Correcting defective pixels in digital color images

1. A method for replacing defective pixels in a digital color image, each pixel including data in at least two color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the reference color channel, computing a sum of the differences between the non-defective data in the selected color channel and the non-defective data in the first reference color channel;

adding the sum of the differences divided by m to the non-defective data value from the first reference color channel to obtain a substitution data value; and

substituting the substitution data value for the defective data.

2. The method of claim 1 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

3. A method for replacing defective pixels in a digital color image, each pixel including data in at least two color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the reference color channel, computing a weighted sum of the differences between the non-defective data in the selected color channel and the non-defective data in the first reference color channel;

adding the weighted sum of the differences divided by the sum of weights to the non-defective data substitution data value from the first reference color channel to obtain a result; and

substituting the substitution data value for the defective data.

4. The method of claim 3 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

5. A method for replacing defective pixels in a digital color image, each pixel including data in three color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the first reference color channel, computing a first sum of the differences between the non-defective data in the selected channel and the non-defective data in the first reference color channel;

adding the first sum of the differences divided by m to the non-defective data value from the first reference color channel to obtain a first result;

for the selected pixel, determining whether a second reference color channel characterized by having non-defective data exists;

if the second reference channel characterized by having non-defective data exists, for each of n neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the second reference color channel, computing a second sum of the differences between the non-defective data in the selected channel and the non-defective data in the second reference color channel;

adding the second sum of the differences divided by n to the non-defective data value from the second reference color channel to obtain a second result;

computing the sum of the first result and the second result and dividing the sum of the first result and the second result by two to obtain a substitution data value; and

substituting the substitution data value for the defective data.

6. The method of claim 5 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

7. A method for replacing defective pixels in a digital color image, each pixel including data in three color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data exists, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the first reference color channel, computing a first weighted sum of the differences between the non-defective data in the selected channel and the non-defective data in the first reference color channel;

adding the first weighted sum of the differences divided by the sum of weights to the non-defective data value from the first reference color channel to obtain a first result;

for the selected pixel, determining whether a second reference color channel characterized by having non-defective data exists;

if the second reference channel characterized by having non-defective data exists, for each of n neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the second reference color channel, computing a second weighted sum of the differences between the non-defective data in the selected channel and the non-defective data in the second reference color channel;

adding the second weighted sum of the differences divided by the sum of weights to the non-defective data value from the second reference color channel to obtain a second result;

computing the sum of the first result multiplied by the first weight and the second result multiplied by the second weight and dividing sum of the first result multiplied by the first weight and the second result multiplied by the second weight by the sum of the first weight and the second weight to obtain a substitution data value; and

substituting the substitution data value for the defective data.

8. The method of claim 7 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

9. The method of claim 7 wherein the first weight used to calculate the first weighted sum is different from the second weight used to calculate the second weighed sum.

10. A method for replacing defective pixels in a digital color image, each pixel including data in at least two color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the reference color channel, computing a sum of the ratios between the non-defective data in the selected color channel and the non-defective data in the first reference color channel;

multiplying the sum of the ratios divided by m with the non-defective data substitution data value from the first reference color channel to obtain a result; and

substituting the substitution data value for the defective data.

11. The method of claim 10 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

12. A method for replacing defective pixels in a digital color image, each pixel including data in at least two color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the reference color channel, computing a weighted sum of the ratios between the non-defective data in the selected color channel and the non-defective data in the first reference color channel;

multiplying the weighted sum of the ratios divided by the sum of weights with the non-defective data substitution data value from the first reference color channel to obtain a result; and

substituting the substitution data value for the defective data.

13. The method of claim 12 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

14. A method for replacing defective pixels in a digital color image, each pixel including data in three color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the first reference color channel, computing a first sum of the ratios between the non-defective data in the selected channel and the non-defective data in the first reference color channel;

multiplying the first sum of the ratios divided by m with the non-defective data value from the first reference color channel to obtain a first result;

for the selected pixel, determining whether a second reference color channel characterized by having non-defective data exists;

if the second reference channel characterized by having non-defective data exists, for each of n neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the second reference color channel, computing a second sum of the ratios between the non-defective data in the selected channel and the non-defective data in the second reference color channel;

multiplying the second sum of the ratios divided by n with the non-defective data value from the second reference color channel to obtain a second result;

computing the sum of the first result and the second result and dividing the sum of the first result and the second result by two to obtain a substitution data value; and

substituting the substitution data value for the defective data.

15. The method of claim 14 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

16. A method for replacing defective pixels in a digital color image, each pixel including data in three color channels, the method comprising:

determining whether each pixel has defective data in a selected color channel and, if so, selecting that pixel;

for the selected pixel, determining whether a first reference color channel characterized by having non-defective data exists;

for each selected pixel having the first reference color channel characterized by having non-defective data exists, correcting the defective data by:

defining a group of neighboring pixels surrounding the selected pixel;

for each of m neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the first reference color channel, computing a first weighted sum of the ratios between the non-defective data in the selected channel and the non-defective data in the first reference color channel;

multiplying the first weighted sum of the ratios divided by a weighting factor with the non-defective data value from the first reference color channel to obtain a first result;

for the selected pixel, determining whether a second reference color channel characterized by having non-defective data exists;

if the second reference channel characterized by having non-defective data exists, for each of n neighboring pixels in the group that have both non-defective data in the selected color channel and non-defective data in the second reference color channel, computing a second weighted sum of the ratios between the non-defective data in the selected channel and the non-defective data in the second reference color channel;

multiplying the second weighted sum of the ratios divided by the sum of weights with the non-defective data value from the second reference color channel to obtain a second result;

computing the sum of the first result multiplied by the first weight and the second result multiplied by the second weight and dividing sum of the first result multiplied by the first weight and the second result multiplied by the second weight by the sum of the first weight and the second weight to obtain a substitution data value; and

substituting the substitution data value for the defective data.

17. The method of claim 16 wherein defining a group of neighboring pixels surrounding the selected pixel comprises defining a group of nine neighboring pixels.

18. The method of claim 16 wherein the first weight used to calculate the first weighted sum is different from the second weight used to calculate the second weighed sum.