Patent Description:
Counterfeiting documents, merchandise, and currency is a growing problem, and validating these items (especially currency) is important. While currency validation (CVAL) systems exist, these systems are too slow, costly, intrusive, and/or bulky to be routinely used at common transaction locations (e.g., store checkouts, ATM machines, banks, etc.). Therefore, a need exists for a low-cost CVAL device that may function alone (e.g., handheld, kiosk, etc.) or as part of a larger system (e.g., point of sale system), and which may be operated to validate items (especially currency) in an easy (e.g., handheld) and unobtrusive (e.g., inconspicuous) way. Reference may be made to: <CIT> which relates to a method for authenticating a security element, and an optically variable security element; <CIT> which relates to media identification; <CIT> which relates to a multifunction point of sale system which provides an indicia reading mode for reading barcodes and a validation mode for multi-spectral validation of security documents; <CIT> which relates to a method of using an indicia reader; <CIT> which relates to an indicia reader for size-limited applications; <CIT> which relates to an apparatus and method for correlating a suspect note deposited in an automated banking machine with the depositor; and <CIT> which relates to a document sensor.

The present invention is defined by the appended independent claims to which reference should now be made. Specific embodiments are defined by the dependent claims.

One exemplary arrangement relates to a currency validation (CVAL) device. The CVAL device includes an imaging subsystem, which includes a high-resolution image sensor and optics for capturing digital images of items in a field of view. The CVAL device also includes an illumination subsystem that has one or more illumination sources and optics for illuminating items in the field of view. The CVAL device also includes a processor (also referred to herein as "processing circuitry") that is configured by software to synchronize and control the imaging and illumination subsystems. The subsystems are communicatively coupled so as to exchanges signals and information.

When the CVAL device is triggered (e.g., by the movement of a switch, spoken command, signal from a point of sale system, etc.) to perform a validation process, the processor activates the illumination sources, individually or in combination (i.e., multiplexed), to sequentially illuminate the item in the field of view with light having various (e.g., different) spectral profiles, wherein the wavelengths in a spectral profile may include visible (e.g., red, blue, green, etc.) and/or invisible (e.g., near infrared, near ultraviolet) light. For each illumination, the CVAL system captures an image (or images) of the item using the image sensor. The processor is also configured to process the image or images (e.g., crop, align, resize, segment the item, recognize the item, etc.) to put them in a condition for analysis. The processor is also configured to control (e.g., activate, deactivate, switch, etc.) and synchronize the illumination and image capturing processes. In one arrangement, the processor is further configured to analyze the captured images and, based on the analysis, validate currency item or invalidate the currency item (e.g., detect a counterfeit). In some arrangements, however, the validation may be performed by a computing device (e.g., as part of a point of sale system) communicatively coupled to the CVAL device.

The validation device may be used alone or as part of a larger system (e.g., a point of sale system, a kiosk, etc.), and in some arrangements, may perform several functions. For example, a dual-purpose, handheld imager may be incorporated with a point of sale system to perform both checkout operations and currency validation. In a first mode (i.e., indicia-reading mode), the handheld imager operates as a typical imaging barcode scanner. In a second mode (i.e., CVAL mode), the handheld imager operates as a currency validator. Changing between the first and second modes of operation may be accomplished either automatically (e.g., set by the point of sale system in response to a transaction, set in response to a scanned barcode, etc.) or manually (e.g., set by an operator).

Capturing multiple images of an item (e.g., banknote) illuminated with various spectral profiles is an important aspect of the optical validation embraced by the present invention. As a result, some arrangements for providing and controlling the illumination are envisioned.

In some arrangements, the illumination subsystem may include multiple light emitting diode (LED) arrays, each configured to radiate light in a particular spectral band (i.e., each having a particular spectral profile). Each LED array may be controlled by the processor to illuminate the field of view with a particular intensity and/or duration. Likewise, multiple LED arrays may be simultaneously activated to illuminate the field of view with a spectral bandwidth that is the combination of each individual LED array. In some arrangements, the light from the LED is sensed (i.e., sampled). The sensing provides feedback, that when interpreted by the processor may be used to control the illumination exposure. This feedback control may be necessary to compensate for device temperature (e.g., LED temperature) or to minimize device variations (i.e., calibration).

In some arrangements, the spectral profiles may be controlled via optical filters placed between the light sources and the item (i.e., in the transmit path) or placed between the item and the image sensor (i.e., in the receive path). To produce images of the item under various spectral conditions, different filters (or combination of filters) may be mechanically moved in/out of the transmit/receive paths. The filters may be absorptive type filters (e.g., colored glass) or interference type filters (e.g., layers of thin films on a substrate) and may be mechanically mounted on a filter wheel that can be rotated to adjust the position of the filters.

The validation device may also include means for providing feedback to a user. This feedback may (i) help a user position the item/validation-device and/or (ii) may provide the results of the validation to a user.

In some arrangements, the validation device may include an aiming subsystem to project a pattern into the handheld imager's field of view that helps a user position the item and/or the validation device (i.e., for handheld arrangements). As a result, the aiming subsystem typically includes a visible light source (e.g., laser, LED, etc.), an image-forming element (e.g., an aperture, a diffractive optical element, etc.), and a projection lens (or lenses). Further, the aiming subsystem may project two distinctly different (e.g., different in size, shape, color, flashing, etc.) targeting patterns, wherein each targeting pattern corresponds to one of the two modes of operation (e.g., indicia reading, CVAL, etc.).

In some arrangements, the validation device may include at least one positioning indicator to help a user position the currency item and/or the validation device (i.e., handheld imager) for validation. Here, the processor may generate real-time indicator signals that activate the (at least one) indicator to guide the repositioning of handheld imager and/or currency item toward an optimal position for validation. The indicator signals may also indicate that an optimal position has been achieved. The indicator signals may also indicate that a portion of the currency item is obscured. The (at least one) indicator may transmit audio, visual, or haptic (e.g., vibration) signals to a user. In some arrangements, the indicator signals may be sent to the aiming subsystem to cause a change (e.g., flashing, color change, etc.) in the targeting pattern based on the determination.

The validation device may provide (to a user) the results of the validation process via interface circuitry <NUM> and indicators/display, either integrated with the validation device or communicatively coupled to the validation device. The indicators may provide visual, audible, and/or tactile messages to a user based on the validation results. These messages may also include instructions for the user regarding the next steps that should be taken in the validation process.

The validation device may be powered by a battery or via a cable connected to a power supply (e.g., a USB power supply). For cases in which the power supplied by the power supply is insufficient, an additional storage element (e.g., a battery, super capacitor, etc.) may be used to provide additional power. In these cases, the storage element may be integrated with the cable.

High quality images of the item (e.g., currency item) improve the validation process. To this end, various components or systems may be integrated with the CVAL device to improve image quality.

In some arrangements, the validation device includes a set of crossed polarizers to remove specular reflections from the item. Here, a first polarizer may be positioned in front of the illumination subsystem's light sources and a second polarizer may be positioned in front of the imaging subsystem's image sensor.

In some arrangements, a banknote (i.e., bill, currency, etc.) holder may be used with the validation device to facilitate the imaging of the currency item. The banknote holder typically has a substrate with a reflective surface (e.g., metallic mirror, dichroic mirror, etc.) onto which a banknote may be placed for verification. When placed on the banknote holder and illuminated by the validation device, a portion of the light from the validation device passes through the banknote and is reflected back through the banknote to the image sensor of the validation device. In this way, features such as watermarks may be imaged. In some arrangements, the banknote holder may itself include one or more illumination sources/illumination devices.

Other exemplary arrangements relate to methods (i.e., processes) for currency validation. In some arrangements, a validation device is provided (e.g., a handheld CVAL device, a fixedly mounted CVAL device, a CVAL device integrated with a point of sale system, etc.). The validation device is capable of illuminating a field of view with light having different spectral profiles, while synchronously capturing at least one digital image of the field of view for each illumination. A currency item is positioned within the imaging device's field of view and the device is triggered to begin operation. The currency item is then illuminated and imaged in accordance with the previously mentioned capabilities of the validation device to obtain a plurality of digital images of the currency item in different spectral conditions. Then, the digital images are processed and the currency item is validated based on the results of the processing. The validation may include determining if an item is authentic or counterfeit. In some arrangements, validation may include determining if a currency item is fit for use.

In some arrangements, the processing includes recognizing characters or features on the currency item, and then comparing these recognized features to one or more comparison standards retrieved from a computer readable memory (e.g., on the device, on a network, etc.). In some possible arrangements, the recognized characters and/or features may be used to identify the banknote (e.g., to help retrieve a comparison standard) or may be stored to memory as part of a record of the validation. In some cases, these records may be turned over to agencies (e.g., law enforcement, manufacturers, store security, etc.) to help a counterfeit investigation.

In some arrangements, the validation process includes identifying one or more regions of interest on the currency item within each digital image. Then, (i) comparing the pixel levels from the one or more regions of interest to one or more comparison standards, (ii) comparing the pixel levels from a particular region of interest within an image to another region of interest within the same image, or (iii) comparing the pixel levels from a particular region of interest within a first image to another region of interest within one or more other images.

Various forms of reporting the results of the verification are embraced by the present invention, and in some cases, the results of the validation may trigger additional process steps. For example, the results of the validation may cause audible, tactile, or visual feedback to indicate if a currency item is valid or counterfeit. In another example, the results of the validation may cause a digital image of the customer to be captured by a camera (e.g., a security camera) at a point of sale.

In some arrangements, the validation process may include steps for providing feedback (e.g., audible, visual, or tactile) to help align the currency item and/or the CVAL device and/or to determine if the currency item is obscured in the digital images.

In some arrangements, the validation device may operate in two modes (e.g., indicia reading mode, CVAL mode). In this case, the validation process may include steps for adjusting the mode of operation based on an analysis of the captured digital image or images.

In some arrangements, the present invention embraces methods for improving the quality of the data (e.g., digital images) acquired for validation. In some arrangements, the validation method (i.e., validation process) may include steps to sense the authenticity of an item (e.g., merchandise, currency, etc.) by applying a chemical substance to the item before illuminating and imaging the item with different spectral profiles. In some arrangements, image-processing steps may be applied to remove artifacts from the captured digital images.

In some arrangements, the present invention embraces methods for improving the repeatability of validation. In some arrangements, the validation process includes steps to calibrate the validation device. In some arrangements, the validation process may include steps for capturing and analyzing a calibration target to determine the optimal illumination and/or image sensor settings. In some arrangements, the validation process may include steps for capturing a portion of the light from the illumination subsystem and then adjusting the exposure/illumination of the sensor/light-sources to match a calibrated value. In some cases, the calibrated value may be based on a known temperature response of the light sources.

The foregoing illustrative summary, as well as other exemplary objectives and/or advantages of the invention, and the manner in which the same are accomplished, are further explained within the following detailed description and its accompanying drawings.

At point of sale (POS), multiple devices are often needed to scan barcodes and to determine the authenticity of items at checkout (e.g., currency, merchandise, stamps/labels, driver licenses, etc.). Using multiple devices can slow-down checkout and is not cost/space efficient.

Referring now to <FIG>, according to various embodiments, a multifunction validation device (e.g., a CVAL device <NUM>) may improve workflow by combining currency verification (CVAL) and indicia reading (e.g., barcode scanning) into a single, hand-held device <NUM> (such as hand-held imager depicted in <FIG>). In operation, the validation device's imaging subsystem <NUM> is used in combination with the illumination subsystem's <NUM> multiplexed light sources <NUM>(e.g., see <FIG>, <FIG> and <FIG>) to sequentially capture the reflected and/or luminescent images of value documents (i.e., including but not limited to banknotes <NUM> and identification labels). The imaging subsystem <NUM> and illumination subsystem <NUM> are contained within the handheld validation device's housing <NUM>. The validation device <NUM> embraced by the present invention embraces some or all of the following features: (i) positioning indication/guidance for operator use; (ii) an indication of evaluation result (e.g., via LED, display <NUM> (<FIG>), etc.); (iii) an auxiliary illumination source in which the object (note under evaluation) obscures the view of the camera system so that transmission measurement can be made; and (iv) an energy storage/charging scheme. The device's imaging subsystem <NUM> and illumination subsystem <NUM> (<FIG>) are typically optimized to a particular distance at which the object is evaluated. The validation device <NUM> allows a user to image items in a variety of positions and orientations.

In order for paper currency to continue to be widely accept for commercial transactions, there needs to be high confidence that the bills being presented at the point-of-sale (and elsewhere) are genuine (and are not counterfeit or forged). An image-based currency evaluation system can provide a higher degree of confidence in a bill's authenticity. Often, such an imaging-based system uses various colored light sources <NUM> (or light sources <NUM> with different spectral profiles) in order to detect wavelength dependent variations in the reflectance from the bills (i.e., banknotes) to determine authenticity.

Filters <NUM> (<FIG>) may be used to create light having different spectral profiles when combined with a broadband (e.g., white light) light source (or light-source combination). The filtering results from the filter's particular transmission, absorption, or reflectance characteristics.

A validation device <NUM> may use filters <NUM> of different construction and/or composition. For example, colored plastic (or glass) may be used or multilayer interface filters may be used. Colored plastic (or glass) filters are relatively insensitive to angular orientation, whereas interface filters may be highly sensitive to angular orientation.

Control of the illumination's spectral profile (e.g., color) may be accomplished by controlling the filters <NUM> and/or the light sources <NUM> in the validation device <NUM>. In various embodiments, a filter (or filters) <NUM> may be positioned in front of a light source <NUM> and mechanically moved in and out of position to change the spectral profile of the illumination. In various embodiments, a multilayer filter <NUM> may be positioned in front of a light source <NUM> and mechanically rotated to change the spectral profile of the illumination. This filter-tuning approach is especially useful if very narrow changes in peak emission wavelengths are needed for validation. In various embodiments, diffractive optical elements (e.g., gratings) may be used to produce illumination having different spectral profiles. In various embodiments, multiple light sources <NUM> (e.g., <FIG> and <FIG>) can be used to produce illumination of various spectral profiles, such as shown in <FIG>. These multiple light sources may be individually controlled (i.e., turned on and off in various combinations) to produce different illumination spectral profiles.

As noted previously, in order for paper currency to continue to be widely accepted for commercial transactions, there needs to be a high degree of confidence that the bills presented at the point-of-sale (and elsewhere) are genuine (i.e., not counterfeit or forgeries). Using an image-based currency evaluation device (i.e., validation device <NUM>) provides a higher confidence of a bill's authenticity. The validation device <NUM> embraced by the present invention captures a plurality of images of an item, wherein each image of the item represents the item's spectral response (e.g., reflectivity, fluorescence, etc.) to a particular wavelength and/or spectral profile (i.e., collection of wavelengths). In some cases, discriminating features used for validation may appear in images of the item for a particular spectral profile, while not appearing or in other spectral-profile images. A valid banknote and counterfeit banknote illuminated and imaged using various spectral profiles are shown in <FIG>.

In various embodiments of the validation device <NUM> embraced by the present invention, the various images are obtained using optical filters <NUM> positioned in front of the imaging subsystem's image sensor <NUM> (i.e., in the return path). A benefit to using filters in this way is that the spectral profile of the light reaching the image sensor <NUM> is controlled, even if ambient light levels vary (e.g., vary in intensity, color, etc.).

The filters <NUM> used in the return path (i.e., receive path) of imaging subsystem <NUM> may be of various constructions and/or compositions. For example, colored (dies) plastic, colored glass, or interface (i.e., multilayer, dichroic, etc.) filters may be used. Colored plastics and glass filters are relatively insensitive to angular orientation, whereas interface filters may be highly sensitive to angular orientation.

In various embodiments, multiple filters <NUM> may be placed in the return path and may be mechanically moved in and out of position to change the spectral profile of the light reaching the image sensor <NUM>. In various embodiments, the angular orientation of an interference filter in front of the image sensor <NUM> may be changed to tune the spectral profile precisely. Similarly, diffractive optical elements (e.g., gratings) may be used to filter the light reaching the image sensor.

Increasing evidence of counterfeiting indicates that currency validation/authentication is a growing need in many parts of the world. Multispectral illumination and imaging for validation is embraced by the present invention to address this problem. The images acquired by a verification (i.e., validation) device <NUM> may contain artifacts (e.g. shadows, glare, fibers, dirt, etc.). These artifacts do not contain valuable information and introduce spatial noise, thereby making validation difficult. The present invention embraces mitigating this spatial noise to improve the quality of the images provided for validation.

Surfaces typically reflect light in two ways: specular and diffuse. Diffuse reflections from a currency item (e.g., banknotes <NUM>) are generally weaker than specular reflections from the currency item but contain the information necessary for validation. Specular reflections contain no valuable information about a printed surface, and as a result, minimizing their intensity is helpful for validation. The present invention embraces minimizing specular reflections from a currency item by controlling polarization of the illumination light and the light detected by the image sensor <NUM>. Specifically, the illumination light may be polarized in a particular direction and the light captured by the image sensor is polarized in a direction orthogonal to the particular direction (if polarizers <NUM> and <NUM> are used). In this way, the light reflected from the currency item is filtered (i.e., by its polarization) to remove the polarization of the illuminating light. As diffuse reflected light is largely unpolarized, a portion of the diffuse reflected light will reach the image sensor <NUM>. As the specular reflected light is largely polarized in the direction of the illumination, the specular reflected light will be substantially blocked. In various embodiments, a linear polarizer is positioned in front of the illumination subsystem and a crossed polarizer is positioned in front of the image sensor. In this way, very little light from the illuminator or from specular reflection is detected by the image sensor.

The validation device <NUM> further comprises a processor <NUM> (also referred to herein as processing circuitry) communicatively coupled to the imaging subsystem <NUM> and the illumination subsystem <NUM>. The processor <NUM> is configured by software <NUM> (stored, for example, in a storage device <NUM> or memory <NUM> of the validation device <NUM>) to activate one or more of the light sources <NUM> in the illumination subsystem <NUM> to illuminate a currency item, capture an image of illuminated currency item, and repeat activating one or more light sources and capturing digital images until a plurality of digital images of the currency item have been captured, and process the plurality of images to validate the currency item. The storage device <NUM> of <FIG> is also depicted as including an operating system <NUM>.

Barcode scanners are ubiquitous at retail checkouts, and the ability to detect counterfeit currency is a growing need. The present invention embraces combining these functions into a single validation device <NUM>, in which the mode of operation is indicated to avoid confusion.

In various embodiments, the validation device <NUM> includes an aiming subsystem <NUM> capable of projecting two different targeting patterns, one for each of the two modes of operation. In a first mode, one light pattern will be projected into the field of view of the device. If the mode of operation is changed, a different pattern will be projected. The targeting pattern will alert the operator of the mode and/or the mode change. The aiming subsystem <NUM> may be communicatively coupled to the mode-selection switch and has one or more aiming-light sources <NUM> and optics <NUM> for projecting (i) a first targeting pattern into the field of view when the CVAL device is in indicia reading mode and (ii) a second targeting pattern into the field of view when the CVAL device is in CVAL mode. The aiming system's one or more aiming-light sources <NUM> may include a first laser for radiating light for the first targeting pattern and a second laser for radiating light for the second targeting pattern.

The aiming subsystem <NUM> may project the targeting pattern into the field of view using a variety of technologies (e.g., aperture, diffractive optical element (DOE), shaping optics, etc. (referred to collectively as projection optics <NUM> (<FIG>)). A combination of technologies may also be used to create the two targeting patterns. In one embodiment, two diffractive rectangular patterns may be used. For barcodes, a pattern with a square aspect ratio could be projected, while for currency a pattern with an aspect ratio that matches the banknote may be projected (e.g., <NUM> X <NUM> aspect ratio). In various embodiments, a red line pattern may be projected for barcodes, while a green line pattern may be projected for currency. In various embodiments, a red rectangular area for barcodes may be projected from an LED, while a green crosshair is projected for currency from a DOE. The present invention envisions any combination of technology and patterns that produce easily visualized modes of operation.

The validation device <NUM> envisioned by the present invention requires significant energy to provide the high-intensity illumination and fast image-capture necessary for operation. As a result, the current consumption required by the validation device may exceed the current limits (e.g., <NUM> milliamps) of a typical power source <NUM> (e.g., USB). For example, current consumption of the illumination subsystem may exceed the power limits of a USB connector if multiple illuminations/image-captures are required.

The validation device <NUM> may store energy in a storage element during periods rest (i.e., nonoperation) and then use the stored energy for illumination, when high current is required. In various embodiments, the storage element is at least one super-capacitor capable of supplying the illumination subsystem energy without depleting the energy necessary for other operations (e.g., scanning). A typical super-capacitor has enough energy capacity for a sequence of illuminations (i.e., "flashes") before charging is required. In various embodiments, the storage element may be a rechargeable battery. The battery may be charged when validation is not required and then may be used to provide energy for the sequences of "flashes" during validation.

The present invention also embraces integrating the storage element (or elements) <NUM> outside the housing <NUM> of the validation device <NUM>. For example, the storage element <NUM> may be incorporated inside the validation device's power/data cable. In this case, efficient charging may be accomplished using a current limiting resistor directly from the power source. The storage element may also be distributed along the cable, using the length of the cable and multiple layers to create a "cable battery" or "cable capacitor".

While various components of an exemplary validation device are depicted in <FIG>, it is to be understood that there may be a fewer or a greater number of components in the validation device <NUM> and their location within and/or outside the validation device may vary.

To combat counterfeiting, banknotes need to be recognized, removed from circulation, and in some cases, reported to authorities for data collection and analysis. Detecting counterfeits immediately at transaction locations offers advantages to law enforcement and commerce. The validation device <NUM> embraced by the present invention may be combined with other systems to create a verification kiosk <NUM> (<FIG>) according to various embodiments of the present invention. The verification kiosk <NUM> (or simply "kiosk") is a convenient way for validating banknotes <NUM> at useful locations.

In various exemplary implementations, banks may use a kiosk <NUM> (<FIG>) to verify the currency items they receive or distribute. In another exemplary implementation, check-cashing centers may provide a kiosk for public use. In another exemplary implementation, a kiosk may be placed near (or integrated with) an automatic teller machine (ATM), and in some cases the ATM/kiosk may be configured to exchange counterfeit banknotes for authentic banknotes. A kiosk <NUM> may also be configured to collect user information and/or take a photo of the user. In addition, a kiosk may collect and provide additional information such as a time/date, a banknote serial number, or human metrics, such as an iris-scan or thumbprint. In various embodiments, a kiosk <NUM> may be configured to permit a user to exchange banknotes/paper money with handling damage (e.g., folds or creases, cuts, stains, rounded corners, etc.) for new banknotes (or at least higher graded banknotes/paper money) with authenticity validated during the exchange.

Still referring to <FIG> and <FIG> and now to <FIG>, according to various embodiments, the present invention also embraces a point of sale system <NUM> with validation capabilities. The point of sale system <NUM> comprises the validation device <NUM> communicatively coupled to a cash register <NUM>. The cash register <NUM> registers and calculates transactions at the point of sale. A point of sale system's validation device <NUM> (e.g., handheld imager as depicted in <FIG>) may be configured for multiple functions (e.g., CVAL, barcode scanning, etc.). In this case, the handheld imager must be capable of switching between modes either automatically or manually. Productivity may depend on the ease and speed of this mode switching.

In various embodiments of automatic mode initiation, image capture is initiated resulting in one or more captured images after which the handheld imager's firmware searches the captured digital images for items (e.g., barcodes, characters, features, artwork, banknotes, etc.) and, upon recognition, changes the mode of operation appropriately. If a barcode is detected (i.e., recognized), barcode decoding mode is initiated and the image or images are processed. If currency item (rather than a barcode) is detected (i.e., recognized), more images may be needed to obtain the full multispectral set of images, after which the images are processed for authentication. In various exemplary implementations of automatic mode initiation, a point of sale computer controls the mode of operation based on a point in a transaction process (e.g., barcode scanning is complete, payment is necessary, etc.). Regardless of the payment form, the validation device <NUM> comprising a dual- or multi- mode CVAL device can be changed to the currency validation mode and used for currency validation. When the POS system <NUM> indicates that the transaction process is complete, the dual- or multimode CVAL device is returned to barcode scanning mode (i.e., indicia reading mode). In various embodiments, the handheld imager (the CVAL device) supports barcode scanning as the primary function, by default. In this case, the handheld imager's decoding process attempts to decode barcodes. If a barcode is detected in a captured image, then the handheld imager does not switch to a new mode. If, however, no barcode is detected, then the handheld imager begins a process to determine if the mode of operation should be changed. As noted previously, such a process could include capturing additional images and/or additional image processing to identify currency features.

The handheld imager's operator may manually initiate the mode of operation (e.g., barcode scanning, CVAL, merchandise validation, etc.). In various embodiments, the operator initiates a mode of operation by activating a dedicated trigger switch <NUM> (e.g., pressing once, repeatedly, or in a pattern). The trigger switch may be a mechanical, optical, magnetic, or capacitive switch. This trigger may also control various functions within a signal mode. For example, pressing the trigger may initiate an aiming subsystem <NUM> to project a targeting pattern to guide the placement of a currency item, and releasing the trigger switch may initiate a verification process.

Other means to change modes are envisioned by the present invention. For example, a special barcode or symbol may be scanned, when the device is in barcode scanning mode, to initiate the authentication mode of operation. After validation is complete, the validation device <NUM> could return to barcode scanning mode after a set period of inactivity (e.g., a few seconds). In another example, a voice command may be used to initiate, change, or terminate the mode of operation, such as through a microphone (e.g., microphone <NUM> in <FIG>) in or outside of the validation device <NUM>.

For commercial transactions, confidence in the validity of banknotes is needed. Using a point of sale system <NUM> configured for validation can provide this confidence by recognizing forgeries through the detection of security features on banknotes (i.e., bills). As many security features are located on the both the front, back, and within the banknote, it is useful to evaluate transmission as well as reflectance characteristics of the bill.

In various embodiments, in the point of sale system <NUM> embraced by the present invention, a banknote holder <NUM> (i.e., bill holder) may be used to obtain the optical transmission characteristics of the bill. The banknote holder <NUM> includes a highly reflective surface. When the back (or front) surface of the banknote <NUM> is placed on the reflective surface and the front (or back) surface of the banknote is illuminated, the light reflected from the reflective surface reveals the transmission characteristics of the banknote. The reflective surface may be a broadband reflective surface (e.g., metallic mirror) or may be a reflective surface with a particular spectral profile that is customized to reflect only specific wavelengths (e.g., infrared (IR) ultra-violet (UV), and/or portions of the visible spectrum). In various embodiments, the banknote holder <NUM> may itself include one or more illumination sources/illumination devices.

Still referring to <FIG> and now to <FIG>, according to various embodiments of the present invention, a method <NUM> for currency validation is provided. The method <NUM> for currency validation comprises activating the verification device <NUM> to begin operation (step <NUM>), illuminating the currency item with light having a particular spectral profile (step <NUM>), capturing a digital image of the illuminated currency item (step <NUM>), repeating the steps of illuminating and capturing to obtain a plurality of digital images of the currency item illuminated by different spectral profiles (step <NUM>), processing the digital images (step <NUM>), validating the currency item using the results of the processing (step <NUM>), and providing feedback (step <NUM>) as herein described.

According to various embodiments, methods <NUM> through <NUM> and methods <NUM> through <NUM> may be standalone methods as respectively depicted in <FIG>, and <FIG> or may be used in conjunction with method <NUM> according to various embodiments as hereinalfter described. When used in conjunction with method <NUM> for currency validation, it is to be understood that certain steps in methods <NUM> through <NUM> and methods <NUM> through <NUM> are the same as or similar to the steps of method <NUM> depicted in <FIG> such that these certain steps are not repeated in performing the respective method in conjunction with method <NUM>. For example, activating step <NUM> of method <NUM> (<FIG>) is the same as activation steps <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. Illumination step <NUM> of method <NUM> is the same as or similar to illumination steps <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, although the target of the illumination may be different. The same is true generally with respect to capturing step <NUM>, repeating step <NUM>, and processing step <NUM> of method <NUM>.

Counterfeiting is a major issue and many POS systems are not configured to validate currency items easily. Current validation methods are slow, expensive, intrusive, and bulky. There is a need for validation at the point of sale that mitigates or solves these problems. The present invention embraces a low-cost, handheld validation device <NUM> that uses multi-spectral imaging and that can validate currency by comparing images (or image portions) of currency items to those of known authenticity as part of validation, according to various embodiments of the present invention.

Regions of interest on a currency item may be identified and compared to comparison standards for each region of interest. Alternatively, ratios between regions of interest may be used as part of validation. Some advantages of multi-spectral imaging for validation include the creation of a large data set for analysis (i.e., gathers more data than existing systems or a human) the identification of features at dimensions beyond what the human eye can verify.

The validation device <NUM> embraced by the present invention includes a camera system (the imaging subsystem <NUM>) used in combination with multiplexed light sources <NUM> to sequentially capture the reflected and luminescent images of value documents (i.e., banknotes, identification labels, etc.). After the multispectral digital images are captured (i.e., after step <NUM>), one or more regions of interest are identified in the digital images in steps <NUM> and/or <NUM>. Gray levels (reflectance/luminescence intensity levels) in the regions of interest are then compared to control regions in the image or to one or more other regions of interest in the image. Next, signal ratios (i.e., values) for one or more regions of interest are computed. The signal ratios for one or more regions of interest are then compared to "gold standard" (i.e., comparison standard <NUM>) signal ratios, stored in a database or lookup table. Validation (step <NUM>) includes determining whether the compared signal ratios for the one or more regions of interest meet a predetermined acceptable value. The validation results are then provided by the validation device <NUM> (or by a system connected to the validation device <NUM>) to a user, an actuator, a system, and/or a recording device as feedback in step <NUM>.

The validation device <NUM> embraced by the present invention may also scan other items (e.g., barcodes, serial numbers, etc.). The validation device <NUM> may include various components (e.g., color filters, cameras, etc.) The stored comparison standards <NUM> may be updated in various ways (e.g., electronically, via web-link, etc.). In some possible embodiments, the validation device <NUM> is not handheld, but rather integrated with a supermarket slot scanner or fixedly mounted options on a counter top or as an overhead document imager.

The validation device <NUM> embraced by the present invention embraces the multispectral imaging of currency items. Multiple light sources <NUM> and/or filters <NUM> may be used to provide illumination having various spectral profiles. For each illumination, the imaging subsystem <NUM> may be controlled (i.e., exposure control) to capture digital images. The present invention embraces different methods for controlling multiple illumination devices (i.e., strings of LEDs, LED arrays, etc.), each having a different spectral profile.

Referring now to <FIG>, according to various embodiments of the present invention, a method <NUM> for controlling image exposure for currency validation is provided. The illumination subsystem of validation device <NUM> is activated in step <NUM> and the field of view illuminated (step <NUM>). The field of view may be illuminated with a particular spectral profile, with each spectral profile in a plurality of spectral profiles. A signal from the sensing subsystem <NUM> (<FIG>) of validation device <NUM> may be analyzed in step <NUM>. In step <NUM>, illumination and/or camera settings of the validation device <NUM> may be adjusted based on the analysis. In various embodiments, digital images of the field of view for each spectral profile may be captured (step <NUM>) and analyzed (step <NUM>) before step <NUM>. In various embodiments, the control methods provide variable sequences, durations, and intensities for multi-wavelength illumination. For example, the illumination may be controlled by adjusting the current for each LED array using DACs, programmable LED drivers (via serial interface), or PWM controls (duty cycle). In another example, the illumination may be controlled by adjusting the illumination time independently for each of the LED arrays. In another example, the illumination may be controlled by activating different LED arrays in a sequence or activating different LED arrays at the same time. In another example, the illumination may be controlled by adjusting the exposure time of the image sensor <NUM> synchronously with illumination time and dependent on the type or spectral profile of LED arrays.

The control method may also be used to control the illumination for other applications. For example, barcodes of poor quality may be imaged using multiple spectral profiles to improve scanning. In another example, documents, currencies, or products may be verified. In still another example, imaging using multiple spectral profiles could be used for crime scene evidence collection (e.g., UV, IR images).

Referring again to <FIG>, according to various embodiments, the validation device <NUM> embraced by the present invention may also provide an indication of validity in step <NUM>. The indication of validity (i.e., the feedback) indicates that the currency item is valid or invalid. In various embodiments, the validation device <NUM> may include a display <NUM> to indicate validity. In various embodiments, the validation device <NUM> includes a sound transducer <NUM> to produce a sound to indicate validity. In various embodiments, the validation device may include a motion transducer <NUM> to product a vibration to indicate validity. In various embodiments, the validation device <NUM> includes a communication subsystem <NUM> to communicate validity to an external service or person (e.g., a manager, a security person, or a service). Validity may be communicated, stored, shared, automatically without operator involvement.

As noted previously, the validation device <NUM> may be capable of operating in either an indicia-reading mode or a CVAL mode. Referring now to <FIG>, according to various embodiments, a method <NUM> for adjusting the mode of operation in a dual-mode validation device <NUM> is provided, according to various embodiments. The user positions an item within the field of view of the validation device <NUM>. The validation device is activated (step <NUM>). An item (an indicia item or a currency item) is illuminated (step <NUM>). A digital image of the illuminated item is captured (step <NUM>). The captured digital image may be analyzed (step <NUM>) for the presence or absence of the indicia item (e.g., a barcode). Based on the analysis of the captured digital image, if the item is a currency item, it is validated or further validated with the validation device <NUM> operating in CVAL mode with the processor performing steps <NUM> through <NUM> of <FIG>. If the captured digital image includes a barcode, the barcode is processed to be decoded (step <NUM>).

In a possible implementation, activating a trigger <NUM> (e.g., by pushing a button, touching a specific area on the validation device <NUM> (i.e., handheld imager)) initiates the validation device <NUM> to capture images and search for a barcode within the captured images (i.e., the processor activates the validation device (step <NUM>). If there is a one or two-dimensional barcode in the captured images, the validation device <NUM> will scan the barcode. If there is no barcode present in the capture images, the validation device <NUM> performs steps <NUM> through <NUM> (of <FIG>). As noted previously, step <NUM> in the CVAL process (<FIG>) includes illuminating the banknote with multiple spectral profiles of light sequentially and in rapid succession and capturing digital images for each illumination. The captured images will then be processed (in step <NUM>) to identify the banknote <NUM> and to compare it to a library <NUM> of information for that type of banknote. Feedback of the validation results may then be provided to a user, other person, or service in step <NUM>. If a barcode or other indicia item is detected in step <NUM>, the indicia item may be decoded in step <NUM> as previously noted.

Referring now to <FIG>, according to various embodiments, a method <NUM> for aligning a currency item with a validation device <NUM> (i.e., CVAL device) is provided. Similar to method <NUM>, method <NUM> comprises activating the validation device (step <NUM>), illuminating the currency item (step <NUM>), capturing a digital image of the currency item (step <NUM>), and repeating the illuminating and capturing steps to obtain digital images (step <NUM>). The captured digital images from step <NUM> are processed in step <NUM> by analyzing the captured digital images of the currency item. The captured digital images may be analyzed to determine the currency item's position relative to an optimal position. The captured digital images may be analyzed to determine if at least a portion of the currency item is obscured. Currency items need to be positioned properly within the validation device's field of view (FoV) (including the depth) for best results. The present invention embraces methods for positioning a currency item with respect to the camera's field of view (FoV) and/or depth of field (DoF) by providing positioning feedback in step <NUM>. The positioning feedback enables a user to understand when a currency item is properly positioned (and when it is not). The positioning feedback may indicate if the currency item needs to be moved in a particular direction, rotated, and/or moved further or closer to the imager to reach an optimal position. The positioning feedback may indicate that the view of the currency item is obstructed, folded, or not clearly visible. The generation of positioning feedback typically requires an image of the entire currency item, however in some cases, or specific regions of interest (ROIs) may suffice. Positioning feedback may be provided to a user in various formats (e.g., visual, audible, and/or tactile). The positioning feedback is typically intuitive. For example, the feedback and positioning feedback may be provided through a speaker <NUM> in the validation device.

One possible method for providing positioning feedback embraced by the present invention is as follows. First, in step <NUM>, information corresponding to a currency item's position and orientation are derived. Next, in step <NUM>, the positioning feedback is generated and communication to indicators that inform a user how to reposition the currency item. This process is iterated until the currency item is in the proper position/orientation.

The positioning feedback/indicators may be embodied in a variety of ways. For example, an indication of good/bad positioning may be conveyed via dedicated colors and/or lights. Indicator lights may also specify the direction the currency item should be moved (e.g., left/right, up, down, closer/further, and/or various forms of rotation). Positioning feedback/indicators may inform a user of an obstructed view. Positioning feedback/indicators may be audible or tactile. Audio indicators may be any combination of sounds, tones, "grunts", or spoken words. The positioning feedback/indicators may include visual text/images projected into the validation device field of view. This feedback may visually indicate where a currency item should be located (at least initially). The various types of feedback/indicators may be combined.

Referring now to <FIG>, a flow diagram of a method <NUM> for currency validation at a point of sale such as in point of sale system <NUM> is provided, according to various embodiments. If validation step <NUM> (<FIG>) finds the currency item to be counterfeit, the processor acts to gather information from the currency item and/or the customer at the point of sale (step <NUM>). Handling customers in possession of counterfeit currency items at checkout is problematic. The results of the validation process should not distress or harm an innocent customer, but on the other hand, steps should be taken to ensure that the counterfeit is taken out of circulation and that the appropriate information is provided to authorities for an investigation. The present invention embraces methods for indicating and collecting information in response to a validation process.

In various embodiments, the validation device <NUM> provides a unique visual indication only to the operator (i.e., cashier, user, etc.) that a counterfeit has been detected, without alerting the customer or bystanders in any way. The customer is asked to provide a valid photo identification (e.g., driver's license) and the photo identification (i.e., photo-ID) will be scanned and recorded. The image of the counterfeit item, a transaction record, and the photo-ID image will be stored and made available to the law enforcement agencies or product manufacturers.

In various embodiments, the CVAL device <NUM> includes a multi-color illuminator, which could be used as an indication of authenticity (e.g., GREEN = valid, RED = counterfeit). The illumination of an item using a specific color (or color combination) indicates authenticity. When a counterfeit is detected, an image of the counterfeit item is automatically stored with transaction. The operator may repeat the verification process or use a secondary validation method (e.g., use a chemical pen to enhance the validation process).

In another possible embodiment, a customer is notified that the item is not authentic and his/her photo ID is requested to be imaged/recorded. If the customer is compliant, then he/she does not incur a loss. If the customer refuses to provide ID, a security camera <NUM> in communication with the validation device <NUM> may be used to surreptitiously capture an image of the customer. The information gathered may be stored (step <NUM>) for future investigations or could be used with other stored information to facilitate "global" tracing of the counterfeit money or merchandise.

The main priority for any validation method is accuracy. There is, however, a substantial cost for highly accurate performance. The present invention embraces introducing a controlled chemical/substance to currency items, documents, or merchandise to improve the accuracy of the multi-spectrum validation device (i.e., before performing method <NUM> of <FIG>).

In various embodiments, the unique chemical/substance is applied to the currency, document, or merchandise immediately before authentication. In another possible embodiment, the unique chemical/substance may be applied to a printed document, label, or packaging (e.g., a chemical in the ink used to print the document) during fabrication. In operation, the multispectral images may be analyzed to detect a unique feature or characteristic corresponding to the chemical/substance. When illuminated with a particular spectral profile, the chemical/substance may reveal an imprinted pattern, text, or number.

Referring now to <FIG>, a method <NUM> for determining the fitness of a currency item (e.g., a banknote) is provided, according to various embodiments of the present invention. Every currency in the world has specifications for conditions when it is taken out of circulation. For example, the United States Federal Reserve provides rules (i.e., "Fitness Guidelines") for validating the acceptability of Federal Reserve Notes (i.e., FRN, paper money, banknotes, currency, etc.). Banks (and other depositories) typically use special high-speed validation systems to evaluate the fitness of bills (e.g., check the series-design, year of issue, amount of soiling, amount of print wear, tears, repairs, etc.) Due to the cost of these systems, they are typically found only at centralized locations. The present invention embraces methods for determining the "fitness" of currency items at other locations. In this case, speed may be sacrificed for cost. The methods utilize a portable validation device <NUM> capable of multi-spectrum illumination/imaging. The portability of the validation device enables fitness validation at a point of sale or local bank/depository.

In various embodiments of a method for determining fitness as depicted in <FIG>, a currency item is illuminated and imaged using the multi-spectrum validation device <NUM> as in steps <NUM> through <NUM> of <FIG>. More specifically, the validation device is activated in step <NUM>. The currency item is illuminated in step <NUM>. The illuminated currency item is captured in step <NUM>. The illumination and capturing steps are repeated in step <NUM>. The digital images are processed in step <NUM>. In step <NUM> of processing the digital images in the method <NUM> for determining the fitness of the banknote, the captured images are analyzed (e.g., optical character recognition) to determine the denomination and series of the banknote. If the banknote's age is not acceptable, fitness feedback would be provided to a user in step <NUM> instructing them to remove the currency item from circulation.

In various embodiments, a currency item is illuminated and imaged using the multi-spectrum validation device <NUM>. The captured images may be analyzed (e.g., reflectance measured) in processing step <NUM> to determine the soiling and print quality of the currency banknote. If unacceptable, fitness feedback may be provided in step <NUM> to a user instructing him/her to remove the currency item from circulation.

In various embodiments in method <NUM> for determining the fitness of a banknote, a currency item is illuminated and imaged using the multi-spectrum validation device <NUM> (steps <NUM> through <NUM>). The captured images are analyzed (e.g., reflectance measured) to determine the shape and to detect tears, holes, tape, and/or missing portions in step <NUM> by analyzing the captured digital images. If unacceptable, fitness feedback may be provided to a user instructing him/her to remove the currency item from circulation (step <NUM>).

Validation using multispectral illumination/imaging requires control of the illumination and image acquisition parameters in order to optimize image quality, optimize repeatability (e.g., two different devices operate similarly), and allow for similar processing of images captured under different conditions. The present invention embraces calibration methods to "normalize" images to one another and between devices so they can be processed similarly.

Referring now to <FIG>, a method <NUM> for calibrating a multi-spectral imaging device (e.g., validation device <NUM>) is provided according to various embodiments. The method <NUM> for calibrating the multi-spectral imaging device comprises activating the validation device (step <NUM>) and then illuminating and capturing digital images of the calibration target using a different spectral-profile illumination for each digital image (steps <NUM> and <NUM> respectively), comparing the captured digital images to a set of standard values in a step for processing the digital images(step <NUM>), adjusting the imaging device's imaging parameters based on the comparison to obtain a set of calibrated imaging parameters, wherein each calibrated imaging parameter in the set of calibrated imaging parameters corresponds to a particular spectral-profile illumination (step <NUM>), and storing (step <NUM>) the calibrated imaging parameters on the imaging device for future multi-spectral imaging and validation (i.e., steps <NUM> through <NUM> of <FIG>).

Calibration may be achieved using a variety of techniques (e.g., automatic gain control, calibrations, etc.) applied either individually or in combination to normalize/equalize the captured digital images. In various embodiments, automatic or preset exposures are assigned for each spectral profile illumination. In various embodiments, automatic or preset illumination intensities may be assigned for each spectral profile illumination. In various embodiments, automatic or preset image gains are assigned for each spectral profile illumination. In these cases, the assignment of the parameters (i.e., calibration) may occur when the device is fabricated or installed. Alternatively, the calibration may occur as a periodic (e.g., scheduled) adjustment or when the application/environment is changed.

In various embodiments, the calibration includes using a multi-spectral validation device <NUM> to capture multiple spectral profile images of a calibration target that has particular color/gray-scale values. The captured images are then analyzed and compared to the known values of the calibration target. Next, the illumination/imaging parameters are adjusted (e.g., illumination strength, exposure time, image gain) for each of the spectral profiles. The adjustment may be automatic or manual and the parameters are adjusted until the normalization is achieved. The final parameter settings are then saved on the validation device and used by the validation device for subsequent illumination/imaging.

Referring now to <FIG>, according to various embodiments, a method <NUM> for automatically adjusting imaging parameters for the multi-spectral imaging device is provided, according to various embodiments. A digital image of the item is captured using a particular spectral profile illumination (step <NUM>). The captured digital image of the item (e.g., a currency item) is analyzed in a processing step (step <NUM>) and the imaging parameters adjusted (step <NUM>) for each spectral profile illumination based on the analysis. In various embodiments, automatic exposure, illumination strength, and/or image gain may be adjusted during the validation device's operation based on data from the first illumination (i.e., the "first flash"). Using this data, the parameter settings for each of the multi-spectral images are adjusted to normalize for the subsequent illumination/imaging.

Validation using the multi-spectral illumination/imaging relies on subtle differences in image levels. As a result, variances in illumination/imaging affect the intended results. Such variances may result from variations associated with the light sources or the image sensor (e.g., thermal variations, operating-characteristic variations, exposure-time variations, etc.). The present invention embraces real-time control of the illumination/imaging settings (i.e., parameters) to counteract these variances and maintain control of the image levels.

There are multiple embodiments for the real-time control, all using feedback from the validation device's light sources <NUM> to monitor the rate at which illuminance is being delivered (i.e., intensity). As exposure is proportional to illuminance multiplied by exposure time, exposure times can be adjusted to achieve the desired total exposure ratio between all spectral profiles.

In all possible embodiments, a validation device <NUM> is factory calibrated to determine the optimal exposure ratio. This optimal ratio is known as the target ratio and is recorded in the validation device's firmware. During operation, an initial exposure level is determined by taking an initial exposure (likely using a combination of LEDs, or perhaps IR only) to get a sense of the imaged item. The initial exposure produces a first image. The first image is used to estimate the appropriate overall exposure level required.

In various embodiments, a small reference target attached to the validation device (e.g., positioned in the periphery of the field of view, occupying the perimeter of the field of view, etc.). This reference target may include a white portion and/or may include multi-colored portions. The target reflects a small amount of light from the light sources (during the initial exposure) back to the image sensor. The signal captured on the image sensor <NUM> corresponding to the reference target is used to adjust the exposure times of the light sources. In some cases, the adjustment also uses the light source's response to temperature. For example, after the initial exposure time ratios are set, a string of exposures would generate captured images, one for each spectral profile. The signal captured on the image sensor <NUM> corresponding to the reference target for these exposures is then used to further adjust the exposure ratio (e.g., closer to the desired exposure ratio).

In various embodiments, a light source sensing subsystem <NUM> may be used to monitor exposure levels. The light source sensing subsystem <NUM> may include a photodiode <NUM> that is positioned to pick off a small amount of light every time a light source <NUM> is activated. The signal from this photodiode <NUM> provides reference information used for adjusting the intensity of the light sources <NUM>. Alternatively, the signal from the photodiode <NUM> may be used as a trigger for the sensor shutter. In this case, a trigger signal would simultaneously turn on a light source <NUM> and open the image sensor's <NUM> shutter. An integrating circuit may be used to integrate the signal from the photodiode <NUM> until a desired level is reached. When the desired level is reached the image sensor's <NUM> shutter would be closed. The real-time integration of the sensor signal ensures the proper exposure ratios. This process may be repeated for each spectral profile.

In various embodiments, a light source sensing subsystem <NUM> is used to generate real-time feedback and integration. This particular embodiment is the same as the last particular embodiment but rather than using a photodiode <NUM>, a portion of the image sensor <NUM> is used as the sensing subsystem, and the feedback signal is generated by the image sensor's response to light reflected from a reference target.

In various embodiments, the light sources (e.g., light emitting diode, LED) <NUM> are controlled to prevent temperature drifts in intensity. Temperature affects LED efficiency. When an LED is turned on, its efficiency can change until a thermal equilibrium is reached. To prevent thermal drift, the LEDs are activated and allowed to reach thermal equilibrium. The activation time (i.e., burn-in time) may be set using an ambient temperature sensor, or set during fabrication as a result of testing. After the burn-in time, the image sensor's shutter would be opened to capture an image. Calibration of the collected image may then be based on the sensed temperature or cataloged data.

In various embodiments, each light source (e.g., LED) <NUM> is assigned a particular initial exposure. The initial exposure is followed a second exposure, which is fine-tuned for processing. This method could be used with or without the initial multi-color single exposure. If the single exposure is used, the single exposure is used as a basis for determining the initial exposures for the spectral profiles. If the single exposure is not used, then the initial spectral profile's exposures could be used to estimate the desired exposure of the next initial color exposure. Results from each initial color exposure are processed to determine exposure refinement for the second exposures. The reference target described above could be used for feedback, or a predetermined quiet region, identified in an image during the initial color exposures, could be used to refine the secondary exposures to optimize the exposure ratios.

When using multi-spectral illumination/image for currency validation, a fold in a currency item may cause shadows in each spectral profile illumination. As a result, the shadow pattern in the images captured from the different illuminations may be used to reduce noise and nonuniformities. This approach can also suppress some features, like serial numbers and magnetic strips.

Referring now to <FIG>, according to various embodiments, a method <NUM> for removing artifacts from images for currency validation is provided. The method for removing artifacts from images for currency validation comprises activating the validation device (step <NUM>), illuminating the currency item with light having a particular spectral profile (step <NUM>), capturing a digital image of the illuminated currency item (step <NUM>), processing the digital item to compute an average pixel value for the currency item (step <NUM>), sequentially illuminating the currency item with light having different spectral profiles (step <NUM>), capturing digital images of the currency item for each spectral profile (step <NUM>), and processing the captured digital images to remove artifacts by normalizing the pixels in the captured digital image by the average pixel value for the currency item (step <NUM>).

In various embodiments, an illumination having a spectral profile in near infrared (NIR) band would be used to minimize illumination artifacts (e.g., shadows) by normalizing validation images to an NIR image. Colored inks often have no contrast in NIR, (i.e., are invisible in NIR image). As the colored ink forms the information measured during validation, it remains relatively intact after normalizing the validation images to the NIR image. For currency items that use a significant amount of black ink (i.e., are visible in the NIR image), the black ink will provide no significant benefit to spectral analysis as it looks black to all colors. As a result, the NIR normalization process is not significantly affected by the information formed by the black ink.

In various embodiments, other spectral profiles may be used for normalization. For example, a plurality of images may be captured for each spectral profile in rapid succession (i.e., to minimize any motion that might occur between frames). The images are then processed to identify the banknote, spatially bin the reflectivity data, and adjust for exposure differences between images. Next, the average NIR return over the banknote in the images is calculated. Then each image is normalized by the image's ratio of the NIR data set to its average NIR. At this point, further normalization algorithms may be applied before validating the banknote.

While validation of banknotes has been described, other currency items such as coins may be validated by the validation device by the same or similar methods according to various embodiments.

Claim 1:
A currency validation, CVAL, device (<NUM>), comprising:
an illumination subsystem (<NUM>) having multiple light sources (<NUM>) and optics for illuminating items in a field of view, each of the light sources (<NUM>) having a different spectral profile;
an imaging subsystem (<NUM>) having an image sensor (<NUM>) and optics for capturing digital images of items in the field of view while illuminated by the illumination subsystem (<NUM>), the captured digital images comprising at least one of reflected and luminescent images; and
a processor (<NUM>) communicatively coupled to the illumination subsystem (<NUM>) and the imaging subsystem (<NUM>), wherein the processor (<NUM>) is configured by software to:
capture one or more images of the field of view of the CVAL device (<NUM>); and
change the mode of operation of the CVAL device (<NUM>) from an indicia reading mode to a CVAL mode when a barcode is not detected in the one or more captured images, wherein in the CVAL mode, the CVAL device is configured to:
repeatedly activate one or more of the light sources (<NUM>) in the illumination subsystem (<NUM>) to illuminate a currency item (<NUM>) in the field of view with illumination flashes of different spectral profiles,
capture at least one reflected and/or luminescent digital image of the illuminated currency item (<NUM>) for each illumination flash to obtain a plurality of digital images of the currency item (<NUM>), and
process the plurality of digital images to validate the currency item (<NUM>).