CN113709326A - Lens shadow correction method and device and electronic equipment - Google Patents

Abstract

The application discloses a lens shadow correction method, a lens shadow correction device and electronic equipment, wherein the method comprises the following steps: acquiring a first image and a target focal length corresponding to a second image, wherein the first image is an image of a camera device under the first focal length, and the second image is an image of the camera device under the target focal length; obtaining a reference image according to the corresponding relation between the first focal length and the target focal length; correcting the second image according to the image data in the reference image; and outputting the corrected second image.

Description

Lens shadow correction method and device and electronic equipment

Technical Field

The application belongs to the field of image processing, and particularly relates to a lens shadow correction method and device and electronic equipment.

Background

Currently, in the existing Lens Shading Correction (LSC) technology, a module manufacturer records a uniform and coarsely calibrated LSC compensation table in a One-Time programmable (OTP) chip during production. In actual debugging, a compensation table burned in the OTP is extracted, and the compensation table and an actually shot shadow map jointly generate an accurate gain map.

The existing LSC technology has good correction function for a lens module with fixed focal length, because the imaging light path diagram and the lens attenuation multiple are stable. However, for the variable focus lens module, since the imaging optical path diagram changes, the lens attenuation trend also changes, if the correction data with fixed focal length is used, overcompensation and undercompensation are easy to occur, and the phenomena of over-brightness and over-darkness are generated due to correction errors.

Content of application

The embodiment of the application aims to provide a lens shading correction method, a lens shading correction device and electronic equipment, which can solve the problem that a shading correction method with a fixed focal length is not suitable for a zoom scene.

In order to solve the technical problem, the present application is implemented as follows:

in a first aspect, an embodiment of the present application provides a lens shading correction method, where the method includes:

acquiring a first image and a target focal length corresponding to a second image, wherein the first image is an image of a camera device under the first focal length, and the second image is an image of the camera device under the target focal length;

obtaining a reference image according to the corresponding relation between the first focal length and the target focal length;

correcting the second image according to the image data in the reference image;

and outputting the corrected second image.

In a second aspect, an embodiment of the present application provides an apparatus for lens shading correction based on continuous zooming, including:

the data acquisition module is used for acquiring a first image and acquiring a target focal length corresponding to a second image, wherein the first image is an image of the camera device under the first focal length, and the second image is an image of the camera device under the target focal length;

the image processing module is used for obtaining a reference image according to the corresponding relation between the first focal length and the target focal length;

a correction module for correcting the second image according to the image data in the reference image;

and the output module is used for outputting the corrected second image.

In a third aspect, an embodiment of the present application provides an electronic device, which includes a processor, a memory, and a program or instructions stored on the memory and executable on the processor, and when executed by the processor, the program or instructions implement the steps of the method according to the first aspect.

In a fourth aspect, embodiments of the present application provide a readable storage medium, on which a program or instructions are stored, which when executed by a processor implement the steps of the method according to the first aspect.

In the embodiment of the application, the reference images are obtained by acquiring the images under the first focal length, each reference image is used as a reference frame, the shadow in the second image is corrected according to the relationship between the image data in the reference image and the images under the target focal length, the point-to-point adjustment can be performed on the images under the target focal length in real time in the shooting process by using the target focal length, and the problems of overcompensation and undercompensation when the shadow correction method with fixed focal length is applied to a zoom scene can be solved.

Drawings

FIG. 1 is a flowchart illustrating steps of a lens shading correction method according to an embodiment;

FIG. 2 is a flowchart illustrating a step of acquiring a reference image according to the present embodiment;

fig. 3 is a flowchart of a step of correcting the second image according to the image data in the reference image according to the present embodiment;

FIG. 4 is a flowchart illustrating another step of correcting the second image according to the image data in the reference image according to the present embodiment;

fig. 5 is a schematic structural diagram of a device for lens shading correction based on continuous zooming according to the present embodiment;

fig. 6 is a schematic structural diagram of an electronic device provided in this embodiment;

fig. 7 is a schematic diagram of a hardware structure of an electronic device according to this embodiment.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application are capable of operation in sequences other than those illustrated or described herein. In addition, "and/or" in the specification and claims means at least one of connected objects, a character "/" generally means that a preceding and succeeding related objects are in an "or" relationship.

A lens shading correction method, a lens shading correction device, and an electronic device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings through specific embodiments and application scenarios thereof.

The inventive concept of this embodiment is to provide a method for correcting the actual lighting compensation of the image generated by the target focal length by using the difference of the brightness distribution of the image at different magnifications and the relationship between the image generated by the first focal length and the image generated by the target focal length during zooming. The correction effect can be effectively improved, and the phenomena of over-brightness and over-darkness caused by correction errors are reduced.

Referring to fig. 1, the method for correcting lens shading provided in this embodiment includes the following steps S1100 to S1400:

and S1100, acquiring a first image and acquiring a target focal length corresponding to a second image.

In this embodiment, the first image is an image of the image pickup device at the first focal length, and the second image is an image of the image pickup device at the target focal length. The target focal length may be greater than the first focal length or smaller than the first focal length, for example, the magnification of the first focal length is 2X, and the magnification of the target focal length is 4X; or the magnification of the first focal length is 4X, and the magnification of the target focal length is 2X.

In this embodiment, the target focal length may be obtained by detecting a real-time focal length of the zoom lens, for example, detecting adjustment data of the lens by the user in real time, and if the focal length of the lens does not change within a certain time, determining that the focal length corresponding to the time is the target focal length, where an image obtained at the target focal length is a second image that the user wants to obtain.

In this embodiment, the image pickup device may be a stand-alone image pickup device, such as a camera, a video camera, or the like. The camera device may also be a shooting device installed on a terminal, such as a shooting component on a smart terminal like a mobile phone or a tablet. It should be noted that the image pickup apparatus in this embodiment is an image pickup apparatus with an adjustable focal length, that is, the lens of the image pickup apparatus is a zoom lens.

S1200, obtaining a reference image according to the corresponding relation between the first focal length and the target focal length.

It is understood that the first image of the present embodiment is captured prior to the second image, and since the imaging at 2X magnification is based on the base magnification imaging at a fixed focal length, it is preferable that the first image is the imaging of the image pickup apparatus at 2X magnification, and the second image is the imaging of the image pickup apparatus at 2X to nX magnification. Wherein the maximum value of n in nX magnification depends on the optical zoom magnification of the image pickup apparatus, for example, n is 30 or 42.

In this embodiment, a reference image is obtained by using a corresponding relationship between a first focal length and a target focal length, specifically, referring to fig. 2, the method includes the following steps S1201 to S1203:

s1201, acquiring the corresponding relation between the first focal length and the target focal length.

In this embodiment, the corresponding relationship between the first focal length and the target focal length may be a multiple relationship between focal lengths with different magnifications, for example, the magnification of the first focal length is 2X, and the magnification of the target focal length is 4X, so that the multiple relationship between the first focal length and the target focal length is 0.5, or the target focal length is 2 times of the first focal length; for example, the magnification of the first focal length is 2X, and the magnification of the target focal length is 10X, then the relationship between the first focal length and the target focal length is 0.2, and it can also be said that the target focal length is 5 times the first focal length.

And S1202, obtaining a magnification relation between the field angle of the first image and the field angle of the second image according to the corresponding relation.

It can be understood that, during shooting, the smaller the focal length, the larger the Field of View (FOV), the closer the shooting distance, the larger the depth of Field, and therefore the larger the image area for imaging at a small focal length. Conversely, the larger the focal length, the smaller the Field of View (FOV), and the further the shooting distance, the smaller the depth of Field, so that the imaging at a large focal length has a smaller image area. Based on this, the corresponding relation between the field angles at different focal lengths can be obtained according to the corresponding relation between different focal lengths. Therefore, the first focal length is smaller than the target focal length in the present embodiment, so that the image of the small FOV is corrected by the image of the large FOV.

It follows that the magnification relationship between the FOV of the first image and the FOV of the second image is inversely related to the magnification relationship between the focal lengths of the first image and the second image. For example, the corresponding relationship between the first focal length and the target focal length is 0.5, and the magnification relationship between the FOV of the first image and the FOV of the second image is 2.

And S1203, cutting the first image according to the magnification relation to obtain a reference image with the same view angle as the second image.

In this embodiment, taking an example in which the first image is an image of the imaging device at 2X magnification and the second image is an image of the imaging device at 4X magnification, since the first image at 2X magnification has a larger FOV and the second image at 4X magnification has a relatively small FOV, in order to make the first image and the second image have the same FOV and thereby obtain a correction relationship corresponding to the magnification, the first image is cropped according to the field angle of the second image to obtain a cropped reference image that is the same as the FOV of the second image.

Specifically, a cropping center point is obtained, which is a center point of the first image, that is, an optical center point of the first image. And then, the first image is cut according to the cutting center point and the FOV size of the second image, and the reference image which is the same as the FOV of the second image can be obtained by taking the cutting center point as the cutting center and the area included in the field angle of the second image as the cutting area. The reference image contains the same objects and scenes as the second image, differing only in light distribution and sharpness.

After step S1200 is performed, step S1300 is performed.

S1300, correcting the second image according to the image data in the reference image.

It should be noted that this step may be during the acquisition of the second image or after the acquisition of the second image.

For example, the pre-shot second image may be acquired in real time during the framing and focusing process of the user, and the pre-shot second image may be corrected by referring to the image data in the image, and after the correction is completed, the corrected second image is directly obtained.

For another example, the second image that is pre-captured may be corrected by referring to the image data in the image after the user has finished framing focus, determining the second image.

Specifically, referring to fig. 3, correcting the second image based on the image data in the reference image includes the following steps S1310 to S1312:

s1310, luminance distribution data in the reference image and luminance distribution data in the second image are acquired.

In this embodiment, the image data in the reference image at least includes brightness distribution data, and the brightness distribution data may include brightness and pixels at each coordinate position in the reference image, and light intensity attenuation information. Similarly, the brightness distribution data in the second image may include the brightness and pixels at the coordinate positions in the reference image, and the light intensity attenuation information.

It should be noted that, since the reference image is obtained by cropping the first image, pixels of the reference image are affected relative to pixels of the first image, and therefore, before the luminance distribution data in the reference image is acquired, the reference image may be subjected to pixel processing to make the sharpness of the reference image consistent with that of the first image, so as to improve the accuracy of the correction.

S1311, a correction compensation table is obtained from the luminance distribution data in the reference image and the luminance distribution data in the second image.

It is understood that, in the case that the lens has a fixed focal length, the LSC technique may be used to perform shading correction for the fixed focal length lens module, and specifically, the initial compensation table may be burned in the OTP. And the correction compensation table in the present embodiment is data different from the initial compensation table.

In a possible example, assuming that the data for shading compensation of the first image is an initial compensation table, the image obtained after shading compensation of the first image using the initial compensation table is an image having ideal shading data. Based on this, the correction compensation table in the present embodiment is compensation data generated on the basis of an image having ideal shading data, that is, the correction compensation table in the present embodiment can be understood as an update of the initial compensation table based on the reference image and the second image, resulting in a new compensation table (i.e., the correction compensation table in the present embodiment).

And S1312, correcting the second image according to the correction compensation table.

The above is an implementation manner of the present embodiment that the second image is corrected by acquiring the brightness distribution data in the reference image and the brightness distribution data in the second image to generate the correction compensation table, and it is able to avoid the phenomena of compensation transition and over-bright four corners caused by using a fixed initial compensation table in the zoom lens.

In this embodiment, the correcting the second image according to the image data in the reference image further includes, with reference to fig. 4, the following steps S1320 to S1322:

s1320, extracting the picture feature point information in the reference image.

In this embodiment, the picture feature point information may be a local feature of the image or a global feature of the image, and specifically, the picture feature point information in the reference image may be obtained by using a gaussian laplacian detection method, or a method using a Hessian matrix (second order differential) of a pixel point and a determinant value thereof, or a scale invariant feature transform algorithm, or the like.

It should be noted that before extracting the picture feature point information in the reference image, the reference image may be buffered so as to be extracted in real time during the process of correcting the second image.

And S1321, acquiring picture characteristic point information in the second image.

Specifically, the pre-captured second image may be acquired in real time and the picture feature point information in the pre-captured second image may be acquired in a case where the user captures with the target focal length.

In this embodiment, after the user finishes framing and focusing, the second image captured by the target focal length may be obtained first, and then the picture feature point information in the second image may be obtained.

S1322, the screen feature point information in the second image is corrected based on the screen feature point information in the reference image.

Specifically, since the reference image and the second image have the same size, the reference image and the second image may be aligned so that the same objects in the reference image and the second image are in a one-to-one correspondence relationship, and after the reference image and the second image are aligned, the feature point information of the reference image and the second image at the same position is obtained so as to facilitate the comparison of each feature point, and each reference image is used as a reference frame.

In this embodiment, the characteristic point information of the second image may be corrected according to the characteristic point information of the reference image by comparing the characteristic point information of the reference image and the characteristic point information of the second image, so as to dynamically realize point-to-point and block-to-block compensation correction in the process of shooting with the target focal length. For example, when the shadow area of a certain feature point in the second image is larger than that of the feature point in the reference image, the shadow area of the feature point in the second image is adjusted to be the same as that of the feature point in the reference image.

In addition, the second image is compensated by referring to the image, so that the color embodiment of the picture can be improved, the edge resolution is improved, and the edge noise and the smearing sense are reduced.

And S1400, outputting the corrected second image.

In this embodiment, the output corrected second image is the image corrected in step S1300 described above.

In the present embodiment, the second image may be corrected by using only the correction compensation table, or by using only the screen feature point information in the reference image, or by combining both, for example, after the second image is corrected by using the correction compensation table, the second image may be corrected for a second time by using the screen feature point information in the reference image, thereby further improving the correction accuracy.

In the above embodiment, the second image is corrected by referring to the picture feature point information in the image, and each reference image is used as a reference frame, so that in the process of shooting by using the target focal length, point-to-point adjustment can be performed on the imaging at the target focal length in real time, point-to-point and block-to-block compensation correction can be dynamically realized, the problems of overcompensation and undercompensation when the shading correction method with a fixed focal length is applied in a zoom scene can be solved, global compensation can be realized, and the precision is improved.

It should be noted that, in the lens shading correction method provided in the embodiment of the present application, the execution subject may be a continuous zooming-based lens shading correction apparatus, or a control module in the continuous zooming-based lens shading correction apparatus for executing the loading lens shading correction method. In the embodiment of the present application, a method for performing lens shading correction based on continuous zooming by using a lens shading correction device based on continuous zooming is taken as an example, and the method for performing lens shading correction based on continuous zooming provided by the embodiment of the present application is described.

In the present embodiment, referring to fig. 5, there is provided an apparatus 500 for lens shading correction based on continuous zooming, the apparatus comprising:

the data acquisition module 501 is configured to acquire a first image and acquire a target focal length corresponding to a second image, where the first image is an image of the camera device at the first focal length, and the second image is an image of the camera device at the target focal length;

an image processing module 502, configured to obtain a reference image according to a correspondence between the first focal length and the target focal length;

a correction module 503, configured to correct the second image according to the image data in the reference image;

an output module 504, configured to output the corrected second image.

In this embodiment, the image processing module 502 is further configured to: acquiring the corresponding relation between the first focal length and the target focal length; obtaining a magnification relation between the field angle of the first image and the field angle of the second image according to the corresponding relation; and cutting the first image according to the magnification relation to obtain a reference image with the same field angle as the second image.

In this embodiment, the correction module 503 is further configured to: acquiring brightness distribution data in the reference image; obtaining a correction compensation table according to the brightness distribution data; and correcting the second image according to the correction compensation table.

In this embodiment, the correction module 503 is further configured to: extracting picture characteristic point information in the reference image; acquiring picture characteristic point information in the second image; and correcting the picture characteristic point information in the second image according to the picture characteristic point information in the reference image. Specifically, in this embodiment, the correction module 503 is further configured to: acquiring feature point information of a reference image and a second image at the same position, wherein the reference image and the second image are arranged in an aligned manner; the feature point information of the reference image and the second image are compared, and the feature point information of the second image is corrected according to the feature point information of the reference image.

The continuous zoom-based lens shading correction apparatus 500 in the embodiment of the present application may be an apparatus, or may be a component, an integrated circuit, or a chip in a terminal. The device can be mobile electronic equipment or non-mobile electronic equipment. By way of example, the mobile electronic device may be a mobile phone, a tablet computer, a notebook computer, a palm top computer, a vehicle-mounted electronic device, a wearable device, an ultra-mobile personal computer (UMPC), a netbook or a Personal Digital Assistant (PDA), and the like, and the non-mobile electronic device may be a server, a Network Attached Storage (NAS), a Personal Computer (PC), a Television (TV), a teller machine or a self-service machine, and the like, and the embodiments of the present application are not particularly limited.

The lens shading correction apparatus based on continuous zooming in the embodiment of the present application may be an apparatus having an operating system. The operating system may be an Android (Android) operating system, an ios operating system, or other possible operating systems, and embodiments of the present application are not limited specifically.

The lens shading correction device based on continuous zooming provided by the embodiment of the application can realize each process realized in the method embodiments of fig. 1 to 4, and is not repeated here to avoid repetition.

In this embodiment, by using each reference image as a reference frame, point-to-point and block-to-block compensation and correction can be dynamically realized during shooting with a target focal length, so as to realize global compensation and improve accuracy.

Optionally, referring to fig. 6, an electronic device 600 is further provided in an embodiment of the present application, and includes a processor 601, a memory 602, and a program or an instruction stored in the memory 602 and executable on the processor 601, where the program or the instruction is executed by the processor 601 to implement each process of the lens shading correction method embodiment, and can achieve the same technical effect, and in order to avoid repetition, details are not repeated here.

It should be noted that the electronic devices in the embodiments of the present application include the mobile electronic devices and the non-mobile electronic devices described above.

Fig. 7 is a schematic diagram of a hardware structure of an electronic device implementing an embodiment of the present application.

The electronic device 1000 includes, but is not limited to: a radio frequency unit 1001, a network module 1002, an audio output unit 1003, an input unit 1004, a sensor 1005, a display unit 1006, a user input unit 1007, an interface unit 1008, a memory 1009, and a processor 1010.

Those skilled in the art will appreciate that the electronic device 1000 may further comprise a power source (e.g., a battery) for supplying power to various components, and the power source may be logically connected to the processor 1010 through a power management system, so as to implement functions of managing charging, discharging, and power consumption through the power management system. The electronic device structure shown in fig. 6 does not constitute a limitation of the electronic device, and the electronic device may include more or less components than those shown, or combine some components, or arrange different components, and thus, the description is omitted here.

The input unit 1004 is configured to capture pictures in a real scene, such as a first image and a second image in this embodiment.

The processor 1010 is configured to acquire a first image and acquire a target focal length corresponding to a second image, where the first image is an image of the camera device at the first focal length, and the second image is an image of the camera device at the target focal length; obtaining a reference image according to the corresponding relation between the first focal length and the target focal length; correcting the second image according to image data in a reference image; and outputting the corrected second image. The specific embodiments of the method are described, and are not described herein again.

It should be understood that in the embodiment of the present application, the input Unit 1004 may include a Graphics Processing Unit (GPU) 10041 and a microphone 10042, and the Graphics Processing Unit 10041 processes image data of still pictures or videos obtained by an image capturing device (such as a camera) in a video capturing mode or an image capturing mode. The display unit 1006 may include a display panel 10061, and the display panel 10061 may be configured in the form of a liquid crystal display, an organic light emitting diode, or the like. The user input unit 1007 includes a touch panel 10071 and other input devices 10072. The touch panel 10071 is also referred to as a touch screen. The touch panel 10071 may include two parts, a touch detection device and a touch controller. Other input devices 10072 may include, but are not limited to, a physical keyboard, function keys (e.g., volume control keys, switch keys, etc.), a trackball, a mouse, and a joystick, which are not described in detail herein. The memory 1009 may be used to store software programs as well as various data, including but not limited to application programs and operating systems. Processor 1010 may integrate an application processor that handles primarily operating systems, user interfaces, applications, etc. and a modem processor that handles primarily wireless communications. It will be appreciated that the modem processor described above may not be integrated into processor 1010.

The embodiment of the present application further provides a readable storage medium, where a program or an instruction is stored on the readable storage medium, and when the program or the instruction is executed by a processor, the program or the instruction implements each process of the lens shading correction method embodiment, and can achieve the same technical effect, and in order to avoid repetition, details are not repeated here.

The processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and so on.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the present application may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal (such as a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present application.

While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A lens shading correction method, the method comprising:

acquiring a first image and a target focal length corresponding to a second image, wherein the first image is an image of a camera device under the first focal length, the second image is an image of the camera device under the target focal length, and the focal length of the camera device is adjustable;

obtaining a reference image according to the corresponding relation between the first focal length and the target focal length;

correcting the second image according to the image data in the reference image;

and outputting the corrected second image.

2. The method according to claim 1, wherein obtaining a reference image according to the correspondence between the first focal length and the target focal length comprises:

acquiring the corresponding relation between the first focal length and the target focal length;

obtaining a magnification relation between the field angle of the first image and the field angle of the second image according to the corresponding relation;

and cutting the first image according to the multiplying power relation to obtain a reference image with the same field angle as the second image, wherein the first focal length is smaller than the target focal length.

3. The method according to claim 1, wherein the correcting the second image according to the image data in the reference image comprises:

acquiring brightness distribution data in the reference image and brightness distribution data in a second image;

obtaining a correction compensation table according to the brightness distribution data in the reference image and the brightness distribution data in the second image;

and correcting the second image according to the correction compensation table.

4. The method according to claim 1, wherein the correcting the second image according to the image data in the reference image further comprises:

extracting picture characteristic point information in the reference image;

acquiring picture characteristic point information in the second image;

and correcting the picture characteristic point information in the second image according to the picture characteristic point information in the reference image.

5. The method according to claim 4, wherein the correcting the picture feature point information in the second image according to the picture feature point information in the reference image comprises:

acquiring feature point information of the reference image and the second image at the same position, wherein the reference image and the second image are arranged in an aligned manner;

and comparing the characteristic point information of the reference image with the characteristic point information of the second image, and correcting the characteristic point information of the second image according to the characteristic point information of the reference image.

6. An apparatus for lens shading correction, comprising:

the data acquisition module is used for acquiring a first image and acquiring a target focal length corresponding to a second image, wherein the first image is an image of the camera device under the first focal length, and the second image is an image of the camera device under the target focal length;

the image processing module is used for obtaining a reference image according to the corresponding relation between the first focal length and the target focal length, wherein the focal length of the camera device is adjustable;

a correction module for correcting the second image according to the image data in the reference image;

and the output module is used for outputting the corrected second image.

7. The apparatus for lens shading correction according to claim 6,

the image processing module is further configured to: acquiring the corresponding relation between the first focal length and the target focal length; obtaining a magnification relation between the field angle of the first image and the field angle of the second image according to the corresponding relation; and cutting the first image according to the multiplying power relation to obtain a reference image with the same field angle as the second image, wherein the first focal length is smaller than the target focal length.

8. The apparatus for lens shading correction according to claim 6,

the correction module is further configured to: acquiring brightness distribution data in the reference image; obtaining a correction compensation table according to the brightness distribution data; and correcting the second image according to the correction compensation table.

9. An electronic device comprising a processor, a memory, and a program or instructions stored on the memory and executable on the processor, the program or instructions when executed by the processor implementing the steps of a lens shading correction method as claimed in claims 1-5.

10. A readable storage medium, on which a program or instructions are stored, which when executed by a processor, implement the steps of a lens shading correction method as claimed in claims 1-5.

Images