Off axis halo mitigation using spatiotemporal dither patterns, each indexed and arranged according to index patterns with diagonal lines of constant index

1. A method for modifying an image to be displayed on a display comprising:

(a) receiving an image to be displayed on said display having a backlight and a transmissive panel;

(b) providing a backlight signal to said backlight for causing said backlight to selectively illuminate different portions of said backlight with different characteristics, wherein said characteristics include at least one of a different color and a different luminance;

(c) providing a panel signal to said panel for causing said transmissive panel to selectively change its transmittivities;

(d) wherein at least one of said backlight signal and said panel signal are modified for a group of pixels in such a manner that the spatial resolution of said image is reduced while the intensity value of at least one pixel of said group of pixels is modified using a plurality of different spatiotemporal dither patterns of intensity adjustments, each indexed and arranged over a plurality of pixels according to a plurality of index patterns so to correct for an off-axis artifact, each pattern of intensity adjustments maintaining the same average intensity as the at least one pixel dithered by the respective pattern, each said at least one index pattern having a diagonal line of constant index, and wherein the plurality of index patterns includes at least one pair of index patterns having a reversed polarity with respect to their respective diagonal lines of constant index and each index pattern in the pair alternating polarity temporally over each of a plurality of sequential frames, where the plurality of sequential frames by which said pair of index patterns alternates polarity is limited to an odd number of frames.

2. The method of claim 1 wherein said at least one of said backlight signal and said panel signal are modified in a manner to reduce off-axis halo artifacts in selected regions of said display.

3. The method of claim 1 wherein all but one of said group of pixels is modified to be toward at least one of fully off and fully on.

4. The method of claim 3 wherein said all but one of said group of pixels is at least one of fully off and fully on.

5. The method of claim 1 wherein the alternating said polarity over an odd number of frames mitigates an interaction between a polarity inversion process and said spatiotemporal dither pattern.

6. The method of claim 1 wherein said modification is based upon a changing dither pattern.

7. The method of claim 1 wherein said modification is based upon a decrease in temporal resolution.

8. The method of claim 1 wherein said modification is based upon a plurality of tonescales.

9. The method of claim 8 wherein said tonescales are changed over time.

10. The method of claim 8 wherein a slope of at least one of said tonescales is non-linear.

11. The method of claim 10 wherein said slope is a slope constrained tonescale.

12. The method of claim 1 wherein a portion of said backlight is selectively decreased in illumination while a corresponding portion of said panel is selectively increased in transmittivity to reduce off-axis artifacts.

13. The method of claim 1 wherein a portion of said backlight is selectively increased in illumination while a corresponding portion of said panel is selectively decreased in transmittivity to reduce off-axis artifacts.

14. The method of claim 1 wherein, when said image has uniform luminance values, different portions of said backlight have different luminances while different portions of said panel have different transmittivities so as to provide a substantially uniform image to a viewer observing said display in a perpendicular direction.

15. The method of claim 1 wherein said transmittivity is substantially modified toward maximum transmittivity in regions of a potential off-axis artifact to a greater extent than it would have been without said potential off-axis artifact.

16. The method of claim 1 wherein said modification is based upon a single image and modifies said single image.

17. The method of claim 1 wherein said modification is based upon selected sub-pixels of said display.

18. The method of claim 1 wherein a selected region of said display determined to have sufficient off-axis artifacts are modified to reduce said off-axis artifacts.

19. The method of claim 18 wherein said selected region is based upon a spatial extent of said selected region.