Abstract:
The present invention is directed to a system and method for providing an overhead image. A scan region receives a document containing an image to be projected. An illumination element illuminates the document to produce image light. A means for capturing and digitizing captures and digitizes the image light as digital information. A video subsystem produces a projection image from the digital information.

Description:
TECHNICAL FIELD  
         [0001]    The present invention is related to a system and method for providing overhead projection and in particular to a system and method for digitally processing a scanned image to provide an overhead projection.  
         BACKGROUND  
         [0002]    Overhead projectors provide a relatively simple mechanism to display information to a relatively large group of spectators to facilitate a discussion regarding a topic. Overhead projectors generally use a relatively high intensity bulb to illuminate a slide or piece of paper. The illuminated image from the slide or paper is enlarged via an optical lens system onto a screen for presentation to the group of spectators. Due to their simplicity, overhead projectors have become nearly ubiquitous at corporate meetings, seminars, university classes, and/or the like.  
           [0003]    However, overhead projectors are quite limited. Specifically, the images produced by the overhead projectors may be of relatively poor quality. The text may be blurred and edges may be softened from enlargement of the image. Also, overhead projectors are quite bulky due to focal length constraints imposed by the optical lens system. Moreover, overhead projectors do not provide the capacity for spectators to retain any tangible form of the information contained in the slides or papers.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed to a system and method for providing an overhead image. A scan region receives a document containing an image to be projected. An illumination element illuminates the document to produce image light. A means for capturing and digitizing captures and digitizes the image light as digital information. A video subsystem produces a projection image from the digital information.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0005]    [0005]FIG. 1 depicts an exemplary block diagram of an overhead projector arranged according to an embodiment of the present invention.  
         [0006]    [0006]FIG. 2 depicts an exemplary view of an overhead projector arranged according to an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0007]    [0007]FIG. 1 depicts an exemplary block diagram of overhead projector  100  arranged according to an embodiment of the present invention. Overhead projector  100  includes illumination subsystem  101  to illuminate to a scan region. A document may be placed in the scan region so that its image will be projected by overhead projector  100 . Any type of document may be utilized such as a paper, photograph, slide, and/or the like. Accordingly, the term “document” is intended to be used broadly as any type of suitable physical medium that can be used to form an image for projection. Overhead projector  101  further includes optic subsystem  100  to focus image light from the scan region onto charge coupled device (CCD)  101 . In lieu of CCD  101 , other optical detectors can be utilized such as a cathode ray tube. Optic subsystem  100  may comprise a lens to focus and reduce image light onto CCD  101 . Optic subsystem  100  may include mirrors or reflective components to redirect image light to thereby create a more compact device housing if desired.  
         [0008]    CCD  101  is a device that is well known in the art. Specifically, CCD  101  is a semiconductor device that provide an array of photo-sensitive elements to capture image light. Specifically, image light causes electronic capacitors to be charged by the incident light. The electronic capacitors are sampled to provide to an analog to digital convertor to create a digital representation of the captured incident light. CCD  101  may be implemented such that the entire image is captured via one operation, i.e., the area of CCD  101  is sufficiently large to capture all of the incident image light after optical reduction by a lens. Alternatively, CCD  101  may be implement as a single row of elements. In this case, CCD  101  may be associated with a carriage which is swept across the scan region to capture the entire image.  
         [0009]    CCD  101  is communicatively coupled to random access memory (RAM)  104  to transfer the digital presentation of the captured image light into memory for processing by central processing unit (CPU)  105 . Additionally, video subsystem  106  is communicatively coupled to RAM  104 . Video subsystem  106  utilizes the digital information to generate a projection image. Specifically, video subsystem  106  drives, for example, a cathode ray tube (CRT) or liquid crystal display (LCD) to generate image light. The generated image light is then projected onto a screen for display to spectators.  
         [0010]    Additionally, printer subsystem  107  is coupled to RAM  104 . Printer subsystem may obtain image information in a suitable format to print a physical copy of the captured image. Specifically, CPU  105  may, in response to user input via user interface  108 , create an appropriate print file in RAM  104  which corresponds to the captured image. For example, CPU  105  may create a POSTSCRIPT™ file in RAM  104 . CPU  105  may cause printer subsystem  107  to receive the file from RAM  104 . Printer subsystem  107  may utilize the file to create a hard copy or copies for spectators. Printer subsystem  107  may provide black and white printouts or color printouts. For example, printer subsystem  107  may include Hewlett-Packard inkjet printer HP deskjet 630c. Such an inkjet printer provides a compact footprint for inclusion in overhead projector  100  while producing appreciable print quality.  
         [0011]    Moreover, CPU  105  may be communicatively coupled to output port  109 . Output port  109  may provide a connection (such as a SCSI or RS-132 interface) to communicate with another processor-based system. Output port  109  can utilize any number of physical mediums and communication protocols. For example, output port  109  can utilize various cable based communication interfaces. Alternatively, output port  109  can utilize various wireless interfaces (e.g., infrared or RF interfaces). Alternatively, output port  109  may be coupled to a peripheral such as a floppy drive. CPU  105  may utilize output port  109  to provide an electronic copy of the captured image to a processor-based system of a spectator. For example, CPU  105  may convert the digital representation into a PDF™ file. A spectator may utilize a personal data assistant (PDA) to receive the file for future retrieval.  
         [0012]    In preferred embodiments of the present invention, CPU  105  provides digital enhancement of the digital representation of the captured image. Specifically, an individual operating overhead projector  100  may supply a paper with a color background. When the specific color is projected onto a screen for viewing, the color background may reduce the readability of information on the paper. For example, relatively small text in footnotes may be obscured. CPU  105  may be operable to receive user input from user interface subsystem  108  to correct this condition. For example, CPU  105  may examine the background color. CPU  105  may replace the background color with a different color (e.g., white) to enhance the readability of the projected image. Alternatively, CPU  105  may be operable to remove or modify any color or color range that otherwise reduces readability of the projected image.  
         [0013]    In another embodiment, CPU  105  may provide contrast enhancement. Specifically, CPU  105  may examine the range of variation between light and dark values in the digital representation stored in RAM  104 . CPU  105  may process the digital information to cause light values to become lighter and to cause dark values to be darker. By doing so, the contrast of the image may be improved to enhance readability.  
         [0014]    In yet another embodiment, CPU  105  may provide edge enhancement. To do so, CPU  105  first detects edges in the digital representation. Specifically, CPU  105  detects adjacent pixels along either side of a path or contour that possess significant variations in color or brightness. Edge enhancement may occur through several techniques. For example, the variation in color or brightness may be accentuated. Alternatively, the width of the path or contour may be widened so as to increase the sharpness of the edge.  
         [0015]    [0015]FIG. 2 depicts an exemplary view of overhead projector  100  arranged according to an embodiment of the present invention. In this embodiment, overhead projector  100  includes CCD  105 . CCD  105  is shown to be physically associated with illumination bulb  201  and mirror  202 . Illumination bulb  201  illuminates a portion of the scan region while mirror  202  causes light reflected from the illuminated portion to be directed to CCD  105 . In this case, CCD  105 , bulb  201 , and mirror  202  are operable to cause image capture and digitization of a relatively small portion of a document via one operation. Accordingly, CCD  105 , bulb  201 , and mirror  202  are preferably implemented on a carriage to sweep the elements across a document to capture and digitize the entire image.  
         [0016]    Overhead projector  100  includes several input elements. Input elements  204   a  and  204   b  allow the user to adjust the brightness of the projected overhead image. Input elements  205   a  and  205   b  allow the user to adjust the processing of the captured digitized image to produce a desired level of contrast. Input element  206  allows the user to cause edge enhancement processing to occur. Overhead projector  100  further includes wireless interface  207  which may allow a user to download a digitized image via a PDA and/or the like. Overhead projector  100  further includes aperture  208  to facilitate output of the overhead image.