Color calibration of color image rendering devices

Abstract

Color calibration of color image rendering devices, such as large color displays, which operate by either projection or emission of images, utilize internal color measurement instrument or external color measurement modules locatable on a wall or speaker. A dual use camera is provided for a portable or laptop computer, or a cellular phone, handset, personal digital assistant or other handheld device with a digital camera, in which one of the camera or a display is movable with respect to the other to enable the camera in a first mode to capture images of the display for enabling calibration of the display, and in a second mode for capturing image other than of the display. The displays may represent rendering devices for enabling virtual proofing in a network, or may be part of stand-alone systems and apparatuses for color calibration. Improved calibration is also provided for sensing and correcting for non-uniformities of rendering devices, such as color displays, printer, presses, or other color image rendering device.

1 - 7 . (canceled) 
     
     
         8 . A digital theater system for reproducing color images on a screen in a room in accordance with tolerances for consistency of color reproduction at multiple sites comprising:
 an image display device providing color images on said screen;   a color measuring instrument for non-contact measuring of said color images on said screen;   a processor for controlling at least said image display device and said color measuring instrument, said processor being capable of rendering one or more calibration images on said screen via said image display device, receiving color measurements from said instrument representative of said rendered calibration images, and modifying color transformations employed by said processor in rendering color images on said screen in accordance with said color measurements;   memory accessible by said processor for storing at least said calibration images, the color images to be rendered by the image display device, and said color transformations; and   a network interface coupled to said processor enabling import or export of at least the color images to be rendered by the image display device from or to at least one other of said multiple sites.   
     
     
         9 . The system according to  claim 8  wherein said image display device represents one of a digital projector or projection display providing images onto said screen. 
     
     
         10 . The system according to  claim 8  wherein said image display device represents a self-luminous flat panel having said screen. 
     
     
         11 . The system according to  claim 8  wherein said room has walls and said color measurement instrument is mounted onto the wall. 
     
     
         12 . The system according to  claim 8  wherein said color measuring instrument is integral with the image display device. 
     
     
         13 . The system according to  claim 8  further comprising one or more speakers for outputting audio associated with said color images, and said color measuring instrument is coupled to one of said speakers. 
     
     
         14 . A method for detecting color errors in a reproduction on a display surface produced by a rendering device, said reproduction representing a source digital image having pixels in one or more color channels, said method comprising the steps of:
 measuring spatial non-uniformities of rendering across said display surface;   capturing a digital image of said reproduction in which said digital image is represented by pixels in different color channels;   generating at least one histogram of the captured digital image of pixels in one or more of said color channels;   modifying said source digital image at least to simulate said spatial non-uniformities of rendering;   cross-correlating one or more regions of said histogram with similar regions of a histogram of pixels of said modified source digital image; and   analyzing said cross-correlated histograms to determine the color error of said reproduction.   
     
     
         15 - 22 . (canceled) 
     
     
         23 . A system for improving color match between at least one page of a color signature and a reference comprising:
 an imaging device capable of producing a digital color image representing one or more pages of a signature printed by an output device, wherein said imaging device is calibrated to provide image data in standard units; and   a computer associated with said imaging device, said computer being capable of communicating with one or more other computers, wherein said computer has access, directly or indirectly, to memory comprising a model of the effects of position within said signature on color reproduction by said output device and said model is utilized to improve color match between colors within said signature and said reference.