Zooming tracking method and system for focusing evaluation value feedback

Abstract

The invention discloses a zoom tracking method and system for focusing evaluation value feedback, and the method comprises the steps: collecting the focusing evaluation values of four continuous frames of images through the system after a zoom motor and a focusing motor complete movement, carrying out the trend analysis, setting an adjustment direction to be an opposite direction if the four frames of data have a continuous decreasing characteristic, and carrying out the adjustment of the focusing evaluation values. A self-adaptive compensation strategy of focusing evaluation value dynamic feedback is fused, a feedback mechanism comprises an object distance adjustment direction and an object distance adjustment step length, and the mechanism constructs a closed-loop correction system by setting a cooperative control rule of the object distance adjustment direction and the step length.

Description

Technical Field

[0001] The present invention relates to the field of image processing, and in particular to a variable magnification tracking method and system with focus evaluation value feedback. Background Art

[0002] The black light full-color camera module has functions of variable magnification and automatic focusing. It has a small structure, is convenient to use, and is easy to assemble, and has been widely used in the field of video surveillance. How to ensure a short variable magnification time, clear images during the entire variable magnification process, fast and accurate focusing is crucial for the black light full-color camera module.

[0003] In the black light full-color camera module, the variable magnification lens and the focusing lens move independently and are controlled by a zoom motor and a focusing motor respectively. To ensure that the image can be focused clearly during the variable magnification process, it is necessary to ensure that the zoom motor and the focusing motor can rotate coordinately and synchronously. In practical applications, due to the uncertainties of scene changes and object distance changes, moving the focusing motor to make the image clear is the biggest problem for the variable magnification tracking algorithm. In the prior art, the commonly adopted solution is to record the relative positions of the zoom motor and the focusing motor at different object distances, make a group of variable magnification tracking curves, and then select a curve corresponding to the current object distance from the group of variable magnification tracking curves to drive the zoom motor and the focusing motor for variable magnification tracking. Currently, most algorithms face the problem that there are multiple curves corresponding to one position of the zoom motor at the wide-angle end when selecting a curve from the group of variable magnification tracking curves that can reflect the curve corresponding to the actual object distance, and it is impossible to select the correct tracking curve. Specifically, since the depth of field is relatively large at the wide-angle end and relatively small at the telephoto end, the curve group is relatively dense at the wide-angle end and relatively divergent at the telephoto end. Due to the error of the curve at the wide-angle end, when tracking to the telephoto end area, the error is amplified, resulting in serious defocusing of the image.

[0004] In summary, a variable magnification tracking method and system with focus evaluation value feedback are needed to solve the deficiencies in the prior art. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a variable magnification tracking method and system with focus evaluation value feedback, aiming to solve the above problems.

[0006] To achieve the above object, the present invention provides the following technical solution: A variable magnification tracking method with focus evaluation value feedback, comprising the following steps:

[0007] Step S1: System initialization and preparation, initializing the image sensor, image signal processing module, main control module, motor drive module, and zoom lens module, and pre-storing a group of variable magnification tracking curves at several object distances;

[0008] Step S2: Preliminary focusing and division. Perform automatic focusing to obtain the positions of the zoom motor and the focus motor, and divide the magnification range according to the degree of dispersion between the zoom tracking curve corresponding to the proximal limit object distance and the zoom tracking curve corresponding to the distal limit object distance;

[0009] Step S3: Calculate the zoom tracking curve corresponding to the actual object distance. By analyzing the group of zoom tracking curves in the movement mechanism memory, find the two zoom tracking curves closest to the actual object distance, and calculate a new mid-end preset actual object distance zoom tracking curve;

[0010] Step S4: Dynamically adjust the focus. Dynamically adjust the object distance through the focus evaluation feedback mechanism. After the movement of the zoom motor and the focus motor, collect the focus evaluation values of four consecutive frames of images for trend analysis;

[0011] Step S5: Dynamically correct the adjustment step size. Calculate the step size according to the magnification range where the movement mechanism is located, and fine-tune the step size through the calculated step size and the change rate of the focus evaluation value to achieve zoom tracking.

[0012] Optionally, the group of zoom tracking curves in step S1 includes a distal limit object distance curve and a proximal limit object distance curve.

[0013] Optionally, in step S3, it is calculated in the following manner:

[0014] Set the position x1 of the zoom motor and the position y1 of the focus motor in the current cleaning and focusing state;

[0015] According to the current position of the focus motor, select two close reference curves from the pre-stored curve group. The upper preset curve is L1, and the lower preset curve is L2. Calculate the deviation degree r of the actual object distance zoom tracking curve:

[0016] r = (y1 - y 12 ) / (y 11 - y 12 ),

[0017] In the formula, y 11 is the position of the focus motor after the curve L1 is in clear focus when the zoom motor is at x1, and y 12 is the position of the focus motor after the curve L2 is in clear focus when the zoom motor is at x1;

[0018] Judge the position of the actual object distance zoom tracking curve according to the deviation degree r, and obtain the mid-end preset actual object distance zoom tracking curve by interpolating to calculate the position of the focus motor corresponding to any position of the zoom motor.

[0019] Optionally, judging the position of the actual object distance zoom tracking curve according to the deviation degree r is done in the following way:

[0020] If r equals zero, the actual object distance is the object distance corresponding to L2; if r equals 1, the actual object distance is the object distance corresponding to L1; if 0 < r < 1, the actual object distance is between the object distance corresponding to L1 and the object distance corresponding to L2.

[0021] Optionally, the corresponding focusing motor position for any zoom motor position is calculated by interpolation in the following way:

[0022] P2 = r * (y 21 -y 22 ) + y 21 , where y 21 is the position of the focusing motor after the curve L1 is in focus when the zoom motor is at x2, and y 22 is the position of the focusing motor after the curve L2 is in focus when the zoom motor is at x2.

[0023] Optionally, in step S5, the step size is calculated according to the magnification range in which the camera module is located in the following way:

[0024] Set the reference step size as S, the magnification of the camera module as Z, the magnification of curve L1 as Z1, and the magnification of curve L2 as Z2;

[0025] If X is less than or equal to Z1, then ;

[0026] If Z1 < Z ≤ Z2, then S(Z) = S * (1 - (Z - Z1) / (Z2 - Z1));

[0027] If Z is greater than Z2, then S(Z) = S * softmax(-γ(Z - Z2)), where γ is the attenuation coefficient.

[0028] Optionally, in step S5, the step size obtained by calculation and the change rate of the focusing evaluation value are used to fine-tune the step size to achieve varifocal tracking in the following way:

[0029] ,

[0030] where γ is the attenuation coefficient, is the change rate of the focusing evaluation value.

[0031] Optionally, the attenuation coefficient γ is adjusted according to the varifocal tracking effect in the following way:

[0032] If is greater than zero and the evaluation value increases, the step size limit is relaxed to accelerate convergence; if is less than zero and the evaluation value decreases, the step size is contracted in a square root relationship.

[0033] A variable magnification tracking system based on the feedback of the focus evaluation value, adopting the variable magnification tracking method based on the feedback of the focus evaluation value, including an image sensor module, an image signal processing module, a main control module, a motor drive module, and a zoom lens module.

[0034] The image sensor module is used to collect the original image data.

[0035] The image signal processing module is used to perform denoising and sharpening processing on the image and calculate the focus evaluation value.

[0036] The main control module, as the core control unit, is used to control other modules.

[0037] The motor drive module is used to control the zoom motor and the focus motor to make them move synchronously.

[0038] The zoom lens module is used to drive the zoom lens and the focus lens to move independently respectively to achieve optical zoom.

[0039] Optionally, the main control module includes a variable magnification tracking curve group acquisition unit, a focus curve partitioning and selection unit, a click control unit, and a focus evaluation value feedback unit.

[0040] The variable magnification tracking curve group acquisition unit is used to collect and store the data of the position relationship between the zoom and focus motors at different object distances.

[0041] The focus curve partitioning and selection unit is used to select or interpolate and generate a tracking curve according to the current object distance.

[0042] The motor control unit is used to send commands to drive the zoom and focus motors to move independently.

[0043] The focus evaluation value feedback unit is used to analyze the trend of the focus evaluation value and dynamically adjust the object distance tracking strategy.

[0044] The beneficial effects of the present invention:

[0045] 1. In the present invention, after the zoom motor and the focus motor complete the movement, the system collects the focus evaluation values of four consecutive frames of images for trend analysis. If the four-frame data shows a continuous decreasing characteristic, the adjustment direction is set to the opposite direction, and an adaptive compensation strategy that integrates the dynamic feedback of the focus evaluation value is adopted. The feedback mechanism includes the object distance adjustment direction and the object distance adjustment step size. This mechanism constructs a closed-loop correction system by setting the collaborative control rules for the object distance adjustment direction and step size.

[0046] 2. In the present invention, in combination with the real-time feedback of the focus evaluation value, the object distance curve is dynamically adjusted to ensure that even if there is a deviation in the initial curve selection, it can be quickly corrected, reducing the error rate of the curve selection at the wide-angle end, improving the focusing accuracy at the telephoto end, and avoiding the problem of image blurring caused by the accumulation of curve errors.

[0047] 3. In the present invention, a focus evaluation value feedback mechanism is introduced to monitor the change of image sharpness in real time. When the object distance changes and causes the FV to decrease, the tracking curve is automatically adjusted without interrupting the zooming process, realizing dynamic object distance tracking. Even if the target moves, the image can be kept clear, reducing the number of refocusing times caused by the change of object distance and improving the zooming efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the method flow of the present invention.

[0049] Figure 2 It is a group diagram of zooming tracking curves of the present invention.

[0050] Figure 3 It is a schematic diagram of the principle of calculating the position of the focusing motor of the present invention.

[0051] Figure 4 It is a graph of the theoretical curve and the actual motor movement of the present invention.

[0052] Figure 5 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0054] As Figures 1 to 4 shown, a zooming tracking method with focus evaluation value feedback includes the following steps:

[0055] Step S1: System initialization and preparation, initializing the image sensor, image signal processing module, main control module, motor drive module, and zoom lens module, and pre-storing a group of zooming tracking curves at several object distances;

[0056] Step S2: Preliminary focusing and division, performing automatic focusing, obtaining the positions of the zoom motor and the focusing motor, and dividing the magnification range according to the degree of dispersion between the zooming tracking curve corresponding to the proximal limit object distance and the zooming tracking curve corresponding to the distal limit object distance;

[0057] Step S3: Calculating the zooming tracking curve corresponding to the actual object distance, by analyzing the group of zooming tracking curves in the movement memory of the movement, finding the two zooming tracking curves closest to the actual object distance, and calculating a new mid-end preset actual object distance zooming tracking curve;

[0058] Step S4: Dynamically adjust the focus. Dynamically adjust the object distance through the focus evaluation feedback mechanism. After the movement of the zoom motor and the focus motor, collect the focus evaluation values of four consecutive frames of images for trend analysis;

[0059] Step S5: Dynamically correct the adjustment step size. Calculate the step size according to the magnification range where the movement mechanism is located, and finely adjust the step size through the calculated step size and the change rate of the focus evaluation value to achieve zoom tracking.

[0060] The method is implemented through the following specific content:

[0061] First, determine the direction of the next rotation of the zoom motor and calculate the step size of the next movement of the zoom motor according to the current position of the zoom motor.

[0062] The magnification range can be divided according to the degree of dispersion between the zoom tracking curve corresponding to the proximal limit object distance and the zoom tracking curve corresponding to the distal limit object distance in a preset manner. The range with a lower degree of dispersion between the zoom tracking curve corresponding to the proximal limit object distance and the zoom tracking curve corresponding to the distal limit object distance is divided into a small magnification range, and the range with a higher degree of dispersion is divided into a large magnification range.

[0063] The greater the degree of dispersion between the zoom tracking curve corresponding to the proximal limit object distance and the zoom tracking curve corresponding to the distal limit object distance, the greater the depth of field of the movement mechanism and the greater the movement range of the focus motor. To ensure the time for the movement mechanism to zoom throughout the process and achieve the effect of clear zooming throughout the process, move the zoom motor with a larger step size in the small magnification section and move the zoom motor with a smaller step size in the large magnification section to limit the large-scale movement of the focus motor. Due to the large depth of field of the movement mechanism in the small magnification section, moving the zoom motor with a larger step size will not cause the image blur to an unacceptable degree.

[0064] Secondly, before starting the zoom, the autofocus is successful and the positions of the zoom motor and the focus motor at the successful focus are read. Calculate the corresponding zoom tracking curve at the current object distance according to the positions of the zoom motor and the focus motor as the zoom tracking curve followed by the next rotation of the zoom motor and the focus motor.

[0065] As Figure 3 shown, determine the two zoom tracking curves closest to the actual object distance according to the current position of the focus motor, and denote them as the upper preset zoom tracking curve L1 and the lower preset zoom tracking curve L2 respectively. Then, fit the zoom tracking curve followed by the next rotation of the zoom motor and the focus motor according to the deviation degree between the position of the focus motor corresponding to the current position of the zoom motor in the lower preset zoom tracking curve and the current position of the focus motor, and denote it as the middle preset actual object distance zoom tracking curve L3.

[0066] Figure 3Among them, P1 indicates that when the zoom motor is at x1, a scene with an unknown object distance is photographed, and after focusing clearly, the position of the focus motor is at y1. Curves L1 and L2 are two preset zoom tracking curves that are the closest to the current object distance calculated based on the position of the focus motor after focusing clearly. P 11 and P 12 are respectively the positions of the focus motor after curves L1 and L2 are in focus when the zoom motor is at x1. Then, the deviation degree between curve L3 and curves L1 and L2 can be expressed by the following relational formula:

[0067] r = (y1 - y 12 ) / (y 11 - y 12 ).

[0068] When the divisor is 0, it means that L1 coincides with L2, that is, the current point is on the preset zoom tracking curve. When r = 0, it means that P1 is on curve L2. In other words, the actual object distance being photographed currently is the object distance corresponding to curve L2. When r = 1, it means that P1 is on curve L1. In other words, the actual object distance being photographed currently is the object distance corresponding to curve L1. When r is between 0 and 1, it means that the actual object distance being photographed currently is between the object distances corresponding to curves L1 and L2. Then, the position of the focus motor when the zoom motor is at any specified position when photographing a scene with the current object distance is calculated through the following relational formula:

[0069] P2 = r * (y 21 - y 22 ) + y 21 , where y 21 is the position of the focus motor after curve L1 is in focus when the zoom motor is at x2, and y 22 is the position of the focus motor after curve L2 is in focus when the zoom motor is at x2.

[0070] Figure 3 Data shows that as the optical magnification increases, the deviation between the far - end limit object distance curve and the near - end limit object distance curve shows an increasing trend. It should be noted that the matching degree between the mid - end preset object distance zoom tracking curve calculated by extrapolating small - magnification data and the actual theoretical curve is relatively low in the low - magnification range, and its error mainly stems from the difference in non - linear characteristics brought about by the magnification change. To solve this error accumulation problem, this solution proposes a progressive approximation method based on depth - of - field dynamic adjustment:

[0071] 1. In the large depth - of - field magnification range, use the far - end limit object distance curve as the reference tracking trajectory to make full use of the allowable deviation characteristics in the large depth - of - field range and reduce the calculation complexity.

[0072] 2. In the medium depth - of - field magnification range, generate the mid - end preset tracking curve through the interpolation operation of the far - end / near - end limit object distance curves to achieve balanced control of the error distribution.

[0073] 3. For the small depth-of-field magnification range, based on the real-time zoom / focus motor position parameters, select the two reference curves with the closest spatial distance for iterative calculation to ensure tracking accuracy.

[0074] This solution innovatively introduces a range constraint mechanism for depth-of-field adaptation. By gradually shrinking the displacement tolerance range of the focus motor in stages, it realizes the gradual approximation of the tracking curve to the theoretical clear point. This hierarchical control strategy not only ensures the system response speed but also significantly improves the focus accuracy within the full magnification range.

[0075] Aiming at the error accumulation problem that exists when the traditional zoom system calculates the tracking curve of the preset object distance at the middle end using small magnification data, this solution proposes an adaptive compensation strategy that integrates the dynamic feedback of the focus evaluation value. The feedback mechanism includes the object distance adjustment direction and the object distance adjustment step size. By setting the collaborative control rules for the object distance adjustment direction and step size, a closed-loop correction system is constructed.

[0076] The specific implementation method is that after the zoom motor and the focus motor complete their movements, the system collects the focus evaluation values of four consecutive frames of images for trend analysis, such as quantization indicators based on gradient intensity or frequency domain energy. If the four-frame data shows a continuous decreasing characteristic, the adjustment direction is set to the opposite direction.

[0077] As Figure 4 shown, based on the depth-of-field characteristics of the optical system and the mechanical accuracy calibration, combined with the preset object distance adjustment step size parameter, a controlled oscillation trajectory of the focus motor near the theoretical clear point is formed. This solution proposes a dynamic adjustment step size model to calibrate the adjustment step size. Through the joint modeling of the optical depth-of-field constraint and the mechanical transmission characteristics, the non-linear adaptive control of the step size with respect to the magnification change is realized.

[0078] The specific calibration steps are as follows:

[0079] Step 1: Set the reference step size S. This parameter corresponds to the minimum effective displacement that can make the focus evaluation value reach the preset threshold at a specific object distance.

[0080] Step 2: Calculate the adjustment step size according to the magnification range where the movement mechanism is located.

[0081] 1. In the low magnification range, X ≤ Z1: The depth-of-field range is relatively wide. Use the square root decay function to expand the step size:

[0082] ,

[0083] In this stage, the focus is on optimizing the focus speed. By increasing the step size, it quickly crosses the wide blurred area.

[0084] 2. In the medium magnification transition range, Z1 < Z ≤ Z2: The depth-of-field begins to shrink significantly. Enable the linear decay mode for smooth transition:

[0085] S(Z)=S*(1 - (Z - Z1) / (Z2 - Z1))

[0086] This function characteristic ensures that the step reduction rate matches the slope of the depth of field change, avoiding the risk of defocusing.

[0087] 3. When the high magnification precision range Z is greater than Z2: Use an exponential decay function to enhance stability:

[0088] S(Z)=S*softmax(-γ(Z - Z2)),

[0089] where the decay coefficient can be adjusted according to the zoom tracking effect of the actual scene.

[0090] Step 3: Implement dynamic correction to adjust the step size

[0091] Introduce the change rate of the focus evaluation value as a fine-tuning factor:

[0092] where the decay coefficient γ can be adjusted according to the zoom tracking effect of the actual scene. When is greater than zero and the evaluation value rises, appropriately relax the step size limit to accelerate convergence; when is less than zero and the evaluation value drops, then shrink the step size in a square root relationship.

[0093] After the zoom motor and the focus motor of the present invention complete the movement, the system collects the focus evaluation values of four consecutive frames of images for trend analysis. If the four-frame data shows a continuous decreasing characteristic, the adjustment direction is set to the opposite direction, integrating an adaptive compensation strategy with dynamic feedback of the focus evaluation value. The feedback mechanism includes the object distance adjustment direction and the object distance adjustment step size. This mechanism constructs a closed-loop correction system by setting the collaborative control rules for the object distance adjustment direction and the step size;

[0094] Combined with the real-time feedback of the focus evaluation value, dynamically adjust the object distance curve to ensure that even if there are deviations in the initial curve selection, it can be quickly corrected, reducing the error rate of the curve selection at the wide-angle end, improving the focus accuracy at the telephoto end, and avoiding image blurring problems caused by the accumulation of curve errors;

[0095] Introduce a focus evaluation value feedback mechanism to monitor the change of image sharpness in real time. When the object distance change causes the FV to drop, automatically adjust the tracking curve without interrupting the zooming process, realizing dynamic object distance tracking. Even if the target moves, the image can be kept clear, reducing the number of re-focusing times caused by the object distance change and improving the zooming efficiency.

[0096] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0097] The above-described embodiments are only a preferred solution of this application, and do not impose any formal restrictions on this application. There are other variations and modifications without exceeding the technical solutions described in the claims.

Claims

1. A variable magnification tracking method based on focusing evaluation value feedback, characterized in that It includes the following steps: Step S1: System initialization and preparation. Initialize the image sensor, image signal processing module, main control module, motor drive module, and zoom lens module, and pre-store a group of variable magnification tracking curves at several object distances. Step S2: Preliminary focusing and division. Perform automatic focusing, obtain the positions of the zoom motor and focus motor, and divide the magnification range according to the dispersion degree between the variable magnification tracking curve corresponding to the proximal limit object distance and the variable magnification tracking curve corresponding to the distal limit object distance. Step S3: Calculate the variable magnification tracking curve corresponding to the actual object distance. By analyzing the group of variable magnification tracking curves in the movement mechanism memory, find the two variable magnification tracking curves closest to the actual object distance, and calculate a new middle-end preset actual object distance variable magnification tracking curve. Step S4: Dynamically adjust focusing. Dynamically adjust the object distance through the focusing evaluation feedback mechanism. After the movement of the zoom motor and focus motor, collect the focusing evaluation values of four consecutive frames of images for trend analysis. Step S5: Dynamically correct the adjustment step size. Calculate the step size according to the magnification range where the movement mechanism is located, and fine-tune the step size through the calculated step size and the change rate of the focusing evaluation value to achieve variable magnification tracking.

2. The variable magnification tracking method based on the feedback of the focusing evaluation value according to claim 1, wherein In step S1, the group of variable magnification tracking curves includes the distal limit object distance curve and the proximal limit object distance curve.

3. The varifocal tracking method based on feedback of a focusing evaluation value according to claim 1, wherein In step S3, it is calculated in the following way: Set the position x1 of the zoom motor and the position y1 of the focus motor in the current cleaning and focusing state. According to the current position of the focus motor, select two close reference curves from the pre-stored curve group. The upper-end preset curve is L1, and the lower-end preset curve is L2, and calculate the deviation degree r of the actual object distance variable magnification tracking curve. r = (y1 - y 12 ) / (y 11 - y 12 ), where y 11 is the position of the focus motor after the curve L1 is in clear focus when the zoom motor is at x1, and y 12 is the position of the focus motor after the curve L2 is in clear focus when the zoom motor is at x1; Judge the position of the actual object distance variable magnification tracking curve according to the deviation degree r, and obtain the middle-end preset actual object distance variable magnification tracking curve by interpolating to calculate the position of the focus motor corresponding to any position of the zoom motor.

4. The variable magnification tracking method based on focusing evaluation value feedback according to claim 3, characterized in that The judgment of the position of the actual object distance variable magnification tracking curve according to the deviation degree r is carried out in the following way: If r is equal to zero, the actual object distance is the object distance corresponding to L2; if r is equal to 1, the actual object distance is the object distance corresponding to L1; if 0 < r < 1, the actual object distance is between the object distance corresponding to L1 and the object distance corresponding to L2.

5. The variable magnification tracking method based on the feedback of the focusing evaluation value according to claim 4, characterized in that The interpolation calculation of the position of the focus motor corresponding to any position of the zoom motor is carried out in the following way: P2 = r * (y 21 - y 22 ) + y 21 , where y 21 is the position of the focusing motor after the curve L1 is in focus when the zoom motor is at x2, and y 22 is the position of the focusing motor after the curve L2 is in focus when the zoom motor is at x2.

6. The variable magnification tracking method based on the feedback of the focusing evaluation value according to claim 1, wherein In step S5, the calculation of the step size according to the magnification range where the movement mechanism is located is carried out in the following way: Set the reference step size as S, the magnification where the movement mechanism is located as Z, the magnification of curve L1 as Z1, and the magnification of curve L2 as Z2. If X is less than or equal to Z1, then ; If Z1 < Z ≤ Z2, then S(Z) = S * (1 - (Z - Z1) / (Z2 - Z1)). If Z is greater than Z2, then S(Z) = S * softmax(-γ(Z - Z2)), where γ is the attenuation coefficient.

7. The varifocal tracking method based on the feedback of the focusing evaluation value according to claim 6, characterized in that In step S5, the step size is fine-tuned through the calculated step size and the change rate of the focusing evaluation value to achieve variable magnification tracking, and it is carried out in the following way: ， where γ is the attenuation coefficient, is the change rate of the focusing evaluation value.

8. The variable magnification tracking method based on focus evaluation value feedback according to claim 7, characterized in that The attenuation coefficient γ is adjusted according to the variable magnification tracking effect, and it is carried out in the following way: If is greater than zero and the evaluation value increases, the step size limit is relaxed to accelerate convergence. If is less than zero and the evaluation value decreases, the step size is contracted in a square root relationship.

9. A variable magnification tracking system based on focus evaluation value feedback, which adopts the variable magnification tracking method based on focus evaluation value feedback according to any one of claims 1-8, characterized in that, It includes an image sensor module, an image signal processing module, a main control module, a motor drive module, and a zoom lens module. The image sensor module is used to collect raw image data. An image signal processing module, which is used to perform denoising and sharpening processing on the image and calculate the focus evaluation value; A main control module, which is the core control unit and is used to control other modules; A motor drive module, which is used to control the zoom motor and the focus motor to make them move synchronously; A zoom lens module, which is used to drive the zoom lens and the focus lens to move independently respectively to achieve optical zoom.

10. The varifocal tracking system based on the feedback of the focusing evaluation value according to claim 9, wherein, The main control module includes a zoom tracking curve group acquisition unit, a focus curve partitioning and selection unit, a click control unit and a focus evaluation value feedback unit. The zoom tracking curve group acquisition unit is used to collect and store the zoom-focus motor position relationship data at different object distances; The focus curve partitioning and selection unit is used to select or interpolate and generate a tracking curve according to the current object distance; The motor control unit is used to send commands to drive the zoom and focus motors to move independently; The focus evaluation value feedback unit is used to analyze the trend of the focus evaluation value and dynamically adjust the object distance tracking strategy.

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