Systems and Methods for Local Dimming in Multi-modulation Displays

Patent metadata

Field	Value
Publication number	US-2016286178-A1
Application number	US-201415034169-A
Country	US
Kind code	A1
Filing date	Oct 29, 2014
Priority date	Nov 3, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

Dual and multi-modulator projector display systems and techniques are disclosed. In one embodiment, a projector display system comprises a light source; a controller, a first modulator, receiving light from the light source and rendering a halftone image of said the input image; a blurring optical system that blurs said halftone image with a Point Spread Function (PSF); and a second modulator receiving the blurred halftone image and rendering a pulse width modulated image which may be projected to form the desired screen image. Systems and techniques for forming a binary halftone image from input image, correcting for misalignment between the first and second modulators and calibrating the projector system—e.g. overtime—for continuous image improvement are also disclosed.

First claim

1 . A projector display system, comprising:
a light source; a controller, said controller receiving input image data and outputting control signals; a first modulator, said first modulator receiving light from said light source, said first modulator receiving said control signals from said controller such that said first modulator is capable of rendering a halftone image of said input image; a blurring optical system; said blurring optical system blurring said halftone image received from said first modulator; and a second modulator, said second modulator receiving said blurred halftone image from said blurring optical system and receiving said control signals from said controller such that said second modulator is capable of rendering a pulse width modulated image, said pulse width modulator image capable of being projected to form the desired screen image.

2 . The projector display system of claim 1 wherein said first modulator further comprises one of a group, said group comprising: a DMD, a MEMS, a digital reflector and an analog reflector.

3 . The projector display system of claim 1 wherein said first modulator further comprises a DMD array that processes a plurality of color channels.

4 . The projector display system of claim 1 wherein said first modulator is capable of rendering a binary halftone image of said input image; and
further wherein said blurred halftone image is substantially brighter than said desired screen image.

5 . The projector display system of claim 4 wherein said blurred halftone image is less bright than said desired screen image when said controller sends control signals to affect bright clipping of said input image data.

6 . The projector display system of claim 4 wherein said binary halftone image substantially comprises a spatial dither pattern.

7 . The projector display system of claim 6 wherein said spatial dither pattern, b(m,n), comprises a dilated input image, x(m,n), that is subject to a threshold, htLevel (m,n); and
further wherein b(m,n)=1, if x(m,n)>htLevel (m,n).

8 . The projector display system of claim 1 wherein said blurred halftone image further comprises substantially a bandlimited minimum upper bound of said desired screen image.

9 . The projector display system of claim 4 wherein said blurred halftone image comprises said binary halftone image smoothed by said blurring optical system; and
further wherein said blurring optical system comprises a bandlimited, limited rise time PSF.

10 . The projector display system of claim 9 wherein said PSF further comprises a PSF with limited spatial extent.

11 . The projector display system of claim 9 wherein said PSF further comprises a substantially radially symmetric PSF.

12 . The projector display system of claim 9 wherein said PSF further comprises one of a group, said group comprising: a Gaussian, a raised-cosine function and a substantially radially symmetric peaked function with limited spatial extent.

13 . The projector display system of claim 1 wherein said second modulator further comprises one of a group, said group comprising: a DMD, a MEMS, a digital reflector and an analog reflector.

14 . The projector display system of claim 1 wherein further comprises projector optics, said projector optics capable of receiving said pulse width modulator image and capable of projected said desired screen image.

15 . A method for projecting desired screen images from input image data in a projector display system, said projector display system comprising a light source, a controller, said controller receiving input image data and outputting control signals, a premod modulator receiving control signals from said controller and light from said light source, a blurring optical system receiving light from said premod modulator, and a primary modulator receiving control signals from said controller and light from said blurring optical system, the method comprising:
creating a binary halftone image from said input image data; creating a blurred binary halftone image from said binary halftone image; creating a pulse width modulated image from said blurred binary halftone image; and projecting a desired screen image from said pulse width modulated image.

16 . The method of claim 15 wherein creating a binary halftone image from said input image data further comprises:
creating a binary halftone image wherein said binary halftone image is substantially brighter than said desired screen image.

17 . The method of claim 16 wherein creating a binary halftone image wherein said binary halftone image is substantially brighter than said desired screen image further comprises:
creating a binary halftone image that is less bright than said desired screen image to affect bright clipping of said input image data.

18 . The method of claim 15 wherein creating a binary halftone image from said input image data further comprises:
creating a spatial dither pattern from said input image data.

19 . The method of claim 18 wherein creating a spatial dither pattern from said input image data further comprises:
dilating said input image data to a blur kernel extent; and
thresholding said dilated image data to a binary value.

20 . The method of claim 15 wherein creating a blurred binary halftone image from said binary halftone image further comprises:
smoothing said binary halftone image with the Point Spread Function (PSF) of the blurring optical system.

21 . The method of claim 20 wherein said PSF comprises one of a group, said group comprising: a PSF of limited spatial extent, a bandlimited PSF, a substantially radially symmetric PSF, a Gaussian, a raised-cosine function and a substantially radially symmetric peaked function with limited spatial extent.

22 . The method of claim 15 wherein said method further comprises:
compensating for any premod modulator to primary modulator alignment errors.

23 . The method of claim 15 wherein said method further comprises:
applying a blur model to said binary halftone image;
reciprocating said blur modeled binary halftone image; and
multiplying said blur modeled binary halftone image with said input image data.

24 . The method of claim 23 wherein applying a blur model to said binary halftone image further comprises:
applying a blur model, said blur model based on a set of PSF models, each PSF model applying to local portion of the image area.

25 . The method of claim 22 wherein compensating for any premod modulator to primary modulator alignment errors further comprises:
applying a primary-to-premod alignment mapping to said input image data;
computing a halftone image;
applying a light field model;
applying a premod-to-primary alignment mapping to produce a primary registered light field; and
sending the primary registered light field to said primary modulator.

26 . A method for calibrating a projector display system, said projector display system comprising a light source, a controller, said controller receiving input image data and outputting control signals, a premod modulator receiving control signals from said controller and light from said light source, a blurring optical system receiving light from said premod modulator, and a primary modulator receiving control signals from said controller and light from said blurring optical system, the method comprising:
receiving input image data; computing

Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Shields Jerome
• Richards Martin J
• Pertierra Juan P

Classifications

• G03B21/208

  Homogenising, shaping of the illumination light · CPC title

• G03B21/005

  Projectors using an electronic spatial light modulator but not peculiar thereto · CPC title

• H04N9/3123

  using pulse width modulation · CPC title

• H04N9/3126 Primary

  for spatial light modulators in series · CPC title

• H04N9/3164

  using multiple light sources · CPC title