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    • 专利摘要:
    The invention relates to a method for identifying a two-dimensional dot code in digital image data of the dot code, the dot code comprising elements of a first and second type, which are arranged in an ordered grid, and having a contour which is an L-shaped clock line with transitions between the First and second type elements and an L-shaped continuous line without transitions between the first and second type elements, wherein approximate corners in the digital image data determine first and second pairs of opposite edge segments along the contour, the method comprising scanning a first one sequentially Edge segment and optionally scanning a second edge segment for a first pair and a second pair, identifying the edge segment of the first pair and the edge segment of the second pair as the L-shaped clock line of the point code, and identifying the edge segment of the first Pa ares and the edge segment of the second pair as the L-shaped solid line of the point code. The invention further relates to a device for identifying point codes.
    公开号:CH708993B1
    申请号:CH00511/15
    申请日:2013-04-30
    公开日:2017-06-15
    发明作者:Aspert François；Bégard Julien；Leroux David
    申请人:Sicpa Holding Sa；
    IPC主号:
    专利说明:

    Description Technical Field The present invention relates to identifying a two-dimensional dot code (bar code).
    More particularly, the present invention relates to a method for identifying a two-dimensional point code in digital image data of the point code, a device configured to identify a two-dimensional point code, in particular, portable devices and fixed modular devices. The present invention also relates to computer-readable media.
    Background Nowadays, one-dimensional and two-dimensional point codes are omnipresent in the form of so-called "labels". In particular, such point codes are found on consumer goods, electronic and non-electronic devices, machines, vehicles, and also on documents such as tickets, papers, banknotes, etc. In addition to the one-dimensional point code, the two-dimensional point code has gained importance in recent years. While the one-dimensional point code is classically limited to coding information in only a linear dimension, the two-dimensional point code, which comprises elements arranged in an ordered grid of at least a first and second type, allows a significant increase in the amount of data that can be encoded.
    Figures 1A and 1B are schematic views of conventional two-dimensional point codes encoding information by arranging elements of at least first and second types such as rectangles, dots, triangles, and the like for encoding information. At least two distinguishable types of elements are used to store information in the form of binary units, i. Bits, to encode. For example, a white-printed square may represent the information "0" as an element of a first type, while a black-printed square as an element of a second type represents the information "1".
    Fig. 1A shows a schematic view of a two-dimensional dot code according to the GS1 (Trade Mark) Data Matrix ECC 200 Standard (where GS1 is an international association providing standards for two-dimensional point codes). This two-dimensional point code comprises two main areas, namely the so-called "finder pattern" 10 and the data 20. The latter data 20 carry the actual payload data of the point code and comprise elements of a first and second type, 21, 22 arranged in an ordered grid. The finder pattern 10 also consists of the elements of the first and second types and is in turn in the so-called "L-finder pattern" 11 (also referred to as L-shaped solid line, L-line, solid line, etc.) and the so-called "clock track" 12 (also referred to as a clock line, L-shaped clock line, etc.) divided.
    According to a convention, the timing line 12 is formed by linearly alternating the arrangement of the first and second type elements 21, 22. Therefore, the clock line 12 provides transitions between the first and second type elements 21, 22 while the solid line 11 does not. Both segments (or legs) of both the continuous line 11 and the tact line 12 intersect each other at a corner substantially at a right angle. Thus, a rectangular-shaped contour of the two-dimensional dot code is formed by the solid line 11 and the clock line 12.
    According to another convention, the intersecting element (intersection element) of the two segments of the timing line 12 is of a predetermined type, either of the first type 21 or the second type 22. In particular, an actual convention defines this intersection element 13 as a light element, for example in the context of the present disclosure, an element of the first type, in contrast to dark elements, for example in connection with the present disclosure, a second type element.
    While Fig. 1A shows a quadratic version of the dot code of DataMatrix 1, the current conventions are not limited to square point codes and Fig. 1B shows an example of a rectangular implementation 1 '. The two-dimensional point code is again delimited by a contour comprising an L-shaped continuous line 11 'and an L-shaped clock line 12'. However, since the general contour is not limited to squares, one segment 111 'of the continuous line 11' may be shorter than the other segment 112 'of the continuous line 11'. Accordingly, one segment 121 'of the timing line 12' may be shorter than the other segment 122 '.
    In general, the elements of the first and second types 21, 22 may take any distinguishable form. This aspect is illustrated in FIG. 2A, which shows the first-type element 21 as a general right-hatched square / rectangle and the second-type element as a general left-hatched square / rectangle 22. This generalization stems from the fact that a two-dimensional dot code is not necessarily printed on white paper using, for example, a black dye. Rather, the two-dimensional point code can also with the help of colored dyes or inks; Thermal printing on heat-sensitive paper; mechanical means, such as milling, embossing, grinding, etc .; or physical / chemical agents, such as laser etching, acid etch, etc. Any type of implementation is possible, as long as the elements can be distinguished in their corresponding manner, for example in digital image data obtained from the two-dimensional point code.
    For example, a digital camera may obtain digital image data of a two-dimensional dot code printed on a paper document or laser etched on a metal can.
    In addition, the various printing techniques can also lead to different "qualities" of a two-dimensional point code. Apart from the more or less optimal representation (as shown for example in FIGS. 1A and 1B), implementations with individual elements such as those shown in connection with FIG. 2B are also possible. In this case, even the solid line 11 between two adjacent elements of the same kind 22 interruptions. However, the average width of such breaks may still ensure the characteristics of no element type transition between adjacent elements, as shown at reference numeral 28. On the other hand, a transition between the element type by means of the characteristic width of the interruption, as shown by reference numeral 29, can be further identified.
    Fig. 2C shows a somewhat opposite situation in which even diagonally adjacent elements merge. However, in this case too, it is assumed that the elements of the first and second types can be distinguished and that their corresponding assignment to positions in an ordered grid is still possible.
    The decoding of a two-dimensional dot code usually begins with the acquisition of a photographic image of the two-dimensional dot code on a particular object, such as a consumer item or a document. This image is then obtained in the form of digital image data defining corresponding pixel values for the pixels of the image. These digital image files are then subjected to image processing by means of a processing unit (e.g., CPU, computer, server, embedded system, ASIC, etc.). Such processing can be divided into several individual steps to ultimately decode the data encoded in the two-dimensional point code.
    Since the taking of the two-dimensional dot code is usually recorded with an arbitrary perspective, it means that the exact distance, angle and general orientation of the pickup device (e.g., a CCD camera) in relation to the two-dimensional dot code is unknown. Therefore, it may be necessary to first identify the shot or area of the two-dimensional dot code within the given digital image data. Once the two-dimensional point code has been identified in the digital image data, processing can continue to identify and decode the individual elements of the point code data.
    The initial steps of image processing may thus include the determination of so-called approximate vertices of the two-dimensional point code within given digital image files. Then the four segments joining these four approximate corners into a rectangle, or more generally a 4-sided polygon, can be scanned to determine the length in individual pixels and / or elements and the transition between first and second type elements to count.
    A conventional method for the above purpose comprises eight scans in which each of the four segments is first scanned to determine the length in terms of pixels and / or elements, and then scanned to determine the transitions between the elements first and second type along this segment. With this information, the long and short segments of the solid line, as well as the long and short segments of the bar line can be identified. The same applies to quadratic implementations of the two-dimensional point code in which the two segments of the clock line and the solid line have an identical length, at least with respect to the elements. The processing may then be continued to identify the payload data since the structure of the grid and the relative position of each identified element within that grid can be obtained.
    As the use of two-dimensional point codes becomes more frequent, the requirements for identifying and / or decoding two-dimensional point codes become more and more demanding. In particular, it may be necessary to quickly and reliably identify and / or decode a two-dimensional point code. For example, two-dimensional point codes can be used in manufacturing lines where a large number of individual items such as consumer goods (e.g., food packaging, metal cans, electronic devices, etc.) must be identified within a short time. A specific example could be a beverage can filling line where the individual cans pass a particular high speed observation point so that only a few milliseconds can be available to identify a single can. Therefore, a two-dimensional point code attached to the individual item must be identified and decoded within a few milliseconds or less.
    Therefore, there is a need for improved time efficiency of the existing identification and decoding schemes so that the total time required from capturing an image from two-dimensional point codes to ultimately obtaining the decoded payload data of the two-dimensional point code can be minimized. At the same time, however, the improved method is also intended to provide reliability in terms of correct identification and / or decoding of the two-dimensional point code.
    Summary The above-mentioned objects and problems are solved by subject matters of the independent claims. Further preferred embodiments are defined in the dependent claims.
    According to one aspect of the present invention, a two-dimensional dot code is identified in digital image data of the dot code, the dot code comprising first and second type elements arranged in an ordered grid and having a contour having an L-shaped timing line Transitions between elements of the first and second type and an L-shaped solid line without transitions between elements of the first and second type, wherein approximate corners in the digital image data determine a first and a second pair of opposite edge segments along the contour, said aspect comprising: Scanning a first edge segment of the first pair in the digital image data and counting the transitions between the first and second type elements along the first edge segment of the first pair; if no transitions along the first edge segment of the first pair have been counted, then scanning in the digital image data of the second edge segment of the first pair and counting the transitions between the first and second type elements along the second edge segment of the first pair; scanning in the digital image data of a first edge segment of the second pair and counting the transitions between the first and second type elements along the first edge segment of the second pair; if no transitions along the first edge segment of the second pair have been counted, then scanning in the digital image data of the second edge segment of the second pair and counting transitions between the first and second type elements along the second edge segment of the second pair; identifying the edge segment of the first pair and the edge segment of the second pair along which transitions have been counted as the L-shaped clock line of the point code, and identifying the edge segment of the first pair and the edge segment of the second pair along which no transitions have been counted , as the L-shaped continuous line of the dot code.
    According to another aspect of the present invention, a two-dimensional point code is identified in digital image data of the point code, the point code comprising first and second type elements arranged in an ordered grid and having a contour that is L-shaped Tact line with transitions between the elements of the first and second type and an L-shaped continuous line without transitions between elements of the first and second type, a crossing element at the corner of the L-shaped clock line, which is of a predetermined type of the first and second type wherein approximate vertices in the digital image data determine first and second pairs of opposing edge segments along the contour, the aspect comprising scanning in the digital image data of a first edge segment of the first pair and counting transitions between the first and second type elements along the first edge segment of the first couple; if no transitions along the first edge segment of the first pair have been counted, then scanning in the digital image data of the second edge segment of the first pair and counting the transitions between the first and second type elements along the second edge segment of the first pair; determining which extremity of the edge segment of the first pair along which transitions have been counted corresponds to the crossing element; scanning the edge segment of the second pair having the crossing element and counting the transitions between the first and second type elements along the edge segment of the second pair having the crossing element; identifying the edge segment of the first pair and the edge segment of the second pair crossing at the crossing element as the L-shaped clock line of the point code and identifying the edge segment of the first pair and the edge segment of the second pair that are not part of the L-shaped one Bar line are as the L-shaped continuous line of the point code.
    In other aspects, a related device and related computer-readable medium is provided.
    Brief Description of the Drawings Embodiments of the present invention, which are presented for ease of understanding the concepts of the invention and do not limit the invention, will now be described with reference to the drawings, in which:
    Figures 1A and 1B show schematic views of a square and rectangular implementation of a two-dimensional point code as one possible input for embodiments of the present invention;
    Fig. 2A is a schematic view of a general implementation of a two-dimensional point code as a possible input for embodiments of the present invention;
    Figures 2B and 2C show schematic views of another implementation of a two-dimensional point code as a possible input for embodiments of the present invention;
    Fig. 3 is a flowchart showing a decoding process of two-dimensional point codes in which embodiments of the present invention may be employed;
    Figures 4A to 4J show additional schematic views accompanying the description of the decoding process described in connection with Figure 3;
    FIGS. 5A and 5B show flowcharts of process details according to embodiments of the present invention;
    FIGS. 6A and 6B show flowcharts of process details according to embodiments of the present invention;
    Figs. 7A to 7C show schematic views of embodiments of devices of the present invention. Detailed Description Fig. 3 shows a flow chart of a possible decoding process that includes identifying and decoding a two-dimensional point code. This process begins with a raw image capture of the two-dimensional dot code that may be attached to an item or document. The recording is obtained in the form of digital image data from the two-dimensional dot code, for example, by conventional digital cameras, video cameras, CCD cameras, scanners, and the like.
    In a first step S1 (= THRESHOLD PROCEDURE), the digital raw input files are subjected to a threshold value operation for the purpose of binarizing the input recording. In general, the thresholding method involves marking individual pixels of the digital image files with respect to their pixel value. In the simplest form of the thresholding method, the pixel value of each pixel is compared to a threshold, e.g. each pixel having a value equal to or above this threshold is assigned to a first group, while all pixels having a value below the threshold are assigned to a second group. In this way, a binarized image is obtained which comprises only pixels of a first and second group. The purpose of the thresholding method is to provide a means to distinguish in the digital image data objects (of possible interest) from the background. Fig. 4A shows such a binarized recording according to the thresholding method in which the two groups are represented by the colors black and white. The image shows a number of features, one of which is already a good candidate for a two-dimensional point code.
    In optional step S2 (= RECALCULATION), the data obtained from the thresholding process can be rescaled to downscale the shot by a given factor. This can then significantly speed up the approximate location of the dot code in the digital image data. As long as no important features are lost through resizing, it is obvious that reducing the data to speed up any subsequent scan can significantly contribute. As shown in Figure 4B, scaling down by a fixed factor of 16 reduces the width and height of the resized mount by a factor of four.
    In step S3 (= EXPANSION), the image data subjected to the threshold process or the threshold process and the re-sizing are subjected to an expansion and hole filling process. This step accordingly includes fusing and filling adjacent pixels of a given value, e.g. black pixels until the number of blocks in the shot is constant. In other words, the expansion and filling steps can be repeated until the number of blocks remains constant. Fig. 4C shows the process of expansion (left) and hole filling (right).
    In this step, the digital image data may nevertheless comprise more than one form, which may be interpreted as a possible candidate of the two-dimensional point code. Therefore, in a subsequent step S4 (= blob DETECTION), detection of blobs is performed to filter the shapes. This can include finding and numbering all shapes in the shot and deleting all shapes with a small area so that small objects and noise are removed. It may then be considered to retain the largest form, which is then believed to be the best candidate for the two-dimensional point code within the image data. The result of this process will be shown in connection with FIG. 4D.
    In a subsequent step S5 (= EROSION) erosion is performed on the data obtained after step S4 to restore the original contours of the recording. For this purpose, it may be considered to apply the same number of erosion steps as the number of steps applied during the previous expansion (see step S3). The result on the processed image data is shown in connection with FIG. 4E, in which a detail view of the erosion is also shown (left).
    In a subsequent step S6 (= RAISING THE LIMITS) the boundaries of the two-dimensional point code are highlighted. This may include applying a filter to the image data that detects the variation in pixel intensity. In general, a conventional edge detection algorithm can be used. The resulting effect on the processed image data is again shown in connection with FIG. 4F.
    In a subsequent step S7 (= LIMITS) the boundary equations are calculated. This can be achieved, for example, by conventional means, such as the detection of parametric objects (lines, circles, etc., by means of the so-called Hough transformation). This involves transforming data in a Cartesian coordinate system (x, y) into a polar coordinate system (R, Θ), i. of y = ax + bzuR = x cos (Θ) + y sin (Θ). Here, R is the distance to the origin, while Θ is the edge angle of the gradient recording. Then, an accumulator array is incremented from these values and final lines are obtained from the four best values in the accumulator. The result of this process is again shown in connection with FIG. 4G.
    In the following step S8 (= CORNER EXTRACTION), the corners can be extracted. Since the intersections of the Hough lines are only approximate vertices of the two-dimensional point code, better and more accurate coordinates must be calculated. This can be accomplished by scanning line by line (or column by column) in a small area around the approximate corners until a black pixel is reached. The approximate corners can be determined by cutting the lines of the boundary as calculated in step S7. The coordinates of the detected black pixel can then be used as a better approximation to the coordinates of the corner. A small area of interest (located in the original image) can be used to ensure the highest precision and a fast process. This corresponding concept is in turn explained in more detail in connection with FIG. 4H.
    In a subsequent step S9 (IDENTIFY LINES), the parameters of the two-dimensional point code are identified. This may apply, in particular, to the identification of the L-shaped solid line and the L-shaped clock line of a DataMatrix point code, as described in connection with FIGS. 1A and 1B. This may include counting the number of black pixels along each segment to obtain a so-called score. The scanned segment that has received the highest score is identified as the longest segment of the L-shaped solid line, the scanned segment that has received the second highest score and is substantially perpendicular to the identified longest segment of the L-shaped solid line, is identified as the second segment of the L-shaped solid line (the angle being calculated from the equations of the boundary line obtained in step S7). The two remaining segments form the L-shaped clock line. Scanning within actual image data is shown in connection with FIG. 4I.
    If an optional resizing was performed in step S2, the size of the two-dimensional dot code and the original grid position are restored in a subsequent step S10 (= RESIZING). This may include scanning the timing line boundaries identified in step S9 and counting the number of transitions so as to determine the size of the grid. This may also include verifying the transient redistribution in space. Optionally, the results may be validated by comparing the transition count with a normalized size of a two-dimensional point code, e.g. 16 x 16, 12 x 26 etc. It is still possible to let the application calculate the size or to force a desired fixed value. This aspect is described in more detail in connection with FIG. 4J.
    In a next step S11 (= BUTTON / DECODE) scanning and decoding is performed taking into account that the original grid position may not be perfect in terms of the scan quality, the original grid position being calculated from the coordinates of the vertices obtained in step S8 and the size of the grating calculated in step S10 or, in the case where no size restoration was made in step S10, a quantity obtained directly by counting the transitions of the L-shaped clock line of the two remaining segments as found in step S9, is obtained. This, in turn, may also include verifying the transient redistribution in space or optionally validating the results as described for step S10. For this reason, a heuristic search pattern for minimizing the number of error correction codewords can be used in the Reed-Solomon algorithm. The grid may be moved along the search path until sufficient quality is achieved and, if a suitable position is found, scanning is performed. If the two-dimensional point code or the image thereof is distorted (e.g., due to pinning and / or acquisition), a 3x3 affine transformation matrix can be calculated. This maps an ideal two-dimensional point code grid onto the actual grid. This transformation can help to precisely restore the real coordinates of any elements in the ideal lattice while correcting a number of defects.
    In general, steps S2 to S9 are for restoring the contour of the two-dimensional dot code, i. the segments of the contour and the beginning and the end (extremities) of each segment, aligned. Two of the segments (a pair of opposing segments) are usually parallel to each other and form the contour with a typical aspect ratio and size. In other words, the steps detect an object within the shot with a global shape that is similar to a two-dimensional point code of a particular type and standard (e.g., DataMatrix); the similarities being based on the detection of four edges forming approximately one parallelogram.
    Fig. 5A shows a flowchart of one embodiment of a method of the present invention. In particular, this embodiment relates to the method which has already been introduced above in connection with FIGS. 3 and 4A. Steps S101 to S105, as now explained in connection with FIG. 5A, replace all steps S1 to S8 explained in connection with FIG.
    This embodiment of a method equally relates to identifying a two-dimensional dot code in digital image data of the dot code. Thus, again, it is assumed that a pick-up of the dot code, which was probably already attached to an object, document or product, was obtained. The digital image data will thus also contain parts that show that item, document or product along with parts of the background or items belonging to, for example, an operator's equipment or an assembly line. In this embodiment, it is also assumed that the point code comprises elements of a first and a second type arranged in an ordered grid and that the point code has a contour which has an L-shaped continuous line without transitions between the elements first and second Type includes.
    According to this embodiment, in a first step S101 (= CALCULATION OF THE GRADIENT), a gradient field is calculated from the digital image data, the gradient field specifying a gradient of the pixel value in the digital image data. Then, the magnitude order data of the gradient is calculated from the gradient field to obtain a scalar value for each pixel representing the order of magnitude of the gradient. This calculation of the gradient may in turn include some preparatory processing, depending on the state and resolution (size) of the digital input image data. These steps are shown in conjunction with FIG. 5B.
    If necessary, the size of the raw input image is changed in an optional step S111 (= SIZE CHANGE / REDUCTION), for example by rescaling via bi-linear subsampling. Similar aspects may apply as previously described in connection with FIG. 4B. Then the resized image can be smoothed using a Gaussian filter in a step S112 (= SMOOTHING), for example by a blur step with a fixed zoom factor. A typical value of the zoom factor may be determined on the basis of the known spot size, the points being increased to the point where adjacent points tend to touch and form a line. Subsequently, in step S113 (= CONTRAST LEAD DETECTION), detection of contrast levels on the smoothed shot is performed. Here, a Sobel operator can compute a two-dimensional spatial gradient from the image data. In step S114 (= APPROXIMATE GRADIENT), an approximate magnitude of the gradient is calculated, which implies that an edge strength is approximately calculated for each image pixel. Then, in step S115 (NON-HIGHEST SUPPRESSION), a non-peak suppression operation is performed on the order of the gradients, which means that the image is scanned along the direction of the image gradient, and if pixels are not part of the local maximums Zero be set with the effect that all image information that is not part of the local maximums is suppressed. This process allows the elimination of poor contrasts, noise, background, etc. Thus, it can be assumed that only the remaining features correspond to the two-dimensional dot code. This may include the assumption that the ink response to illumination when making the raw shot should be the highest, especially in comparison with the background response.
    Referring again to Fig. 5A, the process proceeds to step S102 (= THRESHOLD) based on the obtained gradient field. More specifically, according to this embodiment, in step S12, a threshold operation is performed based on the calculated magnitude data of the gradient, and image data of the edge segments are obtained. The thresholding process may include separation of light and dark areas based on the magnitude of the gradients. This may provide the advantage that the dynamics of the pixel values are greater, in that the range of values to be scanned is very large in comparison with the values of the image pixels themselves (e.g., dynamics are limited to only 256 values). The Otsu method of forming clusters can be used to obtain better visibility of the variations so that a gradient threshold allows better separation of the background information from the information representing the two-dimensional point code in the digital image data. Finally, if necessary, a resizing operation can be performed to restore the original scale. For this purpose, inverse rescaling can be applied by bilinear resampling without eliminating the effects of the blur step. In this way, a binarized picture with only a few enlarged dots and segments can be obtained. Thus, segments can be detected.
    If an optional rescaling has been performed in step S111, then in a subsequent step S103 (= RESET SIZE), the size of the two-dimensional dot code and the original grid position are restored. In general, the steps of S10 as described in connection with FIG. 3 may also be applied here.
    The process then proceeds to step S104 (= DETECT LINEAR SEGMENTS) based on the obtained thresholded image data. More specifically, according to this embodiment, in step S104, detection of linear segments in the image data of the edge segment is performed. For this purpose, an edge following algorithm may be used to detect the beginning and the end of each segment in the binarized image derived from the edge detection step, and the adjacent segments, for example based on distance and angle using the so-called LSD algorithm or a Hough algorithm. To evaluate transformation. The earlier LSD algorithm is described and published in: R.G. v. Gioi, J. Jakubowicz, J.-M. Morel and G. Randall, "LSD: A Line Segment Detector" (in Image Processing On Line (2012); http://dx.doi.org/10.5201/ipol.2012.gjmr-lsd). Optionally, merging of two collinear segments may be considered to iteratively form longer segments from a list of segments.
    Based on the detected segments, in step S105 (IDENTIFY PAIRS) pairs of detected linear segments are identified based on at least one angle criterion between two of the detected linear segments. Likewise, a (second) distance criterion can apply, which is the distance between the next ones
    Limits of the obtained using the application of the (first) angle criterion segments considered. The distance can be compared with a predetermined threshold with respect to falling below it (ideally, the distance for an ideal vertex of an L-shape disappears). In other words, a candidate for segment pairs is searched for a "best L". For this purpose, the angle criterion may only consider approximately rectangular segments most likely to represent the L-shaped solid line or the "finder pattern" forming the L boundary of a two-dimensional dot code of DataMatrix. As a basis, the previously found segments can be consulted by identifying those that are good candidates for forming the L-shape. For example, in a standard orientation, the corner on the lower left side of a DataMatrix point code is the starting point for a short segment corresponding to the height and for a long segment corresponding to the length of the point code (see Fig. 1B).
    The "best L" is then completed to a square, rectangle, parallelogram, or, generally, rectangle, square, or quadrilateral polygon to obtain all four approximate corners on which subsequent steps can build. In particular, within the aforementioned LSD algorithm, each L-shape may define a rectangle by mirroring the L-shape and completing the two L-shapes into a rectangle. Alternatively, according to the Hough transform, the rectangle or polygon is completed by the L-shaped solid line and the clock line.
    Fig. 6A shows a flowchart of one embodiment of a method of the present invention. In particular, this embodiment relates to the method already introduced above in connection with FIG. 3 and FIG. 4A. The steps S21 to S25, as will now be explained in connection with FIG. 6A, replace the step S9 explained in connection with FIG. Similarly, steps S21 to S25 may also follow step 105 as explained in connection with FIG. 5A.
    This embodiment of the method also relates to identifying a two-dimensional dot code in digital image data of the dot code. The dot code includes first and second type elements arranged in an ordered grid, and the dot code has a contour including an L-shaped clock line with transitions between the first and second type elements and an L-shaped solid line without transitions between the first and second type elements. Approximate vertices in the digital image data determine first and second pairs of opposing edge segments along the contour. In other words, this embodiment assumes that, for example, the clock line segment 122 'as shown in Fig. 1B and the corresponding segment of the solid line 112' appear as a pair of opposite edge segments in the digital image data, while the segments 111 'and 121' appear as a another pair of opposite edge segments appear.
    This embodiment takes into account that the approximate corners and thus the segment pairs (i.e., lines) in the digital shot data are known, for example, by the processes described in connection with Fig. 3 or 5A. In a first step S21 (^ FIRST PART OF THE FIRST PAIR) a first edge segment of the first pair in the digital image data is scanned and transitions between the elements of the first and second types are counted along the first edge segment of the first pair. Scanning and counting can be done as separate processes or simultaneously. As such, scanning itself may refer to the process of scanning along a line within digital image data to determine a (pixel) value at a position along the line (see also Figs. 4I and 4J).
    In the optional step S22 (= SECOND SEGMENT OF FIRST COUPLE), if no transitions were counted along the first edge segment of the first pair (ie, in step S21), the second edge segment of the first pair in the digital image data is scanned and the transitions between the first and second type elements along the second edge segment of the first pair. If transitions have already been counted in step S21, it can be determined that the scanned first segment of the first pair is a segment / leg of the L-shaped clock line. The scanning and counting with respect to the second segment of the first pair may thus be omitted since it can be assumed that the length is the same as that of the first segment and, since the two-dimensional point code follows the conventions, the second segment has no transitions to be counted becomes.
    Also, in step S23 (= FIRST SEGMENT OF SECOND PAIR), the process continues by scanning a first edge segment of the second pair in the digital image data and counting transitions between elements of the first and second types along the first edge segment of the first pair second couple. Again, in optional step S24 (= SECOND SECTION OF SECOND PAIR), the second edge segment of the second pair is scanned in the digital image data and transitions between first and second type elements are counted along the second edge segment of the second pair, if along the first edge segment of the second pair no transitions were counted. The optional character of step S24 again becomes clear, for example, from Figs. 1A and 1B, in the same manner as for the optional step S22.
    Then, the process in step S25 (IDENTIFYING CONTINUOUS LINE AND TACTILE LINE) may be identified as identifying the edge segment of the first pair and the edge segment of the second pair along which transitions have been counted as the L-shaped clock line of the point code and identifying of the edge segment of the first pair and the edge segment of the second pair along which no transitions have been counted are continued as the L-shaped solid line of the point code. Using the transient counts of both segments with transitions, the orientation and the longer and shorter sides of the two-dimensional point code can be determined. The number of transitions can also pave the way for defining the ordered lattice to decode the point code.
    The advantage over conventional processing becomes apparent when considering the typical method of scanning the pixels of all edges of the candidate rectangle to detect transitions or no transitions. In the latter case, a segment of the solid line was scanned, otherwise a segment of the line was scanned. In addition, each scanned pixel / element is counted to detect both the long and short segments. In total, eight counts / scans are required, i. two for each of the four segments that make up the contour.
    However, according to this embodiment, the scan / count operations can be reduced to four, three, or even two. Therefore, in any case, a substantial improvement in efficiency over the conventional methods is obtained. This is due to the fact that scanning and counting can be done simultaneously. For this reason, even if all four segments are scanned and counted simultaneously, since, for example, both first segments of both pairs have no transitions, the number of required operations is halved. In addition, only a first segment of a first pair of opposing sides is scanned to detect the presence of transitions, rather than successively viewing the segments around the rectangle, and only the transitions must be counted to determine the long and short part of the timing line , If no transition is detected, then the scanned edge corresponds to one edge of the L-shaped solid line; if at least one transition is detected, then the scanned edge may be considered as corresponding to an edge of the timing line.
    Fig. 6B shows a flowchart of one embodiment of a method of the present invention. In particular, this embodiment relates to the method already described above in connection with FIGS. 3 and 4A. Steps S31 to S35, as now explained in connection with FIG. 6B, replace step S9, as explained in connection with FIG. Similarly, steps S31 through S35 may follow step 105 as explained in connection with FIG. 5A.
    The embodiment of the method also relates to identifying a two-dimensional dot code in digital image data of the dot code. The dot code includes first and second type elements arranged in an ordered grid, and the dot code has a contour including an L-shaped clock line with transitions between first and second type elements and an L-shaped solid line with no transitions between Elements of the first and second kind includes. Approximate vertices in turn determine in the digital image data a first and a second pair of opposite edge segments along the contour. In addition, the two-dimensional point code of the convention follows that a crossing element at the corner of the L-shaped clock line is of a predetermined / known type selected from the first and second types.
    This embodiment enables a further improvement in efficiency by scanning a first edge segment of the first pair in the digital image data and transitions between elements of the first and second types along the first one in a first step S31 (= FIRST PART OF THE FIRST PAIR) Edge segment of the first pair are counted. Again, if no transitions were counted along the first edge segment of the first pair, then scanning the second edge segment of the first pair in the digital image files and counting the transitions between first and second type elements along the second edge segment of the first pair (see optional step S32 = SECOND SEGMENT OF THE FIRST COUPLE).
    Due to the known (predetermined) nature of the crossing element (see element 13 in Fig. 1A), in step S33 (= DETERMINING THE EXTREMITIES) it can be determined which extremity of the edge segment of the first pair along which transitions were counted, the crossing element equivalent. Thus, the process in step S34 (= SEPARATION OF SECOND PAIR) can be performed directly with the scanning of the edge segment of the second pair having the crossing element and the counting of the transitions between the first and second type elements along the edge segment of the second pair forming the Comprises crossing element, and identifying the edge segment of the first pair and the edge segment of the second pair intersecting each other at the crossing element as the L-shaped clock line of the point code in step S35 (IDENTIFYING THE PASSING LINE AND THE CLOCK LINE) and identifying the Edge segment of the first pair and the edge segment of the second pair, which are not part of the L-shaped clock line, as the L-shaped solid line of the point code are continued. Thus, in this embodiment, only three or two operations are necessary due to the determination of the extremity as in step S33.
    Fig. 7A shows a general embodiment of an apparatus of the present invention. In particular, a device 100 is shown which comprises a processing unit 110 and a storage unit 120. The memory unit 120 may store a code that, when executed on the processing unit 110, implements one or more embodiments of methods of the present invention.
    Optionally, the apparatus 100 may include an image capture unit 131 to capture a digital photograph of a two-dimensional dot code, such as is applied to an article or document. In addition, the device 100 may include a communication unit 132 for communicating an identification and / or a decoding result to other locations, such as servers, controllers, and the like. The communication may be via a network such as a local area network (LAN), wireless network (WLAN), the Internet, and the like. In addition, bus systems, such as CAN, can also be used for data exchange.
    Fig. 7B shows a schematic view of a portable embodiment of a device for capturing a capture of the two-dimensional point code and for identifying and (optionally) decoding it. The device 200 includes a window 201 through which a digital photograph of an article 210 may be generated. A two-dimensional dot code 1 "is applied to the article 210 using any of the aforementioned printing, mechanical, physical or chemical processes. The device 200 may also include an integrated processing unit (not shown) to perform one or more methods according to embodiments of the present invention An additional operating element 202 may be provided to turn the device 200 on and off and / or capturing an image, acquiring / obtaining corresponding digital image data, and / or editing the digital image data for identification and / or Decoding the two-dimensional point code 1 "on the object 210 to initiate. Of course, the device may take other forms and may be wired or wireless.
    Fig. 7C shows a schematic view of a fixed embodiment of a device for capturing a capture of the two-dimensional point code and for identifying and (optionally) decoding it. For example, a module that can be mounted on a manufacturing / distribution line to identify two-dimensional point codes on items being transported on the line. The device 200 'in turn comprises a window 201' through which a digital photograph of an article 210 having a two-dimensional point code 1 "may be generated." The device 200 'may further comprise an integrated processing unit (not shown) to implement one or more methods according to embodiments An additional fixation element 202 'may be provided to mount the device 200' on, for example, a production line on which a plurality of articles 210 pass through the device 200 'for identification, of course be wired or wireless.
    According to another embodiment, a method is provided for identifying a two-dimensional point code in digital image data of the point code, the point code comprising first and second type elements arranged in an ordered grid and having a contour comprising a L-shaped clock line with transitions between the elements of the first and second type and an L-shaped solid line without transitions between elements of the first and second type, wherein approximate corners in the digital image data determine a first and a second pair of opposite edge segments along the contour. The method includes a scanning unit that performs: scanning a first edge segment of the first pair in the digital image data and counting transitions between elements of the first and second types along the first edge segment of the first pair; if no transitions have been counted along the first edge segment of the first pair, then scanning the second edge segment of the first pair in the digital image data and counting the transitions between the first and second type elements along the second edge segment of the first pair; scanning a first edge segment of the second pair in the digital image data and counting transitions between first and second type elements along the first edge segment of the second pair; if no transitions have been counted along the first edge segment of the second pair, then scanning the second edge segment of the second pair in the digital image data and counting the transitions between the first and second type elements along the second edge segment of the second pair. The method further includes an identification unit that identifies the edge segment of the first pair and the edge segment of the second pair along which transitions were counted as the L-shaped clock line of the point code and identifying the edge segment of the first pair and the edge segment of the second pair along which no transitions were counted as the L-shaped solid line of the point code performs.
    According to a further embodiment, there is provided a method of identifying a two-dimensional point code in digital point data of the point code, the point code comprising first and second type elements arranged in an ordered grid and having a contour having an outline. shaped bar line with transitions between the first and second type elements and an L-shaped continuous line without transitions between the first and second type elements, a crossing element at the corner of the L-shaped bar line which is a predetermined type of the first and second kind , wherein approximate vertices in the digital image data determine first and second pairs of opposing edge segments along the contour. The method includes a scanning unit that performs: scanning a first edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the first edge segment of the first pair; if no transitions have been counted along the first edge segment of the first pair, then scanning the second edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the first pair. The method also includes a determining unit that determines which extremity of the edge segment of the first pair along which the transitions were counted corresponds to the crossing element. The scanning unit then performs scanning of the edge segment of the second pair having the crossing element and counting the transitions between first and second type elements along the edge segment of the second pair having the crossing element. The method also includes an identification unit that identifies the
    权利要求:
    Claims (16)
    [1]
    Edge segment of the first pair and the edge segment of the second pair intersecting each other at the crossing element as L-shaped clock line of the point code and identifying the edge segment of the first pair and the edge segment of the second pair, which are not part of the L-shaped clock line, as performs the L-shaped solid line of the dot code. Although detailed embodiments have been described, these are merely to provide a better understanding of the invention defined by the independent claims, and are not to be considered as limiting. claims
    A method of identifying a two-dimensional dot code in digital image data of the dot code, the dot code comprising first and second type elements arranged in an ordered grid and having a contour defining an L-shaped clock line with transitions between the elements of the first and second type and an L-shaped continuous line without transitions between the first and second type elements, wherein approximate vertices in the digital image data determine first and second pairs of opposing edge segments along the contour, the method comprising: scanning a first one Edge segments of the first pair in the digital image data and counting transitions between the first and second type elements along the first edge segment of the first pair; if no transitions along the first edge segment of the first pair have been counted, then scanning the second edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the first pair; scanning a first edge segment of the second pair in the digital image data and counting transitions between the first and second type elements along the first edge segment of the second pair; if no transitions along the first edge segment of the second pair have been counted, then scanning the second edge segment of the second pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the second pair; identifying the edge segment of the first pair and the edge segment of the second pair along which transitions were counted as the L-shaped clock line of the point code and identifying the edge segment of the first pair and the edge segment of the second pair along which no transitions were counted , as the L-shaped continuous line of the dot code.
    [2]
    A method of identifying a two-dimensional dot code in digital image data of the dot code, the dot code comprising first and second type elements arranged in an ordered grid and having a contour defining an L-shaped clock line with transitions between the elements of the first and second type and an L-shaped continuous line without transitions between the first and second type elements, a crossing element at the corner of the L-shaped clock line, which is of a predetermined type of the first and second type comprises, wherein approximate corners in determining first and second pairs of opposing edge segments along the contour of the digital image data, the method comprising: scanning a first edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the first edge segment of the first pair of edges; first couple; if no transitions along the first edge segment of the first pair have been counted, then scanning the second edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the first pair; - determining which extremity of the edge segment of the first pair along which transitions have been counted corresponds to the crossing element; scanning the edge segment of the second pair having the crossing element and counting the transitions between the first and second type elements along the edge segment of the second pair having the crossing element; identifying the edge segment of the first pair and the edge segment of the second pair intersecting each other at the crossing element as the L-shaped clock line of the point code, and identifying the edge segment of the first pair and the edge segment of the second pair not forming part of the L; are shaped like the L-shaped solid line of the dot code.
    [3]
    A method according to claim 2, wherein the predetermined-type element is a white-color element or a light-color element, which in the digital image data corresponds to at least one pixel having a pixel value representing a lighter color than a darker color.
    [4]
    4. The method according to any one of claims 1 to 3, wherein the element of the first kind is a white color element or a light color element or a more light reflecting element than the element of the second type, and wherein the element of the second kind a Is a black color element, a dark color element, or a less light reflective element than the first type element, and wherein the first type element in the digital image data corresponds to at least one pixel having a pixel value representing a lighter color and the second element Type in the digital image data corresponds to at least one pixel with a pixel value representing a darker color, darker than the lighter color.
    [5]
    5. The method according to any one of claims 1 to 4, wherein the two-dimensional dot code, printed, for example, black and white printed or color printed, milled, etched, embossed or ground.
    [6]
    6. The method of claim 1, wherein a first leg of the L-shaped timing line is longer than a second leg of the L-shaped timing line and wherein the method further comprises determining the longer leg and the shorter leg of the L-shaped timing line based on the transitions counted along the edge segments along which transitions have been counted.
    [7]
    7. The method of claim 6, wherein a first leg of the L-shaped continuous line is longer than a second leg of the L-shaped solid line, and wherein the method further comprises determining the longer leg and the shorter leg of the L-shaped solid line, based on the determined longer leg and shorter leg of the L-shaped tact line.
    [8]
    8. The method of claim 1, wherein the method further comprises obtaining the digital image data of the two-dimensional dot code.
    [9]
    9. The method of claim 1, wherein the method further comprises decoding the two-dimensional point code based on the identified L-shaped clock line and the L-shaped solid line.
    [10]
    An apparatus configured to identify a two-dimensional point code in digital image data of the point code, the point code comprising first and second type elements arranged in an ordered grid and having a contour having an L-shaped clock line with transitions between the first and second type elements and an L-shaped solid line without transitions between the first and second type elements, approximate corners in the digital image data defining first and second pairs of opposite edge segments along the contour, the one processing unit is configured as follows: - scanning a first edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the first edge segment of the first pair; if no transitions have been counted along the first edge segment of the first pair, then scanning the second edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the first pair; scanning a first edge segment of the second pair in the digital shot data and counting transitions between the first and second type elements along the first edge segment of the second pair; if no transitions have been counted along the first edge segment of the second pair, then scanning the second edge segment of the second pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the second pair; for identifying the edge segment of the first pair and the edge segment of the second pair along which transitions have been counted as the L-shaped clock line of the point code, and for identifying the edge segment of the first pair and the edge segment of the second pair along which no transitions are counted were as the L-shaped continuous line of the point code.
    [11]
    An apparatus configured to identify a point code in digital image data of the point code, the point code comprising first and second type elements arranged in an ordered grid and having a contour defining an L-shaped clock line with transitions between the first and second type elements and an L-shaped continuous line without transitions between the first and second type elements, a crossing element at the corner of the L-shaped clock line being of a predetermined type of the first and second types wherein approximate vertices in the digital image data determine first and second pairs of opposing edge segments along the contour, the device comprising a processing unit configured as follows: scanning a first edge segment of the first pair in the digital image data and counting transitions between them the first and second type elements along the first edge segment of the first pair; if no transitions have been counted along the first edge segment of the first pair, then scanning the second edge segment of the first pair in the digital image data and counting transitions between the first and second type elements along the second edge segment of the first pair; to determine which extremity of the edge segment of the first pair along which transitions have been counted corresponds to the crossing element; scanning the edge segment of the second pair having the crossing element and counting transitions between the first and second elements along the edge segment of the second pair having the crossing element; for identifying the edge segment of the first pair and the edge segment of the second pair intersecting each other at the crossing element as the L-shaped clock line of the point code, and for identifying the edge segment of the first pair and the edge segment of the second pair not forming part of the L; are shaped like the L-shaped solid line of the dot code.
    [12]
    12. Apparatus according to claim 10 or 11, wherein the device is configured as a portable device.
    [13]
    13. Apparatus according to claim 10 or 11, wherein the device is configured as a module.
    [14]
    14. An apparatus according to any one of claims 10 to 13, wherein the apparatus further comprises an image pickup unit adapted to obtain the digital image data of the dot code.
    [15]
    15. An apparatus according to any one of claims 10 to 14, wherein the processing unit is configured to perform a method according to any one of claims 3 to 9.
    [16]
    A computer readable medium which stores the code instructing a processing unit to operate to carry out a method according to any one of claims 1 to 9.
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    WO2014063836A1|2014-05-01|
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