Information reading terminal

Abstract

To provide an information reading terminal that can reduce a processing time required for character recognition processing by reducing or extracting an image with characters to be recognized based on an imaging state of marker light indicating a reading range.SOLUTION: Marker light Lm1 consisting of multiple pieces of dot light arranged in a predetermined direction, is emitted by a marker light emitting unit toward an imaging range of an imaging unit of an information reading terminal. A distance between pieces of dot light in a captured image of the marker light is detected as a dot interval S. In a captured image P1 in a state where character information "ACBDE" on a display surface R is irradiated with the marker light at a long distance, the dot interval S is captured to be relatively large. In a captured image P2 in a state where the character information on the display surface is irradiated with the marker light at a closer medium distance, the dot interval S is captured to be smaller. In a captured image P3 in a state where the character information on the display surface is irradiated with the marker light at a further closer short distance, edges of adjacent pieces of dot light overlap, making the dot interval undetectable.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a portable information reading terminal for reading characters. [Background technology]

[0002] When characters displayed on a display medium are captured with a portable information reading terminal and read using the OCR function, if the distance between the characters and the information reading terminal is not constant, the size of the characters in the captured image will change depending on the distance. For this reason, it is necessary to search for characters across the entire captured image, assuming that the characters may be captured across the entire captured image. Therefore, the larger the captured image size, the longer the processing time required for character recognition processing.

[0003] Regarding such a problem, for example, in the image processing device disclosed in Patent Document 1 below, in the case of reading bib numbers from a captured image of participants in a marathon race, the size and position of a character area including the bib number in the captured image are estimated from the size and position of a face area, which is a feature point, in the captured image, and the image within that range is reduced to extract the character area. By reducing the image within the range estimated as a character area from the feature points in this way, the processing time required for character search can be shortened. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-053763 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a configuration that requires the detection of feature points such as face areas within a captured image as described above, there is a problem in that if feature points cannot be detected from the captured image, it is not possible to identify the search range to be reduced.

[0006] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a configuration that can shorten the processing time required for character recognition processing by reducing or extracting the image to be recognized as a character depending on the imaging state of the marker light indicating the reading range. [Means for solving the problem]

[0007] In order to achieve the above object, one aspect of the present invention is to An information reading terminal (10) that reads imaged character information, an imaging unit (23) that images the character information; a character recognition unit (21) that performs character recognition processing to read the character information using the image captured by the imaging unit; a marker light irradiating unit (25) that irradiates a marker light (Lm1) formed by arranging a plurality of dot lights in a predetermined direction toward an imaging range of the imaging unit; a dot interval detection unit (21) that performs processing to detect the distance between the dot lights in the captured image obtained by capturing the marker light as a dot interval (S); Equipped with The character recognition unit If the dot interval is not detected by the dot interval detection unit, the character recognition process is performed on a first reduced image (Pa1) obtained by reducing the captured image at a first reduction rate; When the dot interval detected by the dot interval detection unit is equal to or less than a predetermined threshold, the character recognition process is performed on a second reduced image (Pa2) obtained by reducing the captured image at a second reduction rate that is less thinning than the first reduction rate; When the dot interval detected by the dot interval detection unit exceeds the predetermined threshold, the character recognition process is performed on an extracted image (Pb) obtained by extracting a central portion of the captured image.

[0008] Another aspect of the present invention is An information reading terminal (10) that reads imaged character information, an imaging unit (23) that images the character information; a character recognition unit (21) that performs character recognition processing to read the character information using the image captured by the imaging unit; a marker light irradiating unit (25) that irradiates a marker light (Lm2) consisting of one dot light toward an imaging range of the imaging unit; a dot size detection unit (21) that performs processing to detect the size of the dot light in the captured image obtained by capturing the marker light; Equipped with The character recognition unit When the size (D) of the dot light detected by the dot size detection unit is equal to or larger than a first size (D1), the character recognition process is performed on a first reduced image (Pa1) obtained by reducing the captured image at a first reduction rate; When the size of the dot light detected by the dot size detection unit is equal to or larger than a second size (D2) set to be smaller than the first size and is smaller than the first size, the character recognition process is performed on a second reduced image (Pa2) obtained by reducing the captured image at a second reduction rate that is less thinning than the first reduction rate, When the size of the dot light detected by the dot size detection unit is less than the second size, the character recognition process is performed on an extracted image (Pb) obtained by extracting the center of the captured image. The symbols in parentheses above indicate the correspondence with the specific means described in the embodiments to be described later. [Effects of the Invention]

[0009] In the present invention, a marker light irradiating unit irradiates a marker light, which is a plurality of dot lights arranged in a predetermined direction, toward an imaging range of an imaging unit, and a dot spacing detection unit performs processing to detect the distance between the dot lights in a captured image captured from the marker light as a dot spacing. Then, in the character recognition unit, if the dot spacing is not detected, character recognition processing is performed on a first reduced image obtained by reducing the captured image at a first reduction rate. If the dot spacing is equal to or smaller than a predetermined threshold, character recognition processing is performed on a second reduced image obtained by reducing the captured image at a second reduction rate that is less thinned than the first reduction rate. If the dot spacing exceeds the predetermined threshold, character recognition processing is performed on an extracted image obtained by extracting a central portion of the captured image.

[0010] The dot light of the marker light irradiated toward the display surface on which character information etc. is displayed changes so that the dot size in the captured image increases as the distance between the display surface (character information) and the information reading terminal (hereinafter also referred to as the imaging distance) decreases. The dot spacing in the captured image also decreases as the imaging distance decreases, and at closer distances, the edges of adjacent dot light overlap and the dot spacing becomes undetectable.

[0011] Therefore, when a dot spacing is not detected, it is assumed that the character information is captured large due to close-range imaging. Character recognition processing is performed on a first reduced image, which is reduced at a first reduction rate so as to thin out the pixels of the captured image. This reduces the number of pixels to be searched for characters, thereby appropriately shortening the processing time required for the character recognition processing. When a dot spacing exceeding a predetermined threshold is detected, it is assumed that the character information is captured small in the center of the image due to long-range imaging. Character recognition processing is performed on an extracted image extracted from the center of the captured image. This reduces the character search range, thereby appropriately shortening the processing time required for the character recognition processing. When a dot spacing less than the predetermined threshold is detected, it is assumed that the character information is captured at a medium distance, which means that the first reduced image may be excessively reduced, resulting in a potential failure of the character recognition processing. Character recognition processing is performed on a second reduced image, which is reduced at a second reduction rate that thins out less than the first reduction rate. This reduces the processing time required for the character recognition processing while preventing failure of the character recognition processing. Therefore, by reducing or extracting the image to be character-recognized depending on the imaging state of the marker light indicating the reading range, the processing time required for the character recognition processing can be shortened.

[0012] The second reduction ratio may be set so that the closer the dot spacing is to a predetermined threshold, the less thinning occurs compared to the first reduction ratio.

[0013] In the present invention, a marker light consisting of one dot of light is irradiated by a marker light irradiating unit toward an imaging range of an imaging unit, and a process for detecting the size of the dot light in a captured image captured by the marker light is performed by a dot size detecting unit. Then, in the character recognition unit, when the size of the dot light is equal to or greater than a first size, character recognition processing is performed on a first reduced image obtained by reducing the captured image at a first reduction rate. When the size of the dot light is equal to or greater than a second size set to be smaller than the first size and less than the first size, character recognition processing is performed on a second reduced image obtained by reducing the captured image at a second reduction rate that is less thinned than the first reduction rate. When the size of the dot light is less than the second size, character recognition processing is performed on an extracted image obtained by extracting a central portion of the captured image.

[0014] Each dot of marker light that is irradiated toward a display surface on which text information, etc. is displayed changes so that the dot size in the captured image becomes larger as the distance (imaging distance) between the display surface (text information) and the information reading terminal becomes closer.

[0015] Therefore, when the size of the dot light is equal to or greater than the first size, it is determined that the character information has been captured large due to close-range imaging, and character recognition processing is performed on a first reduced image reduced at a first reduction rate so as to thin out pixels in the captured image. This reduces the number of pixels to be searched for characters, thereby appropriately shortening the processing time required for the character recognition processing. Furthermore, when the size of the dot light is less than the second size, it is determined that the character information has been captured small in the center of the image due to long-range imaging, and character recognition processing is performed on an extracted image extracted from the center of the captured image. This reduces the character search range, thereby appropriately shortening the processing time required for the character recognition processing. Furthermore, when the size of the dot light is equal to or greater than the second size but less than the first size, it is determined that the character information has been captured at a medium distance, and therefore the first reduced image may be excessively reduced, resulting in a possibility of failure of the character recognition processing. This reduces the processing time required for the character recognition processing while suppressing failure of the character recognition processing. Therefore, by reducing or extracting the image to be recognized as characters depending on the imaging state of the marker light indicating the reading range, the processing time required for the character recognition process can be reduced. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing an information reading terminal according to a first embodiment. [Figure 2] FIG. 2 is a block diagram illustrating an electrical configuration of the information reading terminal. [Figure 3] 3A and 3B are explanatory diagrams illustrating the relationship between the dot spacing of the dot light constituting the marker light and the imaging distance in the first embodiment, where FIG. 3A shows the imaging state at a long distance, FIG. 3B shows the imaging state at a medium distance, and FIG. 3C shows the imaging state at a close distance. [Figure 4] 4 is a flowchart illustrating the flow of character recognition processing performed by the control unit in the first embodiment. [Figure 5] FIG. 10 is an explanatory diagram illustrating a first reduced image that is reduced for character recognition, assuming that the image is captured at a short distance. [Figure 6] FIG. 10 is an explanatory diagram illustrating a second reduced image reduced for character recognition, assuming that the image is captured at a medium distance. [Figure 7] FIG. 10 is an explanatory diagram illustrating an extracted image extracted for character recognition as an image captured at a long distance. [Figure 8] 8A and 8B are explanatory diagrams illustrating the relationship between the dot size of the dot light constituting the marker light and the imaging distance in the second embodiment, where FIG. 8A shows the imaging state at a long distance, FIG. 8B shows the imaging state at a medium distance, and FIG. 8C shows the imaging state at a close distance. [Figure 9] 10 is a flowchart illustrating the flow of character recognition processing performed by a control unit in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] [First embodiment] Hereinafter, a first embodiment of an information reading terminal according to the present invention will be described with reference to the drawings. The information reading terminal 10 according to this embodiment is configured as a portable information processing device that optically reads optical information such as character information and information codes (barcodes, QR codes (registered trademark), etc.).

[0018] 1, the housing 11 constituting the outer shell of the information reading terminal 10 is formed in a substantially thin plate shape, and a large touch panel 26 is disposed on the surface thereof so as to have a narrow frame (narrow bezel). In addition, a reading opening 12 is provided on one longitudinal side of the rear surface of the housing 11 to take in reflected light from text information illuminated by illumination light into the housing.

[0019] Next, the electrical configuration of the information reading terminal 10 will be described with reference to FIG. As shown in FIG. 2, the information reading terminal 10 includes a control unit 21 that handles overall control, a memory unit 22 consisting of a semiconductor memory or the like, an imaging unit 23 configured as a camera, an illumination unit 24 that irradiates illumination light onto the imaging field of the imaging unit 23, a marker light irradiation unit 25 that can irradiate marker light toward the imaging range of the imaging unit 23 to indicate the imaging range, a touch panel 26 whose display content is controlled by the control unit 21, an operation unit 27 that outputs signals to the control unit 21 in response to touch operations on the touch panel 26 or key operations such as a trigger key, a communication unit 28 for communicating with higher-level devices, etc., a power supply unit, a battery, etc. (not shown).

[0020] The marker light irradiator 25 according to this embodiment is configured to irradiate the imaging range of the imaging unit 23 with marker light Lm1, which is composed of a plurality of dot lights arranged in a predetermined direction. Specifically, in this embodiment, the marker light Lm1 is irradiated in a cross shape, with the horizontal portion consisting of dot lights arranged at equal intervals along a horizontal line (hereinafter also referred to as a first marker line M1) extending in the horizontal array direction (left-right direction) of the imaging pixels and the vertical portion consisting of dot lights arranged at equal intervals along a vertical line (hereinafter also referred to as a second marker line M2) extending in the vertical array direction (up-down direction) of the imaging pixels, so that the intersection position of the horizontal portion and the vertical portion coincides with the center of the imaging range. In this embodiment, the marker light Lm1 is irradiated so that the horizontal portion is longer than the vertical portion.

[0021] For this reason, each dot light of the marker light Lm1 irradiated toward the display surface R on which character information and the like is displayed changes so that the size of the dot light in the captured image (hereinafter also referred to as dot size D) increases as the distance between the display surface R and the information reading terminal 10 (hereinafter also referred to as imaging distance) decreases. The distance between the dot lights in the captured image (the distance between one end of the dot light in the arrangement direction and the other end of the adjacent dot light in the arrangement direction: hereinafter also referred to as dot interval S) decreases as the imaging distance decreases, and at closer distances, the ends of adjacent dot lights overlap and the dot interval cannot be detected.

[0022] For example, as illustrated in FIG. 3A, in a captured image P1 in which the marker light Lm1 is irradiated onto the character information "ACBDE" on the display surface R at a long distance, the image is captured so that the dot interval S is relatively large.

[0023] In the captured image P2 when the marker light Lm1 is irradiated onto the character information "ACBDE" on the display surface R at a medium distance closer than the imaging distance in Figure 3(A), the dot spacing S is captured to be smaller than in Figure 3(A), as illustrated in Figure 3(B).

[0024] In the captured image P3 in which the marker light Lm1 is irradiated onto the character information "ACBDE" on the display surface R at a closer distance than the imaging distance in Figure 3(B), the ends of adjacent dot lights overlap, and the dot spacing S cannot be detected, as illustrated in Figure 3(C).

[0025] Therefore, the imaging distance to the character information illuminated by the marker light Lm1 can be estimated based on the dot interval S detected from the captured image obtained by capturing the marker light Lm1. That is, if the dot interval S is not detected, it can be assumed that the character information has been captured at a short distance, if the dot interval S exceeds a predetermined threshold Sth set as described below, it can be assumed that the character information has been captured at a long distance, and if the dot interval S is equal to or less than the predetermined threshold Sth, it can be assumed that the character information has been captured at a medium distance.

[0026] In this embodiment, by utilizing the ability to estimate the imaging distance from the dot spacing S as described above, the processing time required for character recognition processing is shortened by reducing or extracting the image to be recognized based on the dot spacing S in the character recognition processing performed by the control unit 21 using the OCR function.

[0027] The character recognition process performed by control unit 21 in this embodiment will be described in detail below with reference to the flowchart shown in Fig. 4. Note that control unit 21, which performs character recognition process for reading character information, can be an example of a "character recognition unit."

[0028] When the control unit 21 starts character recognition processing in response to a predetermined operation on the operation unit 27, a marker light irradiation process shown in step S101 of Fig. 4 is performed, and the marker light Lm1 is irradiated from the marker light irradiator 25. Subsequently, in a determination process of step S102, it is determined whether or not the trigger key has been turned ON. If the trigger key has not been turned ON, the determination is No, and the process from step S101 is repeated. Then, when the user turns ON the trigger key (Yes in S102), an imaging process shown in step S103 is performed, and an imaging range in a state where illumination light is irradiated by the illumination unit 24 is imaged by the imaging unit 23 through the reading port 12. Note that the imaging process may be performed by the imaging unit 23 at all times, without requiring the operation of the trigger key, etc.

[0029] Next, in the determination process shown in step S104, it is determined whether the imaging state is such that the marker light Lm1 is detected. Specifically, since the brightness value peaks at pixels where the reflected light of the marker light Lm1 is captured, it is determined whether the imaging state is such that the pixels with the peak brightness are detected along both the first marker line M1 and the second marker line M2. Here, in an imaging state where the marker light is not reflected because the reading port 12 is not correctly directed at character information, etc., and therefore the pixels with the peak brightness are not detected along both the first marker line M1 and the second marker line M2, it is determined that the marker light Lm1 is not detected (No in S104), and the process returns to step S101.

[0030] On the other hand, since the marker light is reflected on the display surface of the character information toward which the reading port 12 is directed, in an imaging state in which the pixel with peak brightness is detected along both the first marker line M1 and the second marker line M2, it is determined that the detection of the marker light Lm1 is successful (Yes in S104).

[0031] In this case, a dot interval detection process shown in step S105 is performed to detect the dot interval S of the captured image. In this embodiment, taking into consideration that dot lights captured at positions away from the intersection of the horizontal and vertical portions of the marker light Lm1 (positions away from the center of imaging) tend to be curved and easily captured, a process is performed to detect the distance between the horizontal dot lights closest to the center of imaging as the dot interval S. Note that the distance between the vertical dot lights closest to the center of imaging may be detected as the dot interval S, or the average value of the distance between one or more horizontal dot lights close to the center of imaging and the distance between one or more vertical dot lights close to the center of imaging may be detected as the dot interval S. Furthermore, the control unit 21 that performs the dot interval detection process may correspond to an example of a "dot interval detection unit."

[0032] Next, in the determination process of step S106, it is determined whether or not the detection of the dot interval S was successful. Here, in an image capturing state in which the edges of adjacent dot lights overlap as illustrated in Fig. 3(C), the dot interval S cannot be detected (No in S106), and therefore the first reduced-image generation process shown in step S108 is performed. In this process, since the dot interval S cannot be detected as described above, it is assumed that character information has been captured at a short distance, and a first reduced-image Pa1 is generated by reducing the entire captured image at a first reduction rate so as to thin out many pixels, as illustrated in Fig. 5.

[0033] On the other hand, if the detection of the dot interval S is successful (Yes in S106), a determination is made in step S107 as to whether the detected dot interval S is equal to or less than a predetermined threshold value Sth. If the detected dot interval S is equal to or less than the predetermined threshold value Sth (Yes in S107), a second reduced-image generation process shown in step S109 is performed. In this process, it is assumed that the character information has been captured at a medium distance, and a second reduced-image Pa2 is generated by reducing the entire captured image at a second reduction rate that is set to less thinning than the first reduction rate, as shown in FIG. 6. In this embodiment, the first reduction rate and the second reduction rate are set to 1 / 4 and 1 / 2, but are not limited to these, and may be, for example, 1 / 2 where n is a natural number. n+1 and 1 / 2 n The user may arbitrarily set the threshold value Sth according to the character size of the object to be recognized, etc. In this embodiment, the predetermined threshold value Sth is set according to the largest dot interval S that can be detected during calibration. Specifically, for example, if the maximum detectable dot interval S is 4 pixels, the predetermined threshold value Sth can be set to 2 pixels, which is half of that value.

[0034] Furthermore, if the detected dot spacing S exceeds a predetermined threshold value Sth (No in S107), an extraction image generation process shown in step S110 is performed. In this process, it is assumed that the character information has been captured at a long distance, and an extraction image Pb is generated by extracting the center of the captured image, as shown in Fig. 7. Note that in this embodiment, the center of the captured image is a portion occupying about 1 / 4 of the area of ​​the entire captured image, but this is not limiting, and the center of the captured image may be a portion occupying about 1 / 2 or 1 / 8 of the area of ​​the entire captured image, for example.

[0035] When the first reduced image Pa1, the second reduced image Pa2, or the extracted image Pb is generated as described above, OCR processing is performed in step S111, and the generated image is subjected to a known character recognition process using OCR (Optical Character Recognition) technology. As a result, when the first reduced image Pa1 illustrated in Fig. 5, the second reduced image Pb1 illustrated in Fig. 6, or the extracted image Pb illustrated in Fig. 7 is generated, "ABCDE" is recognized as character information and converted into data.

[0036] As described above, in the information reading terminal 10 according to this embodiment, the marker light irradiating unit 25 irradiates the marker light Lm1, which is formed by arranging a plurality of dot lights in a predetermined direction, toward the imaging range of the imaging unit 23, and a dot spacing detection process is performed to detect the distance between the dot lights in the captured image obtained by capturing the marker light Lm1 as the dot spacing S (S105). If the dot spacing S is not detected, character recognition process is performed on a first reduced image Pa1 obtained by reducing the captured image P at a first reduction rate. If the dot spacing S is equal to or smaller than a predetermined threshold Sth, character recognition process is performed on a second reduced image Pa2 obtained by reducing the captured image P at a second reduction rate that is less thinned than the first reduction rate. If the dot spacing S exceeds the predetermined threshold Sth, character recognition process is performed on an extracted image Pb obtained by extracting the central portion of the captured image P.

[0037] In this way, when the dot spacing S is not detected (No in S106), it is determined that the character information has been captured large due to close-range imaging, and character recognition processing is performed on the first reduced image Pa1, which is reduced at the first reduction rate so as to thin out the pixels of the captured image P. This reduces the number of pixels to be searched for characters, thereby making it possible to appropriately shorten the processing time required for the character recognition processing. Also, when the dot spacing S exceeding the predetermined threshold value Sth is detected (No in S107), it is determined that the character information has been captured small in the center of the image due to long-range imaging, and character recognition processing is performed on the extracted image Pb, which is an extracted central portion of the captured image P, making it possible to appropriately shorten the processing time required for the character recognition processing, since the character search range is narrowed. If a dot spacing S less than the predetermined threshold value Sth is detected (Yes in S107), it is determined that the character information is captured at a medium distance, and therefore the first reduced image Pa1 may be excessively reduced, resulting in a failure of the character recognition process. Therefore, by performing character recognition on a second reduced image Pa2 reduced at a second reduction rate that is less thinned than the first reduction rate, it is possible to reduce the processing time required for the character recognition process while suppressing failure of the character recognition process. Therefore, by reducing or extracting the image to be recognized as characters according to the imaging state of the marker light Lm1 that indicates the reading range, it is possible to reduce the processing time required for the character recognition process.

[0038] As a modified example of this embodiment, the second reduction ratio is not limited to being set to a constant value, but may be set, for example, so that the closer the dot spacing S is to a predetermined threshold value Sth, the less thinning occurs compared to the first reduction ratio.

[0039] Furthermore, in the character recognition process performed by the control unit 21, if the OCR process on the extracted image Pb generated as a result of long-distance imaging fails, the image range extracted from the original captured image may be gradually enlarged and repeated until the OCR process is successful. Furthermore, in the character recognition process performed by the control unit 21, if the OCR process on the first reduced image Pa1 or the second reduced image Pa2 generated as a result of close-distance imaging or medium-distance imaging fails, the OCR process may be repeated until the OCR process is successful, with the entire original captured image being reduced at a reduction rate with less thinning than when the process failed.

[0040] [Second embodiment] Next, an information reading terminal according to a second embodiment of the present invention will be described with reference to the drawings. The second embodiment differs from the first embodiment mainly in that the marker light is composed of a single dot of light. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and their description will be omitted.

[0041] The marker light Lm2 according to this embodiment is irradiated from the marker light irradiator 25 so as to indicate the center of the imaging range with one dot of light.

[0042] Therefore, as illustrated in FIG. 8(A), in a captured image P1 in which the marker light Lm2 is irradiated onto the character information "ACBDE" on the display surface R at a long distance, the dot size D is captured to be small.

[0043] In the captured image P2 when the marker light Lm2 is irradiated onto the character information "ACBDE" on the display surface R at a medium distance closer than the imaging distance in Figure 8(A), the dot size D is captured to be larger than in Figure 8(A), as illustrated in Figure 8(B).

[0044] In the captured image P3 in which the marker light Lm2 is irradiated onto the character information "ACBDE" on the display surface R at a closer distance than the imaging distance in Figure 8(B), the dot size D is captured to be larger than in Figure 8(B), as illustrated in Figure 8(C).

[0045] Therefore, the imaging distance to the character information irradiated with the marker light Lm2 can be estimated based on the dot size D detected from the captured image of the marker light Lm2. Therefore, in the character recognition process performed by the control unit 21 in this embodiment, the image to be subjected to character recognition is reduced or extracted based on the dot size D, thereby shortening the processing time required for the character recognition process.

[0046] Specifically, if the detected dot size D is equal to or greater than a first size D1, it is determined that the character information is captured large due to close-range imaging, and character recognition processing is performed on a first reduced image Pa1 obtained by reducing the captured image P at a first reduction rate. If the dot size D is less than a second size D2, which is set smaller than the first size D1, it is determined that the character information is captured small in the center of the image due to long-range imaging, and character recognition processing is performed on an extracted image Pb obtained by extracting the central portion of the captured image. If the dot size D is equal to or greater than the second size D2 but less than the first size D1, it is determined that the character information is captured at a medium distance, and therefore the first reduced image Pa1 is excessively reduced, which may result in character recognition processing failure. Therefore, character recognition processing is performed on a second reduced image Pa2, which is reduced at a second reduction rate that is less thinned than the first reduction rate. Note that in this embodiment, the first size D1 and the second size D2 are set to, for example, 4 pixels and 2 pixels, respectively, but are not limited thereto and may be set arbitrarily depending on the number of captured pixels, the usage environment, etc.

[0047] 9, in the character recognition process performed by the control unit 21, when it is determined that the detection of the marker light Lm2 is successful (Yes in S104), the dot size detection process shown in step S105a is performed, and the dot size D of the marker light Lm2 in the captured image is detected. The control unit 21 that performs the dot size detection process can be an example of a "dot size detection unit."

[0048] Next, in the determination process of step S106a, it is determined whether the detected dot size D is equal to or larger than the first size D1. If the detected dot size D is equal to or larger than the first size D1 (Yes in S106a), it is assumed that the character information has been captured at a short distance, and a first reduced image Pa1 is generated by reducing the entire captured image at a first reduction rate so as to thin out many pixels (S108).

[0049] Furthermore, if the detected dot size D is less than the first size D1 (No in S106a) and is equal to or greater than the second size D2 (Yes in S107a), it is assumed that the character information is being captured at a medium distance, and a second reduced image Pa2 is generated by reducing the entire captured image at a second reduction ratio (S109).

[0050] Furthermore, if the detected dot size D is less than the second size D2 (No in S107a), it is assumed that the character information is captured at a long distance, and an extracted image Pb is generated by extracting the center of the captured image (S110).

[0051] Then, when the first reduced image Pa1, the second reduced image Pa2, or the extracted image Pb is generated as described above, OCR processing shown in step S111 is performed, and a well-known character recognition process using OCR technology is performed on the generated image, thereby recognizing the captured character information and converting it into data.

[0052] As described above, in the information reading terminal 10 according to this embodiment, the marker light irradiator 25 irradiates the marker light Lm2 consisting of one dot of light toward the imaging range of the imaging unit 23, and a dot size detection process is performed to detect the dot size D of the dot light in the captured image obtained by capturing the marker light Lm2 (S105a). Then, in the character recognition unit, if the dot size D is equal to or greater than the first size D1, the character recognition process is performed on a first reduced image Pa1 obtained by reducing the captured image P at a first reduction rate. If the dot size D is equal to or greater than the second size D2 set to be less than the first size D1 and less than the first size D1, the character recognition process is performed on a second reduced image Pa2 obtained by reducing the captured image P at a second reduction rate that is less thinning than the first reduction rate. If the dot size D is less than the second size D2, the character recognition process is performed on an extracted image Pb obtained by extracting the central portion of the captured image P.

[0053] In this way, when the dot size D is equal to or greater than the first size D1, character information is assumed to be captured large due to close-range imaging, and character recognition processing is performed on a first reduced image Pa1 that is reduced at a first reduction rate so as to thin out pixels in the captured image P. This reduces the number of pixels to be searched for characters, thereby appropriately shortening the processing time required for the character recognition processing. Furthermore, when the dot size D is less than the second size D2, character information is assumed to be captured small in the center of the image due to long-range imaging, and character recognition processing is performed on an extracted image Pb that extracts the central portion of the captured image P. This reduces the character search range, thereby appropriately shortening the processing time required for the character recognition processing. Furthermore, when the dot size D is equal to or greater than the second size D2 but less than the first size D1, character information is assumed to be captured at a medium distance, and therefore the first reduced image Pa1 may be excessively reduced, resulting in a possibility of failure of the character recognition processing. This reduces the processing time required for the character recognition processing while suppressing failures of the character recognition processing. Therefore, by reducing or extracting the image to be recognized as characters depending on the imaging state of the marker light Lm2 indicating the reading range, the processing time required for the character recognition process can be reduced.

[0054] The present invention is not limited to the above-described embodiments, and may be embodied as follows, for example. (1) The present invention is not limited to being applied to an information reading terminal 10 that captures and reads character information, etc., but may also be applied to an information reading terminal that also has the function of reading wireless tags such as RFID tags via contactless communication, for example. [Explanation of symbols]

[0055] 10 Information reading terminal 21 Control unit (character recognition unit, dot spacing detection unit, dot size detection unit) 23 Imaging unit 25 Marker light irradiation unit D Dot Size Lm1, Lm2 marker lights S dot spacing P Captured image Pa1 1st reduced image Pa2 Second reduced image Pb extracted image

Claims

1. An information reading terminal that reads captured character information, an imaging unit that captures the character information; a character recognition unit that performs character recognition processing to read the character information using the image captured by the imaging unit; a marker light irradiating unit that irradiates a marker light, which is formed by arranging a plurality of dot lights in a predetermined direction, toward an imaging range of the imaging unit; a dot interval detection unit that performs processing to detect a distance between the dot lights in the captured image obtained by capturing the marker lights as a dot interval; Equipped with The character recognition unit when the dot interval is not detected by the dot interval detection unit, performing the character recognition process on a first reduced image obtained by reducing the captured image at a first reduction rate; when the dot interval detected by the dot interval detection unit is equal to or less than a predetermined threshold, performing the character recognition process on a second reduced image obtained by reducing the captured image at a second reduction rate that is less thinning than the first reduction rate; When the dot interval detected by the dot interval detection unit exceeds the predetermined threshold, the character recognition process is performed on an extracted image obtained by extracting a central portion of the captured image.

2. 2. The information reading terminal according to claim 1, wherein the second reduction ratio is set so that the closer the dot interval is to the predetermined threshold value, the less thinning occurs compared to the first reduction ratio.

3. An information reading terminal that reads captured character information, an imaging unit that captures the character information; a character recognition unit that performs character recognition processing to read the character information using the image captured by the imaging unit; a marker light irradiating unit that irradiates a marker light consisting of one dot of light toward an imaging range of the imaging unit; a dot size detection unit that performs processing to detect the size of the dot light in the captured image obtained by capturing the marker light; Equipped with The character recognition unit When the size of the dot light detected by the dot size detection unit is equal to or larger than a first size, the character recognition process is performed on a first reduced image obtained by reducing the captured image at a first reduction rate; when the size of the dot light detected by the dot size detection unit is equal to or larger than a second size that is set to be smaller than the first size and is smaller than the first size, performing the character recognition process on a second reduced image obtained by reducing the captured image at a second reduction rate that is less thinning than the first reduction rate; An information reading terminal characterized in that, when the size of the dot light detected by the dot size detection unit is less than the second size, the character recognition processing is performed on an extracted image obtained by extracting the central part of the captured image.

Images