Color Shading Correction Using Color Channel Consistency

1. An imaging system comprising: a color correction circuit configured to perform color shading correction of an image independent of lens shading correction of the image, the color shading correction of the image being based on estimated color consistency models for red and blue color channels of the image; wherein the estimated color consistency model for the red color channel includes a common profile for the red color channel and a scaling factor for the red color channel, the estimated color consistency model for the blue color channel includes a common profile for the blue color channel and a scaling factor for the blue color channel, and the scaling factors for the red and blue color channels correspond to an estimated color temperature for the image.

2. The imaging system of claim 1 , wherein the color correction circuit comprises: a color consistency correction circuit configured to generate color shading correction grids by adapting anti-shading correction grids for the red and blue color channels of the image based on the estimated color consistency models for the red and blue color channels of the image; and an anti-shading correction circuit configured to perform the color shading correction of the image based on the color shading correction grids.

3. The imaging system of claim 2 , wherein the color consistency correction circuit is configured to generate the color shading correction grids by adapting anti-shading correction grids for only the red and blue color channels.

4. The imaging system of claim 2 , wherein the anti-shading correction circuit is further configured to, generate color shading correction functions for each of the red and blue color channels based on the color shading correction grids, and perform the color shading correction of the image by applying the color shading correction functions to each pixel of the image.

5. The imaging system of claim 2 , wherein the anti-shading correction circuit is further configured to perform the lens shading correction of the image.

6. The imaging system of claim 2 , wherein the color consistency correction circuit is further configured to generate the estimated color consistency models for the red and blue color channels of the image based on the estimated color temperature for the image.

7. The imaging system of claim 6 , wherein the color consistency correction circuit is further configured to, obtain reference color consistency models for the red and blue color channels based on the estimated color temperature for the image, and generate the estimated color consistency models for the red and blue color channels based on the obtained reference color consistency models for the red and blue color channels.

8. The imaging system of claim 1 , further comprising: an image sensor operatively coupled to the color correction circuit, the image sensor being configured to capture the image.

9. An imaging system comprising: a color correction circuit configured to perform color shading correction of an image independent of lens shading correction of the image, the color correction circuit including a color consistency correction circuit configured to generate color shading correction grids by adapting anti-shading correction grids for red and blue color channels of the image based on estimated color consistency models for the red and blue color channels of the image, and an anti-shading correction circuit configured to perform the color shading correction of the image based on the color shading correction grids; wherein the estimated color consistency model for the red color channel includes a common profile for the red color channel and an estimated gamma coefficient for the red color channel, the estimated color consistency model for the blue color channel includes a common profile for the blue color channel and an estimated gamma coefficient for the blue color channel, and the estimated gamma coefficients for the red and blue color channels correspond to an estimated color temperature for the image.

10. The color correction circuit of claim 9 , wherein the color consistency correction circuit is configured to generate the estimated gamma coefficient for the red color channel based on a plurality of reference gamma coefficients for the red color channel using interpolation, the plurality of reference gamma coefficients for the red color channel corresponding to a plurality of reference color temperatures.

11. The color correction circuit of claim 9 , wherein the color consistency correction circuit is configured to generate the estimated gamma coefficient for the blue color channel based on a plurality of reference gamma coefficients for the blue color channel using interpolation, the plurality of reference gamma coefficients for the blue color channel corresponding to a plurality of reference color temperatures.

12. An imaging system comprising: a color correction circuit configured to perform color shading correction of an image independent of lens shading correction of the image, the color correction circuit including a color consistency correction circuit configured to generate color shading correction grids by adapting anti-shading correction grids for red and blue color channels of the image based on estimated color consistency models for the red and blue color channels of the image, an anti-shading correction circuit configured to perform the color shading correction of the image based on the color shading correction grids, a color inconsistency information extraction circuit configured to extract color inconsistency information from a plurality of reference images, each of the plurality of reference images being captured under light having a different color temperature among a plurality of reference color temperatures, and a color consistency model estimation circuit configured to generate a reference color consistency model for each of the plurality of reference images, the color consistency model estimation circuit being further configured to store the reference color consistency models in a memory; wherein the color consistency correction circuit is further configured to obtain reference color consistency models for the red and blue color channels based on an estimated color temperature for the image, and generate the estimated color consistency models for the red and blue color channels based on at least a portion of the reference color consistency models and the estimated color temperature for the image.

13. The imaging system of claim 12 , wherein extracted color inconsistency information for a reference image among the plurality of reference images includes a ratio of green-to-red color channels for each pixel of the reference image and a ratio of green-to-blue color channels for each pixel of the reference image.

14. The imaging system of claim 12 , wherein a reference color consistency model for a reference image among the plurality of reference images includes a common profile and a reference gamma coefficient corresponding to a color temperature for the reference image, and wherein the color consistency model estimation circuit is configured to, calculate the common profile based on an initial reference gamma coefficient, calculate an updated reference gamma coefficient based on the calculated common profile, calculate an updated common profile based on the updated reference gamma coefficient, and iteratively repeat the calculation of the updated reference gamma coefficient and the updated common profile until convergence to generate the reference color consistency model for the reference image.