Abstract:
Disclosed are systems and methods for image scanner feature detection comprising an image scanner feature treated to facilitate detection of an associated feature artifact in a scanned image, wherein the treated image scanner provides a predetermined optical diversity attribute.

Description:
FIELD OF INVENTION  
       [0001]     The invention relates generally to image scanning and, more particularly, to image scanner feature detection.  
       DESCRIPTION OF RELATED ART  
       [0002]     Image scanners are used in a variety of applications to scan various media, such as photographs, transparencies, slides, negatives, documents, books, and other objects. Such image scanners often operate by providing translation or movement of a carriage, such as may include a light source and optical array (often referred to as a “scan head”), along a platen, which is generally a plate of glass or other transparent material, against which a medium to be scanned is placed.  
         [0003]     In order to handle one or more of the above media types, image scanners often include apparatus such as an automatic document feeder (ADF) or a transparent media adapter (TMA). For example, in order to properly scan a transparent medium, such as a photo-negative or a slide (as opposed to a reflective medium, such as a photograph or document), an image scanner may be provided with a TMA including a backlight. In use, the backlight may be placed such that a transparent medium is disposed between the backlight and a scan head of the image scanner, thereby providing incident light to the scan head for acquisition of an image from the transparent medium. The TMA may include features useful in scanning transparent media in addition to the aforementioned backlight, such as a calibration window and a slide or negative mounting.  
         [0004]     In some configurations, a TMA may be an optional accessory placed upon the platen of an image scanner when transparent media is being scanned. However, as scanners have developed to be more and more robust in their features, apparatus such as ADFs and TMAs have been integrated into the scanner itself, such as by being disposed in a scanner lid which hingedly covers the scanner platen. Although such an integrated configuration provides convenience with respect to the availability of the ADF and TMA features, integrated configurations sometimes do not provide optimal scanned images because aspects of the feature itself, e.g., a portion of the ADF and/or TMA apparatus, appears in the resulting scanned image. For example, undesirable image artifacts may cause an automatic cropping feature to not only include a desired image (e.g., a photograph) but also include an image of a portion of the scanner feature in the resulting scanned image. As a result, a user may be required to manually intervene and select the desired portion of the scanned image. Such manual intervention may be particularly undesirable where a number of documents are being scanned, such as during use of the aforementioned ADF.  
         [0005]     One past attempt at addressing the appearance of undesirable image artifacts in a resulting scanned image has been to manually block or cover the offending scanner features. For example, a scanner may be provided with a sheet, e.g., a white plastic membrane, sized to obscure particular scanner features from a scanned images. Often the sheet is the same size as the scanner platen, so that it not only covers the particular feature to be obscured, it covers the whole surface of the scanner lid exposed to the platen. The use of the foregoing sheets typically requires the user to manually install the sheet when features are to be obscured and to manually remove the sheet when the features are to be utilized. Moreover, the sheet must be stored and protected from damage when not installed in the scanner.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     An embodiment provides a system for image scanner feature detection comprising an image scanner feature treated to facilitate detection of an associated feature artifact in a scanned image, the treated image scanner feature providing a predetermined optical diversity attribute. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIGS. 1A and 1B  show an image scanner adapted according to an embodiment of the present invention;  
         [0008]      FIGS. 1C and 1D  show another embodiment of an image scanner adapted according to an embodiment of the present invention;  
         [0009]      FIG. 2  shows an example of a scanned image resulting from use of the image scanner of  FIGS. 1A and 1B ;  
         [0010]      FIG. 3  shows a flow diagram of image scanning and processing according to one embodiment of the present invention;  
         [0011]      FIG. 4  shows a flow diagram of image scanning and processing according to an alternative embodiment of the present invention; and  
         [0012]      FIG. 5  shows a flow diagram of image scanning and processing according to another alternative embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Directing attention to  FIG. 1A , an embodiment of an image scanner adapted according to an embodiment of the present invention is shown. Specifically, scanner  100 , or a portion thereof, is adapted to facilitate identification of features, such as a TMA, ADF, or other aspect, that may result in unwanted artifacts appearing in a scanned image. Embodiments are described herein with reference to particular scanner features, such as a TMA or an ADF, for ease of understanding concepts of various embodiments of the present invention. However, concepts of the present invention are applicable to any number of scanner features and, therefore, are not limited to any particular example set forth herein.  
         [0014]     Embodiments of the invention facilitate identification of features that may contribute to unwanted artifacts in a scanned image by causing these features to emit light (referred to herein as feature light) that is different or diverse in some way from the light a desirable object would be likely to emit, whether by reflection (e.g., solid objects) or by transmission (e.g., transparent objects), (referred to herein as image light). For example, feature light may comprise light having a wavelength typically not associated with a scanned image, such as infra-red or ultra-violet, or light emitted at a time during which scanned media or objects are unlikely to emit light. The feature light may be utilized by a controller or algorithm in identifying the presence and/or position of a feature artifact as present in a scanned image, and thus perform operations to identify the feature artifact for subsequent processing and/or to remove or mask the feature artifact from the scanned image.  
         [0015]     In the embodiment of  FIG. 1A , scanner  100 , such as may comprise a flat bed image scanner useful in digitizing images of various media or other objects for use in digital processing, is shown as including housing  101  supporting platen  102 . Platen  102  provides a transparent surface against which media may be placed for image-capturing operations by scanner  100 . For example, a medium may be placed against platen  102  within imaging area  103 , formed between platen  102  and scanner lid  104 , for operation of scanner  100  to capture an image thereof for digital processing. Accordingly, carriage  120 , shown here hosting light source  121  and optical array  122  (such as may provide a linear array of optical elements extending along the X axis), may be driven along the Y axis under control of controller  130  to traverse the length of platen  102  and thereby capture a series of line images that may be composited to create a scanned image.  
         [0016]     Scanner  100  of the illustrated embodiment includes an enhanced media-handling apparatus disposed in scanner lid  104 . Specifically, scanner  100  of  FIG. 1A  includes TMA  110  disposed in scanner lid  104  to correspond with at least a portion of platen  102 , thereby facilitating use of TMA  110  to handle particular media types for scanning by scanner  100 .  
         [0017]     TMA  110  of the illustrated embodiment includes calibration window  112 , media backlight window  113 , media adapter  114 , frame  115 , and housing  111 , such as may incarcerate a backlight mechanism and circuitry. In operation, a transparent medium is placed within imaging area  103 , in juxtaposition with media backlight window  113 , for operation of scanner  100  to capture an image thereof for digital processing. Backlight window  113  is illuminated via a backlight mechanism within housing  111  to provide light that passes through backlight window  113  and through the transparent medium to fall incident upon optical array  122  as scan head  120  is passed along the length of the medium. Calibration window  112  is used to calibrate the image captured by optical array  122  (e.g., to set white balance, light intensity, etcetera) and, therefore, is not blocked by the transparent medium during the aforementioned operation. Media adapter  114  may be utilized to hold transparent media of different sizes and/or configurations, such as to accommodate photo-negatives having a smaller width dimension than slides that may also be accommodated by scanner  100 .  
         [0018]      FIG. 1B  shows a bottom view of a portion of scanner lid  104  and TMA  110  as is visible to optical array  122  through platen  102  when scan head  120  traverses platen  102 . As can be seen in the scanned image of  FIG. 2 , when no document, or a document smaller than the area of platen  102 , is placed in imaging area  103 , a portion of the scanner feature, here TMA  110 , is visible to the optical array and, therefore, is included in a resulting scanned image if no corrective action is otherwise taken. Specifically, image  200  of  FIG. 2  includes not only image portion  201  corresponding to a photograph positioned in imaging area  103 , but also includes undesired artifacts in image portion  202  associated with TMA  110 . Accordingly, if an automatic image cropping algorithm were applied to image  200 , such as by controller  130  of scanner  100  and/or a host system thereof, cropping lines  211  and  212  may result, thereby defining a scanned image including the desired photograph as well as the undesired scanner feature artifact.  
         [0019]     Scanner  100  of  FIG. 1C  includes enhanced media-handling apparatus disposed in scanner lid  104  in the form of ADF  150 . ADF  150  of the illustrated embodiment includes media tray  151 , take-up roller  152 , media input orifice  153 , media handling belts  155 , and media output orifice  154 . In operation, media is placed on media tray  151  and is singulated by take-up roller  152  for introduction into imaging area  103  via media input orifice  153 . Media handling belts  155  position a medium for operation of scanner  100  to capture an image thereof for digital processing and then eject the medium from imaging area  103  via media output orifice  154 .  
         [0020]      FIG. 1D  shows a bottom view of a portion of scanner lid  104  and ADF  150  as is visible to optical array  122  through platen  102  when scan head  120  traverses platen  102 . When no document, or a document smaller than the area of platen  102 , is placed in imaging area  103 , a portion of the scanner feature, here media handling belts  155  of ADF  150 , is visible to the optical array and, therefore, is included in a resulting scanned image if no corrective action is otherwise taken.  
         [0021]     However, scanner  100  has been adapted according to an embodiment of the present invention to cause the enhanced media handling apparatus, or e.g., TMA  110  of  FIG. 1A  and/or ADF  150  of  FIG. 1C , or portions thereof, to emit a predetermined feature light, wherein the predetermined feature light is selected so as to be unlikely to be emitted by media or objects being scanned. Feature light emission according to embodiments of the present invention may be distinguished from light associated with a medium or other object being scanned by having one or more diverse characteristics, including a unique characteristic wavelength, a unique pattern, a unique emission time (e.g., emission at a time different than when substantial light associated with a medium or other object being scanned is present), a unique intensity and/or the like. According to embodiments of the invention, scanner imaging apparatus, such as scan head  120 , is adapted to capture and recognize the feature light emitted from media handling apparatus.  
         [0022]     According to one embodiment, aspects of TMA  110 , or other media handling apparatus, are treated with a material or otherwise adapted to cause aspects of the media handling apparatus to emit a particular wavelength or wavelengths of light. This embodiment may be thought of as providing wavelength diversity for feature identification. For example, TMA  110  may be coated with a fluorescent paint, such as is available from Rosco Laboratories, Markham, Ontario, to cause TMA  110 , or portions thereof, to emit light having a wavelength unique to the fluorescent paint used, thereby providing a feature light which may be recognized for further processing.  
         [0023]     According to another embodiment, aspects of TMA  110 , or other media handling apparatus, are treated with a material or otherwise adapted to cause aspects of the media handling apparatus to emit light at a time other than when a medium or other object is being scanned. This embodiment may be thought of as providing time diversity for feature identification. For example, TMA  110  may be coated with a phosphorescent paint, such as is available from Shannon Luminous Materials, Inc., Santa Ana, Calif., to cause TMA  110 , or portions thereof, to emit light at a time other than when a medium or other object is being scanned, thereby providing a feature light that may be recognized for further processing.  
         [0024]     Although the embodiments described above facilitate identification of features using wavelength diversity and time diversity, alternative embodiments of the present invention may implement optical diversity in addition to or in the alternative to the exemplary diversity aspects. For example, embodiments of the present invention may utilize an intensity diversity technique, wherein feature light is provided at a substantially higher or lower intensity than the image light expected to result from a scanned medium or other object. That is, the feature or portions thereof may be configured to provide a feature light which is greater or less than image light by a threshold value, as may be determined by pixel intensity values or other techniques. Some embodiments may employ a combination of one or more of the foregoing diversity techniques.  
         [0025]     In the foregoing embodiments, light otherwise emitted by scanner  100  during a scanner operation, e.g., white light emitted by light source  121  for a scanning operation, may be utilized in providing a feature light useful as described herein. Specifically, the wavelength diversity embodiment described above may operate to convert wavelengths of light that are normally present in the scanner (e.g., the aforementioned white light) to wavelengths of light that are not normally present in the scanner (e.g., infra-red light). Similarly, the time diversity embodiment described above may operate to store light energy from light that is normally present in the scanner (e.g., the aforementioned white light) and re-radiate the light energy at a later time (e.g., subsequent to an image scan). Accordingly, the feature may then emit feature light that is diverse in at least one aspect from light used in acquiring a desired scanned image.  
         [0026]     Embodiments of the invention may additionally or alternatively adapt scan head  120  to capture emitted feature light and/or to cause TMA  110  to emit the feature light. For example, in some wavelength diversity embodiments, light source  121  is adapted to emit a frequency of light (e.g., ultra-violet) known to stimulate emission of light having a particular wavelength or wavelengths of light by TMA  110 . Similarly, optical array  122  is adapted to capture a light frequency or intensity corresponding to the feature light. According to one embodiment, optical array  122  comprises a light detection circuit, such as a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) optical receiver, that is adapted to capture light having the aforementioned characteristic wavelength, e.g., infra-red, so that optical array  122  not only senses red, green, and blue, but also senses light having a wavelength different than this typical visible spectrum.  
         [0027]     In some time diversity embodiments, light source  121  is adapted to emit a frequency of light (e.g., ultra-violet) known to stimulate emission of light by TMA  110 , such as to increase the time constant (rate of decay of light emission after stimulus) and/or to increase the intensity of light. Similarly, optical array  122  is adapted to capture a light frequency or intensity corresponding to the feature light at a time other than during scanned image capture. According to one embodiment, optical array  122  comprises a light detection circuit, such as a CCD device, that is adapted to capture low intensity light so that optical array  122  not only senses well lighted scanned media, but also senses the low intensity emissions associated with phosphorescence.  
         [0028]     Image processing algorithms utilize the presence of feature light in a scanned image, or otherwise available from operation of the image scanner, to intelligently process the image. Image processing utilizing feature light may include detecting the presence of a feature artifact in an image, notifying an operator of the presence of a feature artifact in an image, providing image manipulation associated with the feature artifact (whether automated or in response to operator input), and/or combinations thereof. Image processing algorithms providing the foregoing image processing may be provided within scanner  100  itself (e.g., firmware or software operable upon controller  130 ) and/or provided within a host system (e.g., software operable upon a personal computer coupled to scanner  100 ).  
         [0029]     According to embodiments of the invention, image processing algorithms utilize the presence of feature light to remove or otherwise mask artifacts in the image associated with TMA  110 . For example, an automatic image cropping algorithm, such as provided by controller  130  of scanner  100  and/or a host system thereof, may be applied to scanned image  200  of  FIG. 2  such that cropping lines  211  and  213  result, thereby defining a scanned image including the desired photograph without the undesired scanner feature artifact.  
         [0030]     Directing attention to  FIGS. 3, 4 , and  5 , flow diagrams setting forth operation according to embodiments for identification of features that may result in unwanted artifacts appearing in a scanned image are shown. Specifically,  FIG. 3  shows a flow diagram of operation according to a wavelength diversity and/or intensity diversity embodiment and  FIG. 4  shows a flow diagram of operation according to a time diversity embodiment.  FIG. 5  shows a flow diagram of operation according to an embodiment which may implement wavelength diversity, intensity diversity, and/or time diversity.  
         [0031]      FIG. 3  shows operation according to wavelength diversity and intensity diversity implementations according to embodiments of the present invention. The embodiment of  FIG. 3  begins an image capturing operation by energizing light source  121  to emit light which passes through platen  102  and is reflected by a medium or other object disposed in imaging area  103 , and as may be reflected by any scanner features visible through platen  102  (box  301 ). Controlling scan head  120  further includes moving scan head  120  to traverse platen  102  along the Y axis ( FIG. 1 ), such as under control of controller  130 . As scan head  120  traverses platen  102 , light energy from light source  121  falls incident on TMA  110  adapted according to the present invention, thereby resulting in portions of TMA  110  being stimulated to re-radiate (e.g., fluoresce) feature light having a characteristic wavelength and/or an intensity different than that likely to be reflected by the medium or object being scanned. Optical array  122  captures light reflected by the medium or other object disposed in imaging area  103  as well as light reflected from TMA  110  or other features of scanner  100  visible through platen  102  (image light). The captured image light forms a scanned image (box  302 ). Optical array  122  further captures light emitted by TMA  110  (feature light) having a characteristic wavelength and/or intensity different than that typically found in the captured image light. Using the feature light information, an image processing algorithm can identify portions of a scanned image associated with or resulting from TMA  110  and process the scanned image accordingly, such as to mask or remove a feature artifact (box  303 ).  
         [0032]     The time diversity embodiment of  FIG. 4 , like the embodiment of  FIG. 3 , begins an image capturing operation by energizing light source  121  to emit light that passes through platen  102  and is reflected by a medium or other object disposed in imaging area  103 . The light from light source  121  may also be reflected by any scanner features visible through platen  102 . Controlling scan head  120  further includes controlling scan head  120  to traverse platen  102  along the Y axis, such as under control of controller  130  (box  401 ). As scan head  120  traverses platen  102 , light energy from light source  121  falls incident on TMA  110  adapted according to the present invention, thereby resulting in portions of TMA  110  absorbing a portion of the light energy for re-radiation (e.g., phosphoresce) at a later time (e.g., having a time constant of 30 to 60 seconds). Optical array  122  captures light reflected by the medium or other object disposed in imaging area  103  as well as light reflected from TMA  110  or other features of scanner  100  visible through platen  102  (image light) (box  402 ). The captured image light forms a scanned image. The time diversity embodiment illustrated in  FIG. 4  controls scan head  120  to de-energize the light source and traverse platen  102  (box  403 ). For example, after completing an image scanning pass in the positive Y direction, light source  121  may be extinguished and scan head  120  returned to a home position, thereby traversing platen  102  in the negative Y direction. Optical array  122  captures light emitted by TMA  110  (feature light) during this scan head pass when little or no image light will be present (box  404 ). Using the feature light information, an image processing algorithm can identify portions of a scanned image associated with or resulting from TMA  110 , and process the scanned image accordingly, such as to mask or remove a feature artifact (box  405 ).  
         [0033]     The embodiment of  FIG. 5  begins operation by energizing light source  121  to emit light that passes through platen  102  and illuminates TMA  110  as scan head  120  traverses platen  102  (box  501 ). The illumination of TMA  110  may be at a time in which no medium is disposed in imaging area  103 . Irrespective of whether wavelength diversity, intensity diversity, or time diversity is used, optical array  122  is utilized to capture light emitted by TMA  110  (feature light) (box  502 ). The captured feature light may be utilized with respect to subsequent image scans and, therefore, may be stored for use in processing such subsequent image scans. Accordingly, after capture of feature light, processing according to box  502  may control scan head  120  to de-energize light source  121  to await invocation of a subsequent image scan. When a medium is to be image scanned, light source  121  is energized and scan head  120  traverses platen  102  (box  503 ). Light from light source  121  is reflected by a medium or other object disposed in imaging area  103 , as well as by any scanner features visible through platen  102 . Optical array  122  captures light reflected by the medium or other object disposed in imaging area  103  as well as light reflected from TMA  110  or other features of scanner  100  visible through platen  102  (image light) (box  504 ). The captured image light forms a scanned image. Using the feature light information, an image processing algorithm can identify portions of a scanned image associated with or resulting from TMA  110 , and process the scanned image accordingly, such as to mask or remove a feature artifact (box  505 ).  
         [0034]     In processing the scanned images according to the embodiments described above, scanned image pixel positions corresponding to pixel positions in which feature light was detected may be identified as a portion of a feature artifact with a high level of confidence. For example, comparing or overlaying a pixel array of a scanned image formed from image light and a pixel array formed from feature light may be utilized to identify the portions of the scanned image in which a feature artifact is present. According to one embodiment, any scanned-image pixels corresponding to feature-image pixels may be removed or masked in the scanned image to thereby provide a scanned image which is free of the feature artifact.  
         [0035]     Additionally or alternatively, scanned-image cropping lines (e.g., outlines of a desired portion of a scanned image) may be accurately placed by identifying a feature-light pixel position nearest to an image scan beginning point or other reference point. For example, according to embodiments, it may be assumed that the scanned object is rectangular, thereby enabling a cropping algorithm to select correct scanned image area as that area between a scan starting point and the first point in both the X and Y axes in which feature light is detected. That is, the algorithm may reference a horizontal cropping line (a line along the X axis) and move this line toward the scan beginning point until feature light is not included in the area and a scanned image is detected. Likewise, the algorithm may reference a vertical cropping line (a line along the Y axis) and move this line toward the scan beginning point until feature light is not included in the area and a scanned image is detected. According to embodiments, a scanned object may be placed anywhere within an imaging area and, therefore, feature light may be detected in various areas around a scanned object, perhaps including completely surrounding the scanned object. Accordingly, embodiments of the invention may facilitate recognition of a scanner feature, or portions thereof, in any number of positions with respect to a scanned object. Moreover, embodiments of the invention facilitate removal or masking of portions of the scanned image, such as using a plurality of vertical and/or a plurality of horizontal cropping lines, to provide a scanned image which is free of a feature artifact.  
         [0036]     Embodiments may additionally or alternatively operate to suspend image capturing when feature light is detected in an image scan. For example, where a scanned object is placed in the center of platen  102 , optical array  122  may capture feature light in a scan pass of carriage  120  before the scanned object is encountered. Algorithms of controller  130  may operate to discard image data captured by optical array  122  during the time in which such image data includes feature light. Accordingly, a resulting scanned image may begin with the scanned object, although a scanner feature is encountered in the scan prior to encountering the scanned object. The foregoing discarding of image data which includes feature light may additionally or alternatively be applied to situations in which the scanner feature is encountered in a scan after the scanned object or in various other situations.  
         [0037]     Although the embodiments discussed above with reference to  FIGS. 3 and 4  provide single scan head pass operation with respect to the configuration using a fluorescent technique and double scan head pass operation with respect to the configuration using a phosphorescent technique, the concepts of the present invention are applicable to different embodiments. For example, according to one embodiment, a first scan head pass is made to capture image light and form a scanned image and a second scan head pass is made with a light source energized to capture feature light resulting from fluorescence of aspects of a feature. According to another embodiment, a first scan head pass is made to capture image light and feature light, wherein the feature light comprises light resulting from phosphorescence of aspects of a feature having a wavelength different than that of the image light.  
         [0038]     The foregoing embodiments provide a solution in which undesired feature artifacts present in a scanned image may be automatically detected, removed, and/or otherwise dealt with. In contrast to a technique using a masking sheet or other visual block to cover features, and thus avoid an undesired artifact in a resulting scan, embodiments of the present invention do not depend upon actions of an operator in removing undesired artifacts. Moreover, separate accessories need not be stored and cared for using embodiments of the present invention.  
         [0039]     Although embodiments have been described above with reference to coating scanner features with a material or materials to facilitate identification of such features, the concepts of the present invention are applicable to various alternative embodiment configurations. For example, phosphorescent or fluorescent material may be added to a material (e.g., plastic) from which a particular scanner feature is made, thereby providing an imbedded adaptation according to the present invention. Additionally or alternatively, a material from which a particular scanner feature is made may be selected so as to facilitate identification of features, perhaps when illuminated with a particular light source, such as ultra-violet.  
         [0040]     Embodiments of the invention provide for adapting all or any portion of a particular scanner feature for facilitating identification of features. For example, all portions of TMA  110  visible through platen  102 , including calibration window  112 , media backlight window  113 , media adapter  114 , and frame  115 , may be coated with a clear or transparent fluorescent paint to result in identification of all aspects of the feature according to embodiments of the invention. However, it may not be desirable to identify all aspects of a particular feature according to embodiments of the present invention. For example, in an embodiment wherein determining appropriate cropping lines with respect to rectangular scanned media is to be accomplished, particular portions of the feature useful for making such cropping determinations (e.g., frame  115 ) may be adapted according to the present invention whereas other portions thereof are not so adapted. Moreover, aspects of a feature need not themselves be fully adapted to facilitate the identification of the feature. For example, a dot, line, cross-hatching, or other pattern may be implemented which provides desired information without a particular aspect of the feature being coated or otherwise treated according to embodiments of the present invention. Additionally or alternatively, specific information may be provided by the feature light according to embodiments of the present invention, such as by forming symbols or shapes (e.g., registration marks, numbers, targets, and/or the like) from materials providing feature light as described herein.  
         [0041]     Although embodiments of the invention have been described herein with respect to adapting a particular feature, such as a TMA or ADF, for its identification, embodiments of the present invention may implement a technique wherein other aspects of a scanner are treated according to concepts of the present invention to facilitate identification of features thereof. For example, a side of scanner lid  104  visible through platen  102  may be provided with a grid of lines or dots of a fluorescent or phosphorescent material, or alternatively fully treated with such a material, for use in identifying scanner features, if desired.  
         [0042]     The concepts of the present invention are not limited to any particular scanner configuration. For example, image scanner feature detection of embodiments of the present invention my be used in vertical or angled as well as horizontal scanner bed configurations.