Image processing

1. A method comprising:

receiving image data representative of at least a portion of an image comprising a first set of pixels associated with a first colour channel and a second set of pixels associated with a second colour channel;

processing a portion of the image data representative of a first pixel of the first set of pixels to determine that the first pixel of the first set of pixels is a saturated pixel;

obtaining, for a first image region comprising the first pixel of the first set of pixels and a first pixel of the second set of pixels, first data based on a value of the first pixel of the second set of pixels,

based on the first data, obtaining, for a second image region comprising a second pixel of the first set of pixels and a second pixel of the second set of pixels, second data based on a value of the second pixel of the first set of pixels and a value of the second pixel of the second set of pixels; and

processing the second data to generate output data representative of an estimated value associated with the first colour channel for the first pixel of the first set of pixels.

2. The method according to claim 1 , comprising:

identifying, within the first image region, an unsaturated pixel of the second set of pixels; and

using the unsaturated pixel of the second set of pixels as the first pixel of the second set of pixels.

3. The method according to claim 1 , comprising:

identifying, within the second image region, an unsaturated pixel of the first set of pixels and an unsaturated pixel of the second set of pixels;

using the unsaturated pixel of the first set of pixels as the second pixel of the first set of pixels; and

using the unsaturated pixel of the second set of pixels as the second pixel of the second set of pixels.

4. The method according to claim 1 , wherein the first data represents an intensity value of the first pixel of the second set of pixels.

5. The method according to claim 1 , wherein obtaining the second data comprises retrieving the second data from a look-up table based on the first data.

6. The method according to claim 5 , wherein the first data represents a first parameter value of a first parameter for the first image region, the first parameter being associated with the second colour channel, the look-up table comprises entries corresponding to a respective first parameter value of a set of first parameter values of the first parameter for the second image region and retrieving the second data from the look-up table comprises:

identifying an entry of the entries corresponding to one of the set of first parameter values with a closest value to the first parameter value;

identifying a second parameter value of a second parameter associated with the first colour channel, the second parameter value associated with the one of the set of first parameter values and being based on the value of the second pixel of the first set of pixels and the value of the second pixel of the second set of pixels; and

retrieving the second parameter value as the second data.

7. The method according to claim 5 , comprising generating the look-up table for the second image region based on:

a respective value for each of a plurality of pixels of the first set of pixels within the second image region, the plurality of pixels of the first set of pixels comprising the second pixel of the first set of pixels; and

a respective value for each of a plurality of pixels of the second set of pixels within the second image region, the plurality of pixels of the second set of pixels comprising the second pixel of the second set of pixels.

8. The method according to claim 7 , wherein:

each of the plurality of pixels of the first set of pixels is an unsaturated pixel, respectively; and

each of the plurality of pixels of the second set of pixels is an unsaturated pixel, respectively.

9. The method according to claim 7 , wherein the first data represents a first parameter value of a first parameter for the first image region, the first parameter being associated with the second colour channel, the look-up table comprises entries corresponding to a respective first parameter value of a set of first parameter values of the first parameter for the second image region, and generating the look-up table comprises:

generating, for the second image region, a histogram comprising a plurality of bins, each associated with a respective range of first parameter values;

selecting a subset of the plurality of bins, each of the subset of the plurality of bins corresponding to a respective entry of the entries; and

for each of the subset of the plurality of bins, storing a corresponding second parameter value of a second parameter associated with the first colour channel as part of a respective entry corresponding to the respective bin of the subset of the plurality of bins.

10. The method according to claim 1 , wherein the second data represents a ratio between the value of the second pixel of the first set of pixels and the value of the second pixel of the second set of pixels.

11. The method according to claim 1 , wherein obtaining the first data comprises obtaining the first data based on the value of the first pixel of the second set of pixels and further based on a value of a first pixel of a third set of pixels associated with a third colour channel, the first image region comprising the first pixel of the third set of pixels.

12. The method according to claim 1 , comprising obtaining, for a further image region comprising at least one further pixel of the first set of pixels and at least one further pixel of the second set of pixels, further data based on a respective value of the at least one further pixel of the first set of pixels and the at least one further pixel of the second set of pixels,

wherein processing the second data comprises processing the second data with the further data to generate the output data.

13. The method according to claim 12 , wherein:

obtaining the second data comprises obtaining the second data from a look-up table; and

obtaining the further data comprises obtaining the further data for the at least one further pixel of the first set of pixels closest to the first pixel of the first set of pixels and for the at least one further pixel of the second set of pixels closest to the first pixel of the first set of pixels.

14. The method according to claim 12 , wherein obtaining the further data comprises:

identifying, within the further image region, at least one unsaturated pixel of the first set of pixels and at least one unsaturated pixel of the second set of pixels;

using the at least one unsaturated pixel of the first set of pixels as the at least one further pixel of the first set of pixels; and

using the unsaturated pixel of the second set of pixels as the at least one further pixel of the second set of pixels.

15. The method according to a claim 1 , comprising demosaicing the at least the portion of the image after generating the output data.

16. The method according to claim 1 , wherein the estimated value is larger than a saturated value of the first pixel of the first set of pixels.

17. The method according to claim 1 , comprising:

determining that the first pixel of the second set of pixels is an unsaturated pixel;

determining that a first pixel of a third set of pixels associated with a third colour channel is a saturated pixel, the first image region comprising the first pixel of the third set of pixels; and

based on the determining, using the first data to represent an intensity value of the first pixel of the second set of pixels.

18. The method according to claim 1 , comprising:

determining that the first pixel of the second set of pixels is an unsaturated pixel;

determining that a first pixel of a third set of pixels associated with a third colour channel is an unsaturated pixel, the first image region comprising the first pixel of the third set of pixels; and

based on the determining, using the first data to represent a first ratio between the value of the first pixel of the second set of pixels and the value of the first pixel of the third set of pixels.

19. An image processing system comprising:

storage for storing:

image data representative of at least a portion of an image comprising a first set of pixels associated with a first colour channel and a second set of pixels associated with a second colour channel;

first data based on a value of a first pixel of the second set of pixels;

second data based on a value of a second pixel of the first set of pixels and a value of a second pixel of the second set of pixels; and

output data representative of an estimated value associated with the first colour channel for a first pixel of the first set of pixels;

a saturation correction system operable to:

process a portion of the image data representative of the first pixel of the first set of pixels to determine that the first pixel of the first set of pixels is a saturated pixel;

obtain, for a first image region comprising the first pixel of the first set of pixels and the first pixel of the second set of pixels, the first data;

based on the first data, obtain, for a second image region comprising the second pixel of the first set of pixels and the second pixel of the second set of pixels, the second data; and

process the second data to generate the output data.

20. The image processing system according to claim 19 , comprising a demosaicing system arranged to demosaic output image data representative of the at least the portion of the image, the output image data comprising the output data.