TW202405520A - Lens focusing method and system performing the same - Google Patents

Abstract

A Lens focusing method and a system performing the same are provided. The lens focusing method performs steps by a computer unit during focusing. The steps are as followings: whenever a focus length position of an image module is adjusted, capturing a focused object image to generate a focused image by the image module; obtaining pixel grayscale values in a local position or a whole position of the focused image; computing a discrete distribution degree of the pixel grayscale values and an average-standard-deviation value of the discrete distribution degree; and after all the average-standard-deviation values respectively corresponding to the focus length positions of the image module are computed, determining a maximum of the average-standard-deviation values as an object focus length position.

Description

Lens focusing method and system

The present invention relates to a focusing method, in particular to a method of focusing using a lens to obtain the maximum average standard deviation of an image.

In terms of the traditional Chip On Board (COB) photography module, it includes a circuit board (or substrate), an image capture die, a lens mount and an optical lens. The image capture die The crystal is set on the circuit board, the lens holder is set on the circuit board at the position corresponding to the image capture die, and the optical lens is movably set on the lens holder, so that the optical lens can move on the lens holder and adjust the optical lens and The distance between the image capturing die is adjusted to achieve the purpose of adjusting the focus position of the image capturing die.

Taking the focus of the optical lens further, please refer to Figure 1 or 2. When the optical lens adjusts the focus, the photography module is usually activated to capture images, and then the human eye is used to judge whether the captured images are clear. Or it is blurry. If it is blurry, adjust the distance between the optical lens and the image capture die until the human eye judges that the image has been clear.

However, now that the resolution of photography modules is getting higher and higher, manual focusing may be easy to misjudge or the focal length consistency of the photography module may be inconsistent. Another optical lens focusing method is Depth From Defocus (DFD). Defocus). The defocus depth method is to calculate the defocus depth of the target object by capturing two or more images at different defocus positions, establishing a suitable mathematical model for the photography module in advance, and combining various parameters of the photography module. Thereby judging the focus position and adjusting the focus. Another method is Depth From Focus (DFF). The Depth From Focus method collects a series of digital images from blur to clear through a computer (or a dedicated circuit system), and evaluates the clarity of each frame of image. Function processing determines whether the focus adjustment is accurate, that is, whether the image is clear, and gives a feedback signal to control the focal length of the optical lens until the collected digital image reaches the clearest level, and finally completes the focus adjustment.

Commonly used evaluation functions include gradient evaluation function, spectrum evaluation function and statistical evaluation function. The gradient function is used to extract the edge information of the image. The image with a high degree of focus is clearer, showing more obvious sharp edges, and the image has a larger gradient function value; the spectrum evaluation function provides two types of discrete cosine transform and Fourier transform Function, extract the high-frequency components in the image as the evaluation function; the statistical evaluation functions mainly include AC power function, DC power function, Range function, Menmay function, Masgrn function and image grayscale variance function. One of the image grayscale In terms of the variance function (D(f)), the image is the clearest when it is fully focused and has a greater grayscale difference than a blurred image. Therefore, the grayscale change can be used as the basis for focus evaluation. The formula is as follows: Among them, x is the coordinate position of the pixel point in the horizontal direction, y is the coordinate position of the pixel point in the vertical direction, is the grayscale value of a pixel at a certain position in the image, is the average grayscale value of the entire image.

According to the above, the automatic focusing process of the image grayscale variance function requires the collection of many images, and the grayscale variance processing data is to increase the grayscale difference. In practical applications, the calculation of the squared difference is still a relatively complex operation. Processing methods, so how to simplify calculations to achieve fast and efficient processing requirements will be an urgent problem to be solved.

In view of the problems of the prior art, the purpose of the present invention is to provide a focusing process to facilitate a simpler and faster evaluation process to find the target focal length position of the photography module.

According to the purpose of the present invention, a lens focusing method is provided. During the focusing process, an electronic computing unit is used to perform the following steps. The photography module captures the focusing target image to generate a focusing image, and the image processing module performs the focusing process. Image analysis extracts the grayscale values of pixels at all locations or local locations. The focus analysis module calculates the discrete distribution degree of the obtained grayscale values of each pixel point and calculates the average standard deviation of the discrete distribution degree. Each adjustment The focal length position of the photography module performs all the aforementioned steps in sequence until the average standard deviation of all focal length positions of the photography module is obtained. The automatic focusing module then finds the largest average standard deviation among all average standard deviations. The focal length position corresponding to the largest one is the target focal length position.

Wherein, the focusing target image is composed of dark squares and light squares arranged vertically and horizontally respectively, preferably the dark squares are black squares and the light squares are white squares. Either the focus adjustment target image is a one-dimensional barcode of different thicknesses, or the focus adjustment target image is a two-dimensional barcode, or the focus adjustment target image is a combination of a one-dimensional barcode and a two-dimensional barcode.

Among them, the way to calculate the degree of discrete distribution of the obtained gray-scale values of each pixel is to calculate the gray-scale values of all pixels and average them to obtain the average gray-scale value. The formula is expressed as follows: in represents the average gray level value, m is the lateral coordinate value of the focusing image, n is the lateral coordinate value of the focusing image, is the coordinate grayscale value. Then subtract the gray level value of each pixel from the average gray level value to obtain the absolute value as the degree of discrete distribution. The formula is expressed as follows: in is the discrete distribution degree of the grayscale value of each pixel, is the coordinate The grayscale value of Represents the average grayscale value.

Among them, obtaining the average standard deviation of each focal length position of the photography module is calculated by averaging all discrete distribution degrees. The formula is expressed as follows: in is the average standard deviation of each focal length position, is the discrete distribution degree of the grayscale value of each pixel, m is the lateral coordinate value of the focusing image, and n is the lateral coordinate value of the focusing image.

According to the purpose of the present invention, a lens focusing system is provided, which includes a photography module, an image processing module, a focus analysis module and a focus adjustment device. The photography module captures a focus target image to generate a focus image, and the image processing The module is connected to the photography module and receives the focus image, and processes the focus image to obtain the grayscale value of the pixels at all positions or local positions. The focus analysis module is connected to the image processing module and receives each pixel. The grayscale value of each pixel is calculated, and the discrete distribution degree of the obtained grayscale value of each pixel is calculated, and the average standard deviation of the discrete distribution degree is calculated. The focal length adjustment device is connected to the photography module, and the focal length adjustment device adjusts the photography module to a plurality of At the focal length position, the photography module captures the focusing target image once at each focal length position and generates respective focusing images.

Among them, the focus adjustment device is further connected to the focus analysis module. Each time the focus analysis module completes obtaining the average standard deviation of the current focus position, it sends a focus adjustment signal to the focus adjustment device, and the focus adjustment device then adjusts the photography module to At the next focal length position, the focus adjustment device completes the adjustment to the next focal length position, which will generate a shooting signal to the photography module, and the photography module will then capture the focus target image to generate the next focus image.

Among them, the focusing analysis module analyzes the change trend of the average standard deviation of each focal length position currently obtained, which gradually increases to one of the average standard deviations of each focal length position and then gradually decreases, that is, it stops sending the focus adjustment signal, and uses the The focal length position with the largest average standard deviation is the target focal length position.

Among them, the focus adjustment device adjusts the focal length position of the photography module based on a plurality of adjustment focus signals, and the focus analysis module analyzes the change trend of the average standard deviation of each focal length position obtained to gradually decrease, then the adjustment signal issued by the focus adjustment device The focal length signal causes the focal length adjustment device to adjust the focal length position in the opposite direction, and causes the changing trend of the average standard deviation to gradually increase to the average standard deviation of one of the focal length positions and then gradually decrease, and to the maximum average standard deviation. The focal length position is the target focal length position.

To sum up, the image processing module of the present invention analyzes the focus image and extracts the grayscale values of the pixels at all positions or local positions, and then calculates the degree of dispersion and average standard deviation of each grayscale value without the need to calculate the square difference, reducing the difficulty of calculation and thus speeding up processing.

The embodiments of the present invention will be further explained below with reference to relevant drawings. Wherever possible, the same reference numbers are used in the drawings and description to refer to the same or similar components. In the drawings, shapes and thicknesses may be exaggerated for simplicity and ease of notation. It should be understood that components not specifically shown in the drawings or described in the specification are in forms known to those of ordinary skill in the art. Those skilled in the art can make various changes and modifications based on the contents of the present invention.

When an element is referred to as being "on", it can generally mean that the element is directly on the other element, or that the other element exists between them. Conversely, when an element is said to be "directly on" another element, it cannot have other elements between them. As used herein, the term "and/or" includes any combination of one or more of the associated listed items.

References below to "one embodiment" or "an embodiment" refer to a particular element, structure, or feature associated with at least one embodiment. Therefore, “one embodiment” or multiple descriptions of “an embodiment” appearing in multiple places below are not directed to the same embodiment. Furthermore, specific components, structures and features in one or more embodiments may be combined in an appropriate manner.

The disclosure is specifically described with the following examples. These examples are only for illustration, because for those who are familiar with this art, various modifications and modifications can be made without departing from the spirit and scope of the disclosure. Therefore, this disclosure The scope of protection of the disclosed content shall be determined by the scope of the patent application attached. Throughout the specification and claims, unless the content clearly dictates otherwise, the meaning of "a" and "the" includes such statements including "one or at least one" of the element or component. Furthermore, as used in this disclosure, the singular article also includes recitations of plural elements or ingredients unless it is obvious from the particular context that the plural is excluded. Furthermore, as applied to this description and all claims below, "in" may mean "in" and "on" unless the context clearly dictates otherwise. Unless otherwise noted, the terms used throughout the specification and patent claims generally have their ordinary meanings as used in the field, in the disclosure and in the particular context. Certain terms used to describe the disclosure are discussed below or elsewhere in this specification to provide practitioners with additional guidance in describing the disclosure. The use of examples anywhere throughout this specification, including the use of examples of any terminology discussed herein, is for illustrative purposes only and does not, of course, limit the scope and meaning of the disclosure or any exemplified terminology. Likewise, the present disclosure is not limited to the various embodiments set forth in this specification.

It should be understood that the terms "comprising", "including", "having", "containing", "involving", etc., as used herein, are open-ended (open-ended), meaning including but not limited to. In addition, any embodiment or patentable scope of the present invention does not necessarily achieve all the purposes, advantages or features disclosed in the present invention. In addition, the abstract part and title are only used to assist in searching for patent documents and are not used to limit the scope of the patent application for the invention.

In addition, if the term "electrical (sexual) coupling" or "electrical (sexual) connection" is used here, it includes any direct and indirect electrical connection means. For example, if a first device is described as being electrically coupled to a second device, it means that the first device can be directly connected to the second device, or indirectly connected to the second device through other devices or connections. device. In addition, if the description is about the transmission and provision of electrical signals, those familiar with this art should be able to understand that the transmission process of electrical signals may be accompanied by attenuation or other non-ideal changes, but if the source and receiving end of the transmission or provision of electrical signals are not special Description, essentially should be regarded as the same signal. For example, if an electrical signal S is transmitted (or provided) from terminal A of an electronic circuit to terminal B of an electronic circuit, it may pass through the source and drain ends of a transistor switch and/or possible stray capacitance. A voltage drop is generated, but if the purpose of this design is not to deliberately use the attenuation or other non-ideal changes produced during transmission (or provision) to achieve certain technical effects, the electrical signal S is at the endpoint A and endpoint of the electronic circuit. B should be regarded as essentially the same signal.

Unless otherwise specified, some conditional sentences or words, such as "can", "could", "might", or "may", usually try to express that the embodiment of this case has, But it can also be interpreted as features, components, or steps that may not be needed. In other embodiments, these features, elements, or steps may not be required.

Please refer to Figure 1. The present invention is a lens focusing system, which includes a photography module 1, an image processing module 2, a focus analysis module 3 and a focus adjustment device 4. The photography module 1 is located at the relative focusing target. a predetermined position of the image, and capture the focus target image to generate a focus image. The image processing module 2 is connected to the photography module 1 and receives the focus image, and the image processing module processes the focus image to obtain the grayscale values of the pixels at all positions or local positions. The focus analysis module 3 is connected to the image processing module 2, and receives the grayscale value of each pixel point, and calculates the discrete distribution degree of the obtained grayscale value of each pixel point, and calculates the average standard deviation of the discrete distribution degree.

Please refer to Figure 2. In the present invention, the photography module 1 includes a circuit board 10 (or substrate), an image capture die 12, a lens mount 14 and an optical lens 16. The image capture die 12 is photographed on On the circuit board 10, the lens holder 14 is disposed on the circuit board around the image capture die 12. The optical lens 16 is movably disposed on the lens holder 14. By adjusting the optical lens 16 and rotating on the lens holder, the adjustment can be made. The distance between the optical lens 16 and the image capture die 12 is determined by adjusting the focal length position by manually adjusting the optical lens 16 or automatically adjusting the focus. In terms of automatic focusing, in the present invention, the focus adjustment device 4 is connected to the photography module. Group 1, the focus adjustment device 4 adjusts the photography module 1 to a plurality of focal length positions. The photography module 1 captures a focus target image at each focal length position and generates respective focus images. Usually, the lens mount 14 and the optical lens 16 are connected together by threads, so the distance between the optical lens 16 and the image capturing die 12 can be adjusted by rotating the optical lens 16.

In the present invention, please refer to FIG. 3A. The focusing target image can use a regular or irregular image with high gray scale contrast. For example, the focusing target image can be a vertical and horizontal image composed of dark colors respectively. The squares and light-colored squares are arranged in a staggered manner. In particular, it is better to have dark-colored squares with black squares and light-colored squares with white squares. Either the focusing target image is a one-dimensional barcode of different thicknesses, or the focusing target image is a two-dimensional barcode, or the focusing target image is a combination of a one-dimensional barcode and a two-dimensional barcode, in which the two-dimensional barcode can be a rapid Quick Response Code (QR Code).

In the present invention, the focus target image composed of dark checkers as black checkers and light checkers as white checkers is used as an example to illustrate the reason for using an image with high gray scale contrast as the focus target image. , when the photography module 1 captures the focus target image formed by the staggered arrangement of dark squares and light squares, the grayscale value of each pixel corresponding to the black checkerboard in the focus image approaches 0 or equals 0 , and the grayscale value of each pixel corresponding to the white checkerboard is close to 255 or equal to 255. Therefore, when the grayscale value difference of each pixel of the focus image is larger, it means the focus image is clearer, so in The one with the largest grayscale value difference among different focusing images is the target focal length position.

In order to more clearly understand the difference in the grayscale value of each pixel in the focus image and the corresponding relationship between the focus images taken at different focal length positions, focus images taken at different focal length positions and their grayscale distribution are provided for explanation. Please Refer to Figures 3A to 3C, which show the focus images taken at the target focal length position and the focus images taken at three non-target focal length positions. Figures 4A to 4C show the X-direction coordinates at the bottom. Distribution map of grayscale values of pixels.

In order to allow the focus adjustment device 4 to further perform focus adjustment after the focus analysis module 3 obtains the average standard deviation of the current focus position each time, in the present invention, the focus adjustment device 4 is further connected to the focus analysis module 3. The focus analysis module 3 obtains the average standard deviation of the current focus position each time, and then sends a focus adjustment signal to the focus adjustment device 4. The focus adjustment device 4 then adjusts the photography module 1 to the next focus position. The focus adjustment After the device 4 completes adjusting to the next focus position, it will generate a shooting signal to the photography module 1, and the photography module 1 will capture the focus target image to generate the next focus image.

However, when the present invention is actually implemented, the focus adjustment device 4 does not have to receive the focus adjustment signal sent by the focus analysis module 3 in order to adjust the focus position of the photography module 1. The focus adjustment device 4 can also be electrically connected to the camera. Module 1, and each time the photography module 1 completes shooting a focus-adjusted image, it receives the shooting completion signal of the photography module 1 as a focus adjustment signal.

In the present invention, the focal length adjustment device 4 can adjust the optical module of the photography module 1 from the focal length position of 0 degrees to 360 degrees at the same angle once to adjust the focus. For example, a total of 360 adjustments can be made by adjusting 1 degree each time. Focusing images from all angles are obtained, and the average standard deviation of the discrete distribution degrees is obtained from these focusing images. The largest one is the target focal length position. However, if the photography module 1 keeps adjusting the focal length in the same direction, so that the distance between the optical module and the image capture die 12 becomes larger or smaller, the corresponding focused image will also gradually become smaller and smaller. clear or increasingly blurry. Therefore, according to such trend changes, when the focus analysis module 3 analyzes the current change trend of the average standard deviation of each focal length position, it gradually increases to one of the average standard deviations of each focal length position. It starts to gradually decrease, that is, it stops sending the focus adjustment signal, and the focus position with the largest average standard deviation is used as the target focus position.

Or, when the focus adjustment device 4 adjusts the focus position of the photography module 1 based on a plurality of focus adjustment signals, and the focus analysis module 3 analyzes the change trend of the average standard deviation of each focus position obtained to gradually decrease, then the focus adjustment The focus adjustment signal sent by the device 4 causes the focus adjustment device 4 to adjust the focal length position in the opposite direction, and the changing trend of the average standard deviation gradually increases to one of the average standard deviations of each focal length position and then gradually decreases. The focal length position with the largest average standard deviation is the target focal length position.

Through the above adjustment method, the photography module 1 does not need to adjust the focus from the focal length position of 0 degrees to 360 degrees. It only needs to adjust the focal length position according to the aforementioned trend changes, which can reduce the number of adjustments and speed up the completion of the focus adjustment.

Please refer to Figure 5. The present invention is a lens focusing method. During the focusing process, an electronic computing unit is used to perform the following steps: (S100) Adjust the focal length position of the photography module 1; (S101) The photography module 1 captures the focus target image to generate a focus image; (S102) The image processing module 2 analyzes the focused image to obtain the grayscale values of pixels at all positions or partial positions; (S103) The focus analysis module 3 calculates the discrete distribution degree of the obtained grayscale value of each pixel point, and calculates the average standard deviation of the discrete distribution degree; (S104) Determine whether the adjustment of each focal length position of the photography module 1 is completed, if so, proceed to step (S105), otherwise, proceed to step (S100); (S105) The automatic focusing module then finds the largest average standard deviation among all average standard deviations. The focal length position corresponding to the largest average standard deviation is the target focal length position.

In the present invention, the focus target image is formed by staggered dark squares and light squares in the vertical and horizontal directions, where the dark squares are black squares and the light squares are white squares. good. Either the focus adjustment target image is a one-dimensional barcode of different thicknesses, or the focus adjustment target image is a two-dimensional barcode, or the focus adjustment target image is a combination of a one-dimensional barcode and a two-dimensional barcode.

In the present invention, the method for calculating the degree of discrete distribution of the obtained gray-scale values of each pixel is to calculate the gray-scale values of all pixels and average them to obtain the average gray-scale value. The formula is expressed as follows: in represents the average gray level value, m is the lateral coordinate value of the focusing image, n is the lateral coordinate value of the focusing image, is the coordinate The gray scale value, Figure 6 is a schematic diagram of the distribution status of the gray scale value of each pixel point in Figure 3A, in the figure The lower line represents the average gray-scale value. Figure 7 is a schematic diagram of the distribution status of the gray-scale value of each pixel in Figure 3C. In the figure The lower line represents the average grayscale value.

Then subtract the gray level value of each pixel from the average gray level value to obtain the absolute value as the degree of discrete distribution. The formula is expressed as follows: in is the discrete distribution degree of the grayscale value of each pixel, is the coordinate The grayscale value of Represents the average grayscale value. Figure 8 is a schematic diagram of the discrete distribution degree of Figure 6, and Figure 9 is a schematic diagram of the discrete distribution degree of Figure 7.

In addition, obtaining the average standard deviation of all focal length positions of the photography module 1 is calculated by averaging all discrete distribution degrees. The formula is expressed as follows: in is the average standard deviation of each focal length position, is the discrete distribution degree of the grayscale value of each pixel, m is the lateral coordinate value of the focusing image, and n is the lateral coordinate value of the focusing image.

In addition, in order to reduce the amount of calculation of the gray scale value, average gray scale value, discrete distribution degree and average standard deviation of the focusing image, the present invention can only use the partial image of the focusing image for calculation, but this is not limited to this. The present invention can only use partial images of the focus-adjusted image for calculation, but the present invention can still perform calculations for all images of the entire focus-adjusted image.

According to the above, the present invention can adjust the focus in a simple and fast manner, and the evaluation function is simpler than the traditional evaluation function, allowing the present invention to complete the calculation more quickly and complete the focus adjustment work of the photography module 1.

The above are only examples to illustrate the preferred implementation of this invention, and are not intended to limit the scope of implementation. All simple substitutions and equivalent changes made based on the patent scope of this invention and the content of the patent specification are all patents of this invention. Application scope.

1: Photography module 10:Circuit board 12:Image capture bare crystal 14: Lens mount 16: Optical lens 2:Image processing module 3: Focus analysis module 4:Focus adjustment device S100~S105: Process steps

Figure 1 is a schematic structural diagram of the lens focusing system of the present invention; Figure 2 is a schematic cross-sectional view of the photography module of the present invention; 3A is a schematic diagram of the focus target image (focus image of the target focus position) of the present invention; Figure 3B is a schematic diagram of a focusing image at a non-target focusing position according to the present invention; Figure 3C is a schematic diagram of a focusing image at another non-target focusing position according to the present invention; Figure 4A is a schematic diagram of the grayscale distribution of one of the pixels in the same horizontal direction in Figure 3A; Figure 4B is a schematic diagram of the grayscale distribution of one of the pixels in the same horizontal direction in Figure 3B; Figure 4C is a schematic diagram of the grayscale distribution of one of the pixels in the same horizontal direction in Figure 3C; Figure 5 is a schematic flow chart of the lens focusing method of the present invention; Figure 6 is a schematic diagram of the grayscale value distribution of all pixels in Figure 3A; Figure 7 is a schematic diagram of the grayscale value distribution of all pixels in Figure 3C; Figure 8 is a schematic diagram of the discrete distribution degree of Figure 3A; Figure 9 is a schematic diagram of the discrete distribution degree of Figure 3C.

1: Photography module

2:Image processing module

3: Focus analysis module

4:Focus adjustment device

Claims (11)

A lens focusing method that uses an electronic computing unit to perform the following steps during the focusing process: Adjust the focal length position of the photography module; Use a photography module to capture a pair of focus target images to generate a focus image; Use an image processing module to analyze the focusing image and obtain the grayscale values of pixels at all positions or partial positions; Use a focus analysis module to calculate a degree of discrete distribution of the obtained grayscale values of each pixel point, and calculate an average standard deviation of the degree of discrete distribution; Determine whether the adjustment of each focal length position of the photography module has been completed; When it is determined that the adjustment of each focal length position of the photography module has been completed, the automatic focusing module then finds the largest average standard deviation among all, and uses the focal length position corresponding to the largest average standard deviation as the target. focal length position; and When it is determined that the adjustment of each focal length position of the photography module has not been completed, the process is performed according to the steps of adjusting the focal length position of the photography module. The lens focusing method according to claim 1, wherein the focusing target image is formed by staggered dark squares and light squares in the vertical and horizontal directions respectively. As for the lens focusing method described in claim 2, it is better that the dark checkerboard is a black checkerboard and the light-colored checkerboard is a white checkerboard. The lens focusing method as described in claim 1, wherein the focusing target image is a one-dimensional barcode of different thicknesses, or the focusing target image is a two-dimensional barcode, or the focusing target image is a one-dimensional barcode and a combination of A combination of 2D barcodes. The lens focusing method as described in claim 1, wherein the focusing analysis module calculates the discrete distribution degree of the obtained gray-scale values of each pixel point by calculating and averaging the gray-scale values of each pixel point. To obtain the average gray level value, the formula is as follows: ; in Represents the average gray level value, m is the lateral coordinate value of the focusing target image, n is the lateral coordinate value of the focusing target image, is the coordinate grayscale value. The lens focusing method as described in claim 5, wherein the grayscale value of each pixel is subtracted from the average grayscale value and the absolute value is taken as the degree of discrete distribution. The formula is expressed as follows: ; in is the discrete distribution degree of the grayscale value of each pixel, is the coordinate The grayscale value of Represents the average grayscale value. The lens focusing method as described in claim 6, wherein obtaining the average standard deviation of all focal length positions of the photography module is calculated by averaging all discrete distribution degrees, and the formula is expressed as follows: ; in is the average standard deviation of each focal length position, is the discrete distribution degree of the grayscale value of each pixel, m is the lateral coordinate value of the focusing image, and n is the lateral coordinate value of the focusing image. A lens focusing system, including: A photography module that captures a focus target image to generate a focus image; An image processing module, the image processing module is connected to the photography module, and receives the focus image, and processes the focus image to obtain the grayscale values of pixels at all positions or partial positions; A focusing analysis module, which is connected to the image processing module, receives the grayscale value of each pixel, and calculates a discrete distribution degree of the obtained grayscale value of each pixel, and calculate a mean standard deviation of the degree of dispersion; and A focal length adjustment device connected to the photography module, the focus adjustment device adjusts the photography module to a plurality of focal length positions, and the photography module captures the focus target image once at each focal length position and separately Produce respective focused images. The lens focusing system as described in claim 8, wherein the focus adjustment device is connected to the focus analysis module, and the focus analysis module sends out the adjustment focus every time it completes obtaining the average standard deviation of the current focus position. The signal is sent to the focal length adjustment device, and the focal length adjustment device then adjusts the camera module to the next focal length position. When the focal length adjustment device completes the adjustment to the next focal length position, a shooting signal is generated to the camera module. The camera module The group then shoots the focus target image to generate the next focus image. The lens focusing system as described in claim 8, wherein the focusing analysis module analyzes the change trend of the average standard deviation of each focal length position currently obtained to gradually increase to the average of each focal length position. After the standard deviation begins to gradually decrease, the focus adjustment signal is stopped, and the focal length position with the largest average standard deviation is regarded as a standard focal length position. The lens focusing system as described in claim 8, wherein the focus adjustment device adjusts the focal length position of the photography module based on a plurality of adjustment focus signals, and the focus analysis module analyzes the average of the obtained focal length positions. If the change trend of the standard deviation is to gradually decrease, the focus adjustment signal sent by the focus adjustment device will cause the focus adjustment device to adjust the focus position in the reverse direction, and the change trend of each average standard deviation will gradually increase to one of the The average standard deviation of each focal length position then gradually decreases, and the focal length position with the largest average standard deviation is a target focal length position.

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