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

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 brightnes 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 decrease 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.

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 gray 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 than 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 gray levels into said second range of color gray levels, such that the low intended brightness and the intended color balance of the image is preserved.

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 gray levels for the input image signal;
• changes the determined range of grey levels to a second range of gray 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 gray levels into said second gray 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 gray levels into said second gray levels such that the low intended brightness of the image is preserved and the intended color balance among the three different colors is preserved.

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.

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.

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.