Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
  • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
  • G06K19/06009—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code with optically detectable marking
  • G06K19/06046—Constructional details
  • G06K19/06075—Constructional details the marking containing means for error correction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
  • B42D25/22—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose for use in combination with accessories specially adapted for information-bearing cards
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
  • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
  • G06K19/06009—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code with optically detectable marking
  • G06K19/06037—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code with optically detectable marking multi-dimensional coding
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V10/00—Arrangements for image or video recognition or understanding
  • G06V10/88—Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F3/00—Labels, tag tickets, or similar identification or indication means; Seals; Postage or like stamps
  • G09F3/02—Forms or constructions
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F3/00—Labels, tag tickets, or similar identification or indication means; Seals; Postage or like stamps
  • G09F3/02—Forms or constructions
  • G09F3/0297—Forms or constructions including a machine-readable marking, e.g. a bar code
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
  • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
  • G06K2019/06215—Aspects not covered by other subgroups
  • G06K2019/06225—Aspects not covered by other subgroups using wavelength selection, e.g. colour code

Definitions

• This invention relates to the field of identification, more particularly to identifying objects by means of labels, and most particularly to labels which are adapted for reading by machine (that is, a digital computer).
• image capture is carried out in possibly adverse circumstances, such as outdoors or where part of the label may be obscured, lost, or contaminated, curled up, or in shade, or the label may be presented obliquely or unsharply,
• (e) labels may be out of reach to a bar-code scanner or the like.
• a particular application is in tracking cut tree trunks (lumber) from felling to export.
• logs are accumulated before loading onto a truck
• it is customary in some forests to attach a pre-printed bar-coded label to the cut end of the trunk in order to identify the tree, which is separately described in relation to ownership, volume, quality, type, and the like.
• the bar-code and the associated data are later entered into a management computer database.
• a barcode is not easy to read later, when for example the log may be one of many on a moving truck, or in a cradle being loaded onto a ship.
• the invention provides a machine-readable label as defined in claim 1, in another aspect the invention provides a set of labels as defined in claim 4 or in another aspect the invention provides a method of identifying one or more items at a site as defined in claim 9.
• the invention comprises a computer-readable label or symbol for identification purposes, comprising a matrix of computer-readable indicia; each indicium containing at least one element of readable information, and in which the matrix of information includes an error-correcting code and at least one indicium serves as a locator to provide a reading machine or computer with the location of the remainder of the matrix.
• the error-correction code is a cyclic code capable of coping with individual bit errors.
• the error-correction code is the BCH code, or a derivative of it, such as a shortened BCH code.
• each of the computer-readable indicia is provided with one of an optically detectable, defined range of specific levels of brightness.
• the label is capable of scattering or reflecting light, and accordingly brightness levels are equivalent to reflectance levels.
• the label is, for the purpose of reading, capable of being illuminated by a transducer-compatible source of electromagnetic radiation.
• the resolution or density of pixels in the image-collecting device of the reading machine is such that an area of at least three by three of the sampling elements used by the reading machine is provided to at least partially cover each indicium.
• the label is surrounded on at least one side by an outer edge composed of a relatively bright surface which is preferably at least three sampling units wide.
• this surface corresponds to the white level of the grey scale.
• At least two sets of indicia serve as locators.
• the locators are, on detection, capable of providing a reading machine with information defining the location (that is, position and/or orientation) of the remainder of die matrix.
• each such locating indicium comprises at least one matrix element surrounded by a field of contrasting matrix elements.
• the matrix element or elements of any one locating indicium may also be used to indicate a step or steps of a scale of brightnesses.
• each cell of the matrix of computer-readable indicia is optically detectable and preferably each indicium has a determined reflectance.
• each cell of the matrix of computer-readable indicia is provided with one of two contrasting reflectances.
• each cell of the matrix of computer-readable indicia is provided with one of more than two contrasting reflectances.
• any cell may be composed of a material having an intermediate level of reflectance.
• the or each intermediate level is evenly spaced between the brightest and darkest levels.
• the optical characteristics of a range of cells providing different levels in a scale may include a type of reflectance which is perceived as a contrasting level by an array of sensors comprising more than one set, each set having a response pattern dependent in a different way on the characteristics of the reflected energy.
• each cell may comprise an array of a plurality of dots of one contrasting surface placed upon a substrate of another contrasting surface in variable proportions in order to simulate intermediate levels of reflectance.
• each cell is large enough that when the anticipated environmental "noise" is superimposed on it, the preferred error correction process sees the interference as random noise rather than burst noise affecting adjacent pixels.
• the matrix of information-carrying indicia is read in a consistent order so that in use each indicium comprises a predetermined part of an array of information, incorporating means for detecting and correcting any errors.
• the error-correcting code is a shortened BCH code.
• the error-correcting code is a full BCH code.
• any other error-correcting code capable of replacing the intended information in the event of corruption of cell brightness may be used.
• a printing device is provided with a generator of printable patterns according to the ternary shortened BCH code information protocol of this invention so that a series of unique labels, compatible with the computer reading process, can be generated.
• a preferred generator of printable patterns comprises a computer capable of receiving a string of characters and converting them into a matrix of cells together with error-correcting code, as described previously in this section.
• the generator of printable patterns may provide a translation of the design and error-correcting codes into a language or form suitable for use in a printer to actually produce the image.
• a preferred label comprises at least a damage-resistant substrate and a display surface capable of holding the indicia of the label.
• the label also includes bar-code and human-readable indicia.
• the invention includes a reading machine which is capable from time to time of capturing an image of a field of view, which may include one or more labels, and holding the image internally in a form comprising a matrix of sampled points each of which may be mapped to a corresponding point within the image.
• an illumination device is provided to flood a field of view with electromagnetic radiation at least during the period of capturing the image.
• a scanning illumination device may be used to illuminate a field of view, in a sequential fashion.
• the reading machine includes a solid-state camera electrically coupled to at least one addressable memory plane accessible to a digital computer operating under a stored program, and includes an output interface.
• a solid-state camera electrically coupled to at least one addressable memory plane accessible to a digital computer operating under a stored program, and includes an output interface.
• the output from the reading machine comprises the information contained within the or each label.
• the reading machine may be physically separated into an image collection portion and an image analysis portion, separated by a communications link.
• the reading machine may be non-optical; that is, it may use microwave radiation or sound (preferably ultrasonic sound) to illuminate a field and collect radiation from discrete sites of the field preferably using phased and/or time-controlled illumination, together with a suitable detector.
• microwave radiation or sound preferably ultrasonic sound
• the symbol and its indicia shall preferably exhibit varying yet controlled degrees of reflectance to the non-optical illumination.
• the reading machine locates the position and orientation of any one label in an image containing one or more labels by first detecting the characteristic appearance of a set of one or more accompanying locators.
• the reading machine determines the actual reflectance of the label by a process of determining the most reflective and the least reflective portions and scaling the apparent reflectance accordingly.
• the reading machine compensates for uneven regional illumination on any one label by examining the apparent brightness of the outer edge and compensating the apparent brightness of the adjacent matrix accordingly.
• the reading machine shall be capable of determining the relative levels of the steps of a grey or colour scale, if any, using the range of reflectances included within locating indicia, so that in use any indicium can be assigned to a corresponding and known level in the scale of reflectances in use.
• the reading machine may be capable of locating the matrix of data cells without the aid of the locators, and in that case it would carry out a series of trial readings until it detected that a reading was valid.
• Fig 1 is an illustration of a computer-readable symbol of the present invention.
• Fig 2 is an illustration of a combined human-readable symbol array, a bar-code array, and a computer-readable symbol upon a printed label of the present invention, ready for use.
• Fig 3 is a block diagram of the processes of the present invention.
• Fig 4 is a grey-scale rendition showing the software analysis process for a symbol according to the present invention.
• PREFERRED EMBODIMENT This invention comprises a computer-readable label or symbol for identification purposes.
• This generally optical label has been optimised in particular for applications where (although at the same time the label shall be as small as possible):-
• image capture is carried out in possibly adverse circumstances, such as outdoors or where part of the label may be obscured, lost, contaminated, lost in shade, curled up, or the label is presented obliquely or unsharply,
• these labels are used to identify tree trunks, or logs.
• Each pre-printed label (which simply serves as a unique identifier) is attached to the cut end of a log and an accompanying bar-code is scanned or the alphanumeric characters are noted down.
• Other data such as quality and ownership are also noted and stored in a master database along with the corresponding label number, so that as the log passes through a series of stations it may be identified and (for example) its ownership may be established.
• these stations are along a transport chain such as trucking, then shipping, then trucking to a destination sawmill.
• a camera system and image analysis procedure capable of snapping a picture of the ends of a bundle of logs while held on a truck or in a cradle, detecting all labels, decoding the data, and passing it to the management system.
• logs are usually placed in a cradle by a lifting machine. A sling is passed around the cradled logs, and they are lifted into the ship. While the logs are in the cradle, they can be photographed.
• error rate specifically a bad label report error, in which a wrong number is unknowingly delivered
• error rate a bad label report error, in which a wrong number is unknowingly delivered
• Another conflicting requirement is to use a low-cost and hence low-resolution digital camera, possibly with an imperfect CCD chip, to capture images.
• a further conflicting requirement is tolerance to damaged or obscured or dirty labels.
• another requirement is tolerance to variable levels of lighting.
• a 6 x 7 matrix of squares each of which may be coloured white, grey, or black.
• Each cell is a minimum element of the information carried by the label.
• This label uses a ternary number base. Some of the 56 cells are reserved, in example labels, for locators (see later) and some are reserved for the site of a conventional barcode.
• Fig 2 shows an example label as it would be used, in which the "ternary BCH" code 100 of the present invention, together with corresponding alphanumeric descriptors (202, 207), an owner's name and/or logo 206, and a corresponding barcode 203 are provided.
• BCH stands for a preferred error correction procedure.
• 205 indicates optional descriptors.
• 204 is an optional tear line for separating part of the label for separate processing.
• This label has a border 201 , merely representing the edge of the paper or like substrate for the symbols.
• Fig 1 shows the actual data cell section itself.
• the actual label 100 has no actual border or boundary, though preferably a space at least three sampling units wide which is preferably in the maximum reflective state (i.e. white) is provided about the entire bar code for reconstructing detailed illumination variation, if required.
• Each unit cell (101,105, 108, 109) is shown here as a dark grey, a speckled, or a white square. (We cannot display squares as black in this specification owing to restrictions on patent drawings - no solid blacks are allowed). Nevertheless, in printed labels the darkest portions are actually black (although as will be elaborated later, a ternary system having three grey levels need not be stretched to either limit of reflectance).
• the locators are shown as cells 101, 102, 103 and 104 together with the surrounding contrasting space such as the space 107. This space is reserved.
• the data matrix 106 may extend about the locators.
• the un-used space between the locators 103 and 104 is reserved in our example label for a bar code 203.
• Future versions of this labels may even cover 256 steps in each of red and green and blue channels giving 2 24"1 combinations per cell, if printing and reading technology (to say nothing of fading inks in daylight) allow such resolution in a cost-effective package.
• a machine version of human-type colour with at least two channels, and perhaps extending to infra-red or ultra-violet) in any one cell, may be used.
• a ternary scale made by black "ink" is preferred.
• the label is sized with respect to the image capture device and intermediate factors (distances, focusing elements and the like) so that each cell at least partially covers at least three pixels and preferably has a spatial resolution corresponding to four pixels per cell along both a horizontal and a vertical line, (or sampling elements, applicable if a scanner and A-D converter is used instead) which are internal to the reading machine.
• This size requirement allows for rejection of pixels that overlap a transition in the label or possibly their incorporation in more sophisticated analysis, or in label reconstruction should a label image be compromised. (It is not generally possible to repeat a photograph in the target environment). It also allows for some latitude in focusing the label onto the image plane of the sensor, or movement smearing or the like. It also allows some latitude for use of cameras that have defects in their CCD arrays. Such defects are well known and include isolated cell defects, row defects, and/or column defects. (Defect-free cameras exist, but dust spots or crystal imperfections can arise from time to time during manufacture and so defect-free cameras command premium prices).
• the external space (see later) is particularly used to determine gradations of illumination over any one label. It should preferably be at least one matrix square (or three pixels of the reading machine's camera) wide, although conveniently it can be wider.
• Each set or locating indicium comprises at least one cell or matrix element 101 surrounded by a field of contrasting matrix elements 107; and generally the surrounding field is white.
• the software is able to determine the intended reflectance of any cell once it can measure the actual brightness of the locators and their surrounding fields, and thereby compensate for variations in lighting or exposure that may otherwise detract from accuracy.
• the locators are, on detection, capable of providing a reading machine with information defining the location (that is, position and/or orientation) of the remainder of the matrix.
• the software uses sub-pixel accuracy to determine locator position.
• no locating indicia are used; in that case the reading machine attempts to make sense of a postulated matrix of cells by a process of repeated trials at different locations and orientations.
• the preferred BCH (Bose-Chaudhuri-Hocquenghem) code family developed in 1959 and 1960, can be regarded as a generalised form of Hamming codes for correcting multiple errors. They are cyclic, constructive codes suitable for communication channels in which errors affect successive symbols independently.
• the well-known Reed-Solomon codes appear to be a special case of BCH codes.
• Fig 3 shows a data processing system 300 for identifying logs.
• a device 301 to generate preferably unique patterns of "ternary BCH” symbols including data, an error code, and locators, with other label material (see Fig 2) according to this invention sends data to a printer 302.
• a preferred printer language is "Postscript".
• the printer may be located at a forest site, or may simply prepare a large stack of labels for field use.
• 303 represents a stack of labelled logs, in front of a camera 304 which passes a digital signal to a Wide Area Network interface 305, which transmits the signal to a receiver 306, then to an image analysing computer 307. This reproduces the data 308 originally contained in the ternary BCH symbols.
• a device 301 to generate data cell matrices based on the preferred ternary BCH code placed at the site where labels are printed, so that a series of unique labels can be generated.
• a computer-driven printing machine 302 is preferred, and one kind is a conventional laser printer applying fused toner to a preferably damage-resistant paper, while another preferred kind is a "Printronics" L5024" type that uses an xenon flashlamp to fuse toner onto a substrate which can include vinyl, a material that has a melting point lower than the temperature used in normal laser printers.
• This machine has the additional benefit that its blacks are matt. Shiny blacks appear white to a camera with a side-mounted flash lamp.
• each cell as printed may comprise an array of a plurality of dots of one contrasting surface placed upon a substrate of another contrasting surface in variable proportions in order to simulate intermediate levels of reflectance; a grey level.
• dots that are about 1 mm square, as shown in Fig 1 at 101, for example.
• the blacks should preferably be matt and not reflective.
• a portable data-gathering station that can rove about a transport site such as a wharf; an individual wearing a backpack and holding the camera is envisaged.
• a battery-driven hand-held solid-state camera 304 containing a CCD chip with an X-Y array of for example 1000 pixels high by 1500 across.
• a "KODAK" DCS 420 camera (IR version) with 1536 x 1024 pixels is in use.
• a higher resolution camera would of course have advantages, but cameras of the preferred type are available as off-the-shelf items from several suppliers, and minimal or (by the use of active correction) minimised-defect examples may be found.
• This camera is assisted by a conventional flashgun, though we prefer to use a flash of infra-red light so that (among other reasons) other people in the yard are not distracted or blinded by the use of the flash, especially at night. Some people are driving 50-tonne log-carrying trucks near the cradles being photographed.
• a Wratten 25 filter on the camera preferably coupled with a filter to block infra-red light beyond about 800 nm; thus admitting the 550-900 nm range to the silicon-based CCD device.
• This red filter allows aiming by the operator. Red or infra-red light may enhance the contrast between the labels and the background of wood which is the usual background.
• a narrow-band source and a narrow-band filter over the camera lens would minimise the contribution of ambient light to the image, and we are experimenting suitable filters. Because the camera is expected to make at least 240 pictures in a four-hour spell between battery changes it is not practical to use a very bright flash (with heavy batteries) to overcome ambient light.
• the camera passes digital image data out for processing as soon as one image has been collected, although as supplied it includes a hard-disk storage device to store about 60 - 70 images.
• a preferred camera lens is an 18 mm fisheye lens, as this allows the operator to approach the cradle or other holder of logs and illuminate it well with the flash lamp, and minimises focus errors especially those caused by an irregular or uneven object plane.
• the CCD sensitive area comprises a small central part (about 10 x 20 mm) of the 24 x 36 mm image plane of the modified "Nikon" camera and a normal or telephoto lens would necessitate too great a working distance for this application.
• a reading device which scans an area with a pencil beam from a laser may be used in some applications, but the total reading time would tend to be too great for a hand-held device. It may be more suitable for a more controlled environment, such as a fixed camera platform reading labels on steadily moving objects such as railway wagons.
• Non-optical images may be used in some applications and for example it might be possible to read suitably created labels inside other structures using microwave or ultrasonic holographic techniques. This may be useful for finding labelled sheets of paper filed within a stack, for example in an office.
• the camera output carrying the image does not (in the preferred embodiment) go directly to a memory plane for image analysis; there is an intermediate data transmission step.
• the camera output may be coupled with other information. For example we digitally encode some variables such as backpack battery condition and transmit this to the base station.
• the ship and the hold of the ship into which logs from that cradle are being loaded may be written on the cradle so that that data is also recorded.
• the image processing computer is relatively large and complex it is housed remotely and data is sent to it over a "Novell" wireless wide-area network system 305 operating at around 2.3 GHz with a 200 Kb/second transmission rate.
• the image data is (at present) an uncompressed TIFF format file and each image is about 1.5 Mbytes in size, so the transmission time is about 8 seconds.
• the camera is connected to a dedicated portable PC constructed in a small case. The case, with batteries, is placed in a backpack. It runs on 12 volts, and is fitted with a self-booting program that downloads its operating programs over the network, then transmits image data together with some additional information, such as the log count and computer and camera battery condition, to a base station 306.
• the log count may be independent, perhaps the operator uses a "sheep counter" or perhaps a stick-shaped device with a counter that also squirts a marker like paint on a log as it is pressed against it.
• Input to this computer is via a preferred "Novell" network and the output 308 may also be sent through a network or by modem to a management database located at some distant site.
• One image processing computer can handle images from several cameras in use at the same transport yard, which may be a dock where several cradles of logs are being loaded at one time.
• any valid labels will be of a certain approximate size, wherein the image of each blob is about 4 pixels by 4 pixels, in order to include an entire cradle of logs in one field of view. Camera operators are told to stand at about a certain distance from the subject. It will be clear that other sizes can be accommodated by either having the program use a scanning approach, perhaps starting with the last suitable "zoom factor” or by programming in a different constant zoom factor.
• Our preferred camera (having a limited number (1536) of image pixels across) gives an about 3 mm square (as referred to the label) pixel size.
• a larger number of camera pixels will provide (a) smaller labels, or (b) more precise reading with more redundancy of data, or (c) more logs on a cradle, but on the other hand 1.5 Mb of data is quicker to transmit and analyse than 16 or even 4 Mb.
• the picture (which may optionally be reconstructed at this point if a defect is recognised) is scanned across perhaps every scan line or row to locate dark blobs of about the right size and edge characteristics.
• the XY co-ordinates of each located blob are saved.
• a suitable dark blob is one in which the brightness declines from a lighter background level to a darker in-blob level, and remains at the darker level for one or two pixels at least, and then rises at about the same rate.
• a graph of displacement/ brightness would have a trapezoidal form.
• the program is quite flexible at this stage about the actual value of a light area or a dark blob, so that varying lighting conditions within a single image can be 20 dealt with. For example a short log bearing a label might be recessed from normal sized logs, so its label would be apparently much darker than the others.
• 25 product is averaged, in both directions.
• some further blob validation is done (such as symmetry, for asymmetrical dark blobs are not like the preferred locators, aa contrasting (usually white) locator border, and the like).
• An accurate centre determination assists in recovering the data from the central pixels of each cell of the information matrix.
• Neighbouring blobs are now located and attempts are made to form "pairs" - blobs at about the right distance from each other that comply with the expected distances between locators.
• Rectangles are then formed by trying to find a fourth blob at about the right position from both the outer blobs. Note that we are tolerant of actual rectangle accuracy; it would be more correct to call the formed areas quadrilaterals. Lens errors, labels which are not perpendicular to the optical axis, and some damaged labels (for example) will give rise to valid, though non-rectangular sets of data.
• a data area is set up within it and the data cells are categorised. Particularly relying on the locators' density values and that of the neighbouring white area, a scale of what is black (i.e. falling within a certain range of densities), what is grey (a distinct and higher range), and what is white (another distinct and even higher range) is constructed.
• the data cells are read as ternary information in a specific order, after orientation has been established by examining the relative darkness levels of the locators, which indicate orientation.
• the "easy label" data cell data is then passed to a decoder, which extracts the actual ternary information, applies error correction, and reports the information in the usual decimal form.
• error conditions such as a splash of mud or the like are detected and corrected through action of the BCH error check.
• the program now reverts to its "too-hard” stack and attempts to recategorise the data cells. Some of the contents of this stack may not be labels at all - just coincidentally similar sets of pixels. Partially shaded labels are dealt with by
• the error correction algorithm (BCH or similar) is applied although if too many bits are lost the information may be unreadable.
• the decoder takes account of orientation, as indicated by the relative intensity of the locator blobs.
• Fig 4 illustrates, at 400, output from a development option of the program.
• the label in this example illustration is inverted and was optically distorted by lens aberrations.
• the size of individual pixels used in the capture of an image is clearly shown as small squares - this illustration is but a small portion of an entire captured image.
• the software has picked out four locators; 402, 403, 404 and 407. It has ignored other dark masses which failed to satisfy the criteria for a locator, which criteria include a certain range of permitted sizes, and a contrasting zone 405 surrounding each locator. Dark masses which were ignored include the data matrix 401, the bar-code array 410, and other dark material 409 in the image.
• the software has verified that the locators belong together, after centroid location of their centres, by constructing a rather crude rectangle (lines and diagonals shown as 408).
• the software has then identified a matrix of 7 x 6 points, and marked them by crosses 406 overlying the expected centres of cells carrying data.
• these crosses are in red, green, or blue corresponding to the ternary values (0,1 or 2) detected by reading the value of the underlying pixel. Not shown is the process for allocating a point on a grey scale to each cell, (which might be shown as a frequency histogram) or compensation for uneven lighting.
• non-rectangular cell markings or indicia such as more prominent locators, which may be circular or elliptical or of any other shape (perhaps a company logo may be one of these).
• Reflective locators may be used for higher contrast. Labels printed on a retro-reflective surface (that is, one which returns light substantially back towards its source) may be used, and in that case the intensity of the flash may be lessened which at least assists the person carrying its battery pack.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Multimedia (AREA)
• Image Processing (AREA)
• Handling Of Sheets (AREA)
• Labeling Devices (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

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• 1996
  • 1996-03-18 AU AU51271/96A patent/AU5127196A/en not_active Abandoned
  • 1996-03-18 CA CA002215026A patent/CA2215026A1/en not_active Abandoned
  • 1996-03-18 HU HU9801931A patent/HUP9801931A3/hu unknown
  • 1996-03-18 EP EP96907801A patent/EP0817727A1/en not_active Withdrawn
  • 1996-03-18 WO PCT/NZ1996/000021 patent/WO1996030217A1/en not_active Application Discontinuation
  • 1996-03-18 KR KR1019970706907A patent/KR19980703503A/ko not_active Application Discontinuation
  • 1996-03-18 JP JP8529229A patent/JPH11502654A/ja active Pending
  • 1996-03-18 BR BR9607985A patent/BR9607985A/pt not_active Application Discontinuation
  • 1996-03-20 TW TW085103344A patent/TW318916B/zh active
  • 1996-03-22 ZA ZA962295A patent/ZA962295B/xx unknown
• 1997
  • 1997-09-09 FI FI973635A patent/FI973635A/fi unknown
  • 1997-09-16 NO NO974285A patent/NO974285L/no unknown

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