Display control

1. A method of controlling display of image data representing an image on a display device comprising a backlight, the method comprising:

determining one or more features of the image data, wherein the one or more features include a feature representative of a level of compression-noise in the image data; and

in dependence on the determining:

adjusting a backlight intensity of the backlight to adjust, in dependence on the level of compression-noise in the image data, an intensity corresponding to a lightest greyscale level displayable by at least a portion of the display device; and

applying a spatially-variant tone mapping operation to the image data, in dependence on the level of compression-noise in the image data.

2. The method according to claim 1 , wherein the feature representative of the level of compression-noise in the image data relates to a format of the image data.

3. The method according to claim 2 , wherein the format, to which the feature representative of a level of compression-noise in the image data relates, is a high dynamic range format.

4. The method according to claim 1 , wherein:

the adjusting the backlight intensity comprises reducing the intensity corresponding to the lightest greyscale level displayable by at least the portion of the display device; and

the applying the spatially-variant tone mapping operation to the image data comprises increasing contrast in a dark area of the image.

5. The method according to claim 1 , wherein:

the one or more features include a feature that a characteristic representative of the level of compression-noise in the image data is higher than a characteristic representative of the level of compression-noise in image data of a previously displayed image;

the adjusting the backlight intensity comprises increasing the intensity corresponding to the lightest greyscale level displayable by at least the portion of the display device; and

the applying the spatially-variant tone mapping operation to the image data comprises reducing contrast in a dark area of the image.

6. The method according to claim 1 , wherein the adjusting the backlight intensity comprises substantially spatially uniformly adjusting the backlight intensity.

7. The method according to claim 1 , wherein the adjusting the backlight intensity comprises adjusting the backlight intensity to adjust an intensity corresponding to a lightest greyscale level displayable by a first portion of the display device by a first amount, and to adjust an intensity corresponding to a lightest greyscale level displayable by a second portion of the display device, different from the first portion, by a second amount, different from the first amount.

8. The method according to claim 7 , wherein the backlight comprises a plurality of light sources, each at a different location, and

the adjusting the backlight intensity comprises adjusting a first intensity of a first light source of the plurality of light sources so that the first intensity is different from a second intensity of a second light source of the plurality of light sources.

9. The method according to claim 8 , wherein the applying the spatially-variant tone mapping operation comprises applying a tone mapping operation to a portion of the image data representing a part of the image corresponding to the first light source.

10. The method according to claim 1 , comprising determining that the image as displayed on the display device includes a halo artifact,

the method comprising adjusting the backlight intensity and applying the spatially-variant tone mapping operation to the image data in further dependence on the determining that the image as displayed on the display device includes the halo artifact.

11. The method according to claim 1 , comprising receiving ambient light data indicative of an ambient light level,

the method comprising adjusting the backlight intensity and applying the spatially-variant tone mapping operation to the image data in further dependence on the ambient light level.

12. The method according to claim 1 , wherein the one or more features include a feature resulting from an analysis of image content of the image.

13. The method according to claim 1 , wherein the determining comprises processing the image data.

14. The method according to claim 1 , comprising applying the spatially-variant tone mapping operation to the image data to alter a dynamic range of the image data.

15. A display controller for controlling display of image data representing an image on a display device comprising a backlight, the display controller comprising:

a luminance adjustment unit; and

a tone mapping module,

wherein the luminance adjustment unit is arranged to adjust a backlight intensity of the backlight to adjust an intensity corresponding to a lightest greyscale level displayable by at least a portion of the display device, in dependence on one or more features of the image data, wherein the one or more features include a feature representative of a level of compression-noise in the image data; and

the tone mapping module is arranged to apply a spatially-variant tone mapping operation to the image data in dependence on the level of compression-noise in the image data.

16. The display controller according to claim 15 , wherein the feature representative of the level of compression-noise in the image data relates to a format of the image data.

17. The display controller according to claim 15 , wherein the luminance adjustment unit is arranged to adjust the backlight intensity to adjust an intensity corresponding to a lightest greyscale level displayable by a first portion of the display device by a first amount, and to adjust an intensity corresponding to a lightest greyscale level displayable by a second portion of the display device, different from the first portion, by a second amount, different from the first amount.

18. A display system comprising:

a display device comprising a backlight; and

a display controller for controlling display of image data representing an image on the display device, the display controller comprising:

a luminance adjustment unit; and

a tone mapping module,

wherein the luminance adjustment unit is arranged to adjust a backlight intensity of the backlight to adjust an intensity corresponding to a lightest greyscale level displayable by at least a portion of the display device, in dependence on one or more features of the image data, wherein the one or more features include a feature representative of a level of compression-noise in the image data; and

the tone mapping module is arranged to apply a spatially-variant tone mapping operation to the image data in dependence on the level of compression-noise in the image data.

19. The display system according to claim 18 , wherein the feature representative of the level of compression-noise in the image data relates to a format of the image data.

20. The display system according to claim 18 , wherein the luminance adjustment unit is arranged to adjust the backlight intensity to adjust an intensity corresponding to a lightest greyscale level displayable by a first portion of the display device by a first amount, and to adjust an intensity corresponding to a lightest greyscale level displayable by a second portion of the display device, different from the first portion, by a second amount, different from the first amount.