WO2003046804A1 - Code reading apparatus - Google Patents

Abstract

An image pickup unit (101) images a code from a recording medium containing data recorded as optically readable codes and a parameter extraction unit (102) extracts a parameter relating to luminance of each predetermined area of an image containing the imaged code. A regular reflection detection unit (105) detects regular reflection for each predetermined area corresponding to the image containing the aforementioned code according to the aforementioned extracted parameters. Thus, when regular reflection is detected, it is reported to an operator prompting re-scan by correcting the scan direction, thereby preventing code imaging in an improper imaging state and increases of defective data reading.

Description

 Specification

Code reader

Technical field

 SUMMARY OF THE INVENTION The present invention relates to a method for reading a code from a recording medium in which audio data, image data, text data, or various data that can be handled by a computer is recorded as an optically readable code. It relates to a code reader for reading.

Background art

 US Pat. Nos. 5,866,895 disclose a system in which digital data is divided into blocks each having a predetermined information amount, recorded on a recording medium, and read. In the above system, each of the divided block data is read together with an address, and the information is reproduced by combining the block data based on the address. . In this way, data is divided into blocks and recorded and played back, so data extensibility and readability are excellent, and data that does not fit in one imaging screen is excellent. Can also be read by scanning the code.

In addition, USP 5, 724, and 364 use the luminance information extracted from continuously captured frame images to set the amount of illumination for the next frame and the threshold for binarization. To provide feedback to Such a system can set the optimal illumination light amount and binarization threshold value by following the luminance change of the image including the code that changes every moment during the code scanning. It is excellent in that defects are reduced. In this way, the effect of controlling the parameters related to imaging and image processing according to the luminance change of the image including the code that changes during the scanning of the code is great. However, care must be taken when the imaging state of the image containing the code is poor.

 As a countermeasure, USP 6, 282, and 319 B1 determine the imaging state of the code and read the block from the side of the imaging screen where the imaging state is good. At the time of block reading, the certainty factor corresponding to the imaging state is stored in association with the data stored in the block at the time of block reading, and a block having a higher certainty factor, that is, a block with a good imaging state is detected. An information reproduction system has been disclosed that reduces the reading of invalid blocks and the reading of bad blocks in the imaging state by overwriting data that has already been read only when data is read. I have. As a result, it is possible to reduce data reproduction failure due to reading of a bad block.

 However, in the information reproducing system disclosed in the above-mentioned USPs 6, 28, 2 and 319 B1, the information is generated by the relationship between the state of the medium surface on which the code is recorded and the illumination. Not enough consideration was given to specular reflection.

 Here, specular reflection will be described.

Normally, as shown in Fig. 1, the illumination light from the light source 1 is reflected on a recording medium 2 made of paper, plastic, metal, etc., and is observed by an image pickup device 4 via a lens 3. Is done. At this time, the directly reflected light (= specular reflection) proceeds to the specular reflection generation area 5 shown in FIG. Therefore, the imaging element 4 captures only the light scattered on the recording medium 2 to perform imaging. However, as shown in FIG. 2, if small scratches 6 or irregularities are present on the surface of the recording medium 2, the direct reflected light from the light source 1 illuminating the code 7 is transmitted to the image sensor 4. May be incident. When such a phenomenon occurs, a value that is far from the feature (luminance information) to be extracted from the image containing the original code 7 is observed. For this reason, if the parameters of imaging and image processing are controlled based on this information, improper illumination light amount and a threshold for binarization may be set, and data reading failure may increase.

 That is, if specular reflection occurs in an image, data may not be properly read according to the imaging state, and there is room for improvement in that respect.

Disclosure of the invention

 It is an object of the present invention to provide a code reading device which can reduce the number of defective readings even when specular reflection occurs in an image including the code.

 A code reading apparatus according to the present invention optically reads a code from a recording medium on which data is recorded as an optically readable code,

 An imaging unit for imaging the code,

 From a predetermined area of an image including the code captured by the imaging unit, a parameter extraction unit that extracts a parameter relating to luminance of the area,

An image processing unit that performs image processing on the predetermined area corresponding to the image including the code by using the parameter extracted by the parameter extraction unit; A data reading unit that reads the data from an image including the code processed by the image processing unit;

 A specular reflection detection unit that detects specular reflection from the corresponding predetermined area of the image including the code based on the parameter set extracted by the parameter set extraction unit;

 It is configured to have:

 That is, the code reading device according to the present invention can detect that specular reflection has occurred when the code is imaged in an improper imaging state in which specular reflection has occurred. By promoting rescanning or correcting parameters, it is possible to prevent code from being imaged in an inappropriate imaging state, thereby preventing data reading errors from increasing. This is possible.

BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a diagram showing a regular reflection generation area in a normal state.

 FIG. 2 is a diagram showing a specular reflection generation area when a flaw is present on the recording medium.

 FIG. 3 is a block diagram of the code reader according to the first embodiment of the present invention.

 Figure 4 shows the physical format of the code.

 Figure 5 shows the parameters extracted for each subframe.

 FIG. 6 is a diagram for explaining the size of the subframe. Figure 7 is a diagram for explaining the change in the parameters between successive frames.

Figure 8 shows the area where specular reflection occurs due to a scratch generated below the imaging screen. FIG.

 FIG. 9 is a block diagram for explaining a modification of the code reader according to the first embodiment of the present invention.

 FIG. 10 is a block diagram of a code reader according to a second embodiment of the present invention.

 FIG. 11 is a diagram showing code having an overlapping block.

 FIG. 12 is a diagram showing another example of a code having an overlapping block.

 FIG. 13 is a block diagram of a code reader according to a third embodiment of the present invention.

 FIG. 14A is a diagram showing a luminance distribution before shading correction.

 FIG. 14B is a diagram showing a luminance distribution after shading correction.

 FIG. 15 is a block diagram of a code reader according to a fourth embodiment of the present invention.

 FIG. 16 is a diagram for explaining the size of the subframe. FIG. 17 is a diagram showing a luminance distribution in a cross section along line C-D in FIG.

 Fig. 18 shows the binarization result of the subframe when there is no regular reflection.

 Figure 19 is a diagram showing the binarization result of the subframe when specular reflection occurs.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. [First embodiment]

 FIG. 3 is a block diagram of the code reader 100 according to the first embodiment of the present invention. The code reader 100 includes an imaging unit 101 and a It comprises a message extracting unit 102, an image processing unit 103, a data reading unit 104, and a regular reflection detecting unit 105.

 In this case, as shown in FIG. 4, the imaging unit 101 is configured to use paper, plastic, metal, or the like so as to be optically readable in a predetermined block array format. The code | cord | chord 300 recorded on the recording medium 200 which consists of this is imaged with an imaging element, such as CCD, and is converted into an electric signal.

 Note that this code 300 divides information to be recorded into blocks 301 and gives each block 301 a mark index 302 or a block address which is a reading index. This is a form to which the address 303 is added. Then, the actual information to be recorded is each data dot 304 represented by the attributes of “black” and “white” corresponding to the “1” and “0”. Included in step 301. This code format is described in detail in the above-mentioned USP5, 8666, 895.

 Thus, the imaging unit 101 continuously captures the code 300 while relatively moving with respect to the recording medium 200, and corresponds to each of the imagings. Image information is output in chronological order.

As shown in FIG. 5, for example, as shown in FIG. 5, the parameter overnight extraction unit 102 provides each imaging screen (frame) captured by the imaging unit 101. The maximum luminance value is extracted as a parameter for each small area (subframe 107) obtained by dividing 106 into 24.

 The image processing unit 103 binarizes each of these subframes 107 based on the maximum value of the luminance extracted in each area by the above-mentioned parameter overnight extraction unit 102. The threshold value is determined, and the image captured by the image capturing section 101 is binarized for each subframe 107. Although the optimum value of the binarization threshold varies depending on the characteristics of the code 300 to be imaged and the recording medium 200, it may be set to, for example, the maximum luminance value of 1 to 2. The data reading unit 104 detects the block 301 from the code image binarized by the image processing unit 103 and reads the data. Known methods such as those disclosed in USP 5,896,403 and USP 5,866,895 can be used for block detection and overnight reading. . That is, for example, in the case of code 300 shown in FIG. 4, raster scan of the code image is performed to detect a black run having a predetermined length. Detects markers 302 placed at the four corners of block 301. Then, the white Z black of the dots on the grid points where the four markers 302 are divided into grids according to the code format are read out in correspondence with the data 0 1.

 The specular reflection detection unit 105 determines whether or not specular reflection is included in the captured image based on the parameters extracted from the imaging screen 106 in the parameter extraction unit 102. It is to detect whether or not.

Here, a method for detecting regular reflection will be described. The small region (subframe 107) for extracting a parameter (maximum brightness) in the parameter extraction unit 102 is, for example, as shown in FIG. Is set as a region that is sufficiently larger than the marker 302 that composes the subframe, and each small region (subframe 107) is divided so as to always include the code background (white).

 Then, when the result of comparing the maximum luminance value extracted between adjacent small regions (sub-frames 107) satisfies a predetermined condition, the specular reflection detection unit 105 determines that small region (sub-frame 107). It is determined that the subframe 107) includes specular reflection.

 For example, the maximum value of the luminance extracted by the parameter overnight extraction unit 102 is a pattern as shown in FIG. 5, and a small region of m rows and n columns is represented by R [m] [n] Let the maximum value of the luminance be represented by L [m] [n]. At this time, if the difference in the maximum luminance value between the small areas (sub-frames 107) adjacent to each other in the imaging screen 106 in the horizontal direction exceeds the predetermined value TH, that is, L [m] [ n] — LC m] [n _ l]> TH, or if the condition of L [m] [n]-L [m] [n + 1]> TH is satisfied, the small region R [m ] It is determined that [n] includes specular reflection.

 Assuming that this predetermined value TH is “20”, in the example shown in FIG. 5, a small area (subframe 107) R indicated by hatching is added.

 Specular reflection is detected in [2] and [5].

Further, the determination of the regular reflection can be made based on the ratio of the maximum value of the luminance of the adjacent small area (subframe 107). That is, if the ratio exceeds a predetermined value, specular reflection will occur. It is determined that it has been detected. In this case, even if the luminance of the entire imaging screen 106 changes, the ratio of the maximum value of the luminance is relatively constant, so that stable regular reflection determination is possible.

 In addition, the comparison of the maximum value of the brightness is not only between the small areas (subframe 107) adjacent in the left and right direction, but also the small areas (subframe 107) adjacent in the vertical direction and 4 neighborhoods. ) Can be compared, and the accuracy of the judgment can be further improved.

 In addition, when the imaging unit 101 continuously captures a code image at a predetermined interval (frame rate), the parameters extracted between consecutive frames are set. Specular reflection can also be detected based on

 In other words, the nighttime extraction unit 102 extracts a nighttime parameter for each code image that is continuously captured. Here, the specular reflection detection unit 105 has a storage unit (not shown) for storing at least the parameter (the maximum value of the luminance) one frame before. Then, the specular reflection detecting unit 105 compares the parameter of the current frame extracted by the parameter extracting unit 102 with the value of the previous frame for each extracted region. Detects a temporal change in luminance, and determines that specular reflection has occurred when a predetermined condition is satisfied.

For example, as shown in Fig. 7, the maximum value of the luminance changes between successive frames, and the luminance changes to the k frame of the small region (subframe 107) R [m] [n]. The maximum value of the luminance to be set is L _k [m].

[n]. At this time, the difference between the maximum luminance values of the small areas (subframe 107) between consecutive frames is a predetermined value T. When H is exceeded, that is, L _k [m] [n] — L _k — [m]

[N]> If a TH, is also rather, if the ratio of the maximum value of the luminance exceeds a predetermined value _{RTH (L k [m] [} n] / L k _ i

When [m] [n]> RTH is satisfied), it is determined that specular reflection has occurred in the small region (subframe 107) R [m] [n] in the k frame. In the example of Fig. 7, the small region (subframe 107) R in the k frame shown with hatching

 [2] It is determined that specular reflection has occurred in [5].

 When regular reflection is detected by comparing the maximum value of luminance between frames continuously imaged at a predetermined time interval in this manner, in the first frame in which imaging is started, There is no luminance information for the previous frame. Therefore, for this first frame, a predetermined default value is used as an initial parameter for comparison.

Such initial parameters can be determined as follows. That is, for each individual code reader 100, a medium such as paper or card having a uniform reflectance similar to the background (white) of the code 300 is imaged, and the parameter extraction unit is used. The parameter (the maximum value of luminance) extracted in 102 is set as the initial parameter. In other words, when the code 300 is picked up by the code reader 100 in an appropriate image pickup state, the maximum value of the luminance that will be extracted by the parameter extracting unit 102 is determined in advance. Please decide. If the code reader 100 has a non-volatile rewritable memory such as a flash memory, this value is stored in a non-volatile memory. At the start of scanning, Is used as the comparison value of the initial frame for specular reflection detection.

 By doing so, the initial parameters can be set up with a code reader.

100 Considering variations in imaging characteristics such as shading of the imaging screen 106 caused by the luminous efficiency of each illumination, the sensitivity of the image sensor, and vignetting by the lens, etc. As a result, specular reflection detection can be performed more accurately than when a uniform default value is used.

 In this way, the specular reflection detecting section 105 detects specular reflection in the captured image. Then, when the regular reflection is detected, the operator is notified of the fact by a display unit such as a buzzer or an LCD (not shown). That is, the operator scans the code 300 again by correcting the positional relationship between the recording medium 200 on which the code 300 is recorded and the code reader 100 0. Prompt.

 As described above, in the present embodiment, regular reflection can be detected based on the parameters extracted from the captured image obtained by capturing the code 300. If the code 300 is read in an improper imaging state where specular reflection has occurred, the operator is informed that the code is read, and the scanning method is corrected again to perform scanning. It is possible to prevent the code 300 from being imaged in an improper imaging state, thereby preventing data reading defects from increasing.

 In this case, the force described in the example of the code 300 in FIG. 4 is used as an example. Needless to say, the same processing can be performed for other one-dimensional or two-dimensional codes. .

In addition, the method of detecting specular reflection from the temporal change of the maximum luminance value was described with reference to Fig. 7, but in this case, the parameter The small area (sub-frame 107) for extracting the image need not be plural as shown in FIG. 7, but may be a predetermined area that may read the entire imaging screen 106 or the code. The maximum luminance value may be extracted only from the area.

 For example, as shown in FIG. 8, if the light source 101A such as an illumination LED in the imaging unit 101 is mounted above the imaging screen 106, the imaging screen 10 6 The brightness at the top is high, and the scratches 400 generated above the imaging screen 106 tend to cause specular reflection (as shown in Fig. 8, the incidence angle is small above the imaging screen). (Close to vertical incidence), it is easy for specular reflection to occur even with shallow scratches, whereas the angle of incidence is large below the screen (close to horizontal incidence), and specular reflection is unlikely to occur for shallow scratches).

 If there is such a specific condition, that is, if the positional relationship between the light source 101A, the imaging element 101B, and the recording medium 200 satisfies a predetermined relationship, the most regular reflection is generated. The parameter extraction can be performed only from a specific small area in the easily captured imaging screen 106. In this case, it is possible to reduce the processes involved in extracting the parameters and comparing them, thereby simplifying the apparatus.

 Further, as shown in the block diagram of FIG. 9, it is also possible to adopt a configuration having an illumination control unit 108 and an illumination unit 109.

At this time, the imaging unit 101 forms an image of the reflected light from the imaging device 101 B such as a CCD and the code 300 illuminated by the illumination unit 109 on the imaging device. It consists of an imaging lens 101C for the purpose. The image sensor 101B is positioned at a predetermined interval (frame Continuously capture images of code 300 at the rate.

 The noise extraction unit 102 extracts the maximum value of the brightness of the imaging screen 106 for each code image continuously imaged.

 The illumination unit 109 includes a light source such as an LED, and illuminates the code 300 captured by the imaging unit 101. The illumination light amount is controlled by the illumination control unit 108. That is, instead of providing a light source with a non-variable light amount in the imaging unit 101, a light source with a variable light amount is provided as the illumination unit 109. Needless to say, an illumination unit 109 may be provided in the imaging unit 101, and the light amount may be controlled by the illumination control unit 108.

 In the lighting control unit 108, the maximum luminance value is within a predetermined range based on the parameters (maximum luminance value) extracted by the luminance and luminance extraction unit 102. Thus, the amount of illumination of the illumination unit 109 when the imaging unit 101 captures the next frame image is controlled such that That is, the amount of illumination is controlled so that the maximum value of the luminance is darker if it is larger than a predetermined range, and it is brighter if it is smaller than the predetermined range, so that an appropriate imaging state can be obtained in the imaging unit 101. For example, if the illuminating unit 109 illuminates by pulse emission of the LED, the illumination light quantity can be controlled by controlling the emission pulse width.

In such a case, if there is specular reflection, extremely high luminance is detected. Therefore, the amount of illumination in the next frame is controlled to be extremely dark, and the amount of illumination becomes insufficient. Therefore, as described above, the specular reflection detection unit 105 detects the specular reflection from the temporal change in the maximum value of the luminance of the code screen extracted by the parameter overnight extraction unit 102 as described above. Detection is performed, and if specular reflection is detected, the operator is notified of this by a buzzer (not shown) or a display such as an LCD, and the operator is notified of the scanning method of code 300 and the like. Corrects the positional relationship between the recording medium 200 on which the code 300 is recorded and the code reader 100 0, and prompts the user to scan again.

 Further, when specular reflection is detected, the maximum value of the luminance at that time may be invalidated so that the illumination control unit 108 does not control the illumination light amount.

 In this way, when specular reflection occurs, the operator is notified of the fact and the scanning method is corrected again to perform scanning, and lighting control is performed based on the parameters at that time. By not performing this, it is possible to prevent the code 300 from being imaged in an improper lighting state and the data reading failure from increasing.

 [Second embodiment]

 Next, a second embodiment of the present invention will be described.

 FIG. 10 is a diagram showing a configuration of a code reading device 100 according to the second embodiment. The code reading device 100 of the present embodiment includes an imaging unit 101, It consists of an evening extraction unit 102, an image processing unit 103, a data reading unit 104, a regular reflection detection unit 105, and a parameter invalidation unit 110. In the following description of the present embodiment, components having the same reference numerals as those in the first embodiment and having no description are those having the same functions as those in the first embodiment. And

The imaging section 101 continuously captures a code image at a predetermined interval (frame rate). At this time, as shown in FIG. 11 or FIG. 12, as a countermeasure against a reading error, a plurality of duplicate blocks having the same contents in the code are scanned. Include step 3 2005. This is because, by having duplicate blocks, even if reading of a block fails on a certain image screen (frame) 106, blocks having the same content again during the same scan By making blocks appear, the probability of block reading failures is reduced, and data reading errors are reduced. The numbers (1, 2, ..., n) in the blocks in Fig. 11 or Fig. 12 schematically represent the block addresses. As described above, it is obvious that the block address 303 and the data dot 304 are recorded.

 The parameter extraction unit 102 extracts the maximum value of the luminance of the entire imaging screen 106.

 The specular reflection detection unit 105 detects the specular reflection detection method as described in the first embodiment from the maximum value of the luminance extracted by the parameter overnight extraction unit 102. When the specular reflection is detected by the specular reflection detecting unit 105, the parameter setting unit 1100 detects the presence or absence of specular reflection. The parameter (maximum luminance value) extracted by 02 is invalidated, and no image processing or data reading processing is performed after that frame.

As described above, the presence or absence of specular reflection is detected, and when specular reflection occurs, the parameter is invalidated and processing is not performed in the frame. Based on the erroneous parameters that occur Image processing, thereby preventing blocks from being read in an improper state.

 [Third embodiment]

 Next, a third embodiment of the present invention will be described.

 FIG. 13 is a diagram showing a configuration of a code reading apparatus 100 according to the third embodiment. The code reading apparatus 100 of the present embodiment includes an imaging unit 101, a NO, and a RAM. Overnight extraction unit 102, image processing unit 103, data overnight reading unit 104, regular reflection detection unit 105, parameter overnight invalidation unit 110, and parameter overnight unit It consists of 1 1 1. In the following description of the present embodiment, components having the same reference numerals as those of the first embodiment and having no description will have the same functions as those of the first embodiment. .

 The parameter overnight extraction unit 102 extracts the maximum value of the luminance for each small area (subframe 107) obtained by dividing the imaging screen 106 into 24, as shown in FIG. 5, for example.

 The specular reflection detection unit 105 uses the specular reflection detection method described in the first embodiment from the maximum value of the luminance extracted by the parameter overnight extraction unit 102. The presence or absence of regular reflection is detected for each small area (subframe 107).

When the specular reflection is detected by the specular reflection detection unit 105, the white light disabling unit 110 is extracted from the detected small area (subframe 107). Disable the parameter (maximum brightness) and do not use it for subsequent image processing. Of course, the parameters (maximum brightness) extracted from the small area (subframe 107) where no regular reflection is detected It is output as it is to the subsequent parameter overnight section 1 1 1.

 In the parameter overnight substituting unit 111, a parameter (subframe 107) of the small area (subframe 107) from which the parameter invalidated by the parameter invalidating unit 110 is extracted is extracted. Is set in the following way. For example, the parameter storage unit 111 stores an effective parameter storage unit that stores a parameter (maximum luminance value) that was valid immediately before a continuously input captured image. In the small area (subframe 107) from which the parameter invalidated by the parameter invalidation unit 110 is extracted, the corresponding small area (subframe 107) is included. Set a valid parameter corresponding to the image, or prepare the maximum value of the average luminance that would be obtained when a code image is captured as a default value in advance. Note that this can be used in place of disabled parameters overnight.

 It should be noted that the effective parameters extracted from the no-launch overnight extraction unit 102 can be set as they are through the above-mentioned parameter overnight invalidation unit 110. Needless to say.

 The image processing unit 103 determines a binarization threshold for each subframe based on the parameter setting (maximum brightness) set by the parameter setting unit 111, The binarization of the code image captured by the imaging unit 101 is performed.

Thus, the maximum value of the luminance of the small area (subframe 107) where the regular reflection is detected is invalidated, and the maximum value of the luminance when the immediately preceding valid regular reflection is not included is included. Or a value calculated from the maximum luminance value of the adjacent small area (subframe 107), or Is used as the default value, and is used as the maximum value of luminance, so that even if a frame has regular reflection, it can be obtained from the original code image in the image processing unit 103. The binarization threshold based on the appropriate maximum luminance is set. Accordingly, appropriate binarization is performed, and block reading failure due to binarization failure ゃ data evening reading error can be reduced.

 Note that there is no need to always have a plurality of small regions for extracting the 、 and ° ラ as shown in FIG. 5, but to extract the maximum luminance value from the entire imaging screen 106. It may be. In this case, the image processing unit 103 determines a binarization threshold based on the maximum value of the detected luminance, and binarizes the entire imaging screen 106 with a uniform binarization threshold. become.

 In addition, if the parameter overnight extraction unit 102 is configured to extract the parameters from a plurality of small regions (subframes 107) in the imaging screen 106, the parameters are extracted. The overnight substituting unit 111 is composed of a plurality of sub-regions (sub-frame 107) adjacent to the sub-region (sub-frame 107) containing the invalidated parameter (maximum brightness). The average of the maximum values of the luminances extracted from the parameters may be used in place of the invalidated parameters.

Further, in the present embodiment, binarization is performed by setting a binarization threshold based on the maximum value of luminance extracted from a predetermined area. However, shading is performed in advance in the image processing unit 103. By performing the correction, it is also possible to perform appropriate binarization with a fixed threshold value.For example, as shown in Fig. 14A, the maximum value of the brightness 5 per subframe 107 is obtained. 0 0 is detected and its luminescence is detected as shown in Figure 14B. By correcting the luminance of the pixels in the subframe so that the maximum value of the degree becomes a predetermined value T, binarization can be appropriately performed at a predetermined threshold value Th. The luminance of a pixel is corrected, for example, by multiplying the luminance of each pixel by a correction coefficient R = T / (the maximum value of the luminance of the subframe 107) for each subframe.

 Here, if the sub-frame 107 is specularly reflected, the pixel brightness will be corrected to be low, and a dark image will be obtained with respect to the shading correction image that is originally desired. . Therefore, the maximum value of the luminance of the subframe 107 in which the specular reflection is detected can be substituted with the maximum value of the luminance of the surrounding subframe 107 or the maximum value of the luminance detected in the previous imaging frame. As a result, correct shading correction can be performed, and appropriate binarization can be performed [Fourth embodiment]

 Next, a fourth embodiment of the present invention will be described.

 FIG. 15 is a block diagram of a code reader 100 according to the fourth embodiment. The code reading device 100 of this embodiment includes an imaging unit 101, a non-linear image extraction unit 102, an image processing unit 103 a data reading unit 104, and a regular reflection detection unit 100. 5, It is composed of a part for invalidating the parameter and the part for parameter setting. Further, the image processing section 103 further includes a provisional binarization section 103A and a main binarization section 103B. In the following description of the present embodiment, components having the same reference numerals as those of the third embodiment described above and having no description are those having the same functions as those of the third embodiment. And

As shown in Fig. 16, the parameter overnight extractor 102 The maximum value of the luminance is extracted for each small region (subframe 107) divided into regions each having a sufficiently larger area than 302.

 The provisional binarization unit 103A of the image processing unit 103 is based on the maximum luminance value extracted for each small region (subframe 107) in the parameter extraction unit 102. A binarization threshold value is determined for each small region (subframe 107), and the code image captured by the imaging unit 101 is binarized. At this time, the binarization threshold is set to a value higher than the threshold suitable for code reading, for example, a value of 80% of the maximum luminance. At this time, if there is no regular reflection, the maximum value of the luminance is L as shown in Fig. 17 and binarization is performed with the binarization threshold = 0.8L. It looks like Figure 18. That is, since the binarization is performed at a threshold higher than the appropriate threshold, a part of the dot is blackened, but the marker 302 and most of the dots are in a recognizable state.

 On the other hand, when specular reflection occurs due to scratches 400 etc. on the recording medium, the maximum value of the luminance is L err shown in Fig. 17 and the binarization threshold = 0.8 L err Is binarized by Therefore, as shown in FIG. 19, most of the binarized result is black except for the portion 600 where specular reflection has occurred, and the code 300 cannot be recognized.

The regular reflection detection unit 105 detects the ratio of black pixels to white pixels for each small area (subframe 107) binarized by the temporary binarization unit 103A, If the ratio of black pixels is equal to or greater than a predetermined ratio, it is determined that specular reflection exists in the subframe 107. The ratio is about 85% for code 300 as shown in Fig. 4. For example, as shown in FIG. 19, it is determined that regular reflection has occurred in a small area (subframe 107) in which 85% or more are black pixels.

 In the parameter overnight disabling unit 110, the parameter overnight extracting unit 1102 corresponding to the small area (subframe 107) in which the regular reflection is detected by the regular reflection detecting unit 105 is used. Invalidate the parameters (maximum brightness) extracted in step (1).

 The parameter overnight substituting unit 111 substitutes for the method described in the third embodiment above in place of the maximum luminance value invalidated by the parameter overnight invalidating unit 110. Set parameters (maximum brightness).

 The binarizing section 103 B of the image processing section 103 sets each small area (sub-frame 107 b) based on the maximum luminance value set by the parameter substituting section 111. ), A binarization threshold (for example, the maximum luminance of 12) is set, and the code image captured by the imaging unit 101 is binarized.

 In this way, the presence or absence of specular reflection is detected based on the ratio of the black and white pixels of the binarization result for each small region (subframe 107), and the small region (subframe 1107) where regular reflection is detected is detected. In 07), binarization is performed by substituting an appropriate maximum brightness value that would be obtained when the code 300 is normally captured. As a result, it is possible to prevent inappropriate binarization based on the maximum value of erroneous luminance due to the reflection, and to reduce data reading defects.

Although the present invention has been described based on the embodiments, the present invention It is needless to say that the present invention is not limited to the embodiments described above, and various modifications and applications are possible within the scope of the present invention.

 Here, the summary of the present invention is as follows. (1) In a code reading device for optically reading the above code from a recording medium on which data is recorded with an optically readable code,

 An imaging unit for imaging the code,

 A parameter extraction unit for extracting a parameter related to the brightness of the region from a predetermined region of an image including the code captured by the imaging unit,

 An image processing unit that performs image processing on the predetermined area corresponding to an image including the code using the parameter extracted by the parameter extraction unit;

 A data reading unit that reads the data from an image including the code processed by the image processing unit;

 A specular reflection detection unit configured to detect specular reflection from the predetermined area corresponding to the image including the code based on the parameter extracted by the parameter extraction unit;

 A code reader characterized by comprising:

That is, when the code is imaged in an inappropriate imaging state in which specular reflection has occurred, it is possible to detect that specular reflection has occurred, and inform the operator of the fact and perform the scanning method again. By correcting and scanning, it is possible to prevent the code from being imaged in an improper imaging state and the data reading error from increasing. (2) The apparatus further comprises: a lane-overnight invalidation section for invalidating the parameter overtime from the predetermined area where the regular reflection is detected by the regular reflection detection section. The code reader according to (1).

 That is, it is possible to prevent image processing based on erroneous parameters caused by specular reflection, and reduce data reading errors.

 (3) In the above-mentioned parameter overnight that has been invalidated by the above-mentioned parameter overnight invalidation section, a parameter overnight section that substitutes another parameter that has been obtained in accordance with a predetermined method is used. The code reader according to (2), further comprising:

 In other words, even if specular reflection occurs, it is possible to set a parameter that would be obtained when an image including a code is normally captured without specular reflection, and an inappropriate image can be set. Prevents image processing and reduces data reading errors.

 (4) a plurality of the predetermined areas are set in advance in an image screen by the image pickup unit;

 The parameter extracting unit extracts the parameter for each of the plurality of predetermined areas, and

 The image processing unit applies the parameters extracted for each of the plurality of predetermined areas to the corresponding plurality of predetermined areas, and the plurality of predetermined areas. When it is configured to perform image processing for each

The parameter replacement unit is configured to receive the parameter from the predetermined area where specular reflection is detected by the specular reflection detection unit. (3) The code reading device according to (3), characterized in that the code reading device is configured to substitute the parameter extracted from a predetermined region adjacent to the region.

 That is, even when normal reflection cannot be extracted due to specular reflection, the parameters of the specular reflection occurrence area are determined based on the parameters extracted from a predetermined peripheral area in the frame. It can be set appropriately.

 (5) The imaging unit continuously captures the code while relatively moving with the recording medium, and outputs time-series image information corresponding to each of the captures. Is composed of

 The parameter / parameter extracting unit extracts the parameter / parameter from a predetermined area of each image information output in time series from the imaging unit, and

 The image processing unit converts each parameter extracted from a predetermined area of the image information into a parameter corresponding to the image information input subsequent to the image information extracted as a parameter. When applied to a predetermined area and configured to perform image processing on a predetermined area of the image information,

 The above-mentioned parameter one-time substituting unit is configured such that the specular reflection is detected by the above-mentioned specular reflection detecting unit, and the above-mentioned parameter is extracted from the predetermined area. (3) The code reading device according to (3), wherein the parameter is extracted from the corresponding predetermined area of the image information input in step (b).

In other words, when normal reflection cannot be extracted due to specular reflection. Even in this case, the parameters of the frame can be appropriately set based on the parameters extracted from the image including the code captured in the past from the frame.

 (6) The imaging unit continuously captures the code while relatively moving with the recording medium, and outputs time-series image information corresponding to each of the captures. Is composed of

 A plurality of the predetermined areas are set in advance in an image screen by the image pickup unit,

 The parameter extracting unit extracts the parameter for each of the plurality of predetermined regions for each piece of image information output in time series from the imaging unit; and

 The image processing unit converts each of the parameters extracted for each of the plurality of predetermined regions into image information that is input subsequent to the image information from which the parameter was extracted. When applied to each of the plurality of predetermined areas corresponding to the plurality of corresponding predetermined areas, image processing is performed for each of the plurality of predetermined areas.

 The parameter change section is configured to include, before the parameter information from the predetermined area in which the specular reflection is detected by the specular reflection detection section, before the image information from which the parameter is extracted. (3) The code reading device according to (3), wherein the parameter is extracted from the corresponding predetermined area of the image information input to the device.

In other words, even when normal parameters cannot be extracted due to specular reflection, the parameters extracted from each small area of the image containing the code captured in the past from the frame are not affected. Based on The parameters of each small area of the frame can be set appropriately, and more appropriate image processing can be performed.

 Furthermore, since the imaging screen can be divided into a plurality of small areas and image processing can be performed based on the parameters extracted for each of the small areas, the illumination and the lens of the imaging unit can be used. Appropriate image processing can be performed even when the brightness of the image screen is uneven due to the sensor characteristics.

 (7) A plurality of the predetermined areas are set in advance in an image screen by the imaging unit,

 The parameter extracting unit extracts the parameter for each of the plurality of predetermined areas, and

 The image processing unit applies the parameters extracted for each of the plurality of predetermined areas to the corresponding plurality of predetermined areas, and the plurality of predetermined areas. When configured to perform image processing for each

 The specular reflection detecting section is configured to detect the specular reflection based on a comparison between parameters extracted for each of the plurality of predetermined regions. ) Code reader.

 That is, it is possible to detect specular reflection within a single imaging screen.

 (8) The imaging unit continuously captures the code while relatively moving with respect to the recording medium, and chronologically obtains image information corresponding to each of the captures. Is configured to output

The parameter extraction unit outputs time series from the imaging unit Extracting the above parameters from a predetermined area of each of the obtained image information; and

 The image processing unit converts each parameter extracted from a predetermined area of each image information into a corresponding one of the image information input subsequent to the image information from which the parameter was extracted. When configured to apply image processing to a predetermined area of the image information by applying to the above-described predetermined area,

 The specular reflection detection unit detects the specular reflection based on a comparison of the parameters between the corresponding predetermined regions in a plurality of pieces of image information output in time series from the imaging unit. The code reading device according to (1), wherein the code reading device is configured to detect the code.

 That is, regular reflection can be detected by detecting a change between parameters, that is, a temporal change of a parameter extracted from an image including a code.

 (9) The imaging unit continuously captures the code while relatively moving with the recording medium, and outputs time-series image information corresponding to each of the captures. Is composed of

 A plurality of the predetermined areas are set in advance in an image screen by the imaging unit,

 The parameter extracting unit extracts the parameter for each of the plurality of predetermined regions for each image information output in time series from the imaging unit, and

The image processing unit converts each of the parameters extracted for each of the plurality of predetermined areas into an image from which the parameter is extracted. It is configured to be applied to each of the plurality of predetermined areas corresponding to the image information input subsequent to the image information, and to perform image processing for each of the plurality of predetermined areas. When

 The specular reflection detection unit, based on a comparison of the parameters between each of the plurality of corresponding predetermined regions in a plurality of pieces of image information output in time series from the imaging unit, The code reader according to (1), wherein the code reader is configured to detect the regular reflection.

 g |] In other words, by detecting the change of each small area between frames, that is, the temporal change of each area, of the parameters extracted from the image including the code, the specular reflection is obtained. Can be detected.

 (10) A plurality of the predetermined areas are set in advance in an image screen by the image pickup unit,

 A parameter extracting unit that extracts the parameter for each of the plurality of predetermined areas; and

 The image processing unit applies the parameters extracted for each of the plurality of predetermined areas to the corresponding plurality of predetermined areas, and the plurality of predetermined areas. When configured to perform image processing for each

 The specular reflection detection unit binarizes each of the plurality of predetermined regions corresponding to each of the parameters extracted from each of the plurality of predetermined regions and each of the thresholds set from each of the predetermined regions. The code reader according to (1), wherein the specular reflection is detected based on a ratio of black pixels to white pixels.

In other words, only the ratio of the number of white pixels and black pixels resulting from the binarization is sufficient. Specular reflection can be easily detected.

 (11) The imaging unit is

 An illumination unit for illuminating a code on the recording medium; an optical system for imaging reflected light from the recording medium illuminated by the illumination unit;

 An image sensor that receives light imaged by the optical system and outputs a corresponding image signal in time series;

 The code reader according to (1), further comprising: In other words, it is possible to take an image of the code in an always stable imaging state using the illumination.

 (12) The predetermined area is determined based on a positional relationship between the illumination unit, the imaging element, and the recording medium, and is most likely to cause regular reflection in an imaging screen of the imaging element. The code reader according to (11), wherein the code reader includes an area.

 In other words, regular reflection is detected reliably and easily by extracting a parameter for regular reflection detection from an area where regular reflection is likely to occur (usually, an area in the imaging area close to the illumination unit). be able to.

 (13) The imaging unit further includes an illumination control unit that controls the amount of illumination by the illumination unit based on the parameters extracted by the parameter extraction unit. The code reader according to (11), characterized in that:

 That is, it is possible to prevent the code from being imaged in an inappropriate lighting state based on an erroneous parameter extracted due to the regular reflection.

(14) The image processing unit is configured to take an image A binarization unit that performs a binarization process for each predetermined region of the image including the code,

 Any of (1) to (13), wherein the parameters extracted by the parameter extraction section are parameters used for the binarization processing. A code reader according to any of the above.

 In other words, even if specular reflection occurs, it is possible to set an appropriate binarization parameter, and due to improper binarization parameter setting, a binarization failure or data reading may occur. Errors can be reduced.

Industrial applicability

 According to the present invention, in a code reading device, audio data, image data, text data, or data that can be handled by a computer can be optically readable. It can read the code from the recorded media and restore the data, so it can be used not only for general logistics but also for ID cards, games, education, etc. Various usage forms can be expected in various fields.

Claims

The scope of the claims  1. In a code reading device that optically reads data from a recording medium on which data is recorded with an optically readable code,  An imaging unit for imaging the code;  A parameter extraction unit that extracts, from a predetermined region of an image including the code captured by the imaging unit, a parameter related to luminance of the region,  An image processing unit that performs image processing on the corresponding predetermined area of the image including the code using the parameter extraction extracted by the parameter extraction unit;  A data reading unit configured to read the data from an image including the code processed by the image processing unit;  A regular reflection detection unit that detects regular reflection from the corresponding predetermined region of the image including the code based on the parameter extracted by the parameter extraction unit;  A code reader characterized by comprising:  2. The apparatus according to claim 1, further comprising a parameter invalidating section for invalidating the parameter from the predetermined area in which the regular reflection is detected by the regular reflection detecting section. Code reading 3. In addition to the parameter set invalidated by the parameter set invalidating section, a parameter set substitute section for substituting another parameter set obtained in accordance with a predetermined method is used. 3. The code reader according to claim 2, further comprising: 4. A plurality of the predetermined areas are set in advance in an image screen of the imaging unit,  The parameter extraction unit extracts the parameter extraction for each of the plurality of predetermined regions; and  The image processing unit applies each parameter extracted for each of the plurality of predetermined regions to a corresponding one of the plurality of predetermined regions, and When it is configured to perform image processing for each  The parameter overnight substituting unit is extracted from a predetermined area adjacent to the predetermined area in the parameter from the predetermined area in which the specular reflection is detected by the specular reflection detecting unit. The code reading device according to claim 3, wherein the code reading device is configured to substitute the parameter set.  5. The imaging unit continuously captures the code while relatively moving with the recording medium, and outputs time-series image information corresponding to each of the captures. Is composed of  The parameter extracting unit extracts the parameter from a predetermined area of each image information output in time series from the imaging unit; and  The image processing unit converts each parameter extracted from a predetermined area of each image information into a parameter corresponding to the image information input subsequent to the image information from which the parameter was extracted. When configured to perform image processing on a predetermined area of the image information by applying to the predetermined area, The parameter overnight section detects regular reflection in the regular reflection detection section. At the same time, the parameters from the given predetermined area are extracted from the corresponding predetermined areas of the image information input before the image information from which the parameters were extracted. 4. The code reader according to claim 3, wherein said code reading device is configured to substitute said parameter.  6. The image capturing unit continuously captures the code while relatively moving with the recording medium, and outputs time-series image information corresponding to each of the captures. Composed,  A plurality of the predetermined areas are set in advance in an image screen by the image pickup unit,  The parameter extracting unit extracts the parameter for each of the plurality of predetermined regions for each image information output in time series from the imaging unit; and  The image processing unit converts each of the parameters extracted for each of the plurality of predetermined regions into image information that is input subsequent to the image information from which the parameter was extracted. When applied to each of the plurality of predetermined areas corresponding to the plurality of predetermined areas, the image processing is performed for each of the plurality of predetermined areas.  The parameter-substituting unit includes, before the parameter information from the predetermined area in which specular reflection is detected by the specular-reflection detecting unit, before the image information from which the parameter is extracted. 4. The code reading apparatus according to claim 3, wherein the parameter information extracted from the corresponding predetermined area of the image information input in step (b) is substituted. 7. The predetermined area is within an image screen of the imaging unit. Pre-set multiple,  The parameter extracting unit extracts the parameter extracting for each of the plurality of predetermined regions; and  The image processing unit applies each parameter extracted for each of the plurality of predetermined areas to each of the plurality of predetermined areas corresponding to the plurality of predetermined areas. When it is configured to perform image processing for each area,  The specular reflection detection unit is configured to detect the specular reflection based on a comparison between each parameter extracted for each of the plurality of predetermined regions. The code reader according to claim 1.  8. The imaging unit is configured to continuously capture images of the code while relatively moving with the recording medium, and output image information corresponding to each of the captured images in time series. And  The parameter extracting unit extracts the parameter from a predetermined area of each image information output in time series from the imaging unit; and  The image processing unit converts each parameter extracted from a predetermined area of the image information into a corresponding one of the image information input subsequent to the image information from which the parameter was extracted. When configured to apply image processing to a predetermined area of the image information by applying to the predetermined area, The specular reflection detection unit detects the specular reflection based on a comparison of the parameters between the corresponding predetermined areas in a plurality of pieces of image information output in time series from the imaging unit. To detect The code reading device according to claim 1, wherein the code reading device is configured as described above.  9. The imaging unit is configured to continuously image the code while relatively moving with the recording medium, and to output image information corresponding to each of the imagings in time series. And  A plurality of the predetermined areas are set in advance in an image screen by the image pickup unit,  The parameter extracting unit extracts the parameter for each of the plurality of predetermined regions for each image information output in time series from the imaging unit; and  The image processing unit converts each of the parameters extracted for each of the plurality of predetermined regions into image information input subsequent to the image information from which the parameter was extracted. When applied to each of the plurality of predetermined areas corresponding to the plurality of predetermined areas, the image processing is performed for each of the plurality of predetermined areas.  The specular reflection detection unit, based on a comparison of the parameters between the corresponding plurality of predetermined regions in the plurality of pieces of image information output in time series from the imaging unit, The code reader according to claim 1, wherein the code reader is configured to detect reflection.  10. A plurality of the predetermined areas are set in advance in an image screen of the image pickup unit,  The parameter extracting unit extracts the parameter for each of the plurality of predetermined regions; and The image processing unit is configured to extract each of the plurality of predetermined regions. Applying each of the obtained parameters to the corresponding plurality of predetermined areas, and performing image processing for each of the plurality of predetermined areas.  The specular reflection detection unit binarizes each of the plurality of predetermined regions corresponding to each threshold set from each parameter extracted for each of the plurality of predetermined regions. 2. The code reader according to claim 1, wherein the specular reflection is detected based on a ratio of black pixels to white pixels at that time.  1 1. The imaging unit  An illumination unit for illuminating a code on the recording medium; an optical system for imaging reflected light from the recording medium illuminated by the illumination unit;  An image sensor that receives light imaged by the optical system and outputs a corresponding image signal in time series;  The code reader according to claim 1, further comprising: 12. The predetermined area includes an area, which is determined based on a positional relationship among the illumination unit, the image sensor, and the recording medium, and is most likely to cause regular reflection in an image captured by the image sensor. The code reader according to claim 11, characterized in that:  13. The imaging unit further includes an illumination control unit that controls the amount of illumination light by the illumination unit based on the parameters extracted by the parameter extraction unit. The code reader according to claim 11. 14. The image processing unit performs a binarization process for each predetermined area of an image including the code captured by the imaging unit. Part,  The code reading device according to claim 1, wherein the parameter extraction extracted by the parameter extraction unit is a parameter extraction used for the binarization processing.