Abstract:
The present application relates to a method, apparatus and programmable product for verifying print quality of a document assembled on a document manufacturing device. In particular, a system and related method for performing print quality assessment of the document in real-time during manufacture of the document are provided. The present teachings allow for identification of the inherent qualities or pre-existing print markings of the document as a separate process from that of a process for identification and verification of markings applied onto the document by the print operation. In this way, a determination of print quality may be determined irrespective of the influence of the inherent qualities or pre-existing print markings.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/992,571, filed Dec. 5, 2007, entitled “CAMERA BASED INK APPLICATION VERIFICATION”, the disclosure of which is entirely incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present subject matter relates to a method, apparatus and programmable product for verifying print quality of a document. 
     BACKGROUND 
     Ink jet is a computer-to-print technology in which digital signals drive droplets of ink through a print head and then directly onto a substrate. The print head may consist of one or more nozzles through which ink droplets are ejected and directed onto the substrate. Ink jet printing differs from other plate-less digital technologies, like copier or toner-based technologies (e.g., as employed in desktop printer applications), because it is non-contact—the printing device never comes into direct contact with the substrate. While employed in consumer applications, ink jet printers are also well suited for various industrial and commercial uses, wherein variable, high speed printing or on-demand print handling capability is necessary. 
     One primary cause of ink jet printing problems is due to ink drying on the print head&#39;s nozzles, causing the pigments and dyes to dry out and form a solid block of hardened mass that plugs the microscopic ink passageways. When this occurs, the expected ink output markings to be applied to the substrate are compromised, often appearing, if at all, as faded, smeared, incomplete, jagged, disoriented, etc. Such occurrences, wherein the appearance of the printed output as placed onto the intended substrate is poor, is considered poor print quality. Obviously, this is not the preferred outcome, particularly in instances where high volumes of documents, packages, or other print items of various substrates are required to be produced with specific print markings. If the exemplary print quality defects described above are discovered too late, additional time, materials and effort must be further employed in reprinting the defective items. 
     Various methods are employed today for identifying print quality issues. For example, clogged nozzles can be detected by periodically printing a test print item (e.g., a page of a document) and verifying the print item for quality. Another method is to intentionally print a known pattern onto a select portion of a print item in process and subsequently verifying the pattern for quality. Instances where the pattern or markings do not exhibit quality—i.e., the actual printed markings differ from the intended print markings—highlights an occurrence of print quality failure. Identification and verification of such failures may be performed through the usage of an imaging system, which may include a camera device and select pattern recognition software (e.g., OCR or image recognition software). 
     While these methods and accompanying tools may be effective, they do not address instances of erroneous print quality verification, and particularly, those instances wherein a print quality failure is erroneously determined due to inaccurate verification. This is common in instances where the substrate upon which the print item is to be composed includes various inherent characteristics that may affect the verification process. For instance, consider a document printing job that requires the generation of hardcopy documents onto a particular pre-printed stock paper. If the verification process does not account for the presence of pre-existing print markings resident upon the paper stock in advance, print quality failure will be the natural result. This would be the only logical conclusion of the imaging system, as additional patterns (the pre-existing markings) besides the actual printed markings would appear on the document subsequent to print. Even if pre-existing markings were accounted for in advance by the verification system, accurate print quality failure could be hampered by the presence of paper creases, folds, wrinkles, grease marks, paper fibers, unintended ink blots and other such inherent qualities of the stock paper. 
     For the reasons stated above, a method and system for improved print verification is needed. Such improved technology, for example, should account for both pre-existing print markings and inherent qualities of a particular substrate, to enable accurate print verification. 
     SUMMARY 
     The teachings herein alleviate one or more of the above noted problems by providing a method, system and programmable product for enhancing print quality verification, for example, irrespective of the inherent qualities of or pre-existing print marking upon the intended print item. The present teachings allow for identification of the inherent qualities of the print item as a separate process than the process for identification and verification of markings placed onto the document by the print operation. In this way, a determination of print quality, and more specifically, the quality of the one or more print heads of a given printer, may be determined irrespective of the influence of the inherent qualities or pre-existing print markings. 
     It is desirable to provide a method and related system for performing print quality assessment of a document in real-time during manufacture of the document by a document manufacturing device. The method includes receiving data representative of a base stock upon which print data is to be applied and applying the print data as printing onto the base stock based on print file instructions. Data representative of the base stock is acquired along with the printing. The received image data representative of the base stock is compared with the acquired image data representative of the base stock to extract a representation of the printing; and the representation of the printing is compared with expected print data contained in the print file instructions. A determination is made as to whether or not there is any difference between the representation of the printing and the expected print data. A print quality assessment is rendered based on results of the determining step to affect subsequent processing of the document. 
     Additional advantages and novel features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples. The advantages of the present teachings may be realized and attained by practice or use of various aspects of the methodologies, instrumentalities and combinations set forth in the detailed examples discussed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1  is an exemplary depiction of a system for verifying the quality of a print process. 
         FIG. 2  is a flowchart depicting the exemplary process by which the print quality of a print process may be determined. 
         FIG. 3  illustrates a network or host computer platform, as may typically be used to implement a server. 
         FIG. 4  depicts a computer with user interface elements. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, “print quality” is a conditional term suggestive of the nature, means or extent to which print data is placed onto a print item by a printer in accord with specified print instructions—i.e., as contained within a print file. In general, when print data intended for placement onto a print item is physically placed onto the print item as instructed, this is generally referred to as an instance of print quality. Conversely, when print data intended for placement onto a print item is not physically placed onto the print item as intended, this is generally referred to as an instance of print quality failure. Failed print quality may be the result of various physical defects relative to the print data as placed onto the print item, including but not limited to fading, smearing, incompletion, jaggedness, or general disorientation of the print data as placed. Furthermore, the teachings herein are applicable to verification of print quality as applied by any print application mechanism, whether ink jet, laser, offset printing or other known implementations. 
     Also, as used herein, the term “print item” refers to any item composed of a substrate suitable for being printed upon, including but not limited to packages of various material composition, plastic wrappers, adhesive labels, and envelopes and paper of a specific fiber content or stock. Various other goods and manufactures of varying material composition may also be print items. In general, print items may be processed in various ways, including via the usage of an inserter device or as part of a print press production process. The exemplary teachings herein are not limited to any one particular print processing environment, document manufacturing device or print production device. Furthermore, the teachings herein are suitable for affecting operation of any subsequent processing devices  400  upon said print items accordingly. 
     Turning now to  FIG. 1 , an exemplary system for enabling print quality verification to be performed on an input print item or base stock  100  is depicted. The input print item  100  in this case is a document composed of a paper stock having various pre-existing print markings  102 . In the example the pre-existing markings  102  were printed onto the document during a prior print processing stage—i.e., a form letter. The pre-existing print markings  102  are detected by the imaging system  124  and used for later comparison with print instructions  122  and output image data  134  as part of the print quality check. Alternately the pre-existing print markings  102  maybe provided as a data file from a system interface instead of from the image paper stock sensor  124 . In this case sensor  124  maybe eliminated along with detection of print substrate defects  104 . As another alternative, the pre-existing print markings  102  maybe determined by observing the pre-printed data  102  during startup by using the imaging lift system  126  which would start imaging pages without knowing what is on paper stock  100 . By comparing the first N images from the image lift system  126 , the image processor  118  can perform a comparison algorithm and identify anything which is common from page to page. This common information would represent the pre-existing markings such as a return address or other common information. After a sufficient number of samples, the image processor  118  would create data representative of the base stock pre-existing markings  102  or  104 . Numerous techniques can be employed by those skilled in the art to identify pre-existing markings on the base stock  100  that do not represent material printed by print system  106 . The data representative of a base stock is received by the image processor and comparator  118  to enable print quality analysis. The exemplary examples of data representative of a base stock which are provided, include but are not limited to input image data  132 , print file data and data derived from images analyzed during start up. Of course, the base stock maybe blank and void of defects, which would require the comparator  118  to perform the print quality analysis using output image data  134  and expected print instructions  122 . Also, while not necessarily intentional, the document  100  also has an inherent quality or feature  104  in the form of a ‘watermark’, logo, picture or a blot or smudge. If feature  104  is a smudge or blot, this would represent a quality defect which may require operator intervention or reject of the document when it is processed by a subsequent processing device  400 . Inherent qualities of a particular print item or the substrate (e.g., paper stock) of which it is composed may include, but is not limited to: creases, folds, wrinkles, grease marks, paper fibers, unintended ink blots, stains, ridges, surface bubbles, tears, stretch marks, indentations, punctures, holes and other such physical characteristics of the print item which may be detected using an imaging system  124 . 
     The document  100  requires various print data to be printed thereon by a printing device  106  complete with one or more print heads  108 - 112  driven by a print driver  123 . The printing device  106  may be controlled by or part of a print controller  117  that provides the necessary print instructions  122  that initialize and activate the print driver  123 . For the sake of clarity with respect to the teachings herein, it should be noted that the print controller  117  may be communicably connected with an image processor and comparator  118 . Alternatively, the print controller  117  may operate independent of the image processor and comparator for enabling execution of the printing device  106  expressly. Those skilled in the art will recognize that either implementation may be employed with respect to the teachings herein. 
     The one or more print heads  108 - 112  operate in connection with the print device  106  to coordinate the release of ink in a manner consistent with the desired print data to be marked onto the document  100 . The print heads  108 - 112  may access one or more ink reservoirs, and may consist of one or more nozzles through which ink droplets are ejected and directed in a precise manner onto the document  100 . In close proximity to said nozzles are one or more image capture devices  140 - 144 , which may be suitably aligned for detecting the application of ink through the nozzle as applied droplet-by-droplet onto the document  100  (more regarding this later). In this example, the print data to be applied by the print heads  108 - 112  are a barcode  114 , a solid horizontal line  115  and a three line address block  116 . Other forms of printed information may include text, logo, pictures or other items that are compatible with the capabilities of the printer system  106 . All of which maybe printed by printers  108 ,  110 ,  112  or printer system  106 . Placement, orientation, text, image characteristics and other properties that affect the physical appearance of the print data  114 ,  115  and  116  is dictated by a print file—the one or more print instructions  122  capable of being interpreted by the printing device  106  for carrying out print requests. 
     The image processor and comparator  118 —which serves as a type of control processor in the context of a print item processing operation—also interfaces with various other devices to orchestrate the print item processing effort and print quality verification effort. This includes imaging devices  124  and  126 , which capture images of the input document  100  and the output document  130  respectively. The image processor and comparator  118  may also communicate with the print controller  117  in order to receive print instructions  122 . Hence, the print data and/or associated print instructions  122  to be carried out with respect to document  100  are accessible to the image processor and comparator  118  via a database  120 . 
     In accord with the teachings, once received the input document  100  is imaged by the first imaging device  124  in order to acquire image data representative of the input document  100  (Event  200  and  202 ). The imaging device  124  may be any system suitable for performing imaging of documents of various sizes and formats and with high resolution for detection of inherent qualities, which may often be subtle. In the case of the input document  100 , input document image data  132  compiled would include image data representative of the pre-existing print marks  102  and the inherent qualities (smudge  104 ) resident upon the document. Hence, while the input document image data  132  would represent a composite image of the entire document, the pre-existing print marks  102  and smudge  104  represent specific data points of interest. More about these data points of interest will be discussed subsequently. 
     Upon image capture, the input document image data  132  is transmitted to the image processor and comparator  118  (Event  202 ), whereupon receipt, it is stored to database  120  (Event  204 ). Subsequently, the print driver  123  drives execution of the print heads  108 - 112  of printer  106  as required for generating the intended or expected print data  122  onto the input document  100  (Event  206 ). By expected print data  122 , it is meant that this data is what is expected to be output onto the input document  100  by the printer  106  in the absence of any print quality issues. Once the instructions are received and the input document  100  is fed to the printer  106 , the one or more print heads  108 - 112  operate accordingly. This yields the output document  130  (Event  208 ), which unlike the input document  100  includes the additional print data  114 - 116 . 
     In the example depicted in  FIG. 1 , the printed address block  116  as rendered to the document is not without error. In this case, a horizontal gap appears across the primary street address (second line) of the address block resulting from a blockage within a given nozzle of a print head  108 - 112 . This error is illustrated in inset drawing  160 , which depicts a blown up subsection of the primary address number with the undesired horizontal gap passing through. Obviously, this error affects the overall legibility of the address block  116  and with the proper verification, should result in a print quality error being determined. This error could be representative of a failed ink jet or a printer control error. 
     To enable such verification, the exemplary teachings further call for the use of the second imaging device  126 , which may also employ high resolution imaging techniques to acquire image data respective to the output document  130 . The imaging device  126  may essentially scan the entire document, similar to device  124 , for acquisition and generation of output document image data  134 . Alternatively, the second imaging device  126  may be comprised of a plurality of image capture devices  140 - 142  (e.g., cameras) positioned within close proximity to the print heads  108 - 112 . This arrangement results in a one-to-one correlation between the nozzle of a given print head  108 - 112  and a given image capture device  140 - 144 , whereby the separate images in combination formulate a representation of the whole output document image data  134 . It should be noted with respect to the latter arrangement, that while  FIG. 1  depicts the second imaging device  126  as not being within close proximity to the nozzles of the print heads, this need not be the case. Indeed, the cameras, linear arrays, area scanners or other imaging devices employed as the second imaging device  126  may be only proximally offset from the print heads  108 - 112  if not directly inline. In alternative arrangements, the image capture devices, in one-to-one direct correlation with a respective print head, may even be movable along a sliding track upon which its respective print head is capable of traversing. 
     Once the output document image data  134  is acquired, it is transmitted to the image processor and comparator  118  (Event  210 ). The image processor and comparator  118  upon receipt of the data then stores it, and performs an analysis of the output document image data  134  as stored with the input document image data  132  as stored (Event  212 ). This analysis process begins with a comparison between the sets of image data to identify any shared or common data points. In keeping with the example herein, the shared or common data points between the input document image data  132  and the output document image data  134  as acquired include those data points representative of the pre-existing address block  102  and the smudge  104 . 
     Once the common data points are identified, the analysis continues with a subtraction of the common data points as shared between the two image data sets from the output document image data  134  (event  214 ). Again, with respect to exemplary  FIG. 1 , the subtraction of the common data points—i.e., that related to the pre-existing address block  102  and the smudge  104 —from the overall data points that comprise the output document image data set  134  yields image data representative of the actual printed data. The actual printed data in this case would be data points representative of address block  116 , horizontal line  115  and barcode  114 . 
     Having determined the actual printed data, the analysis may continue with a comparison of the actual printed data and the expected print data  122  (Event  216 ). This comparison or match process may involve translation of the image data into composite print file data points, or vice versa, for enabling the comparison. Nevertheless, verification of a match between the expected output and the actual output should sufficiently reveal whether a quality print resulted. If the actual printed data is equivalent to the expected print data  122 , this indicates that there was sufficient print quality (Event  218 ). When the actual printed data is not equivalent to the expected print data  122 , this indicates that there was failed print quality (Event  220 ). With this in mind, a verification of failed print quality would be the outcome with respect to the exemplary output document  130 , upon identifying the defect as shown in  160 . Pursuant to this verification, additional procedures may be employed to correct the defective print head—i.e., print head  110  corresponding to the particular defect identified at  160 —including replacement, cleaning or the like. 
     Skilled practitioners will recognize that various techniques exist today for performing the various image analytics described above, including but not limited to image comparison, pixel subtraction, image matching, and image compensation as described above. Interpretation of the various image data may be performed in whole or part via the usage of various object character recognition (OCR) or other image data processing techniques. Typical OCR utilities include an optical scanner for reading numeric or alpha-numeric characters, and sophisticated software for analyzing images and graphic primitives. Alternatively, the OCR system may include a combination of hardware (e.g., specialized circuit boards) and software to recognize characters, or can be executed entirely through software operating within the image processor and comparator  118  or within the imaging devices  124  and  126  themselves. As yet another alternative, in instances where the imaging capability of the image processor and comparator is not direct, the image processing functions may be performed externally (e.g., by an independent processor), and subsequently communicated to the image processor and comparator  118  over a network. Those skilled in the art will recognize that various OCR utilities and configurations may be employed for the purpose of analyzing image data. Indeed, any technique is within the scope of the teachings herein. 
     It should be noted that the imaging devices  124  and  126 , and print device  106  may all function as individual components of an in-line system, such as an inserter device or high speed print item production device. Such devices may feature a transport mechanism upon which print items may be directed along a transport path, whereupon the imaging systems and/or printer may operate upon a given print item. Generally, the imaging devices  124  and  126  and print device  106  would be positioned along the transport, within close range of the print item, for accommodating the movement of the print item at high speeds. Of course, those skilled in the art will recognize that any particular arrangement is within the scope of the art, and that even offline processes may benefit from the approach presented herein. 
     Although the discussion above has focused largely on the methodologies, those skilled in the art will recognize that those methodologies may be controlled or implemented by one or more processors/controllers, such as one or more computers or servers (ref. numeral  118  in  FIG. 1 ). Typically, each such processor/controller is implemented by one or more programmable data processing devices. The hardware elements operating systems and programming languages of such devices are conventional in nature, and it is presumed that those skilled in the art are adequately familiar therewith. 
       FIGS. 3 and 4  provide functional block diagram illustrations of general purpose computer hardware platforms.  FIG. 3  illustrates a network or host computer platform, as may typically be used to implement a server.  FIG. 4  depicts a computer with user interface elements, as may be used to implement a personal computer or other type of work station or terminal device, although the computer of  FIG. 4  may also act as a server if appropriately programmed. It is believed that those skilled in the art are familiar with the structure, programming and general operation of such computer equipment and, as a result, the drawings should be self-explanatory. 
     For example, image processor and comparator  118  may be a PC based implementation of a central control processing system like that of  FIG. 4 , or may be implemented on a platform configured as a central or host computer or server like that of  FIG. 3 . Such a system typically contains a central processing unit (CPU), memories and an interconnect bus. The CPU may contain a single microprocessor (e.g. a Pentium microprocessor), or it may contain a plurality of microprocessors for configuring the CPU as a multi-processor system. The memories include a main memory, such as a dynamic random access memory (DRAM) and cache, as well as a read only memory, such as a PROM, an EPROM, a FLASH-EPROM, or the like. The system memories also include one or more mass storage devices such as various disk drives, tape drives, etc. 
     In operation, the main memory stores at least portions of instructions for execution by the CPU and data for processing in accord with the executed instructions, for example, as uploaded from mass storage. The mass storage may include one or more magnetic disk or tape drives or optical disk drives, for storing data and instructions for use by CPU. For example, at least one mass storage system in the form of a disk drive or tape drive, stores the operating system and various application software as well as data, such as print scheme instructions and image data generated in response to the verification operations. The mass storage within the computer system may also include one or more drives for various portable media, such as a floppy disk, a compact disc read only memory (CD-ROM), or an integrated circuit non-volatile memory adapter (i.e. PC-MCIA adapter) to input and output data and code to and from the computer system. 
     The system also includes one or more input/output interfaces for communications, shown by way of example as an interface for data communications with one or more other processing systems such as the printing device  106  and imaging devices  124 ,  126 . In a document production environment, such as in the case of an inserter computer communications may extend to other reader equipment and to various inserter elements. Although not shown, one or more such interfaces may enable communications via a network, e.g., to enable sending and receiving instructions electronically. The physical communication links may be optical, wired, or wireless. 
     The computer system may further include appropriate input/output ports for interconnection with a display and a keyboard serving as the respective user interface for the processor/controller. For example, a printer control computer in a document factory may include a graphics subsystem to drive the output display. The output display, for example, may include a cathode ray tube (CRT) display, or a liquid crystal display (LCD) or other type of display device. The input control devices for such an implementation of the system would include the keyboard for inputting alphanumeric and other key information. The input control devices for the system may further include a cursor control device (not shown), such as a mouse, a touchpad, a trackball, stylus, or cursor direction keys. The links of the peripherals to the system may be wired connections or use wireless communications. 
     The computer system runs a variety of applications programs and stores data, enabling one or more interactions via the user interface provided, and/or over a network to implement the desired processing, in this case, including those for processing document data as discussed above. 
     The components contained in the computer system are those typically found in general purpose computer systems. Although summarized in the discussion above mainly as a PC type implementation, those skilled in the art will recognize that the class of applicable computer systems also encompasses systems used as host computers, servers, workstations, network terminals, and the like. In fact, these components are intended to represent a broad category of such computer components that are well known in the art. 
     Hence aspects of the techniques discussed herein encompass hardware and programmed equipment for controlling the relevant document processing as well as software programming, for controlling the relevant functions. A software or program product, which may be referred to as an “article of manufacture” may take the form of code or executable instructions for causing a computer or other programmable equipment to perform the relevant data processing steps regarding document printing and associated imaging and print quality verification, where the code or instructions are carried by or otherwise embodied in a medium readable by a computer or other machine. Instructions or code for implementing such operations may be in the form of computer instruction in any form (e.g., source code, object code, interpreted code, etc.) stored in or carried by any readable medium. 
     Such a program article or product therefore takes the form of executable code and/or associated data that is carried on or embodied in a type of machine readable medium. “Storage” type media include any or all of the memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the relevant software from one computer or processor into another, for example, from a management server or host computer into the image processor and comparator. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution. 
     Hence, a machine readable medium may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the sorting control and attendant mail item tracking based on unique mail item identifier. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media can take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer can read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution. 
     While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.