Method for calculating the length of an image

Abstract

The application provides a method for calculating the length of an image, which is used for calculating the length L of an image along a scanning direction obtained by scanning a target object by at least one CIS module, and comprises the following steps: counting the image to obtain the number z of photosensitive chips completely crossed by the target object along the scanning direction; and if z>=1, calculating the L based on the following formula: L=z*k+m+n+2*p, wherein k is the length of a carrier of the photosensitive chip along the scanning direction, m is the length of a first end of the target object partially crossing the photosensitive chip along the scanning direction, n is the length of a second end of the target object partially crossing the photosensitive chip along the scanning direction, and p is the distance between any adjacent light holes in the CIS module. The method can calculate the length of the part completely crossed by the target object by using the carrier of the CIS module with an accurate length, and can significantly improve the calculation accuracy of the length of the image.

Description

Technical Field

[0001] This application belongs to the field of optical scanning image processing technology, and further relates to the processing technology of scanned images from contact image sensors, specifically, providing a method for calculating image length. Background Technology

[0002] In industrial manufacturing and other applications, it is necessary to accurately measure the length of target objects. With the development of automation technology and the need to improve efficiency, automated methods for measuring the length of target objects have been adopted in more and more manufacturing processes.

[0003] A common method for automating the measurement of target objects is to use a CIS (Contact Image Sensor) module, or a contact image scanning device composed of multiple CIS modules, to scan the target object and then calculate its length based on the scanned image. Because CIS modules can scan target objects proportionally, when using a CIS-based scanning device, the size of the target object in the image can be calculated without using a reference object or scaling.

[0004] However, CIS modules do have an absolute error in use. This error stems from an uncertain physical gap between adjacent photosensitive chips during product assembly. Measurements show this gap to be a random number between 30-60µm. Current length calculation methods multiply the aperture spacing on the photosensitive chips by the total number of apertures, discarding this physical gap by default. Since the length of a single photosensitive chip is fixed, the number of photosensitive chips is small when the target object is short, and the error caused by the physical gap is also small. However, when scanning longer target objects (e.g., 1.5 meters or longer), the number of photosensitive chips used increases significantly, leading to a substantial increase in the number of physical gaps and ultimately a sharp increase in the error of the calculated length. Summary of the Invention

[0005] To address the problems existing in the prior art, this application provides a method for calculating image length through embodiments. This method calculates the length L along the scanning direction of an image obtained by scanning a target object using at least one CIS module. Each CIS module includes a photosensitive chip disposed on a carrier and a plurality of light holes evenly spaced along the scanning direction above the photosensitive chip. The method for calculating image length includes the following steps:

[0006] The image is statistically analyzed to obtain the number z of photosensitive chips that the target object completely traverses along the scanning direction;

[0007] If z≥1, then the length L of the image along the scanning direction is calculated based on equation (1):

[0008] L=z×k+m+n+2×p (1),

[0009] Where k is the length of the carrier along the scanning direction, m is the length of the first end of the target object that partially crosses the photosensitive chip along the scanning direction, n is the length of the second end of the target object that partially crosses the photosensitive chip along the scanning direction, and p is the spacing between any adjacent apertures in the CIS module.

[0010] Furthermore, m and n are determined by the following formula:

[0011]

[0012] Where x is the number of light holes covered along the scanning direction on the photosensitive chip partially spanned by the target object at its first end; y is the number of light holes covered along the scanning direction on the photosensitive chip partially spanned by the target object at its second end.

[0013] Preferably, along the scanning direction, the design distance between the outermost aperture of each CIS module and the edge of its carrier is p / 2.

[0014] Preferably, the CIS module scans and images the target object proportionally.

[0015] Preferably, the length of the target object along the scanning direction is greater than the length of the photosensitive chip along the scanning direction.

[0016] Preferably, when the number of CIS modules used to scan the target object is greater than 1, the carriers of each CIS module are aligned in a direction perpendicular to the scanning direction.

[0017] Preferably, when the number of CIS modules used to scan the target object is greater than 1, the carriers of each CIS module are arranged seamlessly along the scanning direction.

[0018] Preferably, the method for calculating the image length further includes the following steps:

[0019] If z = 0, then it is further determined whether the target object partially crosses two photosensitive chips along the scanning direction;

[0020] If so, the length L of the image along the scanning direction is calculated based on equation (2):

[0021] L=m+n+p (2),

[0022] If not, then calculate the length L of the image along the scanning direction based on equation (3):

[0023] L=s×p (3),

[0024] Where s is the number of light holes that the scanned object covers along the scanning direction on the photosensitive chip when the scanned object is scanned by only one photosensitive chip.

[0025] The embodiments of this application provide a method for calculating the length of an image length. By using a carrier with a CIS module having a precise length, the length of the portion completely spanned by the target object is calculated. This method can effectively solve the random error present in the prior art scheme that calculates the length using the number of apertures, and significantly improve the accuracy of image length calculation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the CIS module in an embodiment of this application;

[0027] Figure 2 This is a schematic diagram showing the layout of multiple CIS modules in some embodiments of this application;

[0028] Figure 3 A flowchart illustrating a method for calculating image length according to some embodiments of this application;

[0029] Figure 4 This is a schematic diagram illustrating the scanning of a target object according to a specific embodiment of this application;

[0030] Figure 5 This is the pixel distribution of a row in a scanned image obtained according to a specific embodiment of this application;

[0031] Figure 6 This is a flowchart illustrating a method for calculating image length according to some embodiments of this application.

[0032] Numbers in the diagram

[0033] 1: aperture, 2: photosensitive chip, 3: carrier Detailed Implementation

[0034] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0035] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, in the description of this application, in order to distinguish different units, the terms "first," "second," etc. are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.

[0036] For ease of understanding, various components in the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application. The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application.

[0037] This application provides a method for calculating the length of an image, used to calculate the length L of an image obtained by scanning a target object using at least one CIS module along the scanning direction.

[0038] Figure 1 The structure of a CIS module is shown, such as Figure 1 As shown, each CIS module includes a photosensitive chip 2 disposed on the carrier 3 and a sensor above the photosensitive chip 2 along the scanning direction. Figure 1 Multiple light apertures 1 are evenly spaced along the horizontal direction. When using Figure 1 When the CIS module shown scans the target object, the light emitted by the target object passes through the aperture 1 and is converted into an electrical signal of corresponding intensity by the photosensitive chip 2. After processing such as analog-to-digital conversion and image stitching, a scanned image of the target object is finally formed.

[0039] Figure 1The CIS module shown can scan and image the target object proportionally. That is, the magnification of light passing through the aperture 1 is 1, and the light passing through each aperture 1 forms an image of 1 pixel on the photosensitive chip 2. The pixel size is the same as the actual physical size of its corresponding scanning area. Therefore, when one CIS module can scan the entire target object, the actual size of the scanned target object can be obtained by counting the number of apertures covered by the target object without proportional adjustment.

[0040] When the length of the target object is greater than the length of the imaging chip of a single CIS module, multiple CIS modules need to be stitched together to meet the scan length requirements (e.g., Figure 2 After the three CIS modules are spliced ​​together, it is possible to perform full-size scanning of longer target objects. At this time, the assembly error of the CIS modules needs to be considered.

[0041] like Figure 1 As shown, for a CIS module, the size of its carrier 3 is fixed. The photosensitive chip 2 is mounted on the carrier 3, and its length in the scanning direction is slightly smaller than that of the carrier 3. The distances of the apertures 1 on both sides from the edge of the carrier 3 are a1 and a2, respectively. Generally, the design dimensions of a1 and a2 should be equal, and both equal to p / 2, where p is the distance between two adjacent apertures. However, during the assembly of the CIS module, there is generally an installation error in the position of the photosensitive chip 2 relative to the carrier 3. This error results in an uncertain physical gap between two adjacent photosensitive chips 2. After measurement, this physical gap is approximately a random number of 30-60um. The above error further causes a1 and a2 of each CIS module to not be strictly equal to p / 2, and further causes random errors in the distance between the two apertures 1 at the connection of two CIS modules.

[0042] Current length calculation methods use the spacing of the apertures 1 on the photosensitive chip 2 multiplied by the total number of apertures, discarding this physical gap by default. When the target object is short, the number of photosensitive chips 2 is not large, and the error caused by the physical gap is also small. However, when scanning a longer target object (e.g., 1.5 meters or longer), the number of photosensitive chips 2 used will increase significantly, which in turn will greatly increase the number of physical gaps, ultimately leading to a sharp increase in the error of the calculated length.

[0043] Therefore, this application provides a method for calculating image length to solve the problems in the prior art. For example... Figure 3 As shown, in some preferred embodiments, the calculation method includes the following steps:

[0044] Step 210: Statistically analyze the image to obtain the number z of photosensitive chips that the target object completely traverses along the scanning direction;

[0045] Step 220, if z≥1, then calculate the length L of the image along the scanning direction based on equation (1):

[0046] L=z×k+m+n+2×p (1),

[0047] Where k is the length of carrier 3 along the scanning direction, m is the length of the first end of the target object that partially crosses the photosensitive chip 1 along the scanning direction, n is the length of the second end of the target object that partially crosses the photosensitive chip 2 along the scanning direction, and p is the spacing between any two adjacent apertures 1 in the CIS module.

[0048] Equation (1) consists of four parts. Here, z×k indicates that when z (greater than or equal to 1) photosensitive chips 1 are completely covered by the scanned object, the length of this part is no longer calculated by multiplying the number of apertures by the spacing, but by multiplying the length of the carrier 3, whose size can be accurately determined, by z. m and n represent the lengths of the two ends of the target object that partially span the photosensitive chips 2, respectively. 2×p represents the spacing between the outermost apertures 1 of the two partially spanned photosensitive chips 2 at both ends and the outermost apertures 1 of the adjacent fully spanned photosensitive chips 2 (considering that the design distance between the apertures 1 at both ends and the edge of the carrier 3 is p / 2). By using equation (1) and replacing the existing method of counting all apertures with the carrier length, which can be accurately determined, the problem of the uncertainty of the spacing of the outermost apertures of adjacent imaging chips due to assembly errors, which leads to the rapid accumulation of errors when multiple CIS modules measure the length of the target object, is effectively solved.

[0049] Furthermore, m and n are determined by the following formula:

[0050]

[0051] Where x is the number of light holes 1 covered by the photosensitive chip 2 along the scanning direction on which the target object partially spans at its first end; y is the number of light holes 1 covered by the photosensitive chip 2 along the scanning direction on which the target object partially spans at its second end.

[0052] Preferably, when the number of CIS modules used to scan the target object is greater than 1, the carriers 3 of each CIS module are aligned in a direction perpendicular to the scanning direction, and the carriers 3 of each CIS module are arranged seamlessly in the scanning direction.

[0053] Figure 4A specific embodiment is shown, in which 10 CIS modules are arranged along the scanning direction, and the photosensitive chips included in each module are numbered IC1 to IC10 respectively. The 10 CIS modules are integrated in a housing, and the carriers 3 of each CIS module are seamlessly aligned with each other to form a contact image sensor 4. The image sensor 4 is used to scan a target object 5, wherein the target object 5 completely spans IC2 to IC9, and its two ends partially span IC1 and IC10 respectively. m and n represent the distances by which the left and right boundaries of the target object partially span IC10 and IC1 respectively.

[0054] Figure 5 Further shown Figure 4 The image obtained by the contact image sensor 4 scanning the target object 5 shows one row of the image. The left and right boundaries of the target object 5 in the image can be observed. According to the image data processing, the number of photosensitive chips and the number of apertures in the corresponding hardware can be restored. The length L of the target object image can be calculated using these known size data.

[0055] Specifically, the scanned target object 5 has an image on IC1 to C10, with the left boundary located at the 430th aperture of IC10, the right boundary located at the 429th aperture of IC1, and the middle part completely spanning 8 photosensitive chips IC2 to IC9.

[0056] In the embodiments of this application, the CIS module has a resolution of 600 DPI (aperture spacing 42.3 μm). The carrier 3 in each CIS module has a length of 18.29 mm and is provided with 432 apertures. The number of apertures spanning IC10 on the left boundary is 430, and the number of apertures spanning IC1 on the right boundary is 4. According to equation (1), the object length can be obtained:

[0057] L=18.29×8+0.0423×430+0.0423×4+0.0423×2=164.7682mm.

[0058] The above-mentioned method for calculating image length utilizes a carrier with a CIS module that has precise length to calculate the length of the portion completely spanned by the target object. This effectively solves the random error present in existing methods that calculate length using the number of apertures, and significantly improves the accuracy of image length calculation.

[0059] Figure 6 A flowchart illustrating a method for calculating image length provided by some other preferred embodiments is shown. Figure 6 In the illustrated embodiment, steps 310 and 320 are respectively related to Figure 3Steps 210 and 220 in the illustrated embodiment are the same, the difference being the addition of step 330:

[0060] If z = 0, then it is further determined whether the target object partially crosses two photosensitive chips along the scanning direction;

[0061] If so, the length L of the image along the scanning direction is calculated based on equation (2):

[0062] L=m+n+p (2),

[0063] If not, then calculate the length L of the image along the scanning direction based on equation (3):

[0064] L=s×p (3),

[0065] Where s is the number of light holes that the scanned object covers along the scanning direction on the photosensitive chip when the scanned object is scanned by only one photosensitive chip.

[0066] Step 330 is used to calculate the image length when the target object is short and does not span a complete photosensitive chip. Specifically, if the target object is simultaneously imaged on two adjacent photosensitive chips, equation (2) is used to calculate the image length. In this case, only the aperture spacing p needs to be added as compensation. If the target object is only imaged on one photosensitive chip, equation (3) is used to calculate the image length. In this case, no further compensation for the aperture spacing is required.

[0067] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for calculating image length, used to calculate the length L of an image obtained by scanning a target object using at least one CIS module along the scanning direction, each CIS module comprising a photosensitive chip disposed on a carrier, and a plurality of light holes equally spaced above the photosensitive chip along the scanning direction, characterized in that, Includes the following steps: The image is statistically analyzed to obtain the number z of photosensitive chips that the target object completely traverses along the scanning direction; If z≥1, then the length L of the image along the scanning direction is calculated based on equation (1): L=z×k+m+n+2×p (1), Where k is the length of the carrier along the scanning direction, m is the length of the first end of the target object that partially crosses the photosensitive chip along the scanning direction, n is the length of the second end of the target object that partially crosses the photosensitive chip along the scanning direction, and p is the spacing between any adjacent light holes in the CIS module. The m and n are determined by the following formula: ， Where x is the number of light holes covered along the scanning direction on the photosensitive chip partially spanned by the target object at its first end; y is the number of light holes covered along the scanning direction on the photosensitive chip partially spanned by the target object at its second end. It also includes the following steps: If z=0, then it is further determined whether the target object partially crosses two photosensitive chips along the scanning direction; If so, the length L of the image along the scanning direction is calculated based on equation (2): L=m+n+p (2), If not, then calculate the length L of the image along the scanning direction based on equation (3): L=s×p (3), Where s is the number of light holes that the scanned object covers along the scanning direction on the photosensitive chip when the scanned object is scanned by only one photosensitive chip.

2. The method for calculating image length according to claim 1, characterized in that: Along the scanning direction, the design distance between the outermost aperture of each CIS module and the edge of its carrier is p / 2.

3. The method for calculating image length according to claim 1, characterized in that: The CIS module performs proportional scanning imaging of the target object.

4. The method for calculating image length according to claim 1, characterized in that: The length of the target object along the scanning direction is greater than the length of the photosensitive chip along the scanning direction.

5. The method for calculating image length according to claim 1, characterized in that: When the number of CIS modules used to scan the target object is greater than 1, the carriers of each CIS module are aligned in a direction perpendicular to the scanning direction.

6. The method for calculating image length according to claim 1, characterized in that: When the number of CIS modules used to scan the target object is greater than 1, the carriers of each CIS module are arranged seamlessly along the scanning direction.

Images