Noise reduced color image using panchromatic image

1. A method for providing a noise-reduced value for a color pixel from a digital image having panchromatic pixels and color pixels, comprising:

a. providing a first image having sparsely sampled panchromatic pixels and color pixels corresponding to at least two color photoresponses;

b. interpolating the panchromatic pixels to provide a full-resolution panchromatic image; and

c. providing a noise-reduced value for a particular color pixel in the first image, by:

i. selecting a neighborhood of color pixels surrounding and including the particular color pixel, each selected color pixel having a value and having the same color photoresponse as the particular color pixel;

ii. selecting a neighborhood of panchromatic pixels from the full-resolution panchromatic image, each selected panchromatic pixel having a value and being associated by location with a color pixel in the selected neighborhood of color pixels; and

iii. using the values of the pixels from the selected neighborhoods of color and panchromatic pixels to provide the noise reduced value for the particular color pixel, wherein using the values of the pixels from the selected neighborhoods of color and panchromatic pixels includes setting a spatial color pixel difference averaged over the neighborhood of color pixels equal to a spatial panchromatic pixel difference averaged over the neighborhood of panchromatic pixels.

2. The method of claim 1 , wherein the spatial color pixel difference is a first spatial color pixel difference and the spatial panchromatic pixel difference is a first spatial panchromatic pixel difference.

3. The method of claim 1 , wherein the spatial color pixel difference is a second spatial color pixel difference and the spatial panchromatic pixel difference is a second spatial panchromatic pixel difference.

4. The method of claim 1 , wherein the neighborhood of panchromatic

pixels has the same dimensions as the neighborhood of color pixels.

5. The method of claim 1 , wherein the spatial color pixel difference is a

combination of a first spatial color pixel difference and a second spatial color pixel difference.

6. A method for providing a noise-reduced value for a color pixel from a digital image having panchromatic pixels and color pixels, comprising:

a. providing a first image having sparsely sampled panchromatic pixels and color pixels corresponding to at least two color photoresponses;

b. interpolating the panchromatic pixels to provide a full-resolution panchromatic image; and

c. providing a noise-reduced value for a particular color pixel in the first image, by:

i. selecting a neighborhood of color pixels surrounding and including the particular color pixel, each selected color pixel having a value and having the same color photoresponse as the particular color pixel;

ii. selecting a neighborhood of panchromatic pixels from the full-resolution panchromatic image, each selected panchromatic pixel having a value and being associated by location with a color pixel in the selected neighborhood of color pixels; and

iii. using the values of the pixels from the selected neighborhoods of color and panchromatic pixels to provide the noise reduced value for the particular color pixel, wherein using the values of the pixels from the selected neighborhoods of color and panchromatic pixels includes generating weighting coefficients based on differences in panchromatic values and differences in color values, wherein the panchromatic values are from the neighborhood of panchromatic pixels and the color values are from the neighborhood of color pixels.