JP2008021009A - Bar code recognition device, method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise possibility of decoding as much as possible even if there exist partly thick parts or thin parts in each bar of a read bar code. <P>SOLUTION: A plurality of scan lines are set to a bar code image, and decoding is performed along with each of these scan lines. Then a majority is taken for every character in the decoding result. The most common decoding result value is adopted as a decoding result of the character concerned. When there is a character which cannot be decided by majority, a scan line is added and the character is decoded along with the added scan lines, and the decoding result is added and the majority is taken again. The scan line is added until the decoding result is decided by majority. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for recognition of a one-dimensional barcode.

  In order to make it easy to recognize a one-dimensional bar code (hereinafter simply referred to as “bar code”), many methods for binarizing a bar code reading result with an optimum threshold have been proposed. However, in recent years, as a large amount of paper documents have been digitized, images such as forms are often scanned with binary and low resolution in order to reduce the amount of data. In the case of an image that has been binarized in this way, it is often optimized for characters, photographs, etc., and binarization is not always performed with a threshold suitable for barcodes. In that case, the individual bars are often partially thick or thin.

  Although not limited to the case of binarization, there is known a conventional technique in which a majority vote method is used to increase recognition accuracy in the recognition of barcodes that are partially thick or thin.

  For example, in the apparatus disclosed in Patent Document 1, in a barcode image input in binary, each line in the bar length direction has black pixels that are equal to or greater than a predetermined ratio of a predetermined number of pixels on each line. If it is a pixel, it is a black line, otherwise it is a white line. The thickness of the black bar is determined by the number of continuous black lines in the bar arrangement direction, and the thickness of the white bar is determined in the same manner. This is to determine the black and white of each line by majority vote.

  In the method disclosed in Patent Document 2, after a plurality of identical barcodes are read, a character code is recognized from the read barcode by a barcode recognition means. Thereafter, a plurality of character codes recognized by the character code correctness determination means are compared, and when the majority of the character codes are the same, it is determined that the same character code is correct.

  The apparatus disclosed in Patent Document 3 sets a plurality of scanning lines extending in the bar arrangement direction, decodes a barcode along each scanning line, and takes the majority of the decoding results of each scanning line. Also, if the bar code is inspected in units of scan lines and the bar code establishment condition is not satisfied, the two scan lines are combined and inspected according to the bar code standard establishment condition, and the corresponding block of the two scan lines In the meantime, the barcode image is synthesized by replacing the established block that does not satisfy the establishment condition with the establishment block that satisfies the establishment condition, and the inspection is performed according to the barcode establishment condition.

  Patent Document 4 discloses a step of selecting a first scanning line substantially parallel to a bar and space of a bar code symbol, and scanning the symbol along the first scanning line to obtain a first value. And selecting a second scan line that is substantially parallel to the bar and space of the bar code symbol and that has a distance from the first scan line that is less than the width of the image pixels. A pixel image comprising: scanning the symbol along the second scan line to generate a second value; and decoding the symbol according to the first value and the second value. A method for reading a bar code symbol is described.

  In Patent Document 5, a barcode reader and related components scan a barcode symbol composed of a series of linear elements having different light reflectances, generate a representation of the barcode symbol, and represent the representation of the barcode symbol. A method of decoding a bar code symbol to attempt to create a legal character message containing legal characters that can be decoded and decoded (all undecipherable characters are illegal), corresponding to a first scanning path across the symbol Storing a first representation of the barcode symbol to be stored, storing a second representation of the barcode symbol corresponding to a second scanning path across the symbol, and at least one illegal character of the first representation A method comprising the steps of creating an improved representation by replacing an element with at least one element of the corresponding character of the second representation is disclosed.

JP 2005-165948 A JP 2000-251111 A JP 2001-043300 A Japanese Patent Laid-Open No. 10-187876 Japanese Patent Laid-Open No. 03-189787

  In the method disclosed in Patent Document 1, when the bar is thin (or thick in the majority) in the most part along the longitudinal direction of the bar as in the bar 100 of FIG. 1, the thickness of the bar is affected by the influence. Is erroneously determined, which leads to decoding failure. In particular, when the barcode image has a low resolution, it is easy to be adversely affected by such thickening and thinning.

  Further, in the method of adopting the majority vote for each character code as in Patent Document 2, there are cases where the entire bar code cannot be decoded regardless of the scanning line due to the thickness or thinness of each bar. For example, in the barcode shown in FIG. 2, for example, the bar 100 and the bar 102 are thin at different positions in the longitudinal direction of the bar, so that the scanning line is along the scanning line for both the A and B lines. The entire barcode cannot be decoded. For example, in line A, the fourth character from the left cannot be decoded, and in line B, the leftmost character cannot be decoded. If the combination of the thickness and thinness of each bar is bad, the entire barcode cannot be decoded regardless of the scanning line. In particular, such a problem becomes more prominent in a low-resolution image.

  Further, in the technique of Patent Document 3, according to the description in paragraphs (0002), (0015), and (0016) of the document, whether the width of the bar (black bar) and the space (white bar) is appropriate. It is determined by whether or not. Then, according to paragraph (0014), after the non-established block is replaced with the established block, the feasibility of the entire barcode is further determined by the check digit. After all, the technique of Patent Document 3 cannot finally recognize a proper code unless it is a bar code including a check digit.

  In the methods of Patent Documents 4 and 5, when the same character is decoded into different values in two scanning lines, it is impossible to determine which one is appropriate.

  An object of the present invention is to increase the possibility of decoding a barcode that does not include additional information such as a check digit.

(1) In one aspect of the present invention, a decoding unit that decodes an image of a barcode including a plurality of characters along each of a plurality of scanning lines set at different positions in the longitudinal direction of the bar; For each character position of the barcode image, in the decoding result of each scanning line obtained by the decoding unit for the code part at that character position, the code part of the code part is based on the character that occupies the maximum proportion of the characters successfully decoded. There is provided a bar code recognition device comprising: a determination unit that determines a character string by determining a character string.

(2) In one aspect, in the configuration (1), the determination unit includes, among the plurality of scanning lines, in the decoding result of each scanning line for the code portion at a certain character position, When there are a plurality of characters with the maximum proportion, one or more further scanning lines at different positions in the longitudinal direction of the bar until the number of characters occupying the maximum proportion is one for the character position. And the decoding unit decodes the code portion of the added scanning line.

(3) In another aspect, in the configuration (1), the determination unit obtains the number of characters as a result of decoding for each of the plurality of scanning lines by the decoding unit, and determines the number of characters for each scanning line. In the decoding result of the scanning line corresponding to the maximum number of characters, the character of the code portion is determined based on the character that occupies the maximum proportion of the characters that have been successfully decoded.

(4) In another aspect of the present invention, a barcode image including a plurality of characters is decoded along each of a plurality of scanning lines set at different positions in the longitudinal direction of the bar, and the barcode For each character position in the image, the character of the code portion is determined based on the character that occupies the maximum proportion of the characters successfully decoded in the decoding result of each scanning line obtained by the decoding portion for the code portion of the character position. Thus, a barcode recognition method for determining a character string represented by the barcode is provided.

(5) In still another aspect of the present invention, a bar code image including a plurality of characters is decoded along each of a plurality of scanning lines set at different positions in the longitudinal direction of the bar. For each character position of the code image, in the decoding result of each scanning line obtained by the decoding unit for the code part of the character position, the character of the code part is determined based on the character that occupies the maximum proportion of the characters successfully decoded. By determining, a program for determining the character string represented by the barcode and causing the computer to execute processing is provided.

  According to the above configurations (1), (4), and (5), it is possible to increase the possibility of decoding a barcode that does not include additional information such as a check digit.

  According to the configuration (2), it is possible to determine the decoding result even for the code portion where the decoding result cannot be determined only by the scan line used first.

  According to the configuration (3), for example, even when the barcode image is inclined with respect to the scanning line, appropriate decoding can be performed.

  Hereinafter, the processing procedure of this embodiment for barcode recognition will be described with reference to FIG.

  First, an image including a barcode is input to the barcode recognition apparatus of the present embodiment (S1). The barcode recognition device cuts out an area including the barcode (S2). The region including the barcode can be cut out using various methods including a known method. For example, the user may previously specify an area including a barcode in the entire image. In addition, an area where black and white is repeated in one direction in a predetermined frequency range may be cut out as an area including a barcode. Further, a technique disclosed in Japanese Patent Laid-Open No. 5-324896 or Japanese Patent Laid-Open No. 8-96059 may be used.

  Next, the barcode recognition apparatus selects one of a plurality of preset scanning lines, and decodes the image of the barcode area along the scanning lines (S3). Here, in the barcode recognition apparatus, a predetermined number (for example, eight) different positions along the vertical direction of the barcode area are registered as the positions of the scanning lines. The scanning line is a line extending in the horizontal direction from each of the registered positions.

  The vertical direction here is in principle the longitudinal direction of the bars constituting the barcode, and the horizontal direction is in principle the direction in which these bars are arranged (referred to as the bar arrangement direction). However, in reality, there is an error due to the inclination of the paper when reading the paper on which the barcode is printed, so the vertical direction and the horizontal direction are not necessarily exactly equal to the longitudinal direction of the bar and the bar arrangement direction. Depending on the error, the direction may be different.

  The position of each scanning line in the vertical direction used in step S3 is determined in advance so that the distance between adjacent scanning lines is equal to or greater than a predetermined value. This is because if the scanning lines are too close to each other, there is a high possibility that deviation will occur in the majority decision described later. For example, the scanning lines are distributed at equal intervals in the vertical direction of the barcode area.

  The bar code recognition apparatus repeats the decoding process of S3 for all of a plurality of preset scanning lines (S4).

  A specific example of the decoding process is shown in FIG. In the example of FIG. 4, as shown in (a), decoding is performed for five scanning lines in S3 and S4. The decoding results for these five lines are as shown in (b). Here, “*” indicates a start code and a stop code, and “?” Indicates that decoding is impossible. The character cannot be decoded means that in the portion corresponding to the position of the character in the barcode image, the arrangement pattern of the thick bar and the thin bar indicates which character (for example, “1,2,3, 4,5,6,7,8,9,0, * ").

  In the example of FIG. 4, since the barcode is slightly inclined with respect to the direction of the scanning line, up to the fifth character (including the start code) in the first scanning line set near the upper end in the vertical direction. Only decoded. On the other hand, 11 characters (including a start code and a stop code) are decoded for the remaining second to fifth scan lines.

  The barcode recognition apparatus obtains the maximum number of characters in the decoding result of the predetermined number of scanning lines obtained in S3 and S4, and determines that this is the number of characters of the inputted barcode (S5). In the example of FIG. 4, 11 is the maximum frequency. The bar code recognition device extracts the scanning line corresponding to the maximum number of characters (S6), and takes the majority of the decoding results for each character among the decoding results of the extracted scanning lines (S7). In the majority decision of S7, the character value that becomes the maximum number among the decoded character values is finally set as the decoding result of the character except for those that cannot be decoded ("?"). In the example of FIG. 4, the majority of each character is taken for the decoding results of the second to fourth scanning lines. For the 1st to 5th characters and the 7th to 11th characters from the left, a single decoding result can be determined by majority vote. For example, since the fifth character from the left is “4” three times and “2” once, the decoding result is determined to be “4”.

  On the other hand, the sixth character from the left has the same number as “5” once and “8” once, so the decoding result cannot be determined by majority vote.

  The bar code recognition apparatus determines whether all characters have been decoded in the result of the majority decision for each character in S7 (S8). If there is a character that could not be decoded, a scan line is added to such an unresolved character to try decoding by majority vote (S9). The scan lines to be added may be added between the scan lines used in S3 and S4, or as shown as "additional lines" in FIG. It may be set. The number of scan lines added in S9 may be one or a plurality of predetermined lines. The position for adding the scanning line (position in the vertical direction) is set in advance in the barcode recognition device. The position at which the scan line is added is determined so as to be a position separated by a predetermined distance or more from the existing scan line, for example.

  In the example of FIG. 4, the decoding result of the sixth character along the additional line is 5. Therefore, when the majority result of the decoded character value is taken together with the decoding result of the sixth character along each existing scanning line (S7), "5" is the final decoding result of the sixth character. It is determined. In the example of FIG. 4, since all 11 characters have been decoded in this way, the determination result in S8 becomes affirmative (Yes), and the decoding of the barcode ends.

  If an unresolved character cannot be decoded even after adding a scan line in S9 and decoding, an additional scan line is added again in S9 and an attempt is made to decode the unresolved character. The processes of S7 to S9 are repeated until decoding of all unresolved characters is completed.

  In the above example, the largest character value among the decoding results of the characters on each scanning line is adopted as the final decoding result of the character. However, the maximum number is not used instead of the maximum number. The maximum number of character values may be adopted as a decoding result only when a predetermined ratio (for example, a majority) or more among those that can be decoded.

  The barcode recognition process described above is typically realized by executing a program that describes the processing content of each step described above on a computer. The computer has, for example, a circuit configuration in which a CPU (Central Processing Unit), a memory (primary storage), various I / O (input / output) interfaces and the like are connected via a bus as hardware. Also, a hard disk drive and a disk drive for reading portable nonvolatile recording media of various standards such as a CD, a DVD, and a flash memory are connected to the bus via, for example, an I / O interface. Such a drive functions as an external storage device for the memory. A program in which the processing content of the embodiment is described is stored in a fixed storage device such as a hard disk drive or other type of nonvolatile storage device via a recording medium such as a CD or a DVD, or via a network, and is stored in a computer. Installed. The program stored in the fixed storage device is read into the memory and executed by the CPU, whereby the processing of the above embodiment is realized.

  The barcode recognition apparatus according to the present embodiment can be realized as a computer in which such a program is installed, for example. This apparatus may receive the scanned image from the scanner and perform the processing as shown in FIG. 3 on this image. Further, the above-described program may be installed and executed in an apparatus having both a scanner function and a printer function, such as a digital copying machine or a digital multifunction machine.

  A functional block diagram of the barcode recognition apparatus according to the embodiment is, for example, as shown in FIG. The barcode recognition device 20 receives the image read by the scanner 10, and the barcode extraction unit 21 performs the process of S2 on the image. The scanning line setting unit 22 has information for determining the positions of the initial scanning lines used in S3 and S4 and the scanning lines to be added in S9 (for example, the position itself or rule information for determining the position). ing. The decoding unit 23 performs a decoding process from S3 to S9. In this decoding process, the decoding unit 23 refers to the scanning line setting unit 22 and sets the scanning lines in S3 and S9. Each unit of the barcode recognition device 20 can be realized by a program.

It is a figure for demonstrating the barcode with partial weight and thinness. It is a figure for demonstrating that the barcode with a partial thickness or thin cannot be decoded by one scanning line. It is a flowchart which shows an example of the process sequence of barcode recognition of embodiment. It is a figure which shows the mode of the barcode recognition by the process sequence of embodiment using a specific example. It is a functional block diagram of a barcode recognition apparatus.

Explanation of symbols

  10 scanner, 20 barcode recognition device, 21 barcode extraction unit, 22 scanning line setting unit, 23 decoding unit.

Claims (5)

A decoding unit that decodes a barcode image including a plurality of characters along each of a plurality of scanning lines set at different positions in the longitudinal direction of the bar;
For each character position of the barcode image, in the decoding result of each scanning line obtained by the decoding unit for the code part of the character position, the code part By determining a character, a determination unit that determines a character row represented by the barcode,
A barcode recognition device comprising: In the plurality of scanning lines, when the decoding result of each scanning line for the code portion at a certain character position in the plurality of scanning lines includes a plurality of the maximum proportion of characters that have been successfully decoded, Until one character occupies the maximum ratio, one or more additional scan lines are added at positions different from the plurality of scan lines in the longitudinal direction of the bar, and the code portion is decoded for the added scan lines. To the decoding unit,
The bar code recognition apparatus according to claim 1. The determination unit obtains the number of characters of the decoding result for each of the plurality of scanning lines by the decoding unit, and decodes the scanning line corresponding to the maximum number of characters among the number of characters for each scanning line. In the result, the character of the code portion is determined based on the character that occupies the maximum proportion of the characters that have been successfully decoded.
The bar code recognition apparatus according to claim 1. A barcode image including a plurality of characters is decoded along each of a plurality of scanning lines set at different positions in the longitudinal direction of the bar,
For each character position of the barcode image, in the decoding result of each scanning line obtained by the decoding unit for the code part of the character position, the code part By determining the character, the character string represented by the barcode is determined.
Bar code recognition method. A barcode image including a plurality of characters is decoded along each of a plurality of scanning lines set at different positions in the longitudinal direction of the bar,
For each character position of the barcode image, in the decoding result of each scanning line obtained by the decoding unit for the code part of the character position, the code part By determining the character, the character string represented by the barcode is determined.
A program that causes a computer to execute processing.

Images