Patent Publication Number: US-2007097386-A1

Title: Imaging system and method

Description:
BACKGROUND OF THE INVENTION  
      Scanning devices typically use a fluorescent lamp (e.g., a cold cathode fluorescent lamp (CCFL)) to illuminate a media object during a scanning operation. However, such fluorescent lamps emit light having spectrum peaks at particular frequencies or frequency ranges. Software is used to compensate for image colors in a media object falling outside the peak frequency ranges of the fluorescent lamp. However, increasingly subtle colors in the media object falling outside the peak frequency ranges are particular difficult for such software products to accurately reproduce. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:  
       FIG. 1  is a diagram illustrating an embodiment of an imaging system in accordance with the present invention; and  
       FIG. 2  is a diagram illustrating an exemplary spectral response of the imaging system of  FIG. 1 .  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      The preferred embodiments of the present invention and the advantages thereof are best understood by referring to  FIGS. 1 and 2  of the drawings, like numerals being used for like and corresponding parts of the various drawings.  
       FIG. 1  is a diagram illustrating an embodiment of an imaging system  10  in accordance with the present invention. In the embodiment illustrated in  FIG. 1 , system  10  comprises a scanning device  12  having a processor  14 , a photosensor element  16  and a plurality of different light sources  18 . Scanning device  12  may comprise any type of device for generating a scanned image of a media object such as, but not limited to, a scanner, facsimile machine or copier. Photosensor element  16  may comprise any type of device for generating electrical signals from optical signals such as, but nor limited to, a charge-coupled device (CCD). It should be understood that embodiments of the present invention may be used in both reflective and transmissive scanning applications.  
      In the embodiment illustrated in  FIG. 1 , scanning device  12  also comprises a memory  20  having a scanning control module  22  and an imaging application  24 . Scanning control module  22  and imaging application  24  may comprise hardware, software, or a combination of hardware and software. In  FIG. 1 , scanning control module  22  and imaging application  24  are illustrated as being disposed in memory  20  so as to be accessible and/or executable by processor  14 . However, it should be understood that scanning control module  22  and/or imaging application  24  may be otherwise stored, even remote from scanning device  12 . Scanning control module  22  is used to activate/de-activate light sources  18  for scanning and/or otherwise illuminating a media object to be scanned. Imaging application  24  is used, in some embodiments of the present invention, to generate a scanned image of the media object using image data obtained from a plurality of scans of the media object.  
      In the embodiment illustrated in  FIG. 1 , light sources  18  are each preferably configured having different spectral response frequency characteristics to produce enhanced color information in the scanned image of the media object. For example, in the embodiment illustrated in  FIG. 1 , light sources  18  comprise a cold cathode fluorescent lamp (CCFL 1 )  30 , a CCFL 2    32  and a light emitting diode (LED) set  34 . It should be understood that additional types of light sources may also be used. Embodiments of the present invention may be configured having a variety of different light source  18  combinations to produce different spectral response frequency characteristics for a scanned image of the media object. For example, in one embodiment of the present invention, scanning device  12  is configured having a primary light source  18  with predetermined spectral response characteristics and a secondary light source  18  having different spectral response characteristics than the primary light source  18 . As used herein, “primary” and “secondary” are used to differentiate between different light sources  18  and not to designate a preferred light source  18 . It should also be understood that “secondary” does not otherwise limit scanner device  12  to only two light sources  18  as it should be understood that three or more light sources  18  may also be used.  
      Embodiments of the present invention utilize a cold cathode fluorescent lamp (e.g., CCFL 1    30 ) in combination with another cold cathode fluorescent lamp (e.g., CCFL 2    32 ) and/or at least one LED set  34  to emit light having different spectral response characteristics to generate a scanned image of a media object having enhanced color characteristics. As used herein, a “set” may comprise a single LED or multiple LEDs. Preferably, each LED of set  34  is selected having a spectral response characteristic different than the spectral response characteristics of the selected fluorescent lamps (e.g., lamps  30  and/or  32 ).  
      For example, in one embodiment of the invention, scanning device  12  is configured having a single CCFL 1    30  and LED set  34  where one or more LEDS of LED set  34  each have a different spectral response characteristic than CCFL 1    30 . Thus, the LED set  34  is used to provide a shifted spectral response relative to the response of CCFL 1    30 , thereby providing broader color spectrum response for the optimized scanned image. In another embodiment of the present invention, scanning device  12  is configured having CCFL,  30  and CCFL 2    32 , where CCFL 2    32  is configured having a different spectral response frequency characteristic than CCFL 1    30 . Preferably, different phosphor mixtures and/or coatings are used to create different spectral response characteristics for each of CCFL 1    30  and CCFL 2    32 . However, it should be understood that other methods may be used to produce light sources  18  having different spectral response characteristics. Thus, for example, CCFL 2    32  is preferably configured having spectral response characteristics that are shifted relative to the spectral response characteristic of CCFL,  30  such that a broader color spectrum is obtained for a scanned image of the media object. In yet another embodiment of the present invention, scanning device  12  is configured having CCFL 1    30 , CCFL 2    32  and LED set  34  each having different spectral response frequency characteristics. Accordingly, it should be understood that a variety of combinations of light sources  18  may be used to obtain broader color spectrum coverage (e.g., CCFL 1    30  and CCFL 2    32 ; CCFL 1    30  and LED set  34 ; CCFL 2    32  and LED set  34 ; or CCFL 1    30 , CCFL 2    32  and LED set  34 ).  
      In operation, scanning device  12  generates a scanned image of a media object by illuminating the media object with at least two different light sources  18  where each light source  18  has a different spectral response characteristic, thereby providing enhanced color characteristics for the scanned image. The light sources  18  are selected such that each light source  18  “fills” the spectral response gaps of another selected light source  18 . In some embodiments of the present invention, scanning device  12  is configured to use a single light source  18  for general scanning operations and use multiple light sources  18  for scanning operations where an enhanced color scanned image is desired (e.g., in response to a user input request for an enhanced color scanned image or otherwise). However, it should be understood that scanning device  12  may be configured to automatically use multiple light sources  18  as a default scanning mode. It should be understood that scanning device  12  may also be configured having different levels of color enhancement where different and/or additional light sources  18  are used for each different level of enhanced color (e.g., CCFL,  30  for a general scanning mode; CCFL 1    30  and CCFL 2    32  for an enhanced color scanning mode; and CCFL 1    30 , CCFL 2    32  and LED set  34  for a further enhanced color scanning mode). Thus, based on a selected scanning mode, control module  22  controls activation of the corresponding light sources  18  for the selected scanning mode.  
      In the embodiment illustrated in  FIG. 1 , memory  20  comprises a database  40  having image data  42 . Image data  42  comprises information associated with scanned images of a media object using one or more light sources  18 . For example, in the embodiment illustrated in  FIG. 1 , image data  42  comprises frequency spectrum scan data  44  and combined scan image data  46 . Frequency spectrum scan data  44  comprises information associated with one or more scans of a particular media object using one or more different light sources  18 , concurrently or alternately. For example, in some embodiments of the present invention, a scanned image of a media object is obtained by illuminating one of light sources  18  (e.g., CCFL 1    30 ) during a first scanning pass of the media object, and illuminating another light source  18  (e.g., CCFL 2    32  and/or LED set  34 ) during a second scanning pass of the media object. The scanned image information obtained during each scanning pass is stored as frequency spectrum scan data  44 . It should be understood that, alternatively, light sources  18  may be alternately illuminated at each scan line instead of entire pass scanning. In the above example, each scan of the media object using a different light source  18  is combined to form a color-enhanced scanned image of the media object, represented in  FIG. 1  as combined scan image data  46 . For example, in some embodiments of the present invention, imaging application  24  is configured to overlay each of the scanned images obtained using a different light source  18  to generate the color-enhanced scanned image  46  of the media object. However, it should be understood that imaging application  24  may be configured to generate the scanned image  46  of the media object using a variety of different methods (e.g., merging, blending and/or otherwise manipulating the scanned image data).  
      It should be understood that in some embodiments of the present invention, multiple light sources  18  are activated concurrently by control module  20  during a single scanning pass to generate a color-enhanced scanned image of a particular media object. In this example, a single scan of the media object provides a color-enhanced scanned image of the media object without further post-scan processing (e.g., without having to combine multiple scanned images of the media object).  
      Thus, in operation, scanning control module  22  controls activation and de-activation of light sources  18  for a particular scan of a media object. As described above, multiple light sources  18  may be activated concurrently or alternately to generate one or more scanned images of a media object. The different light sources  18  used to illuminate the media object for each scan thereby produce different spectral response characteristics to form and/or otherwise produce enhanced color of the scanned image over a visible frequency spectrum.  
       FIG. 2  is a diagram illustrating spectral response characteristics of system  10 . For example, in  FIG. 2 , CCFL 1    30  may be configured having spectral response characteristics with peaks at approximately 430 nanometers (e.g., blue), 546 nanometers (e.g., green) and 612 nanometers (e.g., red). Other light sources  18  of scanning device  12  are preferably configured having spectral response characteristics different than the spectral peaks illustrated in  FIG. 2  for CCFL 1    30  to obtain enhanced or broader color information across the visible spectrum. For example, in some embodiments of the present invention, CCFL 2    32  is configured having spectral response characteristics such that spectral peaks of CCFL 2    32  are located at approximately 452 nanometers, 575 nanometers, and 635 nanometers. It should be understood that the particular spectral peaks of each of light sources  18  may be otherwise configured. In  FIG. 2 , CCFL 1    30  and CCFL 2    32  are illustrated each generally having three spectral peaks. However, it should be understood that each selected light source  18  may have a greater or lesser quantity of spectral peaks. For example, in addition to the spectral peaks illustrated in  FIG. 2  associated with CCFL,  30  and CCFL 2    32 , an LED set  34  may be combined therewith to provide one or more additional spectral peaks (e.g., a single LED for an additional spectral peak at a predetermined frequency or multiple LEDs for multiple additional spectral peaks at predetermined spectral frequencies).  
      Thus, embodiments of the present invention use different light sources  18  configured having different spectral response characteristics to provide additional color information in different spectral regions. As described above, the image information obtained from scanning a media object with at least two different light sources  18  each having different spectral response characteristics is used to generate a scanned image of the media object having enhanced color characteristics.