Display panel compensation methods

1. A method of compensating for non-uniformity of a plurality of pixels of a display panel, each pixel having a light-emitting device, the method comprising:

for each pixel of the plurality of pixels,

retrieving from a memory a respective offset value for each of a plurality of predetermined greyscale drive levels, the plurality of greyscale drive levels being only a subset of the operational greyscale drive levels of the display panel, each respective offset value stored in the memory using a bit depth less than the bit depth of each predetermined greyscale drive level; and

correcting an input drive level for the pixel to compensate for said non-uniformity with use of said respective offset values.

2. The method of claim 1 , wherein the plurality of greyscale drive levels span a significant portion of a usable greyscale drive level range for the display panel.

3. The method of claim 1 , wherein, for each pixel of the plurality of pixels, the respective offset value for each predetermined greyscale drive level is determined from an offset from that predetermined greyscale drive level which creates a uniform flat field.

4. The method of claim 1 , further comprising:

for each pixel of the plurality of pixels,

determining a uniformity correction function with use of said respective offset values,

wherein correcting the input drive level for the pixel to compensate for said non-uniformity is performed with use of the uniformity correction function.

5. The method of claim 1 , wherein each respective offset value is stored in an array in the memory.

6. The method of claim 1 , further comprising:

for each pixel of the plurality of pixels,

measuring the pixel at each of the plurality of predetermined greyscale drive levels,

determining said respective offset values with use of said measurements; and

storing said respective offset values in the memory.

7. The method of claim 6 , wherein measuring the pixel comprises taking optical measurements of luminosity with use of at least one of an external optical measurement system and an integrated optical measurement device.

8. The method of claim 3 , wherein the uniform flat field comprises a uniform luminosity produced by each pixel of the plurality of pixels.

9. The method of claim 6 , wherein measuring the pixel comprises taking electrical measurement of an output current of the pixel with use of a monitoring system of the display panel.

10. The method of claim 3 , wherein the uniform flat field comprises a uniform current output by each pixel of the plurality of pixels.

11. The method of claim 6 , wherein determining said respective offset value with use of said measurements comprises determining said respective offset value with use of measurements made previously.

12. The method of claim 6 , wherein determining said respective offset value with use of said measurements comprises iteratively adjusting an initial respective offset value from said predetermined greyscale drive level and repeatedly measuring the pixel until reaching the respective offset value which creates a uniform flat field.

13. The method of claim 4 , wherein the number of selected predetermined greyscale drive levels is two and wherein the uniformity correction function is a linear uniformity correction function generated from the respective offset values for each predetermined greyscale drive level.

14. The method of claim 13 , wherein said linear uniformity correction function is a function of said input drive level and the respective offset values for each predetermined greyscale drive level.

15. The method of claim 4 , wherein the number of selected predetermined greyscale drive levels N is greater than two and wherein the uniformity correction function is a piecewise linear uniformity correction function generated from the respective offset values for each predetermined greyscale drive level.

16. The method of claim 15 , wherein said piecewise linear uniformity correction function is a function of said input drive level and the respective offset values for each predetermined greyscale drive level.

17. The method of claim 4 , wherein the number of selected predetermined greyscale drive levels N is greater than two and wherein the uniformity correction function is a curve fit polynomial uniformity correction function of order N−1 or lower generated from the respective offset values for each predetermined greyscale drive level.

18. The method of claim 17 , wherein said polynomial uniformity correction function of order N−1 or lower is a function of said input drive level and said respective offset values for each predetermined greyscale drive level.

19. The method of claim 6 , wherein each light-emitting device comprises an organic light emitting devices (OLED).