Systems and methods for controlling dual modulation displays

Patent metadata

Field	Value
Publication number	US-9607556-B2
Application number	US-201314406471-A
Country	US
Kind code	B2
Filing date	Jun 10, 2013
Priority date	Jun 15, 2012
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

In one embodiment, a dual modulator display systems and methods for rendering target image data upon the dual modulator display system are disclosed where the display system receives target image data, possible HDR image data and first calculates display control signals and then calculates backlight control signals from the display control signals. This order of calculating display signals and then backlight control signals later as a function of the display systems may tend to reduce clipping artifacts. In other embodiments, it is possible to split the input target HDR image data into a base layer and a detail layer, wherein the base layer is the low spatial resolution image data that may be utilized as for backlight illumination data. The detail layer is higher spatial resolution image data that may be utilized for display control data.

First claim

The invention claimed is:

1. A method for rendering target image data upon a dual modulator display system, said dual modulator display system further comprising a backlight; said backlight comprising a set of emitters, each said emitter capable of independent control from a set of backlight control signals; a display modulator, said display modulator comprising a set of modulating elements, each said modulating element capable of independent control from a set of display control signals; and a controller, said controller configured to receive target image data and to send emitter control signals and display control signals to the backlight and display modulator respectively, the steps of said method comprising:
receiving target image data;
calculating display control signals;
calculating target backlight illumination data from said display control signals and said target image data;
calculating said backlight control signals from said target backlight illumination data;
sending backlight control signals to said emitters; and
sending said display control signals to said modulating elements.

2. The method as given in claim 1 wherein the step of calculating display control signals further comprises:
determining an LCD image that is within the dynamic range limitation of said dual modulator display system.

3. The method as given in claim 2 wherein the step of calculating said target backlight illumination data further comprises:
determining target backlight control signals that increase the dynamic range according to the target image data.

4. The method as given in claim 1 wherein the step of calculating display control signals further comprises:
tone mapping said target image data;
determining an LCD image from said tone mapped target image data.

5. The method as given in claim 4 wherein the step of calculating said target backlight illumination data further comprises:
determining target backlight control signals by subtracting said tone mapped target image data from said target image data.

6. The method as given in claim 1 wherein said method further comprises the step of:
splitting said target image data into a base layer and a detail layer.

7. The method as given in claim 6 wherein said base layer comprises low spatial frequency information of said target image data and said detail layer comprises high spatial information of said target image data.

8. The method as given in claim 7 wherein said backlight further comprises an array of LED emitters, each said LED emitter comprising a point spread function (PSF).

9. The method as given in claim 8 wherein said method further comprises the step of:
determining said base layer as a convolution of said PSF of said emitters and said target image data.

10. The method as given in claim 8 wherein said method further comprises the step of:
determining said base layer as a multiplication of said target image data and said PSF in the frequency domain and converting said multiplication to the spatial domain.

11. The method as given in claim 8 wherein said method further comprises the step of:
determining said base layer by down-sampling said target image data, convolving with said PSF and upsampling the convolution.

12. The method as given in claim 7 wherein said method further comprises the step of:
determining said detail layer by dividing said target image data by said base layer.

13. The method as given in claim 12 wherein said step of determining said detail layer further comprises the step of:
tone mapping said detail layer.

14. The method as given in claim 13 wherein said step of tone mapping said detail layer further comprises the step of:
calculating the tone mapping detail layer as:

Detail
TM

=

c
1

*
Detail

1
+

c
2

*
Detail

wherein c1 and c2 comprise tone curve parameters.

15. The method as given in claim 12 wherein said method further comprises the step of:
re-calculating the base layer as a function of said target image data and said detail layer.

16. The method as given in claim 15 wherein said step of re-calculating the base layer further comprises:
calculating the base layer as:
Base=Target/(LCD·(1−CR)+CR)

wherein LCD is the detail layer and CR is contrast ratio.

Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Atkins Robin
• Ward Rabab Kreidieh

Classifications

• G09G2320/0271

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

• G02F1/133

  Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements (arrangements or circuits for control of liquid crystal elements in a matrix, not structurally associated with these elements G09G3/36) · CPC title

• G06F3/1423

  controlling a plurality of local displays, e.g. CRT and flat panel display · CPC title

• G09G2320/0266

  Reduction of sub-frame artefacts · CPC title

• G09G3/3611

  Control of matrices with row and column drivers · CPC title