White balance correction in digital camera images
View Patent ↗A method of enhancing a digital image produced by a digital imaging device, includes using the digital imaging device to capture at least two original digital images of the same scene with each digital image being under two different lighting conditions and producing for each such digital images a plurality of pixels; using the pixel values of at least two of the captured digital images under different lighting conditions to produce difference values; and modifying the pixel values of the original digital image in response to the corresponding difference values.
1. A method of enhancing the white balance of a digital image produced by a digital imaging device, comprising:
(a) using the digital imaging device to capture at least two original digital images of the same scene with each digital image being under two different lighting conditions wherein the lighting conditions are flash and without-flash and producing for each such digital images a plurality of pixels;
(b) using the pixel values of at least two of the digital images captured under different lighting conditions to produce a difference map representing a luminance difference between the flash and without-flash digital images;
(c) selecting a threshold value to threshold the difference map separating the difference map into a flash portion and a non-flash portion;
(d) partitioning the pixels in the flash image into pixel values that were affected by the flash corresponding to the flash portion of the difference map and pixel values that were not affected by the flash corresponding to the non-flash portion of the difference map; and
(e) providing a first white balance modification to the pixel values of the flash image that were affected by the flash, and a second white balance modification to the pixel values of the flash image that were not affected by the flash so that an enhanced white balance digital image is produced, and wherein the first and second white balance modifications are not based on the pixel values of the without-flash digital image.
2. The method of claim 1 wherein the used pixel values of the digital images have a logarithmic relationship corresponding to the intensity of light received from the original scene.
3. The method of claim 1 wherein pixel values of the digital images have red, green, and blue components and the modifying step includes changing the color of the pixel values.
4. The method of claim 3 further including:
(a) calculating a luminance pixel value from the red, green, and blue components respectively for the flash digital image and the without-flash digital image; and
(b) calculating the difference values as the difference between corresponding luminance pixel values.