• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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  • 优先权
    • 专利摘要:
    In one embodiment, the present invention is a barcode reader comprising: a first image forming assembly adapted to record a first image; a second imaging assembly positioned relative to the first imaging assembly and arranged to receive a second image; and a control module communicatively coupled to the first imaging assembly and the second imaging assembly. The control module is arranged to: calculate a first contrast level in a first area in the first image; calculate a second contrast level in the second area in the second image; perform a first barcode decoding operation on the first image when the first contrast level is greater than the second contrast level; and perform the first barcode decoding operation on the second image when the second contrast level is greater than the first contrast level.
    公开号:BE1026236B1
    申请号:E20195257
    申请日:2019-04-17
    公开日:2020-07-17
    发明作者:Harry E Kuchenbrod；David P Goren；Chinh Tan
    申请人:Zebra Tech Corp；
    IPC主号:
    专利说明:

    Optimized Barcode Decoding in Multi Imaging Barcode Readers and Imaging Base Modules Background Barcode readers are commonly found in use in a variety of locations such as retail environments, warehouses, product transport facilities, factories, and so on.
    In many cases, these barcode readers are expected to operate over a wide range of distances, giving the operator the ability to read barcodes from a few inches away to tens of feet away.
    While it is possible to construct such readers using a single imaging assembly, this design is not cost effective since it requires complex optical components that operate to record image data over the wide operating range.
    In contrast, a more common approach relies on multiple (often two) imaging assemblies where each assembly is arranged to record image data over a subset of the entire workspace.
    This method is advantageous since it uses simpler optical components that can be both more robust and cost effective.
    However, there are also disadvantages.
    For example, by using multiple imaging assemblies, the barcode reader can be instructed to attempt to decode a barcode into multiple respective images.
    This can increase computational resources allocated to image analysis, slow overall scan operation, and / or increase power consumption resulting in faster battery drain in wireless reader cases.
    Therefore, there is a need to optimize decoding operations in barcode readers with multiple imaging assemblies.
    Summary Accordingly, at least some embodiments of the present invention are directed to devices, systems and methods for optimizing decoding operations in barcode readers with multiple imaging assemblies.
    According to an aspect of the invention, a barcode reader is provided comprising: a first imaging assembly arranged to record a first image over a first field of view (FOV); a second imaging assembly positioned relative to the first imaging assembly and arranged to record a second image over a second FOV; and a control module communicatively coupled to the first imaging assembly and the second imaging assembly. The control module is arranged to: calculate a first contrast level in a first area, the first area being in the first image; calculate a second contrast level in a second area, the second area being in the second image; perform a first barcode decoding operation on the first image when the first contrast level is greater than the second contrast level; perform the first barcode decoding operation on the second image when the second contrast level is greater than the first contrast level.
    The control module may further be arranged to perform a second barcode decoding operation on the second image when the first contrast level is greater than the second contrast level and the first barcode decoding operation is unsuccessful; and performing the second barcode decoding operation on the first image when the second contrast level is greater than the first contrast level and the first barcode decoding operation is unsuccessful.
    Advantageously, the first imaging assembly includes a first linear imaging module and the second imaging assembly includes a second linear imaging module.
    Alternatively and / or additionally, the control module may be arranged to calculate the first contrast level in the first area by determining a first white level and first black level, and associating the first contrast level with a difference between the first white level and the first black level, and wherein the control module is arranged to calculate the second contrast level in the second area by determining a second white level and a second black level, and associating the second contrast level with a difference between the second white level and the second black level.
    Furthermore, the barcode reader may be provided in which the first white level is associated with a first lowest brightness value of a subset of brightest pixels of the first area, the first black level is associated with a first highest brightness value of a subset of darkest pixels of the first area, wherein the second white level is associated with a second lowest brightness value of a subset of brightest pixels of the second area, and the second black level is associated with a second highest brightness value of a subset of darkest pixels of the second area.
    The subset of brightest pixels of the first area may comprise a first predetermined percentage of pixels of the total number of pixels in the first area and the subset of darkest pixels of the first area may comprise a second predetermined percentage of pixels of the total number of pixels in the first area.
    The subset of brightest pixels of the second area may comprise a third predetermined percentage of the total number of pixels in the second area, and the subset of darkest pixels of the second area may comprise a fourth predetermined percentage of the total number of pixels in the second area. second area.
    Furthermore, the control module may be arranged to determine the first white level and the first black level from a first histogram of the first area, and the control module may be arranged to determine the second white level and the second black level from a second histogram of the second area.
    According to another aspect of the invention, an image-forming base module is provided for use in a barcode reader. The image-forming base module includes: a first image-forming assembly arranged to record a first image over a first FOV; a second image-forming assembly positioned relative to the first image-forming assembly and arranged to record a second image over a second FOV; and a control module communicatively coupled to the first imaging assembly and the second imaging assembly. The control module is arranged to: calculate a first contrast level in a first area, the first area being in the first image; calculate a second contrast level in a second area, the second area being in the second image; perform a first barcode decoding operation on the first image when the first contrast level is greater than the second contrast level; and performing the first barcode decoding operation on the second image when the second contrast level is greater than the first contrast level.
    The control module may be arranged to calculate the first contrast level in the first area by determining a first white level and first black level, and associate the first contrast level with a difference between the first white level and the first black level, and the control module may be arranged calculate the second contrast level in the second area by determining a second white level and a second black level, and associating the second contrast level with a difference between the second white level and the second black level.
    The first white level can be associated with a first lowest brightness value of a subset of the brightest pixels of the first area, the first black level being associated with a first highest brightness value of a subset of 5 darkest pixels of the first area, the second white level can be associated with a second lowest brightness value of a subset of brightest pixels of the second area, and the second black level may be associated with a second highest brightness value of a subset of darkest pixels of the second area.
    The subset of brightest pixels of the first area may comprise a first predetermined percentage of pixels of the total number of pixels in the first area, the subset of darkest pixels of the first area comprising a second predetermined percentage of pixels of the total number of pixels in the first area, wherein the subset of brightest pixels of the second area may comprise a third predetermined percentage of the total number of pixels in the second area, and the subset of darkest pixels of the second area may comprise a fourth predetermined percentage of the total number of pixels in the second area.
    The control module may further be arranged to determine the first white level and the first black level from a first histogram of the first area, and the control module may be arranged to determine the second white level and the second black level from a second histogram of the second area.
    According to still another aspect of the invention, there is provided a method of decoding a barcode with a barcode reader having a control module communicatively coupled to a first imaging assembly and a second imaging assembly, the method comprising: recording a first image via the first imaging assembly over a first FOV; recording a second image via the second imaging assembly over a second FOV; calculating, via the control module, a first contrast level in a first area, the first area being in the first image; calculating, via the control module, a second contrast level in a second area, the second area being in the second image; performing a first barcode decoding operation on the first image when the first contrast level is greater than the second contrast level; and performing the first barcode reading operation on the second image when the second contrast level is greater than the first contrast level. Advantageously, the operation of recording the first image and the operation of recording the second image can be performed simultaneously.
    Furthermore, the method may include: wherein the operation of calculating the first contrast level in the first area comprises determining a first white level and a first black level, and associating the first contrast level with a difference between the first white level and the first black level , and wherein the operation of calculating the second contrast level in the second area comprises determining a second white level and a second black level, and associating the second contrast level with a difference between the second white level and the second black level.
    The first white level can be associated with a first lowest brightness value of a subset of brightest pixels of the first area, the first black level being associated with a first highest brightness value of a subset of darkest pixels of the first area, where the second white level can be are associated with a second lowest brightness value of a subset of brightest pixels of the second area, and the second black level may be associated with a second highest brightness value of a subset of darkest pixels of the second area.
    In addition, the subset of brightest pixels of the first area may comprise a first predetermined percentage of pixels of the total number of pixels in the first area, wherein the subset of darkest pixels of the first area may comprise a second predetermined percentage of pixels of the total number pixels in the first area, wherein the subset of brightest pixels of the second area may comprise a third predetermined percentage of the total number of pixels in the second area, and the subset of darkest pixels of the second area may comprise a fourth predetermined percentage include the total number of pixels in the second area.
    The method may further include: determining a first histogram of the first area; and determining a second histogram of the second area, wherein the operation of determining the first white level and the first black level is based on the first histogram, and the operation of determining the second white level and the second black level is based on the second histogram.
    Advantageously, the first imaging assembly may comprise a linear imaging module or a two-dimensional imaging module.
    These and other features, aspects and advantages of the present description will be better understood with reference to the following drawing, description and claims that follow. The figures are merely schematic representations of embodiments of the invention which are described as non-limiting examples. In the figures, the same or corresponding parts are designated by the same or comparable reference numerals.
    Figures
    Herein shows
    FIG. 1 front and rear perspective views of a barcode reader in accordance with an embodiment of the present invention;
    FIG. 2 is a schematic block diagram of a portion of a barcode reader in accordance with an embodiment of the present invention;
    FIG. 3A is a perspective view of some components of a barcode reader in accordance with an embodiment of the present invention;
    FIG. 3B is a cutaway top view of the components of FIG. 3A;
    FIG. 4A is a flowchart representative of an exemplary method of decoding a barcode with a barcode reader in accordance with an embodiment of the present invention;
    FIG. 4B is a flowchart representative of an exemplary method of decoding a barcode with a barcode reader in accordance with an embodiment of the present invention;
    FIG. 5A is an exemplary image recorded by an image-forming assembly;
    FIG. 5B is a histogram of the image of FIG. 5A;
    FIG. 6A an exemplary image recorded by an image-forming assembly, and
    FIG. 6B is a histogram of the image of FIG. 6A.
    Detailed Description Referring to FIG. 1, an exemplary barcode reader 100 is shown having a housing 102 with a cavity for housing internal components, a trigger 104, and a window 106. The barcode reader 100 can be used in a hands-free mode as a stationary workstation when it is on the counter. placed in a supporting carrying device (not shown). The barcode reader 100 can also be used in a hold mode when it is taken from the counter (or any other surface) and held in the hand of an operator.
    In hands-free mode, products can be scrolled, swept, or displayed to the window 106.
    In the hold mode, the barcode reader 100 can be aimed at a barcode on a product and the trigger 104 can be manually depressed to initiate the imaging of the barcode.
    In some implementations, the support carrying device may be omitted and the housing 102 may also have other holding or non-holding forms.
    FIG. 2 shows a schematic block diagram of a portion of a barcode reader 100 in accordance with some embodiments.
    It is to be understood that FIG. 2 is not drawn to scale.
    The barcode reader 100 in FIG. 2 includes the following components: (1) a first image forming assembly 110 that includes a first linear image sensor 112 and a first lens assembly 114; (2) a second imaging assembly 116 that includes a second linear image sensor 118 and a second lens assembly 120; (3) an illumination source 122; (4) an aligning light assembly 123 with an aligning light source 125 and an aligning lens assembly 127 (also called aligning beam former); (5) a printed circuit board (PCB) 124 that supports the first and second linear image sensors 112, 118 and the lighting source 122; (6) a control module 126 positioned on the PCB 124 communicatively coupled to the first and second linear image sensor 112, 118 and the illumination source 122; (7) a memory 128 connected to the control module 126; and (8) an illumination lens assembly 130 positioned in front of the illumination source
    122. When referencing, portions of the barcode reader can be grouped and referred to as a “basic imaging module”. In some cases, the basic imaging module may include image recording components such as the image sensor (s). In other cases, the imaging base module may include additional elements, such as, for example, an aligning light assembly. In still other instances, a basic imaging module may include image recording components such as the image sensor (s) together with the control module to which they are coupled. Additionally, references to a control module may include multiple integrated circuits that function together to control various reading components and / or analyze / perform various calculations and / or steps. These functions can be performed by programming the control module with certain instructions provided in the form of computer code and / or by arranging a particular action to be performed by hardware response to an input signal.
    The first and second linear imaging sensors 112, 118 may be CCD or CMOS linear imaging sensors which generally comprise multiple photo-sensitive pixel elements aligned in a one-dimensional grid. The first and second linear imaging sensor 112, 118 operate to detect light absorbed by the first and second lens assemblies 114, 120, respectively, along an optical path or axis 132, 134 through the window 106, generally. Image sensor and imaging lens assembly pair designed to work together to record light scattered, reflected or emitted from a barcode as pixel data over a one-dimensional field of view (FOV) extending along a linear FOV plane. However, any lens / imaging sensor pair
    (also referred to as an optical assembly) is arranged with various parameters.
    In the embodiment described here, the first image-forming assembly 110 is designed to read barcodes over a relatively far operating distance range extending between FWD1 and FWD2. In some embodiments, FWD1 is about 24 inches from window 106 and FWD2 is about 600 to 680 inches from window 106. In some embodiments, FWD2 extends beyond 680 inches. Additionally, imaging assembly 110 absorbs light from a relatively narrow FOV 136.
    On the other hand, the second optical assembly 116 is designed to read barcodes over a relatively near working distance range extending between NWD1 and NWD2. In some embodiments, NWD1 is about 0 inches from the window 106 and NWD2 is about 28 to 32 inches from the window 106. In addition, the imaging assembly 116 absorbs light from a relatively wider FOV 138.
    An example of the component arrangement of FIG. 2 is illustratively shown in a perspective view of FIG. 3A and the exploded top view of FIG. 3B showing some of the components of the reader 100 in a partially assembled form. In this embodiment, the aligning light assembly 123 is positioned between the first imaging assembly 110 and the second imaging assembly 116. In a preferred arrangement, the aligning assembly is positioned closer to the second (near) imaging assembly than the first imaging (distant) assembly. This can be advantageous if the change of the directional light pattern relative to the FOV 138 of the second (near) imaging assembly 116 is reduced by parallax. Additionally, in the embodiment shown in FIG. 3A and FIG. 3B, the first linear image sensor 112 and the second linear image sensor 118 positioned on a substrate (such as a PCB 124) so that a distance between the first linear image sensor 112 and the first lens assembly 114 differs from a distance between the second linear image sensor 118 and the second lens assembly 120 In addition, the imaging assemblies 110, 116 and the alignment assembly 123 may be positioned so that their fields of view (shown as being co-planar in FIG. 4 and FIG.
    5) and the planes along which they extend are at an oblique angle to a PCB plane defined by the longitudinal and transverse directions of the PCB 124.
    To optimize the operation of the barcode reader 100, the preprocessing of image data recorded by each image forming assembly can be performed before performing decoding operations. Preferably, the preprocessing operation is performed in less time than a full decoding operation and provides an indication as to which image should be used (at least initially) in the full decoding operation. An example of such preprocessing operations can be implemented using image contrast levels, as will be described below.
    With reference to FIG. 4A, a flowchart representative of an exemplary method 400 for decoding a barcode with a barcode reader is shown. The barcode reader may be reader 100 that includes a control module 126 communicatively coupled to a first imaging assembly 110 and a second imaging assembly 116. The method includes steps 402 and 404 where, by means of the first and second imaging assemblies, the reader first and record second images of an environment. When used with the reader 100 which has a configuration as shown in FIG. 2, the first image is captured by the first imaging assembly 110 over a first field of view (FOV) 136 and the second image is captured by the second imaging assembly 116 over a second FOV 138. Preferably, but not necessarily, the images are simultaneously included. Since both fields of view 136, 138 generally point in the same direction, at least a portion of a target (usually comprising a barcode to be read) will appear within both of those fields of view. However, since one FOV (e.g. FOV 136) may be arranged to record image data over a more distant operating range than the other FOV (e.g. FOV 138), one of the recorded images is likely to be more focused than the other image. Additionally, due to the use of different optics in the imaging assemblies, the actual composition of the images will vary. An example of a first image captured by the first image-forming assembly 110 of a target positioned a predetermined distance from the reader 100 is shown in FIG. 5A and an example of a second image captured by the second imaging assembly 116 of the same target positioned at the same predetermined distance from the reader 100 is shown in FIG. 6A. Since the imaging assemblies 110, 116 have been described in examples as comprising linear imaging modules, originally recorded first and second images 500, 600 have a height of one pixel. However, for illustrative purposes, the height of this pixel (and thus of the entire images) increases, creating some distortion in the aspect ratio of the images. In other words, the images are stretched in the vertical direction.
    When recording the images 500, 600 in steps 402, 404, the images have been preprocessed by the control module to determine which of the images should be used (at least first) to perform a decoding operation. As shown in step 406, this includes the operation of calculating a first contrast level in a first area of the first image. While it may be possible to use the entire first image 500 as the first area to perform necessary calculations, in a preferred embodiment, the first area is a subset of the first image 500. Limiting the first area to a portion of the entire image 500 may allow a reduced computational load on the control module and the auxiliary components, potentially increasing processing times and decreasing power consumption.
    In addition, concentration on a target area of an image can result in a more consistent and better results since areas likely outside the intended target can be ignored during image analysis.
    Therefore, the first area can be selected as a subset (i.e., a portion) of the first image according to criteria that have been found to be appropriate and / or desired.
    For example, the first area may include a predetermined percentage (e.g., 5%, 15%, 20%, 25%, 30%, 33%, 35%, 40%, or other suitable percentage) of the first image where the first area is centered, for example, around the center of the first image.
    Thus, applying this example to a linear image, such as image 500, would
    that is 2500 pixels wide, a range equivalent to a portion that covers 20% of the entire image and that is centered around the center of the image covers pixels 1001-1500 when the pixels are numbered sequentially from 1 to 2500. With others the range would cover the central 500 pixels.
    In addition, the specific portion of the image covered by the region of interest may be determined by any number of underlying factors that may, but may not, require some additional analysis.
    For example, an area of interest may not be centered around the center of an image, but instead around a calibrated point that is intended to indicate a zero parallax point at a given working distance.
    Accordingly, an area of an image may ultimately be any set or subset of pixels of that image, the set / subset being dictated by some underlying factors.
    The same concept could further be applied to a two-dimensional sensor where the desired area is formed from an appropriate or desired portion of the entire image.
    In the embodiment described here, the first region 502 is selected as a set of 166 consecutive horizontal pixels centered around a predetermined zero parallax point (pixel)
    504. In some embodiments, the contrast level can be calculated in this area by determining a white level and a black level, and associating the contrast level with a difference between the white level and the black level. The white level can be defined as a lowest brightness value of a subset of the region's brightest pixels, and a black level can be defined as a highest brightness value of a subset of the region's darkest pixels. One way to obtain these values is to derive and analyze a histogram of the region of interest. FIG. 5B shows a histogram of the example area 502 that plots the pixel count in the area as a function of an 8-bit brightness scale ranging from 0 to 255.
    To calculate the white level from this histogram, the subset of brightest pixels of the area can be set to a predetermined value, such as, for example, 5%, 10%, 12%, 12.5%, 13%, 15%, 20%, etc. of the total amount of pixels in the area. Assuming, for the purpose of this example, that the subset of brightest pixels of area 502 is 12.5% of said area, that would mean that said subset includes 21 brightest pixels 506 (12.5% of 166 pixels of area 502 rounded to a whole pixel count) in that area, indicated by a solid black color in FIG. 5B. By combining that with the histogram data, it is possible to obtain the lowest brightness value in the 21 brightest pixels 506. Another way to see it would be to start from the right side of the graph (brightness value 255) and move to the left side, add the pixel count until 21 pixels are reached. The brightness value where 21 pixels are reached indicates the lowest brightness value within the 21 brightest pixels, and thus the white level of the area 502. In FIG. 5B, the white level is shown as having a brightness value of 125.
    Similar to the white level, the black level can also be derived from the histogram. However, instead of evaluating a subset of the brightest pixels, black level calculation focuses on the highest brightness value of a subset of the area's darkest pixels. As with the brightest pixels subset, the darkest pixels subset of the area can be set to a predetermined value, such as, for example, 5%, 10%, 12%, 12.5%, 13%, 15%, 20%, etc. of the total amount of pixels in the area. Additionally, the size of the subset of darkest pixels may be, but is not necessarily, the same as the size of the subset of brightest pixels. Assuming, for the purpose of this example, that the subset of darkest pixels of the area 502 is 12.5% of said area, that would mean that said subset includes 21 darkest pixels 508 (12.5% of 166 pixels of the area 502 rounded to a whole pixel count) in that area, which are indicated by solid black color in FIG. 5B. By combining that with the histogram data it is possible to obtain the highest brightness value in the 21 darkest pixels 508. Another way to see it would be to start with the left side of the graph (brightness value 0) and move to the right side, add the pixel count until 21 pixels are reached. The brightness value where 21 pixels are reached indicates the highest brightness value within the 21 darkest pixels, and thus the blackness level for the area 502. In FIG. 5B, the black level is shown with a brightness value of 100. Once the white and black levels are determined, the contrast level for the area 502 can be calculated by finding the difference between the white level and the black level. In the case of the area 502, the contrast level is 25 (= 125 [white level] -100 [black level]).
    Similar to calculating the first contrast level, a second contrast level is calculated for an area in the second image 600 in step 408. Area selection, white level calculation and black level calculation techniques described above in relation to the first image 500 are similarly applicable to the second image 600. As such, it is not necessary to re-write them literally since they apply to the second image 600. Considering the above, the second area 602 is selected as a set of 166 consecutive pixels centered around a predetermined, zero-parallax point (pixel) 604. To determine the contrast of this area, the white and black levels are first calculated from the histogram shown in FIG. 6B. For the purpose of this embodiment, the white level is associated with the lowest brightness value of a subset 606 of brightest pixels of the area 604, the subset being equivalent to 12.5% of the total amount of pixels in the area. Similarly, for the purpose of this embodiment, the black level is associated with the highest brightness value of a subset 608 of darkest pixels of the area 604, the subset being equivalent to 12.5% of the total amount of pixels in the area. Based on the histogram of FIG. GB one can determine that the white level has a value of 127 and the black level has a value of 36. It follows that the contrast level for the area 604 is equal to 91 (= 127 [white level] - 36 [black level).
    Once the first and second contrast levels are obtained, a comparison of one contrast level with the other contrast level can be made to help determine whether the first image 500 or the second image 600 should be subjected to a barcode decoding operation. If it is determined that the first contrast level C1 is greater than the second contrast level Cz, the control module is instructed
    (i.e., arranged) to perform a decoding operation 412 on the first image 500. Otherwise, if it is determined that the second contrast level C2 is greater than the first contrast level C1, the control module can be instructed to perform a decoding operation 414. on the second image
    600. In the unlikely event that the first contrast level C1 is equal to the second contrast level, the control module can be programmed (i.e., arranged) to perform a decoding operation on one of the two pictures recorded by random selection, on one of the images that is considered a standard image, or on further analysis of the images.
    Ideally, the above steps will result in the Correct image being selected for the barcode decoding operation, resulting in the control module successfully performing a barcode decoding analysis on only one of the two images. As one of the advantages, this can shorten barcode read times and reduce necessary computing resources. However, there may be cases when the image with a higher contrast level does not include a legible barcode. Accordingly, the method 400 can be supplemented with additional steps that help the reader capture the correct image for successful barcode decoding.
    For example, in the embodiment shown in FIG. 4A, in determining that the initial decoding operation performed in step 412/414 is unsuccessful, the control module can be programmed to return to step 402 to record a new set of pictures and extract the relevant analysis on the new set of pictures. to feed. In another embodiment shown in FIG. 4B, in determining that the initial decoding operation performed in step 412/414 is unsuccessful, the control module can be programmed to perform a decoding operation on the other pictures not yet used for the decoding operation. Thus, if the control module has performed an unsuccessful decoding operation 412 on the first image, it may be further instructed to perform a decoding operation 416 on the second image 600. Conversely, if the control module has performed an unsuccessful decoding operation 414 on the second image, it can be further instructed to perform a decoding operation 418 on the first image 500. From there, if the decoding operation was successful, the back routine ends. Otherwise, the control module can be programmed to return to step 402 to record a new collection of images and perform the relevant analysis on the new collection of images. In addition, in some embodiments, the control module may be programmed to keep count of successive unsuccessful decoding based on an image recorded by the same imaging module and manually decoding the image recorded by the other of the imaging modules. if the number of unsuccessful decoding exceeds a predetermined threshold. For example, if the reader tries to unsuccessfully decode a barcode from the image recorded by the first imaging module and this occurs X number of times in a row (where X is the threshold number), as dictated by the calculated contrast levels, the X + 1 attempt to perform a read operation, the control module are programmed to perform a decoding operation on the image recorded by the second imaging module regardless of the calculated contrast levels.
    It is noted that in some embodiments, individual regions selected for contrast analysis, as described above, may result from additional contrast level analysis that is first initiated on a larger initial region. For example, referring back to the image of FIG. 5A, an initial area of 600 pixels centered around the point 504 can be analyzed, dividing that area into, for example, three sub-areas of equal pixel count 200. The contrast levels of each of those areas can be further evaluated against each other with the sub-area having the highest contrast level from the three selected as the total area whose contrast will be compared to an area of another image. It is to be understood that this approach can be applied equally to all images under evaluation.
    Specific embodiments have been described in the foregoing description. It is noted, however, that various modifications and changes can be made without departing from the scope of the invention as set out in the claims below. Accordingly, the description and figures are to be considered in an illustrative rather than a limiting sense, and all such adaptations are intended to be included within the scope of the present teachings. Additionally, the described embodiments / examples / implementations should not be interpreted as mutually exclusive, and should instead be understood as potentially combinable if such combinations are possible in any way. In other words, any measure described in any of the above-described embodiments / example / implementations may be included in any other previously described embodiment / example / implementation. In addition, no steps of a method described herein should not be presumed to have a specific sequence unless it is expressly stated that another sequence is not possible or required by the remaining steps of the process. Also, some of the figures may or may not be drawn to scale.
    The benefits, solutions to problems, and any element that may lead to any benefit, or solution that is occurring or more pronounced, should not be interpreted as a critical, necessary, or essential measure or element of any or all of the claims. The invention is defined only by the appended claims including modifications made while the pending of this application and all equivalents of those granted claims. For the purpose of clarity and a brief description, features herein are described as part of the same or separate embodiments. It should be noted, however, that the scope of the invention may include embodiments having combinations of all or some of the features described herein. It can be assumed that the embodiments shown include similar or equivalent components, except where described as otherwise.
    In addition, in this document, relative terms such as first and second, top and bottom, and the like can only be used to distinguish one entity or action from another entity or action without necessarily necessitating any of these factual relationships or orders between such entities or actions is or is implied. The terms "includes", "comprising", "has", "having", "contains", "containing" or any other variation thereof, are intended to cover a non-exclusive inclusion such that a process, method, article , or device that includes a list of elements includes not only those elements, but may also include other elements not expressly stated or inherent in such a process, method, article, or device. An element preceded by “includes… a”, “has… a”, “contains… a” does not, without limitation, exclude the existence of additional identical elements in the process, the method, the article, or the device that element includes, has, contains. The term “one” is defined as one or more, unless explicitly stated otherwise herein. The terms "substantially", "essential", "about", or any other version thereof, are defined as being close by, as understood by those skilled in the art, and in one non-limiting embodiment, the term is defined as being within 10%, in a another embodiment as being within 5%, in another embodiment as being within 1% and in another embodiment as being within 0.5%. The term "linked" as used herein is defined as connected, although not necessarily direct and not necessarily mechanical. A device or structure that is "configured" in some way is configured in at least that way, but it can also be configured in ways not indicated.
    Note that some embodiments may include one or more generic or specialized processors (or "processing devices"), such as microprocessors, digital signal processors, customized processors, and field programmable gate arrays (FPGAs) and uniquely stored program instructions (including both software and hardware) controlling the one or more processors, in combination with certain non-processor circuits, to implement some, most, or all of the functions of the method and / or device described herein. Alternatively, some or all of the functions could be implemented by a state machine that does not have stored program instructions, or in one or more application-specific integrated circuits (ASICS), in which each function or some combinations of certain functions are implemented as custom logic (on custom made). Of course, a combination of the two approaches could be used. In addition, an embodiment may be implemented as a computer readable storage medium having stored thereon a computer readable code for programming a computer (e.g., comprising a processor) to perform a method as described and claimed herein. Examples of such computer readable storage media include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (read-only memory), a PROM (programmable read-only memory) , an EPROM (erasable programmable read-only memory), an EEPROM (electrically erasable programmable read-only memory) and a flash memory. It is further noted that despite potentially significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles described herein, one will easily be able to generate such software instructions and programs and ICs with minimal experimentation.
    The summary of the description is provided to enable the reader to quickly understand the nature of the technical description. It is submitted on the assumption that it will not be used to interpret the claims or to limit their scope of protection. In addition, in the foregoing comprehensive description, several features may be grouped together in various embodiments for the purpose of streamlining the description. This method of description is not to be interpreted as reflecting an intention that the embodiments claimed require more measures than are expressly enumerated in each claim. Rather, as the following claims express, the subject matter of the invention lies in less than all features of a single described embodiment. So the following conclusions have been incorporated into the detailed description, with each conclusion standing on its own as separate claimed matter. The mere fact that certain measures are mentioned in mutually different claims does not indicate that a combination of these measures cannot be used for an advantage. A large number of variants will be clear to the skilled person. All variants are considered to be included within the scope of the invention as defined in the following claims.
    权利要求:
    Claims (20)
    [1]
    A barcode reader comprising: a first image-forming assembly arranged to record a first image over a first field of view (FOV); a second imaging assembly positioned relative to the first imaging assembly and arranged to record a second image over a second FOV; and a control module communicatively coupled to the first image-forming assembly and the second image-forming assembly, the control module being arranged to: calculate a first contrast level in a first area, the first area being in the first image; calculate a second contrast level in a second area, the second area being in the second image; perform a first barcode decoding operation ut on the first image when the first contrast level is greater than the second contrast level; and performing the first barcode decoding operation on the second image when the second contrast level is greater than the first contrast level.
    [2]
    The barcode reader according to claim 1, wherein the control module is further adapted to: perform a second barcode decoding operation on the second image when the first contrast level is greater than the second contrast level and the first barcode decoding operation is not is successful; and performing the second barcode decoding operation on the first image when the second contrast level is greater than the first contrast level and the first barcode decoding operation is unsuccessful.
    [3]
    The barcode reader according to claim 1 or 2, wherein the first imaging assembly comprises a first linear imaging module, and wherein the second imaging assembly comprises a second linear imaging module.
    [4]
    The barcode reader according to any of the preceding claims, wherein the control module is arranged to calculate the first contrast level in the first area by determining a first white level and first black level, and associating the first contrast level with a difference between the first white level and the first black level, and wherein the control module is arranged to calculate the second contrast level in the second area by determining a second white level and a second black level, and associating the second contrast level with a difference between the second white level and the second black level.
    [5]
    The barcode reader of claim 4, wherein the first white level is associated with a first lowest brightness value of a subset of brightest pixels of the first area, the first black level is associated with a first highest brightness value of a subset of darkest pixels of the first area. wherein the second white level is associated with a second lowest brightness value of a subset of brightest pixels of the second area, and the second black level is associated with a second highest brightness value of a subset of darkest pixels of the second area.
    [6]
    Barcode reader according to claim 5,
    wherein the subset of brightest pixels of the first area comprises a first predetermined percentage of pixels of the total number of pixels in the first area, and wherein the subset of darkest pixels of the first area comprises a second predetermined percentage of pixels of the total number of pixels in the first area.
    [7]
    The barcode reader according to claim 6, wherein the subset of brightest pixels of the second area comprises a third predetermined percentage of the total number of pixels in the second area, and wherein the subset of darkest pixels of the second area comprises a fourth predetermined percentage. of the total number of pixels in the second area.
    [8]
    The barcode reader according to any one of claims 4-7, wherein the control module is arranged to determine the first white level and the first black level from a first histogram of the first area, and wherein the control module is arranged to determine the second white level and the second black level to be determined from a second histogram of the second area.
    [9]
    An image-forming base module for use in a barcode reader, comprising: a first image-forming assembly arranged to record a first image over a first field of view (FOV); a second image-forming assembly positioned relative to the first image-forming assembly and arranged to record a second image over a second FOV; and a control module communicatively coupled to the first imaging assembly and the second imaging assembly, the control module configured to:
    calculate a first contrast level in a first area, the first area being in the first image; calculate a second contrast level in a second area, the second area being in the second image; perform a first barcode decoding operation on the first image when the first contrast level is greater than the second contrast level; perform the first barcode decoding operation on the second image when the second contrast level is greater than the first contrast level.
    [10]
    The basic imaging module of claim 9, wherein the control module is arranged to calculate the first contrast level in the first area by determining a first white level and first black level, and associating the first contrast level with a difference between the first white level and the first black level. , and wherein the control module is arranged to calculate the second contrast level in the second area by determining a second white level and a second black level, and associating the second contrast level with a difference between the second white level and the second black level.
    [11]
    The basic imaging module according to claim 10, wherein the first white level is associated with a first lowest brightness value of a subset of brightest pixels of the first area, wherein the first black level is associated with a first highest brightness value of a subset of darkest pixels of the first area. area,
    wherein the second white level is associated with a second lowest brightness value of a subset of brightest pixels of the second area, and the second black level is associated with a second highest brightness value of a subset of darkest pixels of the second area.
    [12]
    The basic imaging module according to claim 11, wherein the subset of brightest pixels of the first area comprises a first predetermined percentage of pixels of the total number of pixels in the first area, wherein the subset of darkest pixels of the first area comprises a second predetermined percentage. pixels of the total number of pixels in the first area, the subset of brightest pixels of the second area comprising a third predetermined percentage of the total number of pixels in the second area, and the subset of darkest pixels of the second area fourth predetermined percentage of the total number of pixels in the second area.
    [13]
    The basic imaging module according to any one of claims 10-12, wherein the control module is arranged to determine the first white level and the first black level from a first histogram of the first area, and wherein the control module is arranged to determine the second white level and the second black level from a second histogram of the second area.
    [14]
    A method of decoding a barcode with a barcode reader having a control module communicatively coupled to a first imaging assembly and a second imaging assembly, the method comprising:
    recording a first image through the first imaging assembly over a first field of view (FOV); recording a second image via the second imaging assembly over a second FOV; calculating, via the control module, a first contrast level in a first area, the first area being in the first image; calculating, via the control module, a second contrast level in a second area, the second area being in the second image; performing a first barcode decoding operation on the first image when the first contrast level is greater than the second contrast level; and performing the first barcode reading operation on the second image when the second contrast level is greater than the first contrast level.
    [15]
    The method of claim 14, wherein the operation of recording the first image and the operation of recording the second image are performed simultaneously.
    [16]
    The method of claim 14 or 15, wherein the operation of calculating the first contrast level in the first area comprises determining a first white level and a first black level, and associating the first contrast level with a difference between the first white level and the first black level, and wherein the operation of calculating the second contrast level in the second area comprises determining a second white level and a second black level, and associating the second contrast level with a difference between the second white level and the second black level.
    [17]
    The method of claim 16, wherein the first white level is associated with a first lowest brightness value of a subset of brightest pixels of the first area, wherein the first black level is associated with a first highest brightness value of a subset of darkest pixels of the first area. wherein the second white level is associated with a second lowest brightness value of a subset of brightest pixels of the second area, and the second black level is associated with a second highest brightness value of a subset of darkest pixels of the second area.
    [18]
    The method of claim 17, wherein the subset of brightest pixels of the first area comprises a first predetermined percentage of pixels of the total number of pixels in the first area, wherein the subset of darkest pixels of the first area comprises a second predetermined percentage of pixels of the total number of pixels in the first area, the subset of brightest pixels of the second area comprising a third predetermined percentage of the total number of pixels in the second area, and the subset of darkest pixels of the second area comprising a fourth predetermined percentage of the total number of pixels in the second area.
    [19]
    The method of any of claims 16-18, further comprising: determining a first histogram of the first area; and determining a second histogram of the second area,
    wherein the operation of determining the first white level and the first black level is based on the first histogram, and wherein the operation of determining the second white level and the second black level is based on the second histogram.
    [20]
    The method of any of claims 14-19, wherein the first imaging assembly is a linear imaging module or a two-dimensional imaging module.
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    同族专利:
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    GB201905383D0|2019-05-29|
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    法律状态:
    2020-08-26| FG| Patent granted|Effective date: 20200717 |
    优先权:
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