image processing apparatus according to claim 7, wherein the region to be corrected is defined as a sphere or a circle having a radius r, the center of the sphere or the circle is located at the center of the region to be corrected,

the input value determining section determines whether or not the distance between the input values and the center of the region to be corrected is smaller than or equal to the radius r.

10. An image processing apparatus according to claim 7, wherein the region to be corrected is defined as a cube or a square having a length r on each side, the center of the cube or the square is located at the center of the region to be corrected,

wherein the input value determining section determines whether or not all of the coordinate components of the input values are located within the region to be corrected.

11. An image processing apparatus according to claim 10, wherein the input value determining section determines whether or not all of coordinate components of the input values are located within the region to be corrected, by determining whether or not a relationship of (a distance corresponding to the coordinate component of the input values)<

(a distance corresponding to the length r of the sphere or the square) is satisfied for each of the coordinate components of the input values.

12. An image processing apparatus according to claim 10, wherein the input value determining section determines whether or not all of coordinate components of the input values are located within the region to be corrected, by determining whether or not a relationship of (a minimum value of the coordinate value of the sphere or the square)<

(the coordinate component of the input values )<

(a maximum value of the coordinate value of the sphere or the square) is satisfied for each of the coordinate components of the input values.

13. An image processing apparatus according to claim 1, further comprising:

a distance calculating section for calculating a distance between the input values and the center of the region to be corrected and outputting a voltage value corresponding to the distance;

a comparing section for comparing the voltage value output from the distance calculating section with a voltage value corresponding to conditional data which defines the region to be corrected; and

a signal selection section for selecting one of the color correction outputs from the color correction section and the input values, in accordance with the comparison result by the comparing section.

14. An image processing apparatus according to claim 13, wherein the comparing section includes an AND gate.

15. An image processing apparatus according to claim 13, wherein the movement amount calculating section is initiated in response to the output from the comparing section.

16. An image processing apparatus according to claim 13, wherein the signal selection section selects the color correction outputs from the color correction section when the input values are located within the region to be corrected, and selects the input values when the input values are not located within the region to be corrected.

17. An image processing apparatus according to claim 1, wherein the input image signals are one of L*a*b* signals, RGB signals, CMYK signals, YUV signals and YCbCr signals of color specification systems.

18. An image processing apparatus according to claim 1, wherein the color coordinate system is a color coordinate system for one of L*a*b* signals, RGB signals, CMYK signals, YUV signals and YCbCr signals of color specification systems.

19. An image processing apparatus according to claim 1, wherein the color coordinate system is a coordinate system of a luminance/color space for L*a*b* signals or a coordinate system of a color plane for a*b* signals.

20. An image processing apparatus according to claim 1, wherein the region to be corrected is a local range in two dimensions or three dimensions.

21. An image processing apparatus according to claim 1, wherein the region to be corrected is one of a sphere, a circle, a cube, a square, a rotating object formed by rotating an ellipse around a long axis of the ellipse, an ellipsoid, a column, an ellipsoidal column and a square column.

22. An image processing apparatus according to claim 1, wherein the region to be corrected includes at least one of a skin color region, a blue color region and a green color region.

23. An image processing apparatus according to claim 1, wherein conditional data which defines the region to be corrected is a radius r when the region to be corrected is a sphere or a circle, and conditional data which defines the region to be corrected is a length r on each side when the region to be corrected is a cube or a square.

24. An image processing apparatus according to claim 1, wherein the color correction section performs a luminance correction on the input values in addition to the color correction on the input values.

25. A camera apparatus comprising:

a solid state imaging apparatus including a plurality of pixels; and

an image processing apparatus according to claim 1,

wherein image signals for the respective pixels output from the solid state imaging apparatus are input to the image processing apparatus as the input image signals.

26. An image output apparatus comprising:

an image processing apparatus according to claim 1; and

an output apparatus for outputting image signals subjected to the color correction by the image processing apparatus.

27. An image processing method used in an image processing apparatus for performing color correction on input values of input signals received by the image processing apparatus in a predetermined region to be corrected in a color coordinate system, comprising the steps of:

(a) calculating movement amounts indicating how much the input values should be moved, in accordance with a distance between the input values and the center of the region to be corrected;

(b) performing color correction on the input values, by moving the input values based on the calculated movement amounts; and

(c) outputting for display, by the image processing apparatus, color corrected input values based on the calculated movement amounts,

wherein in the step (a), the movement amounts are calculated, such that the movement amounts become smaller as the distance between the input values and the center of the region to be corrected becomes larger, and

wherein in the step (a) further calculates the movement amount in accordance with an equation having a distribution with a kurtosis greater than that of the distribution defined by the equation;

(1−

(the distance between the input values and the center of the region to be corrected) /(conditional data which defines the region to be corrected))×

(a maximum distance of the movement amounts).

28. An image processing method according to claim 27, wherein in the step (a), the movement amounts are calculated, such that the movement amounts become close to “

0”

as the input values approach an outer peripheral boarder of the region to be corrected.

29. An image processing method according to claim 27, wherein in the step (a), the movement amounts are calculated, such that the movement amounts become “

0”

when the input values are located at an outer peripheral boarder of the region to be corrected.

30. An image processing method according to claim 27, further comprising the step of:

determining whether or not the input values are located within the region to be corrected, in accordance with the distance between the input values and the center of the region to be corrected,

wherein, when it is determined that the input values are located within the region to be corrected, the movement amounts are calculated in the step (a), and the color correction is performed in the step (b).

31. An image processing method according to claim 30, further comprising the step of:

calculating a distance between the input values and the center of the region to be corrected.

32. An image processing method according to claim 27, wherein in the step (b), a luminance correction on the input values is performed in addition to the color correction on the input values.

33. A color correction processing program stored on a computer readable medium for making a computer execute an image processing method for performing color correction on input values of input signals in a predetermined region to be corrected in a color coordinate system, the image processing method comprising the steps of:

(a) calculating movement amounts indicating how much the input values should be moved, in accordance with a distance between the input values and the center of the region to be corrected;

(b) performing color correction on the input values, by moving the input values based on the calculated movement amounts; and

(c) outputting for display, by the image processing apparatus, color corrected input values based on the calculated movement amounts,

wherein in the step (a), the movement amounts are calculated, such that the movement amounts become smaller as the distance between the input values and the center of the region to be corrected becomes larger, and

wherein in the step (a) further calculates the movement amount in accordance with an equation having a distribution with a kurtosis greater than that of the distribution defined by the equation;

(1−

(the distance between the input values and the center of the region to be corrected) /(conditional data which defines the region to be corrected))×

(a maximum distance of the movement amounts).