Abstract:
A reading machine includes an image input device including a lens and a polarizer disposed over the lens, a flash and a second polarizer disposed over the flash. The image input device also includes a computing device coupled to the image input device for capturing images, the computing device, including a processor to execute instructions and a computer program product residing on a computer readable medium, the computer program product comprising instructions for causing the processor to process the captured images to recognize features in the captured images.

Description:
BACKGROUND 
       [0001]    Reading machines use optical character recognition (OCR) and text-to-speech (TTS) i.e., speech synthesis software to read aloud and thus convey printed matter to visually and developmentally impaired individuals. Reading machines read text from books, journals, and so forth. 
         [0002]    Reading machines can use commercial off-the-shelf flat-bed scanners, a personal computer and optical character recognition (OCR) software. The computer processes an image with the OCR software and produces a text file. The text file is fed to text-to-speech synthesis software to provide electrical signals that are fed to audio output devices to render speech and thus read any recognized text aloud to the user. 
         [0003]    One manner in which a reading machine can capture an image is through an imaging device that is attached to the reading machine. One such use is to capture images of a scene to convey content of the scene to a user. A scene can represent contents of an image that is being read. A scene can be a memo or a page of a book, or it can be a door in a hallway of an office building. The type of real-world contexts to “read” may include visual elements that are words, symbols or pictures, colors and so forth. 
         [0004]    In addition to processing the image to recognize text, other recognition processes can include object recognition, such as recognizing faces, expressions on faces and so forth. 
       SUMMARY 
       [0005]    In applications of reading machines with use of a flash to increase the light available to capture the image, there can be glare from glossy surfaces of a document or from, e.g., eyeglasses for facial recognition when a flash is used. Also there may be natural glare under strong lighting conditions all of which can interfere with recognition processing. 
         [0006]    According to an aspect of the present invention, an image input device includes an image input device includes a lens, a flash window and a polarizer assembly having a pair of polarizers, the polarizer assembly disposed over the image input device, with one of the pair of polarizers covering the lens having a linear polarization that is orthogonal to a linear polarization of the other polarizer of the pair that covers the lens. 
         [0007]    The following are embodiments within the scope of the invention. 
         [0008]    The image input device is a camera. The polarizer assembly includes a frame member holding the polarizers. The device is a reading machine with the reading machine including a computing device coupled to the image input device for capturing images, the computing device, including a processor to execute instructions and a computer program product residing on a computer readable medium. The computer program product includes instructions for causing the processor to process the captured images to recognize features in the captured images. The computer program product further includes instructions to recognize text in the captured images and produce text and convert the recognized text to speech using text-to-speech software. 
         [0009]    The polarizer assembly includes a frame comprised of a material that is stiffer that the material of the polarizers, with one of the polarizers disposed in a first portion of the frame that is aligned to the lens and the other one of the polarizers disposed in a second portion of the frame that is aligned with the flash window of the image input device. The device includes a pair of opposing channel members that are disposed on a face of the image input device, the pair of opposing channel members configured to accept the polarizer assembly. The pair of opposing channel members each have a groove that accepts one of a pair of opposing edges of the polarizer assembly. The pair of opposing channel members are each arranged and configured to allow the polarizer assembly to be disposed over the flash and lens of the image input device in a first orientation and to be retracted from image input device in a second, different orientation. 
         [0010]    The device includes a case having a window portion, with the case accepting the polarizer assembly in the window portion of the case. The case has pair of opposing grooves adjacent the window portion to accept a pair of opposing edges of the polarizer assembly. The case has a hinged member affixed to a face of the case, with the polarizer assembly affixed to the hinge member to permit the polarizer assembly to be moved over and away from the flash and lens of the image input device. The case has a hinged member affixed to a face of case, with the polarizer assembly being an integral part of the hinge member to permit the polarizer assembly to be moved over and away from the flash and lens of the image input device. 
         [0011]    According to another aspect of the present invention, a polarizer assembly includes a frame member and a pair of polarizer elements secured by the frame, with one of the polarizer elements having a linear polarization that is orthogonal to a linear polarization of the other of the polarizer elements. 
         [0012]    The following are embodiments within the scope of the invention. 
         [0013]    The frame member has a pair of regions that are configured to hold the polarizers. The frame is comprised of a stiff material relative to the stiffness of the polarizers. The frame includes an accommodation to attach the frame to a housing of an image input device. The accommodation is a protrusion. The accommodation is an indentation for a mating with a protrusion on the image input device. The frame includes a member that has a generally C-shaped cross-section that is configured to slide over the body of an image input device to position the pair of polarizer elements to cover a flash and lens portion of the image input device. The edges of the frame have a lip portion configured to secure the assembly to the image input device. 
         [0014]    According to another aspect of the present invention, a case for an image input device includes a body portion of the case configured to house an image input device, the body portion having a window; and an accommodation for accepting in the window a polarizer assembly. 
         [0015]    The following are embodiments within the scope of the invention. 
         [0016]    The accommodation in the window portion of the case is a pair of opposing grooves that are disposed to accept a polarizer assembly into the window of the case. The polarizer assembly is affixed to the window of the case. 
         [0017]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  is a block diagram of a portable reading machine with attached, portable imaging device. 
           [0019]      FIG. 2  is a block diagram. 
           [0020]      FIGS. 3A and 3B  are diagrams depicting a polarizer kit. 
           [0021]      FIGS. 4-6  are diagrams depicting an image input device with polarizers. 
           [0022]      FIG. 7  is a diagram depicting an image input device with keyed polarizers. 
           [0023]      FIG. 8  is a plan view of an alternative polarizer kit. 
           [0024]      FIG. 9  is a flow chart. 
           [0025]      FIGS. 10A and 10B  show alternative attachment techniques for the polarizers. 
           [0026]      FIGS. 11A-11C  are diagrams depicting an image input device and polarizer assembly. 
           [0027]      FIGS. 12A-12C  are diagrams depicting the polarizer assembly on an image input device. 
           [0028]      FIGS. 13A-13B  are diagrams depicting a case with polarizers for an image input device. 
           [0029]      FIG. 14  is a perspective view of a hinged polarizer assembly. 
           [0030]      FIG. 15  is a cross-sectional view of a case. 
           [0031]      FIGS. 16A-16B  are diagrams depicting an alternative arrangement for the polarizer assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Referring to  FIG. 1  a configuration of a portable reading machine  10  is shown. The portable reading machine  10  includes a portable computing device  12  and image input device  26 , as shown. The image input device  26  can be integrated into the reading machine  10 . Alternatively, the portable reading machine  10  can be a camera with enhanced computing capability (that implements the functions of the portable computing device  12 ). The portable reading machine  10  can also be implemented as a mobile telephone, e.g., so-called smart phones such as the Nokia N95 (Nokia, Inc.) having an image input device and enhanced computing resources. Such a smart phone can be modified to have the computing resources execute application software that implements reading machine functionality (discussed below). 
         [0033]    The image input device, e.g. a still camera, a video camera, portable scanner, etc, built-in camera on a cell phone, collects image data that is processed by portable computing device  12 . The portable reading machine  10  has the image input device  26  coupled to the computing device  12  using a cable (e.g. USB, Firewire) or by wireless technology (e.g. Wi-Fi, Bluetooth, wireless USB) and so forth. An example is a consumer digital camera coupled to a pocket PC or a handheld Windows or Linux PC, a personal digital assistant and so forth which executes applications to implement reading machine functionality. 
         [0034]    In general, as in  FIG. 1 , the portable computing device  12  of the portable reading machine  10  includes at least one processor device  14 , memory  16  for executing computer programs and persistent storage  18 , e.g., magnetic or optical storage, PROM, flash PROM or ROM and so forth that persistently stores computer programs and other data used by the reading machine  10 . In addition, the portable reading machine  10  includes input and output interfaces  20  to interface the processing device to the outside world, such as to the image input device and user controls. 
         [0035]    The portable reading machine  10  can include a network interface, device (not shown) to interface the reading machine to a network (including the Internet), e.g., to upload programs and/or data used in the reading machine  10 . As a mobile phone, the phone can connect to the Internet, via the wireless carrier or to a local network via WiFI and Bluetooth. The network connectivity is useful for cooperative processing, in which the mobile device captures an image pre-processes the image to produce smaller bitmaps that could be sent to a more powerful computer for recognition processing. The recognized text (or object) information could be sent back to the mobile device. 
         [0036]    The portable reading machine  10  includes an audio output device  24  to convey synthesized speech to the user from operation of the reading machine  10 . The camera and audio devices can be coupled to the computing device using a cable (e.g. USB, Firewire) or using wireless technology (e.g. Wi-Fi, Bluetooth) etc. The portable reading machine  10  may have two cameras, or video input devices  26 , one for high resolution and the other for lower resolution images. The lower resolution camera may be support lower resolution scanning for capturing gestures or directed reading, whereas the higher resolution one can be used to capture images that are process to recognize text and which text is used to synthesize speech. 
         [0037]    The portable reading machine can be used with a pair of “eyeglasses”  28 . The eyeglasses  28  may be integrated with one or more cameras  28   a  and coupled to the portable reading machine, via a communications link. The eyeglasses  26  provide flexibility to the user. The communications link  28   b  between the eyeglasses and the portable reading machine can be wireless or via a cable, as discussed above. The reading glasses  28  can have integrated speakers or earphones  28   c  to allow the user to hear the audio output of the portable reading machine. 
         [0038]    Referring now to  FIG. 2 , elementary functions executed on the reading machine  10  are shown. Residing in storage  18  and executed in memory  16  under control of the processor  14  are an operating system  32 , optical character recognition software  34  (or object recognition software), text-to-speech synthesis software  36  and a reading machine application  38  that accesses these software modules. The reading machine application  38  may include other more advanced functions and operate under different modes of operation as desired. 
         [0039]    Referring now to  FIG. 3 , a polarizer kit  40  is shown. The polarizer kit is configured to be operable with the image input devices, especially if those devices are used, where varying lighting conditions can cause glare and other optical interference that can diminish the quality of the image and thus the effectiveness of OCR operation. For example, when the flash is used to image paper, often the paper has a glossy enough surface to produce glare that obliterates text. Magazines in particular have a very large amount of glare. The polarizers when installed on the image input device can improve performance in reading documents with a glossy finish. While the reader machine may continue to function normally without the polarizers, the reading quality may be sacrificed for glossy documents. While a user can tilt the camera at a slight angle from the text, to reduce the effects of glare, however this tilt would tend to also diminish the effectiveness of recognition processing, thus making it desirable to use the polarizers. 
         [0040]    The polarizer kit includes a sheet of polarizer film  44 , having a front protective layer  42  and a back protective layer  46 . The protective layers  42 ,  46  are intended to be removed after installation. That is, the back protective layer is intended to be removed to allow the polarizer to be affixed to the device, whereas, the front protective layer  42  is intended to be removed before the first use of the imaging device. The back protective layer  46  protects an adhesive layer or surface  45  that is provided on the back surface of the polarizer film  44  and which back surface attaches to a lens or a flash window of the video input device  12 , as will be discussed below. It is to be understood that the sheet of polarizer film  44  as well as the front protective layer  42  and the back protective layer  46  are relatively thin e.g., in a range of, e.g., 0.006″ to 0.03″ with 0.01″ being a typical thickness, other thicknesses possible. The thicknesses are exaggerated in  FIG. 2  for clarity in illustration. The protective layer&#39;s thickness is 0.003″ other thicknesses are possible. 
         [0041]    One such polarizer film is a linear polarizing Polyvinyl Alcohol-Iodine filter that polarizes in the visible light spectrum. The visible light transmission is 42% with an extinction transmittance of 1.7%. Optical density is measured using a beam of 100% linearly polarized light. Polarizers are available in 19″×50″×0.010″ sheets obtained from American Polarizers, Inc. 141 South Seventh Street Reading, Pa. 19602 USA. 
         [0042]    One example of an adhesive is a water-based acrylic pressure sensitive type adhesive. Such adhesives are high performance screen printable adhesives for instrument panels, touch panels, or appliqués that can be selectively applied and provide substantially, permanent adhesion and high peel strength properties for the particular application. One such example is “NFi Printed Adhesive,” a water based acrylic pressure sensitive adhesive obtained from Nameplates For Industry, Inc. 213 Theodore Rice Blvd., New Bedford, Mass. 02745. Other adhesives and adhesive types can be used, provided that they are substantially transparent to optical wavelengths of interest, compatible with the polarizer and the material of the lens and flash window. 
         [0043]    Also disposed in the polarizer kit  40  are perforations  47  that define a flash polarizer  52  and lens polarizer  54  elements and permit the flash polarizer  52  and the lens polarizer  54  to be released from the protective layer  46 . 
         [0044]    The polarizers  52  and  54  converts incident un-polarized or mixed-polarization beam of electromagnetic waves (e.g., light) into an output beam with a single polarization state (e.g., a single linear polarization). The polarizer layer  44  can be comprised of a Polaroid™ film that is made from polyvinyl alcohol (PVA) plastic with an iodine doping. Stretching of the sheet during manufacture aligns the PVA chains in one particular direction. Electrons supplied by the iodine dopant are able to travel along the chains, ensuring that light polarized parallel to the chains is absorbed by the sheet; whereas light polarized perpendicularly to the chains is transmitted. 
         [0045]    Thus, since each of the flash polarizer  52  and the lens polarizer  54  have a particular orientation it is important that the flash polarizer  52  and the lens polarizer  54  are applied in a manner that that the polarizers have a polarization that are perpendicular to each other. 
         [0046]    Referring now to  FIGS. 4-6 , steps in the process of applying the flash polarizer  52  and the lens polarizer  54  to the flash  56  and lens  58  of the image input device  26  are illustrated. Since misalignment of the polarizers can degrade text recognition, it is desirable that the polarizers are installed by a sighted person or that the polarizers are manufactured on the device in order to avoid misalignment. 
         [0047]    In  FIG. 4 , the flash polarizer  52  is applied over flash window  56  and the front protective layer  42  on the flash polarizer  52  is subsequently removed. In  FIG. 5 , the lens polarizer  54  is applied over the lens  58  and the front protective layer  42  on the lens polarizer  54  is subsequently removed. Care is taken when removing the front protective layer  42  from both the flash polarizer  52  and the lens polarizer  54  so as not to detach the flash polarizer  52  and the lens polarizer  54  from the flash  56  and lens  58 , respectively. 
         [0048]    As an aid to assist users in applying the flash polarizer  52  and the lens polarizer  54  to an image input device, keyed polarizers, such as a keyed flash polarizer  52   a  and a keyed lens polarizer  54   a  are provided. The keyed flash polarizer  52   a  and the keyed lens polarizer  54   a  are each provided with a perimeter that conforms at least a portion of the perimeter of the flash polarizer  52   a  and the keyed lens polarizer  54   a  to corresponding portions of the lens and flash window of the image input device. In other words, to assist in application of the polarizers to the lens and flash, the polarizers are customized in size and shape for particular models of such image input devices. For instance, as shown in  FIG. 7 , the keyed flash polarizer  52   a  has a shape that allows a portion of the perimeter of the keyed flash polarizer  52   a  to follow a contour of the housing for the lens. Similarly, the keyed lens polarizer  54   a  has truncated upper and lower edges of the perimeter that could be used to assist the user in applying the keyed lens polarizer  54   a  to the lens such that those edges are parallel to a reference on the image input device, and so forth. 
         [0049]    A corresponding kit  40 ′ is shown in  FIG. 8  with the keyed flash polarizer  52   a  and the keyed lens polarizer  54   a . The user would rotate the lens polarizer 90° relative to the flash window polarizer before applying the lens polarizer to the lens. 
         [0050]    Referring to  FIG. 9 , operation of the reading machine  10  is shown. In one mode of operation, the reading machine application  38  in conjunction with the image input device  26  causes the reading machine  10  to capture  72  an image of a scene, e.g., document, outdoor environment, device, etc. The reading machine application  38  processes the image in the computing system  12 . Part of the processing of the image includes optical character recognition (OCR) processing  74  on the image. Processing of the image, results in an output  76  of text, e.g., as a text file or data structure. The text file or data structure is processed  78  by a text-to-speech application that converts the text to electrical signals that are rendered as speech. 
         [0051]    The polarizers once installed on the image input device with the protective layer removed, should be protected from scratches, dirt, and direct sunlight. Intense heat may affect the polarizer&#39;s adhesion to the lens or flash window. The polarizers should not be touched with fingers or any cutting material or come in contact with dirty surfaces. Ideally, the image input device is stored in a pouch with the reader to protect the surfaces. 
         [0052]    The polarizers may be cleaned using a soft piece of fabric, such as the type of fabric used to clean regular glasses. 
         [0053]    The polarizers for the camera flash output may require a replacement after approximately one year of use. The need for a replacement is indicated when the quality of the text recognition appears to be decreasing. Misalignment of the polarizers can also degrade text recognition. 
         [0054]    Other arrangements are possible. For instance the polarizers can be provided as individual units with fittings  58  which clip into receptacles  59  provided in the image input device  12 , as shown in  FIG. 10A . For instance, the polarizers can be carried by a plastic frame that has protrusions  58  that snap into receptacles  59  adjacent the flash and lens on an image input device. 
         [0055]    As shown in  FIG. 10B , a pouch assembly  60  that is used to carry the image input device can be have regions  62  that are comprised of the polarization film at the proper orientation over the flash  56  and over the lens  58 , when the image input device is fitted into the pouch  60 . In this example, the polarizing window  62  has been manufactured such that the portion of the polarizing window that is over the lens  58  is in an orthogonal linear polarization with regard to the portion of the polarizer  62  that is over the flash window  56 . 
         [0056]    Referring now to  FIGS. 11A-11C , a polarizer assembly  140  ( FIG. 11B ) for an image input device  26  is shown. The image input device, such as a camera  26  has a lens  58  and flash  56  ( FIG. 4 ). Various ways of removably applying polarizer elements to the lens  58  and flash  56  are described. The polarizer assembly  140  is configured to be operable with the image input devices, e.g.,  26  especially if those devices are used where varying lighting conditions can cause glare and other optical interference that can diminish the quality of the image and thus the effectiveness of OCR operation. For example, when the flash  56  is used to image paper, often the paper has a glossy enough surface to produce glare that obliterates text. Magazines in particular have a very large amount of glare. The polarizer assembly  140  when installed on the image input device  26  can improve performance in reading documents with a glossy finish. While the reader machine  10  may continue to function normally without the polarizer assembly  140 , the reading quality may be sacrificed, especially for glossy documents. While a user can tilt the camera at a slight angle from the text, to reduce the effects of glare, however this tilt would tend to also diminish the effectiveness of recognition processing, thus making it desirable to use the polarizer assembly  140 . 
         [0057]    The polarizer assembly  140  includes a frame  142  comprised of a stiff material to hold polarizer elements in place. The polarizer elements are comprised of sheets of polarizer film. Polarizer element  144  is oriented in vertical direction for the flash  56 , whereas the other polarizer  146  is oriented in a horizontal direction for the lens  58 . It is to be understood that the sheet of polarizer film is relatively thin e.g., in a range of, e.g., 0.006″ to 0.03″ with 0.01″ being a typical thickness, other thicknesses possible. A center member  141  separates the elements  144 ,  146  and provides additional rigidity and strength to the polarizer assembly  140 . 
         [0058]    The polarizer film elements  144 ,  146  can be a linear polarizing Polyvinyl Alcohol-Iodine filter that polarizes in the visible light spectrum. The visible light transmission is 42% with an extinction transmittance of 1.7%. Optical density is measured using a beam of 100% linearly polarized light. Polarizers are available in 19″×50″×0.010″ sheets obtained from American Polarizers, Inc. 141 South Seventh Street Reading, Pa. 19602 USA (as mentioned above). 
         [0059]    Referring now to  FIG. 11C , the polarizer assembly  140  is placed on top of the image input device  26  and aligned, as shown, such that one polarizer is over the flash and the other is over the lens with the mutually orthogonal orientations as shown. Many arrangements to secure the polarizer assembly  140  on the image input device  26  are possible. Because the polarizer elements  144 ,  146  in the polarizer assembly  140  are oriented perpendicular to each other, the ideal amount of glare is reduced from the image captured by the image input device. The polarizer assembly  140  can be permanently attached to the camera  26  or to a camera case or pouch (described below). The permanent attachment can be made with glue (not shown) or other techniques. Alternatively, rather than permanently attaching the assembly  140 , the assembly  140  can be removable, because not all photographic conditions would benefit from the use of the polarizer assembly. For example, in a dark room, with a non-glossy surface it may be best to take a picture with no polarizer elements. Other ways can be used to removably attach polarizer elements to the image input device  26 . 
         [0060]    Referring now to  FIGS. 12A-12C , the polarizer assembly  140  can be configured as a slider mechanism  160  that allows the polarizer elements  144 ,  146  to be moved over and away from the lens  58  and flash  56 . The slider  160  mechanism, as shown, has an upper channel  162  and a lower channel  164 . Each channel  162 ,  164  has a groove  163 ,  165  ( FIG. 12B ) that holds the polarizer assembly  140 , allowing the polarizer assembly  140  to slide over the flash and lens (as shown in  FIG. 12A ) or to slide the polarizers out of the way of the flash  56  and lens  58 , over to another part of the image input device ( FIG. 12C ). 
         [0061]    In  FIG. 12B  the slider mechanism is shown as attached to the image input device. The slider mechanism  160  and its attached polarizer assembly  140  could instead be attached to a camera pouch or a camera attachment of some kind. 
         [0062]    Referring now to  FIGS. 13A ,  13 B, a pouch or case  180  used to, e.g., protect the device (e.g., camera, camera-phone, and so forth) can be configured to house the polarizer assembly  140 . A soft fabric case is shown in  FIG. 13A . The case is comprised of a soft fabric or other material, e.g., leather or alternatively a hard material within which is disposed a window or opening  182  in the case  180  that allows the lens  58  and flash  56  of the image input device  26  to be exposed for picture-taking. The polarizer assembly  140  is attached to the case as shown in  FIG. 13B . The polarizer assembly  140  can be permanently attached with glue (not shown) to the case. Then when it is desired to take a picture without the polarizers, the image input device  26 , e.g., camera can be removed from the case  80 . The polarizer assembly  140  is shown attached to the outside of the case in  FIGS. 13A ,  13 B. Attaching the assembly  140  to the inside of the case  180  is an alternative which can help protect the polarizers from being scratched. 
         [0063]    Referring now to  FIGS. 14 and 15 , the polarizer assembly  140  can also be permanently attached to the case with a hinge  186  ( FIG. 14 ) or a slider mechanism  190  ( FIG. 15 ) or any number of other mechanisms. 
         [0064]    In  FIG. 14 , the hinge  86  is used to move the polarizer assemble  140  over, and away from, the lens and flash portions of the camera. The hinge  186  bends to allow the polarizer assembly  140  to cover the window opening and the lens and flash or to be bent back to expose the window opening. The hinge  186  is part of or is attached to the case  180  and the case  180  has a window portion  182  that is covered by the polarizer assembly  140 , when the polarizer is swung in place over the flash and lens. The polarizer assembly  140  and hinge  86  are shown attached to the outside of the case  180  in  FIG. 14 . In  FIG. 14 , the hinged polarizer mechanism is shown midway between covering the lens/flash and being fully open. 
         [0065]    Referring to  FIG. 15 , the polarizer assembly  140  is attached to the case  180  by a slide mechanism  190 .  FIG. 15  the soft fabric case  80  surrounds the image input device  26 . The case  180  has an accommodation for accepting the polarizer assembly  140 , placing the polarizer assembly  140  over the lens and flash. The accommodation in case of  FIG. 15  can be for instance, a slider mechanism  190  allowing the polarizer assembly  140  to slide over the lens and flash or to slide out of the way of the lens and flash similar to the slider mechanism described above. 
         [0066]    The slider  190  mechanism, as shown, has an upper channel  192  and a lower channel  194 . Each channel  192 ,  194  has a groove  193 ,  195  that holds the polarizer assembly  140 , allowing the polarizer assembly  140  to slide over the flash and lens or to slide the polarizers out of the way of the flash  56  and lens  58 , over to another part of the image input device. 
         [0067]    Referring now to  FIGS. 16A ,  16 B, polarizer assembly  140  can be configured as an attachment member  200  that can clip or slide onto the image input device  26 . In one configuration the attachment member  200  has a generally C-shaped cross-section that conforms to the outer dimensions and features of a pair of opposing sides of the housing of the image input device  26 . Opposing edges of the attachment member, have lip portions  201   a ,  201   b  that are configured to protrude over opposing edges of the image input device housing  26   a  to secure the attachment member to the input device housing  26   a . The polarizer assembly  140  can be integral with the attachment member  200 , as shown, or dropped into or otherwise secured to the attachment member  200 . The attachment member  200  is comprised of, for example, a hard, but flexible plastic material. The attachment member  200  is configured to conform to the shape and features of the particular device housing  26   a  such that the attachment member  200  carrying the polarizer assembly  140  reliably snaps onto the device or reliably slides over the lens/flash of the device housing  26   a.    
         [0068]    The polarizer assembly  140  attachment can be secured to a cord  203  so that when polarizer assembly  140  is unsnapped from or slid off of the device, the polarizer assembly  140  is still connected to the device to prevent it from getting lost. 
         [0069]    As an aid to assist users in applying the polarizer assembly  140  to an image input device, the polarizer assembly  140  can be keyed; such that the polarizer assembly  140  can be slid on or attached in only one configuration. 
         [0070]    Another arrangement (not shown) has the image input device  26  with a groove or indentation around its edge to accommodate the lips  201   a  and  201   b , (of the attachment member  200   FIG. 16B ) so that the attachment member  200  can clip onto the device  26 . Similarly, the device  26  may have a ridge or bump or any kind of extruding shape which can accommodate an attachment member  200  with the matching groove to fit the ridge, bump or in general the extruding shape. Therefore, other mechanical attachment mechanisms can be used. 
         [0071]    Other accommodations on the frame are possible, such as a protrusion, e.g., a lip, a bump, a knob, and so forth. Additionally, the accommodation can be indentation such as a groove, hole, slot, with a corresponding accommodation on the image input device or case). For example, the polarizer assembly can be removably attached to a metal camera with magnets, if the outside frame and camera are made of magnetized material. Other arrangements include Velcro® strips, snaps and so forth. 
         [0072]    In addition, the polarizer assembly  140  can be provided with a tacky surface on the frame that can attach onto the image input device  26 , as needed and removed. After removal a protective sheet of e.g., plastic can cover the tacky surfaces and eventually, when the tackiness has worn-out, the polarizer assembly  140  can be replaced. This is especially useful in retrofit applications. 
         [0073]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. 
         [0074]    For example, the polarizer is shown as a film having an adhesive surface. Alternatively, the polarizer can be built into the image input device or can be affixed to the lens and flash of the image input device via other mechanisms such as by use of a frame that hold the polarize and attaches to the lens and/or flash using a threaded, a bayonet or other mechanical affixation. In addition, other keying mechanisms could be used. 
         [0075]    Another alternative arrangement is that the delicate and thin polarizers could be transparently bonded to a more durable transparent material, such as glass or clear plastic. The rigid frame would not be necessary for the purpose of keeping the polarizers from bending. 
         [0076]    Accordingly, other embodiments are within the scope of the following claims.