A method and imaging device are provided. A pixel output signal is obtained for each green pixel in a group of pixels of an image. The group of pixels includes a plurality of pixel arrays, where each pixel array of the plurality of pixel arrays includes a first green pixel and a second green pixel. A green imbalance value is determined for the group of pixels based on the obtained pixel output signals. For each pixel array, a difference between the pixel output signal for the first green pixel and the pixel output signal for the second green pixel is calculated. An average of the calculated differences is determined. The pixel output signal of at least one of the green pixels in the group of pixels is adjusted based on the green imbalance value.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method comprising: obtaining a pixel output signal for each green pixel in a group of pixels of an image captured by a pixel array device, the group of pixels including a plurality of non-overlapping pixel arrays, wherein each pixel array of the plurality of pixel arrays includes (i) a first green pixel in a row that includes a red pixel, and (ii) a second green pixel in a row that includes a blue pixel; determining a green imbalance value for the group of pixels based on the obtained pixel output signals, the determining of the green imbalance value including: for each pixel array of the plurality of pixel arrays, calculating a difference between the pixel output signal for the first green pixel and the pixel output signal for the second green pixel, and for each of the calculated differences, determining if the calculated difference is a result of image edge pixels in the group of pixels; and adjusting the pixel output signal of at least one of the green pixels in the group of pixels based on the green imbalance value.
2. The method of claim 1 , further comprising, after the calculating of the differences and before the adjusting, for each of the calculated differences: comparing the calculated difference to a threshold; and if the respective difference exceeds the threshold, then setting the difference to the threshold.
3. The method of claim 2 , further comprising: determining the threshold by: acquiring a flat field image using the pixel array device; performing lens shading correction on the flat field image to generate a corrected image; dividing the corrected image into a plurality of locations; measuring a calibration green imbalance value for a location, from among the plurality of locations, that includes the group of pixels; and setting the threshold to the calibration green imbalance value plus a margin value.
4. The method of claim 1 , further comprising: setting the green imbalance value to an average of the differences.
5. The method of claim 1 , wherein the adjusting includes: raising the pixel output signal of at least one of the first green pixels by half the green imbalance value and lowering the pixel output signal of at least one of the second green pixel by half the green imbalance value.
6. The method of claim 1 , further comprising, after the calculating of the differences and before the adjusting, for each of the calculated differences: comparing the difference to an upper threshold and to a lower threshold; if the respective difference exceeds the upper threshold, then setting the difference to the threshold; and if the respective difference is lower than the lower threshold, then setting the difference to the lower threshold.
7. The method of claim 1 , wherein the adjusting includes using the determined green imbalance value to adjust the pixel output signal of (i) only one of the first green pixels from one pixel array of the plurality of pixel arrays and (ii) only one of the second green pixels from another pixel array of the plurality of the pixel arrays.
8. The method of claim 7 , wherein said only one of the first green pixels and said only one of the second green pixels are diagonally adjacent to each other.
9. The method of claim 1 , wherein the plurality of pixel arrays consists of four pixel arrays, and each pixel array is a square array of four pixels.
10. The method of claim 1 , wherein the method is performed by an electronic device that includes the pixel array device.
11. A non-transitory processor-readable medium storing program instructions configured to be executed by a processor to: obtain a pixel output signal for each green pixel in a group of pixels of an image captured by a pixel array device, the group of pixels including a plurality of non-overlapping pixel arrays, wherein each pixel array of the plurality of pixel arrays includes (i) a first green pixel in a row that includes a red pixel, and (ii) a second green pixel in a row that includes a blue pixel; determine a green imbalance value for the group of pixels based on the obtained pixel output signals, the determining of the green imbalance value including: for each pixel array of the plurality of pixel arrays, calculating a difference between the pixel output signal for the first green pixel and the pixel output signal for the second green pixel, and for each of the calculated differences, determining if the calculated difference is a result of image edge pixels in the group of pixels; and adjust the pixel output signal of at least one of the green pixels in the group of pixels based on the green imbalance value.
12. The processor-readable medium of claim 11 , wherein the program instructions are configured to be executed by the processor to, after the calculating of the differences and before the adjusting, for each of the calculated differences: compare the difference to a threshold; and if the respective difference exceeds the threshold, then set the difference to the threshold.
13. The processor-readable medium of claim 12 , wherein the threshold is determined by: acquiring a flat field image using the pixel array device; performing lens shading correction on the flat field image to generate a corrected image; dividing the corrected image into a plurality of locations; measuring a calibration green imbalance value for a location, from among the plurality of locations, that includes the group of pixels; and setting the threshold to the calibration green imbalance value plus a margin value.
14. The processor-readable medium of claim 11 , wherein the program instructions are configured to be executed by the processor to: set the green imbalance value to an average of the calculated differences.
15. The processor-readable medium of claim 11 , wherein the adjusting includes: raising the pixel output signal of at least one of the first green pixels by half the green imbalance value and lowering the pixel output signal of at least one of the second green pixel by half the green imbalance value.
16. The processor-readable medium of claim 11 , wherein the program instructions are configured to be executed by the processor to, after the calculating of the difference and before the adjusting, for each of the calculated differences: compare the calculated difference to an upper threshold and to a lower threshold; if the respective difference exceeds the upper threshold, then set the difference to the threshold; and if the respective difference is lower than the lower threshold, then set the difference to the lower threshold.
17. The processor-readable medium of claim 11 , wherein the adjusting includes using the determined green imbalance value to adjust the pixel output signal of only one of the first green pixels from one pixel array of the plurality of pixel arrays and only one of the second green pixels from another pixel array of the plurality of the pixel arrays.
18. The processor-readable medium of claim 17 , wherein said only one of the first green pixels and said only one of the second green pixels are diagonally adjacent each other.
19. The processor-readable medium of claim 11 , wherein the plurality of pixel arrays consists of four pixel arrays, and each pixel array is a square array of four pixels.
20. An system comprising: a pixel array device configured to capture a pixel output signal for each green pixel in a group of pixels of an image, the group of pixels including a plurality of non-overlapping pixel arrays, wherein each pixel array of the plurality of pixel arrays includes (i) a first green pixel in a row that includes a red pixel, and (ii) a second green pixel in a row that includes a blue pixel; a processor, and a memory storing instructions configured to be executed by the processor to process the captured pixel output signals by: determining a green imbalance value for the group of pixels based on the obtained pixel output signals, the determining of the green imbalance value including: for each pixel array of the plurality of pixel arrays, calculating a difference between the pixel output signal for the first green pixel and the pixel output signal for the second green pixel, and for each of the calculated differences, determining if the calculated difference is a result of image edge pixels in the group of pixels; and adjusting the pixel output signal of at least one of the green pixels in the group of pixels based on the green imbalance value.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 14, 2014
February 23, 2016
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.