Image pickup apparatus and its light source estimating apparatus

1. A light source estimating apparatus for estimating a type of a light source used when an input image is picked up, the apparatus comprising:

a pixel selection circuit means for selecting effective pixel data, the pixel selection circuit selecting pixels not having the pixel data of zero or near zero and selecting pixels not having the pixel data of a maximum value or near the maximum value;

distribution retaining means which retains a distribution, in a predetermined space, of the selected effective pixel data picked up under a first or second light source and stores parameters for light source estimation;

coordinate determining means which determines coordinates of the selected effective pixel data of the input image in the predetermined space and performs a calculation between the selected effective pixel data picked up under the first or second light source and the parameters stored in the distribution retaining means; and

distribution judging means which judges distribution of the selected effective pixel data picked up under the first or second light source to which the coordinates belong,

wherein an estimation result by the light source estimating apparatus is supplied to an image parameter setting means, the image parameter setting means supplying white balance gains and a color correction matrix corresponding to the estimated light source to a white balance processing means and a color reproduction processing means.

2. The light source estimating apparatus according to claim 1 , wherein:

the space is a one-dimensional space; and

the distribution is a distribution obtained by projecting the pixel data on the one-dimensional space.

3. The light source estimating apparatus according to claim 1 , further comprising:

majority decision means which estimates a light source through majority decision of judgment results on which distribution of the pixel data picked up under the first or second light source the coordinates of a plurality of pixel data of the input image belong to.

4. The light source estimating apparatus according to claim 1 , wherein the first light source includes an LED.

5. The light source estimating apparatus according to claim 1 , wherein:

the first light source is any one of a plurality of types of light sources; and

the second light source is one of the plurality of types of light sources other than the first light source.

6. The light source estimating apparatus according to claim 5 , wherein the plurality of types of light sources include an LED.

7. The light source estimating apparatus according to claim 1 , wherein:

the first light source is one of four types of light sources including sun light, a fluorescent lamp, an incandescent lamp, and an LED; and

the second light source is one of the four types of light sources other than the first light source.

8. The light source estimating apparatus according to claim 1 , wherein:

the first light source is one of a plurality of types of light sources; and

the second light source is one of the plurality of types of light sources other than the first light source of the plurality of types of light sources.

9. The light source estimating apparatus according to claim 8 , wherein the plurality of types of light sources include an LED.

10. The light source estimating apparatus according to claim 8 , wherein:

the first light source is one of four types of light sources including sun light, a fluorescent lamp, an incandescent lamp, and an LED; and

the second light source is one of the four types of said plurality of types of light sources other than the first light source.

11. An image pickup apparatus, comprising:

image pickup means which picks up an input image;

a light source estimating circuit means for estimating a light source, comprising:

a pixel selection circuit means for selecting effective pixel data, the pixel selection circuit selecting pixels not having the pixel data of zero or near zero and selecting pixels not having the pixel data of a maximum value or near the maximum value,

distribution retaining means which retains a distribution, in a predetermined space, of the selected effective pixel data picked up under a first or second light source and stores parameters for light source estimation,

coordinate determining means which determines coordinates of the selected effective pixel data of the input image in the predetermined space and performs a calculation between the selected effective pixel data picked up under the first or second light source and the parameters stored in the distribution retaining means, and

distribution judging means which judges distribution of the selected effective pixel data picked up under the first or second light source to which the coordinates belong;

white balance processing means which performs a white balance process of the input image in accordance with a judgment result;

color reproduction processing means which performs a color reproduction process of an output of the white balance process in accordance with the judgment result; and

parameter setting means which supplies white balance gains and a color correction matrix corresponding to the light source estimated by the light source estimating circuit means to the white balance processing means and the color reproduction processing means.

12. The image pickup apparatus according to claim 11 , further comprising:

light source limiting means which limits the first light source to a specific type of a light source and making the distribution judging means conduct the judgment.

13. The image pickup apparatus according to claim 12 , further comprising:

electronic flash emission light detecting means which detects whether electronic flash light emission was effected when the input image was picked up, wherein:

the light source limiting means makes the distribution judging means conduct the judgment, in accordance with a detection result of the electronic flash light emission.

14. The image pickup apparatus according to claim 11 , wherein:

the first light source is one of a plurality of types of light sources; and

the second light source is one of the plurality of types of light sources other than the first light source.

15. The image pickup apparatus according to claim 14 , further comprising:

light source limiting means which limits the plurality of types of light sources to a specific type of a light source and making the distribution judging means conduct the judgment.

16. The image pickup apparatus according to claim 15 , wherein:

the light source limiting means limits the plurality of types of light sources to a fluorescent lamp and makes the distribution judging means conduct the judgment.

17. The image pickup apparatus according to claim 11 , wherein:

the white balance processing means utilizes white balance gains of sun light in a case where the judgment results indicates that the light source is an LED.

18. A light source estimating method for a light source estimating apparatus provided with pixel selection circuit means which selects effective pixel data, the pixel selection circuit selecting pixels not having the pixel data of zero or near zero and selecting pixels not having the pixel data of a maximum value or near the maximum value, and distribution retaining means which retains a distribution, in a predetermined space, of the selected effective pixel data picked up under a first or second light source, estimates a type of a light source used when an input image is picked up, and stores parameters for light source estimation, the method comprising steps of:

determining coordinates in the space of the selected effective pixel data of the input image;

performing a calculation between the selected effective pixel data picked up under the first or second light source and the parameters stored in the distribution retaining means; and

judging distribution of the selected effective pixel data picked up in the first or second light source to which the coordinates belong,

wherein an estimation result by the light source estimating apparatus is supplied to an image parameter setting means, the image parameter setting means supplying white balance gains and a color correction matrix corresponding to the estimated light source to a white balance processing means and a color reproduction processing means.

19. A computer program product tangibly embodied in a computer-readable storage medium for a light source estimating apparatus provided with pixel selection circuit means which selects effective pixel data, the pixel selection circuit selecting pixels not having the pixel data of zero or near zero and selecting pixels not having the pixel data of a maximum value or near the maximum value, and distribution retaining means which retains a distribution, in a predetermined space, of the selected effective pixel data picked up under a first or second light source, estimates a type of a light source used when an input image is picked up, and stores parameters for light source estimation, the computer program product comprising instructions operable to cause a data processing apparatus to perform the following steps:

determining coordinates in the space of the selected effective pixel data of the input image;

performing a calculation between the selected effective pixel data picked up under the first or second light source and the parameters stored in the distribution retaining means; and

judging distribution of said selected effective pixel data picked up in said first or second light source to which the coordinates belong,

wherein an estimation result by the light source estimating apparatus is supplied to an image parameter setting means, the image parameter setting means supplying white balance gains and a color correction matrix corresponding to the estimated light source to a white balance processing means and a color reproduction processing means.

20. A light source estimating apparatus for estimating a type of a light source used when an input image is picked up, the apparatus comprising:

a pixel selection section which selects effective pixel data, the pixel selection circuit selecting pixels not having the pixel data of zero or near zero and selecting pixels not having the pixel data of a maximum value or near the maximum value;

a distribution retaining section which retains a distribution, in a predetermined space, of the selected effective pixel data picked up under a first or second light source and stores parameters for light source estimation;

a coordinate determining section which determines coordinates of the selected effective pixel data of the input image in the predetermined space and performs a calculation between the selected effective pixel data picked up under the first or second light source and the parameters stored in the distribution retaining section; and

a distribution judging section which judges distribution of the selected effective pixel data picked up under the first or second light source to which the coordinates belong,

wherein an estimation result by the light source estimating apparatus is supplied to an image parameter setting section, the image parameter setting section supplying white balance gains and a color correction matrix corresponding to the estimated light source to a white balance processing section and a color reproduction processing section.