Method and system for handling mixed illumination in video and photography

1. A method comprising:

obtaining, with an image processing apparatus, a white point that corresponds to an image captured by a camera with only the natural light as a light source;

obtaining, with the image processing apparatus, a white point that corresponds to an image captured by the camera with only a high efficiency artificial light as a light source;

determining, with a spatial sensor of the image processing apparatus, a ratio of an intensity of near infrared light in natural light for a pixel to an intensity of high efficiency artificial light for the pixel within an image captured by a camera under mixed illumination of the natural light and the high efficiency artificial light; and

determining, with the image processing apparatus, a white point for the pixel in the image under mixed illumination based on the ratio of the intensity of near infrared light to the intensity of high efficiency artificial light for the pixel in the image, the white point for only the natural light, and the white point for only the high efficiency artificial light.

2. The method of claim 1 , wherein the natural light is sunlight and the high efficiency artificial light is light from a fluorescent light source, compact fluorescent light source, or a light emitting diode.

3. The method of claim 1 , wherein the obtaining steps each include reading the respective white points from a memory.

4. The method of claim 1 , wherein the spatial sensor and the camera are a co-axial camera with a channel for near infrared light and a channel for visible light.

5. The method of claim 1 , wherein the spatial sensor is co-axial with the camera.

6. The method of claim 1 wherein the spatial sensor has some, but less than all, pixels that are near infrared sensitive.

7. The method of claim 1 , wherein the intensity of high efficiency artificial light is a measure of red light.

8. A system comprising:

a camera that captures an image under mixed illumination of natural light and high efficiency artificial light;

a processor that obtains a white point that corresponds to an image captured by a camera with only the natural light as a light source, obtains a white point that corresponds to an image captured by the camera with only the high efficiency artificial light as a light source, determines a ratio of an intensity of natural light for a pixel to an intensity of high efficiency artificial light for the pixel within an image captured by a camera under mixed illumination of the natural light and the high efficiency artificial light, and determines a white point for the pixel in the image under mixed illumination based on the ratio of the intensity of natural light to the intensity of high efficiency artificial light for the pixel in the image, the white point for only the natural light, and the white point for only the high efficiency artificial light; and

a spatial sensor that measures near infrared light, wherein the processor uses an output of the spatial sensor to determine the ratio.

9. The system of claim 8 , wherein the natural light is sunlight and the high efficiency artificial light is light from a fluorescent light source, compact fluorescent light source, or a light emitting diode.

10. The system of claim 8 , further comprising a memory, wherein the processor obtains the white point that corresponds to the image captured by the camera with only the natural light as the light source from the memory and obtains the white point that corresponds to the image captured by the camera with only the high efficiency artificial light as the light source from the memory.

11. The system of claim 8 , wherein the spatial sensor and the camera are a co-axial camera with a channel for near infrared light and a channel for visible light.

12. The system of claim 8 , wherein the spatial sensor is co-axial with the camera.

13. The system of claim 8 , wherein the spatial sensor has some, but less than all, pixels that are near infrared sensitive.

14. The system of claim 8 , wherein the processor determines the ratio by determining a ratio of red light to the near infrared light.

15. A non-transitory computer readable storage medium encoded with instructions, which when executed by an image processing apparatus causes the image processing apparatus to execute a method comprising:

obtaining, with an image processing apparatus, a white point that corresponds to an image captured by a camera with only the natural light as a light source;

obtaining, with an image processing apparatus, a white point that corresponds to an image captured by a camera with only the natural light as a light source;

obtaining, with the image processing apparatus, a white point that corresponds to an image captured by the camera with only a high efficiency artificial light as a light source;

determining, with the image processing apparatus, a ratio of an intensity of infrared light in natural light for a pixel to an intensity of high efficiency artificial light for the pixel within an image captured by a camera under mixed illumination of the natural light and the high efficiency artificial light; and

determining, with the image processing apparatus, a white point for the pixel in the image under mixed illumination based on the ratio of the intensity of the near infrared light in the natural light to the intensity of high efficiency artificial light for the pixel in the image, the white point for only the natural light, and the white point for only the high efficiency artificial light.

16. The non-transitory computer readable storage medium of claim 15 , wherein the image processing apparatus determines the ratio by calculating a ratio of red light to the near infrared light

17. The non-transitory computer readable storage medium of claim 15 , wherein the neat infrared light a spatial sensor that measures the near infrared light.