JP2000132634A - Bar code recognition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely recognize a bar code formed of bar and peripheral numeral even if the size of a signal largely changes by sequentially checking bar areas arranged at prescribed intervals in accordance with the specification of the bar code and judging the presence or absence of the bar. SOLUTION: A bar code printed on a mail is converted into multivalue picture data by a scanner 201 and a bar code recognition part 202 converts it into bar code data. The bar code recognition part 202 investigates prescribed areas near a start bar and a stop bar and obtains respective bar candidates and center lines. The cut piece and the inclination of the bar candidate are obtained from the center point of the bar candidate near the start bar and from the center point near the stop bar, and the position of the bar code is almost specified. When the bar area is within the range of the bar code, the bar area is finely adjusted and the presence of the bar is judged when a difference between the center part of the bar area and the value of a peripheral part exceeds a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recognizing a bar code printed on a medium having non-uniform colors, patterns, materials, etc., and more particularly, to a method for recognizing a bar printed on mail using a special ink such as a fluorescent ink. How to recognize the code.

[0002]

[Prior Art] In line with the new postal code system introduced in 1998, sophisticated processing of standard postal items by machine has been advanced.
It has been automated up to the point where the mailers arrange mail in the order in which they are to be delivered. For that purpose, it is necessary to mechanically read the postal code or address printed on the mail and sort the mail according to the information. At that time, the postal code, address, and the like are converted into bar codes, printed directly on the mail using special ink such as fluorescent ink, and used for automatic sorting.

[0003] The bar code printed on the mail is read with a special light to read the bar, but the material, color, pattern,
The size of the signal changes greatly due to the overlap with the written characters. Conventionally, special hardware (Japanese Patent Laid-Open No. 9-15402) is used to recognize this signal as a barcode.
No. 2), differentiation processing (Japanese Patent Application Laid-Open No. 9-319821), Fourier analysis (Japanese Patent Application Laid-Open No. 9-160997).
Detect bar edges using complex formulas such as
The signal was being converted.

[0004]

The problem to be solved by the present invention is described above (Japanese Unexamined Patent Publication No.
A barcode recognition method using edge detection or a complicated calculation formula as disclosed in JP-A No. 4022, JP-A-9-319821 and JP-A-9-160997) complicates hardware and increases cost. In addition, when a change occurs in the barcode standard or the like, it takes time to deal with the change. Further, the more complicated the calculation formula for barcode recognition, the longer the calculation time.

It is an object of the present invention to simplify hardware by using multi-valued image data of a bar code read by a scanner without processing the hardware by hardware, and by recognizing the data as it is, and to use a complicated calculation formula. An object of the present invention is to provide a barcode recognition method that speeds up the recognition process by eliminating the above.

Further, a bar code superimposed on a character, a complicated pattern, or the like is difficult to recognize because the signal magnitude fluctuates extremely. An object of the present invention is to correctly recognize a bar code based on a bar and values around the bar even when the magnitude of the signal greatly changes.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a multi-valued bar code image data obtained by a scanner or the like. Examine a certain area in the vicinity in detail, determine multiple bar candidates,
The presence / absence of a barcode and the center of the barcode are determined, and bar regions arranged at regular intervals are sequentially examined in accordance with the barcode standard to determine the presence / absence of a bar.

Further, according to the present invention, the values of the central portion and the peripheral portion of the bar area are treated as a signal value and a noise value, respectively, and the presence or absence of a bar is determined from the difference between the signal value and the noise value.

Further, according to the present invention, when investigating each bar area, the inclination of the bar code as a whole and the bar area are corrected in order to correct the inclination, expansion and contraction of the bar code caused by the printing state of the bar code, the reading accuracy and the like. The position of the bar area is finely adjusted based on the deviation of the values between the central part and the peripheral part.

Further, according to the present invention, the threshold value for judging the presence or absence of a bar is dynamically determined in accordance with the values of the center portion and the peripheral portion of each bar region. Also, the presence or absence of a bar can be correctly determined.

Further, the present invention divides a bar region center portion and a peripheral portion into a plurality of sub-regions, determines presence / absence of a bar for each sub-region, and determines whether a bar exists in any of the sub-regions. In the bar area, it is determined that there is a bar, so that the presence or absence of a bar can be correctly determined even when many signals in the bar area are missing.

In addition, according to the present invention, when it is necessary to recognize a difference in the shape or position of a bar, for example, when information is different depending on the upper half and the lower half of the bar, the center of the bar region and the peripheral portion are divided into a plurality of sub-regions. The bar code is divided, the presence or absence of a bar is determined for each sub-region, and the value of each sub-region is compared to prevent erroneous reading due to ink bleeding of the bar code.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, a barcode printed on a mail is recognized. This forms part of the bar code reading device of the mail sorting machine.

[0014] The postal zone toilet machine prints three types of barcodes corresponding to address information and the like on mail using special ink that is invisible with natural light, and optically applies ultraviolet rays or the like to the mail if necessary. By reading and recognizing barcodes, mail items are classified. There are three types of barcodes: an ID number that is uniquely assigned to a mail, a postal code of a destination, and an address display number that codes the address of a destination.

FIG. 2 is a block diagram of the bar code reader. The barcode printed on the mail is first converted into multi-valued image data by the scanner 201, and then converted into barcode data by the barcode recognition unit 202. Next, the barcode decoding unit 203 decodes the barcode data into the above-described address information and the like, and transfers the data to a control unit 204 that controls the entire postal sorting machine. The present invention is applied to the barcode recognition unit 202 in FIG. 2 and directly recognizes multi-valued image data read by the scanner 201. Therefore, the scanner 20
There is no need for processing such as compression, differentiation, edge detection, and the like between hardware 1 and the barcode recognition unit 202 using hardware or the like.

The three types of barcodes described above are, as shown in FIG. 3, the position, length, width,
The intervals and the like are finely defined including the allowable range. ID
In order to read all of the barcode 302, the address display number barcode 303, and the postcode barcode 304, it is necessary to read the entire reading range 301 with a scanner.

Incidentally, the ID bar code 302 has a bar and is in only two states without a bar. However, the address display number bar code 303 and the postal code bar code 304 have four bars of an upper bar, a lower bar, an upper and lower bar, and no bar. There is a state.

Next, the processing of the bar code recognition unit to which the present invention is applied will be described in detail by taking an ID bar code as an example.

FIG. 4 shows an outline of the process performed by the barcode recognition unit. First, a certain area near the start bar is investigated to obtain a bar candidate and a center line (401). Since the positions of the start bar and the stop bar in the multi-valued image data are narrowed down to a substantially constant range according to the standard, the vicinity thereof is examined. In this case, as shown in FIG. 5, the fixed area 502 near the start bar may or may not include the start bar 501 itself. However, if possible, start bar 5
The closer to 01, the higher the recognition accuracy.

The search in the fixed area 502 near the start bar can be performed, for example, as follows. First, one point of the fixed area 502 is set as the inspection point A, and points separated from this point by a certain distance to the left and right are set to the inspection point B and the inspection point C, respectively. By comparing the respective values, the survey point A becomes the survey points B and C.
If it is larger than a certain value, the survey point A is set as a bar candidate.
This survey is performed over the entire survey range, and the first bar candidate is determined.

Next, among the primary bar candidates, those located at positions that deviate greatly from the bar code standard are canceled as noise, and the bar candidates are narrowed down to become secondary bar candidates. Among the secondary bar candidates, those whose values exceed a certain value within a certain range in the vertical direction are defined as third bar candidates. Next, a center line 503 of a certain area near the start bar is obtained from the third bar candidate. Finally, one final bar candidate is selected from the third bar candidates. For example, a bar candidate having the largest signal may be selected.

Similarly, a predetermined area near the stop bar is examined to obtain a bar candidate and a center line 402. Either of the investigation 401 of the fixed area near the start bar and the investigation 402 of the fixed area near the stop bar may be performed first.

Next, the intercept and inclination of the bar code are obtained from the center point of the bar candidate near the start bar and the center point of the bar candidate near the stop bar (403). This is a case where a straight line connecting the centers of the bars of the bar code is assumed, this is regarded as a linear function, and a point in the reading range 301 in FIG. 3 is assumed as the origin.

Since the position of the barcode has been almost specified by the processing up to this point, the bar recognition processing 404 is performed based on this. Hereinafter, details of the bar recognition processing 404 will be described.

FIG. 1 shows the flow of the bar recognition process.

First, it is checked whether or not the bar area is within the range of the bar code (101). If it is out of the range, there are no more bars, and the process ends.

For the first bar area, for example, a bar candidate obtained in a certain area near the start bar or the stop bar may be used.

If it is within the range of the bar code, fine adjustment of the bar area is performed (102). The bar area includes a central portion 603 and a peripheral portion 602 as shown in FIG. 6, and the center is adjusted so as to overlap the center of the bar 601. this is,
This is performed in order to avoid the influence of noise or slight displacement of the bar 601 due to the printing state or reading conditions. In practice, the adjustment is made based on the barcode intercept and inclination obtained earlier, the value at the center of the bar inspection area, and the like.

Next, the values of the center portion and the peripheral portion of the bar area are determined (103), and if the difference exceeds a certain value, it is determined that a bar exists (104). At this time, it is also possible to divide the central portion and the peripheral portion into a plurality of sub-regions, determine the presence / absence of a bar for each of the sub-regions, and determine the presence / absence of a bar from the result. In this case, the presence or absence of a bar can be accurately determined even if the signal of the bar is largely missing due to noise, the background of the bar, or the like. By using this method, a bar code having a signal value significantly different depending on the material or background of a mail can be correctly read. Furthermore, if the threshold value for determining the presence or absence of a bar is determined for each bar by the values of the bar area peripheral portion 602 and the bar area central portion 603, even if the material or pattern of the mail material changes significantly in the middle of the bar code, the bar is not changed. Can be correctly determined.

When the presence or absence of a bar is determined, the bar survey area is moved to the next bar position 105. Since the bar interval is determined by the standard, the bar inspection area may be moved by the interval. Then, the processing returns to the top of FIG. 1 and continues.

If the first bar area is a start bar or a stop bar, the bar may be recognized from there to the end on the opposite side, but the first bar area may be a bar in the middle of the bar code. Therefore, for example, first, the bar on the right side of the first bar area is recognized, then the bar on the left side of the first bar area is recognized, and finally, the results may be integrated.

The description of the recognition of the ID barcode is completed.

As described above, the address display number bar code 30
The 3 and zip code barcodes 304 have four states: an upper bar, a lower bar, an upper and lower bar, and no bar. The processing method is almost the same as that for the ID barcode. The difference is that in the case of determining the presence or absence of a bar in FIG. 1 (104), in the case of an ID bar code, it is only necessary to determine whether or not there is a bar, but in the case of an address display number bar code and a postal code bar code. Is where the four states must be distinguished. This is possible, for example, as follows.

The bar area center 603 and the peripheral area 60 in FIG.
2 is divided into three sub-regions: an upper portion, a central portion, and a lower portion. The presence of the upper bar is determined by the upper part of the center and the upper part of the periphery. Similarly, the presence or absence of the lower bar is determined from the lower part of the center and the lower part of the peripheral part. Thus, the above four states can be determined. Here, if it is determined that there is a bar on both the upper and lower sides, and if the difference or ratio between the upper value and the lower value is significantly different, the bar with a smaller value may be determined to have a bar due to ink bleeding on the opposite bar. Since a bar having a small value is re-determined as having no bar, it is possible to correctly determine a subtle difference in the shape of the bar.

The presence or absence of a bar near the center of the bar can be determined based on the center of the center and the center of the periphery. The signal at the top and bottom of the bar may be significantly weakened by the pattern, so by re-determining the larger value of the top or bottom as having a bar,
It can reduce misreading due to postal materials and patterns.

[0036]

If the present invention is applied to a barcode recognition unit, special hardware such as differential processing of image data and edge search is not required, and complicated calculations are not required. Barcodes can be accurately recognized.

[Brief description of the drawings]

FIG. 1 is a flowchart of a bar recognition process according to the present invention.

FIG. 2 is a block diagram of a barcode reading device.

FIG. 3 is a view showing Ministry of Posts and Telecommunications standards such as a printing position, a length, a width, and an interval of a barcode.

FIG. 4 is a flowchart of an outline of a barcode recognition process.

FIG. 5 is an enlarged view near a start bar.

FIG. 6 is a diagram showing a bar area.

[Explanation of symbols]

201: scanner, 202: barcode recognition unit, 20
3. Bar code decoding unit, 204 control unit, etc. 301
Reading range, 302 ... ID barcode, 303 ...
Address display number bar code 304 Post code bar code 501 Start bar 502 Fixed area near start bar 503 Center part of fixed area near start bar 601 Bar, 602 Bar area periphery 603: central part of bar area.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tetsuro Kiyomatsu 1st Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Prefecture Inside the Information Equipment Division of Hitachi, Ltd. Hitachi, Ltd. Information Equipment Division (72) Inventor Toshinori Kajiura 1, Ikegami, Haruoka-cho, Owariasahi-shi, Aichi F-term, Hitachi Information Equipment Division 5B072 CC24 CC33 CC33 DD23 DD25 FF00 FF01

Claims (1)

[Claims] 1. An area where a bar is present is roughly determined according to a bar code standard, and while fine adjustment is performed based on the read multi-valued image data, only an area where a bar is expected is examined in detail in order. A bar code recognition method characterized by recognizing a bar code.