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

Abstract

A display apparatus includes a passive display, a light source, and a video signal input, in operation in response to a video signal the passive display modulates light from the light source to provide an image, and the intensity of the light source is controlled by the video signal. A method of producing a displayed image using a passive display illuminated by a light source is characterized in controlling the light source to obtain a displayed image with a desired amount of information, gray scale and/or color characteristics. A method of reducing power consumption by a display system in which a light modulating display modulates incident light from a light source to provide images is characterized in controlling power provided to the light source to reduce output thereof for relatively dark images.

1 .- 88 . (canceled) 
     
     
         89 . A display device for displaying an image having a low intended brightness, the display device comprising:
 a display;   an illuminating light source;   a computer control, wherein the computer control:   receives brightness information, and determines brightness and a range of grey levels for the input image signal, and   if an image corresponding to the input image signal is a dim image of a low intended brightness and low contrast, increases the range of grey levels used to display the image on the display corresponding to the input image signal, and decreases an amount of light from the illuminating light source so as to alleviate any increase of brightness of the image which is caused by said increasing of the range of grey levels performed such that the low intended brightness of the image is preserved.   
     
     
         90 . A display device for displaying an image having a low intended brightness and an intended color balance, comprising:
 a display capable of displaying an image within a predetermined range of grey levels;   an illuminating light source capable of producing at least three different colors; and   a computer control arranged for receiving an input image signal, said image signal including color grey level information of an image relating to the at least three different colors and a brightness information of said image;   wherein the computer control:   receives said brightness information and said color grey level information, and determines a range of color grey levels for the input image signal;   changes the determined range of color grey levels to a second range of color grey levels which is larger that said determined range of color grey levels, if the brightness of said input image signal represents a dim image of low brightness low contrast; and   decreases an amount of light from the illuminating light source if the brightness of the input image signal represents said dim image, so as to reduce increase of brightness of the image which is produced as a result of said change of the range of color grey levels into said second range of color grey levels, such that the low intended brightness and the intended color balance of the image is preserved.   
     
     
         91 . A display device for displaying an image having a high intended brightness or a low intended brightness and an intended color balance, comprising:
 a display capable of displaying an image within a predetermined range of grey levels;   an illuminating light source capable of producing at least three different least colors; and   a computer control arranged for receiving an input image signal, said image signal including color grey level information and the brightness information of said image by color component;   wherein the computer control:   receives said brightness information and said color grey level information, and determines a range of grey levels for the input image signal;   changes the determined range of grey levels to a second range of grey levels which is larger than said determined range of grey levels, if the brightness of said input image signal represents a high brightness image of high intended brightness with low contrast or a dim image of low intended brightness with low contrast;   increases an amount of light from the illuminating light source if the brightness of the input image signal represents said high brightness image, so as to reduce decrease of brightness of the image which is produced as a result of said change of the range of grey levels into said second grey levels such that the high intended brightness of the image is preserved and the intended color balance of the at least three different colors is preserved; and   decreases an amount of light from the illuminating light source if the brightness of the input image signal represents said dim image, so as to reduce the increase of brightness of the image which is produced as a result of said change of the range of grey levels into said second grey levels such that the low intended brightness of the image is preserved and the intended color balance among the three different colors is preserved.   
     
     
         92 . A method of controlling contrast of an image having a low intended brightness displayed by a display apparatus capable of displaying an image within a predetermined range of grey levels, the display apparatus including an illuminating light source and a computer control, the method comprising:
 processing brightness information of an input image signal and determining brightness and a range of grey levels for the input image signal; and   if the image corresponding to the input image signal is a dim image of a low brightness and low contrast, changing the determined range of grey levels to a second range of grey levels greater than the determined range of grey levels; and decreasing the amount of light from the illuminating light source so as to alleviate any increase of brightness of the image which is caused by performing the control of changing the range of grey levels to the second range of grey levels, such that the low intended brightness of the image is preserved.   
     
     
         93 . A method of controlling contrast of an image displayed by a display apparatus capable of performing color display within a predetermined range of grey levels, the display apparatus including an illuminating light source and a computer control, the method comprising:
 processing brightness information of an input image signal to determine a range of grey levels for an image corresponding to said input image signal and to determine whether the image corresponding to the input image signal is a bright image of a high brightness and low contrast or a dim image of a low brightness and low contrast; and   controlling contrast by;   increasing the determined range of grey levels toward a darker side if the image corresponding to the input image signal is a bright image of a high brightness and low contrast,   increasing the determined range of grey levels toward a brighter side if the image corresponding to the input image signal is a dim image of a low brightness and low contrast; and   adjusting the amount of light from the illuminating light source by increasing the amount of light from the illuminating light source, if the input signal corresponds to a bright image, and decreasing the amount of light from the illuminating light source, if the input signal corresponds to a dim image.   
     
     
         94 . A method of controlling contrast of an image displayed by a display apparatus capable of displaying an image within a predetermined range of grey levels, the display apparatus including an illuminating light source and a computer control, the method comprising:
 processing brightness information of an input image signal and determining brightness and a range of grey levels for the input image signal to determine if the image corresponding to the input image signal is a dim image of a low brightness and low contrast; and   if the image corresponding to the input image signal is a dim image of a low brightness and low contrast, changing the determined range of grey levels to a second range of grey levels which is expanded greater than said determined range of grey levels toward a brighter side, and decreasing the amount of light from the illuminating light source.   
     
     
         95 . A display device for displaying an image, comprising:
 a display capable of displaying an image within a predetermined range of grey levels;   an illuminating light source;   a computer control, wherein the computer control:   receives brightness information, and determines brightness and a range of grey levels for the input image signal to determine If the image corresponding to the input image signal is a dim image of a low brightness and low contrast, and   if an image corresponding to the input image signal is a dim image of a low brightness and low contrast, increases the range of grey levels used to display the image on the display corresponding to the input image signal to have the range of grey levels expanded greater than the determined range of grey levels toward a brighter side, and decreases an amount of light from the illuminating light source.