WO2018103105A1

WO2018103105A1 - Method and system for correcting image blur caused by lens tilt

Info

Publication number: WO2018103105A1
Application number: PCT/CN2016/109319
Authority: WO
Inventors: 刘锦潮; 洪航庆; 刘志远; 麦练智
Original assignee: 东莞佩斯讯光电技术有限公司
Priority date: 2016-12-09
Filing date: 2016-12-09
Publication date: 2018-06-14

Abstract

Provided are a method and system for correcting image blur caused by lens tilt, relating to the technical field of miniature cameras capable of automatic focus and optical image stabilization; the invention solves the technical deficiency of existing camera modules of low imaging quality when the absolute value of defocus distance is large; an image sensor is controlled to photograph while an actuator driver chip is queried, and the current path of the lens and the angle of inclination of the lens are obtained from the actuator driver chip; according to the current path of the lens and data of the angle of inclination of the lens, the model is combined and the amount of blur at different positions in the image outputted by the image sensor is calculated; according to the amount of blur at different positions in the image, deblurring image processing is performed on the image to obtain a clear image; thus optimal improvement of image quality is achieved and the situation of inadequate or unnatural sharpness is prevented.

Description

Title: Method and system for correcting image blur caused by lens tilt

[0001] The present invention relates to the field of micro-cameras with autofocus or optical image stabilization, and in particular to improvements in demolding processing.

Background technique

[0002] In different focusing distances or in the optical image stabilization process, the camera module will inevitably appear to tilt the lens, resulting in a decrease in the resolution of the image edge, which affects the image quality. The main cause of lens tilt can be assembly or component error, or motion principle. For example, in the actuator of the CN2015106221318 patent, the lens may have different degrees of tilt during the optical image stabilization process. Although camera module and actuator manufacturers are trying to alleviate this problem in design or production, it is still impossible to complete the problem of production and structure.

[0003] Referring to FIGS. 1a to 1D, the camera module includes a lens 1, an image sensor 2, and a lens actuator actuator 3 that controls the stroke of the lens and the tilt angle of the lens to achieve autofocus or optical image stabilization. La and Figure lb show that the lens 1 has different degrees of lens tilt when the distance between the far focus and the near focus is different. Figure lc and Figure Id show that lens 1 exhibits varying degrees of lens tilt before optical image stabilization and after optical image stabilization. The cause of the lens tilt may be caused by assembly or component errors, or by motion.

[0004] Figures 2a and 2b show that when the lens tilt angle "吋, the imaging will be tilted, an angle Θ will be generated between the imaging and image sensors, and the edge between the imaging and image sensor will appear ₂₁ The defocusing distance of the image causes the defocusing and resolution of the image to appear green. According to Scheimpflug principle (see GB Patent No. 1139), the relationship between 0 and α can be accurately estimated. If the imaging is a perfect plane _吋 , the relationship between Θ, a, A _Zl , and Δ is:

[0005] A _Zl oc 0 oc a (1)

[0007] As seen from equations (1) and (2), the defocus distance ( ₂₁ and) and the lens tilt angle (") have a proportional relationship.

[0008] FIG. 3a illustrates the imaging out-of-focus distance and the X-image position (where the X-image position is 0 represents the image center position) Relationship. The relationship between the image out-of-focus distance (Δ _Ζ ) and the image position is:

[0009] A z = x tan( θ) (3)

[0010] FIG. 3b depicts a situation in which image defocusing results in an amount of image blur in one example. When the absolute value of the out-of-focus distance is large, the amount of image blur will usually increase. The relationship between the out-of-focus distance and the amount of image blur depends on the optical characteristics of the lens, including the aperture and focal length.

[0011] Since the degree of image blurring caused by tilting the lens is not uniform, it is usually clear at the center and blurred at the side. Therefore, if the entire image is deblurred image processing (Deblurring Image Processing), the photo may be caused by this. Positions (for example: center position) appear unnatural or oily, but other positions (such as corner positions) appear to be insufficiently sharp.

[0012] Since the degree of defocus blur of the lens is also related to the defocus distance, the degree of defocus blur of the lens is closely related to the tilt angle of the lens. The tilt angle of the lens can cause the resolution of the image edge to decrease, affecting the image quality. Because this problem cannot be cured in production and structure in most camera modules.

technical problem

[0013] In summary, the object of the present invention is to solve the problem that the existing camera module has a large absolute value of the out-of-focus distance and the image quality is poor, and proposes a method for correcting the image blur caused by the tilt of the lens. And system.

Problem solution

Technical solution

[0014] In order to solve the technical problem proposed by the present invention, the technical solution adopted is:

[0015] A method for correcting image blur caused by lens tilt is characterized in that the steps of the method are as follows: [0016] 1), a model for accurately establishing different image positions, lens tilt angles, and lens blur amounts in advance

, storing the model in memory;

[0017] 2) before the photographing, the image processor reads a model of different image positions in the memory and a relationship between the tilt angle of the lens and the amount of lens blur;

[0018] 3), the image processor sends a command to the actuator driving chip, and drives the lens to perform auto focus or optical anti-shake processing;

[0019] 4), the image processor sends a command to the image sensor, controls the image sensor to take a photo, and asks The actuator drives the chip, and obtains a stroke and a lens tilt angle of the current lens from the actuator driving chip;

[0020] 5) The image processor calculates, according to the stroke of the current lens and the lens tilt angle data, the blur amount of different positions of the image output by the image sensor according to the model;

[0021] 6), the image processor defuzzifies the image according to the amount of blur of different positions of the image

, get a clear image;

[0022] 7) The image processor transmits the processed defuzzified clear image to the main controller.

[0023] In the first step, the model of the relationship between different image positions and the lens tilt angle and the lens blur amount can be accurately established by the lens optical simulation software or the experimental method.

[0024] a system for implementing the method, characterized in that the system comprises a motherboard and a camera module;

[0025] The main board includes a main controller and an image processor; the main controller is connected to the control image processor, and receives and outputs a clear image that is defuzzified after being processed by the image processor;

[0026] The camera module includes: a lens for optical imaging, an image sensor located at the rear of the lens for photoelectric conversion to form an electronic image output, controlling the stroke of the lens and the tilt angle of the lens to achieve auto focus or optical image stabilization. a lens actuator, connected to an actuator driving chip that controls the lens actuator, and a memory that stores models of different image positions and relationship between the lens tilt angle and the lens blur amount;

[0027] the image sensor is connected to the image processor, and the image processor is provided with a real image and a photographed image; the image processor is connected to control the image sensor to take a picture;

[0028] the image processor is connected to control the actuator driving chip to perform auto focus or optical anti-shake processing, and the actuator driving chip outputs the stroke and lens tilt angle data of the current lens to the image processor; [0029] The memory provides image processing for the image processor to perform defuzzification image processing for reference model information.

[0030] The main controller replaces or includes an image processor, or is integrated in a camera module.

Advantageous effects of the invention

Beneficial effect

[0031] The beneficial effects of the present invention are as follows: The present invention proposes to achieve an optimal image quality improvement effect according to the optical characteristic model of the lens and the degree of tilt combined with the image processing method, thereby avoiding the lack of sharpness or unnaturalness of the local position of the image. . The invention can correct the image blur caused by the tilt of the lens, and can pass the mirror The head optical simulation software accurately models the relationship between different image positions and lens tilt angles and lens blur. The deblurring force can be adjusted at different image positions by the model. For example, when the tilt angle is large, the de-blurring intensity of the image edge needs to be increased, but the de-blurring force closer to the center position needs to be lowered according to the estimated relationship.

[0032] The present invention and the conventional defuzzification image processing can more appropriately defuzzify the images at different positions according to the optical characteristic model of the lens and the degree of tilt, thereby achieving the best image quality improvement effect. Avoid situations where the sharpness of the image is insufficient or unnatural.

[0033] In addition, in the traditional process of manufacturing a high-pixel autofocus or optical image stabilization camera module, the degree of tilt of the lens must be strictly controlled, resulting in extremely high machine and production costs, and the camera module is extremely expensive, failing to Widely promoted to ordinary users. By the method and system of the invention, the standard of the lens tilt degree can be reduced, which is beneficial to improving the production yield and reducing the cost, so that ordinary users can enjoy the joy of high pixel shooting.

DRAWINGS

[0034] FIG. 1a is a state diagram of the camera module in a far focus;

[0035] FIG. 1b is a state diagram of the camera module in a near focus state;

[0036] FIG. 1c is a state diagram of the camera module before optical image stabilization;

[0037] FIG. 1d is a state diagram of the camera module after optical anti-shake;

[0038] FIG. 2a is a schematic diagram 1 of the tilting of the lens causing the imaging tilt 吋;

[0039] FIG. 2b is a schematic diagram 2 of the tilting of the lens causing the imaging tilt 吋;

[0040] FIG. 3a is a relationship diagram of an image out-of-focus distance and an image position;

[0041] FIG. 3b is a relationship diagram between the out-of-focus distance and the image blur amount;

[0042] FIG. 4a is a force relationship diagram before adjusting deblurring;

[0043] FIG. 4b is a diagram showing the relationship of the force after adjusting the defuzzification;

[0044] FIG. 5 is a block diagram of the present invention capable of correcting an image blurring system caused by tilting of a lens;

6 is a flow chart of a method for correcting image blur caused by tilt of a lens according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

BEST MODE FOR CARRYING OUT THE INVENTION The invention will now be further described with reference to the drawings and preferred embodiments of the invention.

Referring to FIG. 6, the present invention can correct the image blur caused by the tilt of the lens, and includes the following steps:

[0048] 1), a model for accurately establishing different image positions and relationship between the lens tilt angle and the lens blur amount in advance

, storing the model in memory;

[0049] 2) before the photographing, the image processor reads a model of different image positions in the memory and a relationship between the tilt angle of the lens and the amount of lens blur;

[0050] 3), the image processor sends a command to the actuator driving chip, and drives the lens to perform auto focus or optical anti-shake processing;

[0051] 4), the image processor sends a command to the image sensor, controls the image sensor to take a picture, and simultaneously queries the actuator drive chip to obtain the stroke and the lens tilt angle of the current lens from the actuator drive chip;

[0052] 5) The image processor calculates, according to the stroke of the current lens and the lens tilt angle data, the blur amount of different positions of the image output by the image sensor according to the model;

[0053] 6), the image processor defuzzifies the image according to the amount of blur of different positions of the image

, get a clear image;

[0054] 7) The image processor transmits the processed defuzzified clear image to the main controller.

[0055] In the first step, the model of the relationship between different image positions and the lens tilt angle and the lens blur amount can be accurately established by the lens optical simulation software or the experimental method.

[0056] Referring to FIG. 4a, the velocity relationship diagram before the defuzzification is adjusted and FIG. 4b adjusts the velocity relationship diagram after the defuzzification; the invention adjusts the defuzzification intensity according to different degrees of image blur. The edge of the image before correction is more blurred than the middle. After the correction, the overall image becomes clear and no unnatural images appear.

[0057] The core of the present invention is to estimate the degree of image blurring at different positions according to the model according to the degree of tilt of the lens in different situations, and perform appropriate defuzzification image processing on different image positions.

[0058] A model for establishing a blur amount of a lens at different inclinations can be obtained by actually measuring an image, or an optical simulation method. Regarding the degree of tilt of the lens in different situations, the degree of tilt of the individual lens under different conditions, or the mechanical structure model, can be measured according to the actual situation.

[0059] Referring to FIG. 5, the present invention can correct a system for blurring an image caused by tilting of a lens, including a master. Board and camera module;

[0060] The main board includes a main controller and an image processor; the main controller is connected to the control image processor, and receives and outputs a clear image that is defuzzified after being processed by the image processor;

[0061] The camera module includes: a lens for optical imaging, an image sensor located at the rear of the lens for photoelectric conversion to form an electronic image output, controlling the stroke of the lens and the tilt angle of the lens to achieve auto focus or optical image stabilization. a lens actuator, connected to an actuator driving chip that controls the lens actuator, and a memory that stores models of different image positions and relationship between the lens tilt angle and the lens blur amount;

[0062] the image sensor is connected to the image processor, and the image processor is provided with a real image and a photographed image; the image processor is connected to control the image sensor to take a picture;

[0063] the image processor is connected to control the actuator driving chip to perform auto focus or optical anti-shake processing, and the actuator driving chip outputs the stroke and lens tilt angle data of the current lens to the image processor; [0064] The memory provides image processing for the image processor to perform defuzzification image processing for reference model information.

[0065] The main controller replaces or includes an image processor, or is integrated in a camera module.

The present embodiment is a preferred embodiment of the present invention, and other principles and methods are the same as or similar to those of the present embodiment, and are all within the protection scope of the present invention.

Claims

Claim

[Claim 1] A method of correcting image blur caused by tilt of a lens, characterized in that the steps of the method are as follows:

1), accurately establishing a model of different image positions and lens tilt angles and lens blur amount relationships in advance, and storing the models in the memory;

2) Before the camera is taken, the image processor reads a model of different image positions in the memory and the relationship between the lens tilt angle and the lens blur amount;

3), the image processor sends a command to the actuator driving chip, and drives the lens to perform auto focus or optical anti-shake processing;

4), the image processor sends a command to the image sensor, controls the image sensor to take a picture, and simultaneously queries the actuator drive chip, and obtains the stroke and the lens tilt angle of the current lens from the actuator drive chip;

5), the image processor combines the model according to the stroke of the current lens and the lens tilt angle data, and calculates a blur amount of different positions of the image output by the image sensor;

6) The image processor defuzzifies the image according to the amount of blurring of the image at different positions, and obtains a clear image;

7) The image processor transmits the processed defuzzified clear image to the main controller.

[Claim 2] A system for implementing the method of claim 1 wherein said system comprises a motherboard and a camera module;

The main board includes a main controller and an image processor; the main controller is connected to the control image processor to receive and output a defuzzified clear image processed by the image processor; the camera module comprises: Optical imaging lens, image sensor located behind the lens for photoelectric conversion to form an electronic image output, lens actuator that controls lens stroke and lens tilt angle for autofocus or optical image stabilization, and connection to control lens actuator actuation a driver chip, and a memory for storing models of different image positions and lens tilt angles and lens blur amounts;

The image sensor is connected to the image processor to provide a real image for the image processor and to output an image after photographing; the image processor is connected to control the image sensor to take a picture; The image processor is connected to control an actuator driving chip for autofocus or optical anti-shake processing, and the actuator driving chip outputs a stroke and a lens tilt angle data of the current lens to the image processor;

The memory provides image processing for the image processor to perform defuzzification image processing for reference model information.

[Clave 3] The system according to claim 2, wherein: the main controller replaces or includes an image processor, or is integrated in a camera module.