Optical display system and method, active and passive dithering using birefringence, color image superpositioning and display enhancement with phase coordinated polarization switching

A method of improving dynamic range of a passive display operable in response to a video signal in combination with an illuminating light source to display an image and capable of displaying a preset range of gray levels, the illuminating light source being capable of modulation, comprising sampling the video signal for image brightness information;

• expanding a range of gray levels represented in the video signal across substantially all of the preset range of gray levels;
• and adjusting the intensity of the illuminating light source.

A display system including a display for modulating light from an illuminating source in response to a signal to provide a displayed image, the illuminating source being capable of modulation, comprising means for sampling the signal for image brightness information, means for modifying the signal to optimize contrast in the image by expanding a range of gray levels represented in the signal across substantially all of a preset range of gray levels, and means for adjusting the illuminating source to set the brightness of the display in synchronization with the presentation of the image.

A display system comprising a display for modulating light from an illuminating source in response to a signal to provide a displayed image, wherein the illuminating source is capable of modulation, a sampling device sampling the signal for image brightness information, a circuit modifying the signal to optimize contrast in the image by expanding a range of gray levels representing the image across substantially all of a preset range of gray levels, and adjusting device operable to adjust the illuminating source to set the brightness of the display in synchronization with the presentation of the image.

A method of improving dynamic range of a passive display operable in response to a video signal in combination with an illuminating light source to display an image, the illuminating light source being capable of modulation, characterized in sampling the video signal for image brightness information;

• adjusting the video signal for improved contrast by expanding a range of gray levels represented in the video signal across substantially all of a preset range of gray levels;
• and adjusting the intensity of the illuminating light source for improved brightness all in synchronization with the display.

A method of reducing power consumption of a display apparatus, the display apparatus comprising a controller, a passive display device, and a backlight, the method comprising:

• sensing brightness levels and range of gray levels of an input image signal;
• and
• decreasing intensity of light from the backlight when the brightness level of the input image signal is dim while increasing transmission of the passive display panel by expanding the range of gray levels in a displayed image to be greater than the range of gray levels of the input image signal.

A method of operating a display system that includes a light source and a passive display device to modulate light received from the light source to provide images of scenes represented in an input image signal, the method comprising:

• adjusting gamma of the passive display device;
• and
• controlling the intensity of light produced by the light source as a function of brightness of a scene, whereby for relatively brighter scenes and relatively darker scenes, the intensity of light produced by the light source is, respectively, relatively higher and relatively lower, wherein such control corresponds to the adjusting gamma of the passive display device.