Image processing method for reduced colour shift in multi-primary LCDs

Patent metadata

Field	Value
Publication number	US-9262977-B2
Application number	US-201213632270-A
Country	US
Kind code	B2
Filing date	Oct 1, 2012
Priority date	Oct 6, 2011
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

A method of processing an image comprises: receiving pixel data constituting an image, the pixel data including at least four sub-pixel color components having respective data values, and modifying one or more of the sub-pixel color component data values. The data values of corresponding sub-pixels from two pixels are modified in opposite directions to one another and such that the overall luminance of the display panel appears substantially unchanged to an on-axis viewer of the display panel.

First claim

The invention claimed is:

1. A method of processing an image for display, the method comprising:
obtaining pixel data constituting an image, wherein data for each pixel in the pixel data includes at least four sub-pixel colour components having respective data values, wherein the at least four sub-pixel colour components comprise only one of each of four different color components,
modifying one or more of the sub-pixel colour component data values, and displaying the modified image on a display panel;
wherein the modification of the one or more of the sub-pixel colour component data values includes:
modifying relative to one another the data values of the sub-pixels for the same colour components from the given pair of pixels such that:
the data value for one sub-pixel for a given colour component in the pair of pixels is increased and the data value for the other sub-pixel for the given colour component in the pair of pixels is decreased; and
a colour shift of the image perceived by an off-axis viewer is reduced and the overall luminance of the display panel appears to change by no more than 1% to an on-axis viewer of the display panel.

2. A method as claimed in claim 1 and comprising modifying the data values of sub-pixels in a pixel so as to minimise a change in overall luminance of the pixel to an on-axis viewer of the display panel.

3. A method as claimed in claim 2 , and comprising modifying the data value of at least one sub-pixel of a pixel relative to the data value of at least another sub-pixel of the pixel such that the value of the at least one sub-pixel of the pixel is increased and the data value of the at least another sub-pixel of the pixel is decreased.

4. A method as claimed in claim 1 , and comprising, for a pair of pixels, modifying the data values of corresponding sub-pixels in the pair of pixels so as to minimise a change in overall luminance of each pixel of the pair of pixels to an on-axis viewer of the display panel.

5. A method as claimed in claim 1 and comprising, for a plurality of pair of pixels, modifying the data values of corresponding sub-pixels in the pairs of pixels on a pixel pair-by-pixel pair basis so as to minimise a change in overall luminance of each pixel of the pairs of pixels to an on-axis viewer of the display panel.

6. A method as claimed in claim 1 and comprising, for a plurality of pair of pixels, modifying the data values of corresponding first sub-pixels in the pairs of pixels on a pixel pair-by-pixel pair basis and modifying the data values of corresponding second sub-pixels in the pairs of pixels in the same manner for a first pixel pair and for a second pixel pair.

7. A method as claimed in claim 1 , wherein the display is an RGBW display, and comprising, for a pair of pixels, modifying the data values of corresponding sub-pixels in the pair of pixels so as to minimise a change in overall chrominance of the pair of pixels to an on-axis viewer of the display panel.

8. A method as claimed in claim 1 and comprising modifying data values for the primary sub-pixels and for the non-primary sub-pixel(s) such that the overall change in luminance of the primary sub-pixels is approximately equal and opposite to the overall change in luminance of the non-primary sub-pixel(s).

9. A method as claimed in claim 8 and comprising, for a first pixel in the pair of pixels, modifying the data values for the primary sub-pixels in an opposite direction to the data value(s) for the non-primary sub-pixel(s).

10. A method as claimed in claim 9 and comprising, for a second pixel in the pair of pixels, modifying the data values for the primary sub-pixels in an opposite direction to the data value(s) for the non-primary sub-pixel(s), and comprising modifying the data values for the primary sub-pixels of the second pixel of the pair of pixels in an opposite direction to the data values for the primary sub-pixels of the first pixel of the pair of pixels.

11. A method as claimed in claim 1 wherein modifying data values comprises, for at least one sub-pixel component, mapping each data value into at least two modified data values.

12. A method as claimed in claim 11 wherein the average of the luminances generated by the modified values is equal to the luminance generated by the unmodified value.

13. A method as claimed in claim 11 and comprising storing the modified data values into at least two modified data values in a look-up table.

14. A method as claimed in claim 1 and comprising outputting the modified sub-pixel colour component data values to a multi-primary display panel.

15. A method as claimed in claim 1 wherein the two pixels of the pair of pixels are spatially close to one another.

16. A method as claimed in claim 1 wherein a first pixel of the pair of pixels occurs in a first frame and a second pixel of the pair of pixels occurs in a second frame, the first and second frames being consecutive frames.

17. A method as claimed in claim 1 wherein a first pixel of the pair of pixels occurs in a first group of frames and a second pixel of the pair of pixels occurs in a second group of frames, the first and second groups of frames being consecutive groups of frames.

18. A method as claimed in claim 16 wherein changes to the data values of a sub-pixel are co-ordinated with changes in drive polarity of the sub-pixel.

19. A method as claimed in claim 17 , wherein the timing of the change in data value for one sub-pixel may be different from the timing of the change in data value for another sub-pixel.

20. A method as claimed in claim 1 , wherein the obtained image has the same resolution as the modified image.

21. The method of claim 1 , further comprising, after compensating for the increase in the data value of the given sub-pixel:
within a given pixel of the pair of pixels, if a difference between the modified data values of the sub-pixels within the given pixel are greater than a given threshold, return the data values of the sub-pixels to their unmodified data values.

22. The method of claim 1 , wherein the at least four sub-pixel colour components comprise only one red sub-pixel, only one blue sub-pixel, and only one green sub-pixel.

23. A method of processing an image for display, the method comprising:
receiving pixel data constituting an image, wherein data for each pixel in the pixel data includes at least four sub-pixel colour components having respective data values and each of the at least four sub-pixel colour components are either primary sub-pixels or non-primary sub-pixels, wherein the at least four sub-pixel colour components comprise only one of each of four different color components;
modifying one or more of the sub-pixel colour component data values; and
displaying the modified image on a display panel;
wherein the modification of the one or more of the sub-pixel colour component data values includes:
modifying relative to one another the data values of the sub-pixels for the same colour components from the given pair of pixels such that:
the data value for one sub-pixel for a given colour component in the pair of pixels is increased and the data value for the other sub-pixel for the given colour component in the pair of pixels is decreased; and
for the given pixel, modifying data values for the primary sub-pixels of the given pixel and for the non-primary sub-pixel(s) of the given pixel such that;
a colour shift of the image perceived by an off-axis viewer is reduced and the overall change i

Assignees

• Borgers Charlotte Wendy Michele
• Broughton Benjamin John
• Gass Paul Antony
• Walton Harry Garth
• Nonweiler John
• Sharp Kk

Inventors

• Borgers Charlotte Wendy Michele
• Broughton Benjamin John
• Gass Paul Antony
• Walton Harry Garth
• Nonweiler John

Classifications

• G09G2320/0242

  Compensation of deficiencies in the appearance of colours · CPC title

• G09G3/3648 Primary

  using an active matrix (G09G3/367 - G09G3/3696 take precedence) · CPC title

• G09G2300/0452

  Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components · CPC title

• G09G2320/0271

  Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping · CPC title

• G09G2320/068

  for control of viewing angle adjustment · CPC title