Use of ambience light for copy protection of video content displayed on a screen

Abstract

The invention provides a method for impeding making a useful copy with an optical recording device of video content displayed on a screen, wherein the method comprises displaying the video content on the screen, illuminating with ambience light of an ambience light source the screen, the ambience light comprises light having a wavelength in the visible part of the spectrum, wherein the ambience light is controlled as function of the video content, and wherein the ambience light is intensity modulated with an intensity modulation having an intensity modulation frequency selected from the range of 40 Hz to 500 Hz.

1 . A method for preventing pirates from copying video content displayed on a screen by impeding an optical recording device from making a non-disturbed copy of the displayed video content, the method comprising the steps of:
 displaying the video content on the screen, wherein the video content comprises a plurality of images to be displayed sequentially, and   illuminating the screen with ambience light of an ambience light source,   wherein the ambience light comprises light having a wavelength in the visible part of the spectrum,   wherein the ambience light is controlled as function of the video content, the ambience light comprising one or more colors determined on one or more average colors of one or more sub-sections of an image or wherein the ambience light comprises one or more colors determined on one or more average colors of one or more sub-sections of a plurality of subsequent images, and   wherein the ambience light is intensity-modulated with an intensity modulation frequency selected from the range of 40 Hz to 500 Hz.   
     
     
         2 . The method according to  claim 1 , wherein the video content is displayed on the screen with a frame rate, and wherein the frame rate and the intensity modulation frequency have a frequency difference in the range of 0.5 Hz to 50 Hz. 
     
     
         3 . The method according to  claim 1 , wherein the ambience light is intensity-modulated with an intensity modulation frequency of at least 50 Hz, and wherein the intensity modulation frequency is selected from the group consisting of 24x Hz, 25x Hz, 30x Hz, 48x Hz, 50x Hz, 60x Hz, 72x Hz, 120x Hz, and 300x Hz, wherein x is a non-integer number larger than zero. 
     
     
         4 . The method according to  claim 1 , wherein the ambience light source comprises a LED based light source. 
     
     
         5 . The method according to  claim 1 , wherein the ambience light source is configured relative to a screen to allow only part of the visible ambience light impinge on the screen. 
     
     
         6 . The method according to  claim 1 , including illuminating the screen with the ambience light in an indirect way. 
     
     
         7 . The method according to  claim 1 , wherein the intensity of the ambience light is controlled as function of the video content. 
     
     
         8 . The method according to  claim 1 , wherein the intensity modulation frequency is varied in time. 
     
     
         9 . The method according to  claim 1 , further comprising providing with the ambience light a watermark on the screen. 
     
     
         10 . A LED-based ambience light source configured to provide ambience light that is variable in intensity, wherein the ambience light comprises light having a wavelength in the visible part of the spectrum, and wherein the LED-based ambience light source comprises a modulator that is configured to modulate the intensity of the ambience light with an intensity modulation frequency selected from the range of 40 Hz to 500 Hz. 
     
     
         11 . A cinema system comprising a controller configured (i) to control a display device for displaying video content on a screen, and (ii) to control an ambience light source for providing ambience light with variable intensity, wherein the controller is further configured (iii) to control the ambience light as function of the video content and (iv) to modulate the intensity of the ambience light with an intensity modulation frequency selected from the range of 40 Hz to 500 Hz. 
     
     
         12 . The cinema system according to  claim 11 , further comprising the display device and the ambience light source, wherein the ambience light of the ambience light source comprises light having a wavelength in the visible part of the spectrum, wherein the display device is configured to display the video content on the screen with a frame rate, and wherein the cinema system is configured to provide the video content and the ambience light with a frequency difference between the frame rate and the modulation frequency in the range of 0.5 Hz to 50 Hz. 
     
     
         13 . A display space, comprising the cinema system according to  claim 11  and the screen.