CN106127211A - Whiteboard detection method and device - Google Patents

Abstract

The disclosure is directed to a kind of blank detection method and device, belong to image identification technical field.Wherein, blank detection method, including: obtain image to be detected；Determine the length of image cathetus section, and determine the edge of whiteboard area in image according to the length of straightway.Position in the picture, whiteboard area can be detected exactly, provide data support for follow-up whiteboard area is further processed.

Description

Whiteboard detection method and device

technical field

The present disclosure relates to the technical field of image recognition, in particular to a whiteboard detection method and device.

Background technique

With the rapid development of technology, more and more people are accustomed to using smartphones to process documents. First, the user can take a photo of the whiteboard. Wherein, the whiteboard may be a rectangular area containing information such as text, such as a blackboard, a whiteboard, a certificate, a bank card, or a presentation PPT. Then detect the picture obtained by taking pictures, detect the edge of the whiteboard area in the picture, and finally recognize the text information in the whiteboard area, so as to realize document processing. How to accurately identify the edge of the whiteboard area has become a key research topic.

Contents of the invention

In order to overcome the problems existing in the related art, the present disclosure provides a whiteboard detection method and device.

According to a first aspect of an embodiment of the present disclosure, a whiteboard detection method is provided, including:

Obtain the image to be detected;

Determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment.

The whiteboard detection method as described above also includes:

Acquiring a preset area in the image;

Detecting the line segments contained in the preset area based on the least significant difference algorithm LSD;

Clustering the line segments in the preset area, and determining a straight line segment in the preset area according to the line segments in the preset area.

According to the whiteboard detection method described above, determining the straight line segment in the preset area according to the line segment in the preset area includes:

Obtain the straight line equation of the line segment in the preset area;

Calculate the slope difference between every two described line segments and the intercept difference between every two described line segments according to the straight line equation;

When the slope difference between at least two line segments is less than a first threshold and the intercept difference between the at least two line segments is less than a second threshold, the at least two line segments are clustered to generate first line segment;

The first line segment is determined as the straight line segment.

In the whiteboard detection method described above, the determining the edge of the whiteboard area in the image according to the length of the straight line segment includes:

When the length of the straight line segment is greater than a preset length, it is determined that the straight line segment is an edge corresponding to the whiteboard area.

In the whiteboard detection method described above, the preset area includes at least one of an upper area, a lower area, a left area, a right area, and the image itself.

According to the whiteboard detection method described above, determining that the straight line segment is the edge corresponding to the whiteboard area includes:

When there are multiple straight line segments greater than the preset length, the straight line segment with the longest length is determined as the corresponding edge of the whiteboard area.

In the whiteboard detection method described above, when there are multiple straight line segments greater than a preset length, determining the edge of the whiteboard area includes:

When the preset area is the upper area, intercept area blocks of the same size on the lower side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than a preset threshold, determine that the straight line segment at the upper end is the upper edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the lower end is the upper edge of the whiteboard area.

In the whiteboard detection method described above, when there are multiple straight line segments greater than a preset length, generating the corresponding edge of the whiteboard area includes:

When the preset area is the lower area, intercept area blocks of the same size on the upper side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than the preset threshold, determine that the straight line segment at the lower end is the lower edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the upper end is the lower edge of the whiteboard area.

In the whiteboard detection method described above, when there are multiple straight line segments greater than a preset length, generating the corresponding edge of the whiteboard area includes:

When the preset area is the left area, intercept area blocks of the same size on the right side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than the preset threshold, determine that the straight line segment at the left end is the left edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the right end is the left edge of the whiteboard area.

In the whiteboard detection method described above, when there are multiple straight line segments greater than a preset length, generating the corresponding edge of the whiteboard area includes:

When the preset area is the right area, intercept area blocks of the same size on the left side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than a preset threshold, determine that the straight line segment at the right end is the right edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the left end is the right edge of the whiteboard area.

According to a second aspect of an embodiment of the present disclosure, a whiteboard detection device is provided, including:

The first acquisition module is used to acquire the image to be detected;

The first determination module is configured to determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment.

The whiteboard detection device as described above, the device also includes:

a second acquiring module, configured to acquire a preset area in the image;

A detection module, configured to detect the line segments contained in the preset area based on the least significant difference algorithm LSD;

The second determination module is configured to cluster the line segments in the preset area, and determine the straight line segments in the preset area according to the line segments in the preset area.

The whiteboard detection device as described above, the second determination module is used for:

Obtain the straight line equation of the line segment in the preset area;

Calculate the slope difference between every two described line segments and the intercept difference between every two described line segments according to the straight line equation;

When the slope difference between at least two line segments is less than a first threshold and the intercept difference between the at least two line segments is less than a second threshold, the at least two line segments are clustered to generate first line segment;

The first line segment is determined as the straight line segment.

According to the above-mentioned whiteboard detection device, the first determination module is used for:

When the length of the straight line segment is greater than the preset length, it is determined that the straight line segment is an edge corresponding to the whiteboard area.

In the whiteboard detection device described above, the preset area includes at least one of an upper area, a lower area, a left area, a right area, and the image itself.

In the above-mentioned whiteboard detection device, when there are multiple straight line segments greater than a preset length, the first determination module is configured to:

When the preset area is the upper area, intercept area blocks of the same size on the lower side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than a preset threshold, determine that the straight line segment at the upper end is the upper edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, the straight line segment at the lower end is determined as the upper edge of the whiteboard area.

In the above-mentioned whiteboard detection device, when there are multiple straight line segments greater than a preset length, the first determination module is configured to:

When the preset area is the lower area, intercept area blocks of the same size on the upper side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than the preset threshold, determine that the straight line segment at the lower end is the lower edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the upper end is the lower edge of the whiteboard area.

In the above-mentioned whiteboard detection device, when there are multiple straight line segments greater than a preset length, the first determination module is configured to:

When the preset area is the left area, intercept area blocks of the same size on the right side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than the preset threshold, determine that the straight line segment at the left end is the left edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the right end is the left edge of the whiteboard area.

In the above-mentioned whiteboard detection device, when there are multiple straight line segments greater than a preset length, the first determination module is configured to:

When the preset area is the right area, intercept area blocks of the same size on the left side of the plurality of straight line segments;

Calculate the difference between the gray value of each two area blocks;

When the gray value difference is less than a preset threshold, determine that the straight line segment at the right end is the right edge of the whiteboard area;

When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the left end is the right edge of the whiteboard area.

According to a third aspect of an embodiment of the present disclosure, a whiteboard detection device is provided, including:

processor;

memory for storing processor-executable instructions;

Wherein, the processor is configured as:

Obtain the image to be detected;

Determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment.

The technical solution provided by the embodiments of the present disclosure may include the following beneficial effects: by acquiring the image to be detected, determining the length of the straight line segment in the image, and determining the edge of the whiteboard area in the image according to the length of the straight line segment, it is possible to accurately detect The position of the whiteboard area in the image provides data support for subsequent further processing of the whiteboard area.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description serve to explain the principles of the disclosure.

Fig. 1 is a flow chart of a whiteboard detection method shown according to an exemplary embodiment;

Fig. 2 is a flowchart of determining a straight line segment in an image;

Figure 3 is a schematic diagram of the effect of dividing an image into four regions;

Fig. 4 is a schematic diagram of the effect of determining the right edge of the whiteboard area;

Fig. 5 is a block diagram of a whiteboard detection device according to an exemplary embodiment;

Fig. 6 is a block diagram of a whiteboard detection device 600 according to an exemplary embodiment.

detailed description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatuses and methods consistent with aspects of the present disclosure as recited in the appended claims.

Fig. 1 is a flowchart of a whiteboard detection method according to an exemplary embodiment. As shown in Fig. 1, the whiteboard detection method includes the following steps;

In step S101, an image to be detected is acquired.

For example, the image may be a photo including a presentation obtained by taking a photo of the mobile terminal, or may be a picture including an ID card scanned by a scanner. In this embodiment, the area occupied by the presentation and the ID card is the whiteboard area. How to accurately detect the whiteboard area is the purpose of the present invention.

In step S102, the length of the straight line segment in the image is determined, and the edge of the whiteboard area in the image is determined according to the length of the straight line segment.

Before determining the length of the straight line segment in the image, it is necessary to determine the straight line segment in the image. In one embodiment, as shown in FIG. 2, determining a straight line segment in an image may include the following steps:

S103. Acquire a preset area in the image.

Exemplarily, the preset area may include at least one of an upper area, a lower area, a left area, a right area, and the image itself. The part located on the upper side of the image is the upper area, for example, the area formed by moving down from the upper edge of the image for a certain distance and accounting for about 20%-50% of the total area is the upper area; similarly, moving up from the lower edge of the image for a certain distance The area formed by the distance and accounting for about 20%-50% of the total area is the lower area. The area formed by moving a certain distance from the left edge of the image to the right and occupying about 20%-50% of the total area is the left area. The right area is the area formed by moving a certain distance from the right edge of the image to the left and accounting for about 20%-50% of the total area.

As shown in FIG. 3 , in an embodiment, the image can be divided into four areas: an upper left area, an upper right area, a lower left area, and a lower right area. In this embodiment, the upper left area and the upper right area are combined into the upper area, the lower left area and the lower right area are combined into the lower area, the upper right area and the lower right area are combined into the right area, and the upper left area and the lower left area are combined into the left area.

S104. Detect the line segments contained in the preset area based on the least significant difference algorithm LSD.

S105. Cluster the line segments in the preset area, and determine the straight line segments in the preset area according to the line segments in the preset area.

In one embodiment, the straight line equation of the line segment in the preset area can be obtained, and then the slope difference between every two line segments and the intercept difference between every two line segments can be calculated according to the straight line equation. When the slope difference between at least two line segments is less than the first threshold and the intercept difference between at least two line segments is less than the second threshold, at least two line segments can be clustered to generate the first line segment, and then The first line segment is determined as a straight line segment.

For example, due to factors such as lighting, the edges of the whiteboard area may not be continuous, and may be detected as multiple line segments. Therefore, it is necessary to judge whether multiple line segments belong to the same straight line. Specifically, the slopes of these line segments are obtained, and the slope difference between every two line segments is calculated. Then calculate the distance between adjacent line segments, which is the intercept difference. If the slope difference between the two line segments is less than a preset angle such as 1 degree, and the distance between the two line segments is less than a preset distance of 5mm, it can be determined that the two line segments belong to the same straight line. The two line segments are then clustered to form the first line segment. The first line segment is a straight line segment.

After the straight line segment in the image is determined, the length of the straight line segment in the image can be determined, and then the edge of the whiteboard area in the image can be determined according to the length of the straight line segment. Specifically, when there are multiple straight line segments longer than the preset length, it may be determined that the straight line segment with the longest length is the edge corresponding to the whiteboard area. For example: in the upper area of the image, assuming that there are three straight line segments with lengths of 11 cm, 12 cm and 15 cm respectively, all of which are greater than the preset length of 10 cm, it can be determined that the straight line segment with a length of 15 cm corresponds to the whiteboard area. upper edge. Similarly, use the same method to determine the lower edge of the whiteboard area corresponding to the lower area, the right edge of the whiteboard area corresponding to the right area, and the left edge of the whiteboard area corresponding to the left area.

Of course, in order to further improve the detection accuracy, the edge of the whiteboard area can also be determined by the following method. Specifically, when multiple straight line segments are detected in the upper area of the image, area blocks of the same size may be intercepted on the lower side of the multiple line segments, and then the gray value difference between each two area blocks may be calculated. If the gray value difference is smaller than the preset threshold, it means that the two area blocks belong to the whiteboard area, and the straight line segment at the upper end can be used as the upper edge of the whiteboard area. If the gray value difference is greater than the preset threshold, it means that the two area blocks do not belong to the same area, so the straight line segment at the lower end can be used as the upper edge of the whiteboard area.

Similarly, when multiple straight line segments are detected in the lower area of the image, regional blocks of the same size can be intercepted on the upper side of the multiple straight line segments, and the difference between the gray values of each two regional blocks can be calculated. If the gray value difference is smaller than the preset threshold, the straight line segment at the lower end is used as the lower edge of the whiteboard area. If the gray value difference is greater than the preset threshold, the straight line segment at the upper end is used as the lower edge of the whiteboard area.

Similarly, when multiple straight line segments are detected in the left area of the image, area blocks of the same size can be intercepted on the right side of the multiple straight line segments, and the gray value difference between each two area blocks can be calculated. If the gray value difference is smaller than the preset threshold, the straight line segment at the left end is used as the left edge of the whiteboard area. If the gray value difference is greater than the preset threshold, the straight line segment at the right end is used as the left edge of the whiteboard area.

Similarly, when multiple straight line segments are detected in the right area of the image, area blocks of the same size can be intercepted on the left side of the multiple straight line segments, and the difference between the gray values of each two area blocks can be calculated. If the gray value difference is smaller than the preset threshold, the straight line segment at the right end is used as the right edge of the whiteboard area. If the gray value difference is greater than the preset threshold, the straight line segment at the left end is used as the right edge of the whiteboard area.

The following takes determining the right edge of the whiteboard area as an example to describe in detail. As shown in FIG. 4 , there are two line segments longer than a preset length in the right area of the image: line segment 301 and line segment 302 . Wherein, the line segment 301 is located on the left side of the line segment 302 . Then, the first area block 303 can be selected at the left middle position of the line segment 301 ; the second area block 304 of the same size can be selected at the left side of the line segment 302 and the right middle position of the line segment 301 . The gray values of the two area blocks are calculated respectively, and then the difference between the gray values of the two area blocks is obtained. If the gray value difference is less than the preset threshold, it means that the two blocks are located in the whiteboard area, then it can be determined that the line segment 302 is the right edge of the whiteboard area, and the line segment 301 may be the edge of a certain window in the whiteboard area. If the gray value difference is greater than the preset threshold, it means that the first area block 303 is located in the whiteboard area, and the second area block 304 is located outside the whiteboard area, as shown in Figure 4, then it can be determined that the line segment 301 is the right edge of the whiteboard area .

After the edge of the whiteboard area is determined, the whiteboard area can be extracted according to the edge for subsequent further processing of the whiteboard area.

To sum up, the whiteboard detection method provided in this embodiment can accurately detect the whiteboard region in The position in the image provides data support for subsequent further processing of the whiteboard area.

Fig. 5 is a block diagram of a whiteboard detection device according to an exemplary embodiment. The whiteboard detection device can be implemented by software, hardware or a combination of both. As shown in FIG. 5 , the whiteboard detection device includes a first acquisition module 11 and a first determination module 12 .

The first acquiring module 11 is configured to acquire an image to be detected.

The first determination module 12 is configured to determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment.

Specifically, the first determining module 12 is configured to determine that the straight line segment is an edge corresponding to the whiteboard area when the length of the straight line segment is greater than a preset length.

More specifically, the first determining module 12 is configured to determine that the longest straight line segment is the edge corresponding to the whiteboard area when there are multiple straight line segments longer than the preset length.

More specifically, the first determination module 12 is configured to intercept area blocks of the same size on the lower side of multiple straight line segments when the preset area is an upper area; calculate the difference between the gray values of every two area blocks; When the grayscale value difference is less than the preset threshold, determine the upper straight line segment as the upper edge of the whiteboard area; when the grayscale value difference is greater than the preset threshold, determine the lower straight line segment as the upper edge of the whiteboard area.

The first determination module 12 is configured to intercept the area blocks of the same size on the upper side of multiple straight line segments when the preset area is the lower area; calculate the difference between the gray values of every two area blocks; When the difference is smaller than the preset threshold, it is determined that the straight line segment at the lower end is the lower edge of the whiteboard area; when the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the upper end is the lower edge of the whiteboard area.

The first determination module 12 is configured to intercept the area blocks of the same size on the right side of multiple straight line segments when the preset area is the left area; calculate the difference between the gray values of every two area blocks; When the difference is smaller than the preset threshold, it is determined that the straight line segment at the left end is the left edge of the whiteboard area; when the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the right end is the left edge of the whiteboard area.

The first determination module 12 is configured to intercept the area blocks of the same size on the left side of multiple straight line segments when the preset area is the right area; calculate the difference between the gray values of every two area blocks; When the difference is smaller than the preset threshold, it is determined that the straight line segment at the right end is the right edge of the whiteboard area; when the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the left end is the right edge of the whiteboard area.

In addition, the whiteboard detection device may further include a second acquisition module 13 , a detection module 14 and a second determination module 15 .

The second acquisition module 13 is configured to acquire a preset area in the image.

The detection module 14 is configured to detect the line segments included in the preset area based on the least significant difference algorithm LSD.

The second determining module 15 is configured to cluster the line segments in the preset area, and determine the straight line segments in the preset area according to the line segments in the preset area.

Specifically, the second determination module 15 is configured to obtain the straight line equation of the line segment in the preset area; calculate the slope difference between every two line segments and the intercept difference between every two line segments according to the straight line equation; when there is at least When the slope difference between the two line segments is less than the first threshold and the intercept difference between the at least two line segments is less than the second threshold, at least two line segments are clustered to generate the first line segment; the first line segment is determined is a straight line segment.

With regard to the whiteboard detection device in the above embodiment, the specific manner of performing operations of each module has been described in detail in the embodiment of the whiteboard detection method, and will not be described in detail here.

To sum up, the whiteboard detection device provided in this embodiment can accurately detect the whiteboard region in The position in the image provides data support for subsequent further processing of the whiteboard area.

Fig. 6 is a block diagram of a whiteboard detection device 600 according to an exemplary embodiment.

As shown in FIG. 6 , apparatus 600 may include one or more of the following components: processing component 602 , memory 604 , power component 606 , sensor component 608 , and communication component 660 .

The processing component 602 generally controls the overall operations of the whiteboard detection apparatus 600, such as operations associated with display, data communication, and recording operations. The processing component 602 may include one or more processors 620 to execute instructions to complete all or part of the steps of the above method. Additionally, processing component 602 may include one or more modules that facilitate interaction between processing component 602 and other components.

The memory 604 is configured to store various types of data to support the operation of the whiteboard inspection device 600 . Examples of such data include instructions for any application or method operating on whiteboard detection device 600 . The memory 604 can be implemented by any type of volatile or non-volatile storage device or their combination, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable Programmable Read Only Memory (EPROM), Programmable Read Only Memory (PROM), Read Only Memory (ROM), Magnetic Memory, Flash Memory, Magnetic or Optical Disk.

The power component 606 provides power to various components of the whiteboard inspection device 600 . Power components 606 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power for whiteboard inspection device 600 .

Sensor assembly 608 includes one or more sensors for providing various aspects of status assessment for whiteboard detection device 600 . The sensor component 608 may include an acceleration sensor and a pressure sensor configured to detect acceleration and pressure values.

The communication component 660 is configured to facilitate wired or wireless communication between the whiteboard detection apparatus 600 and other devices. The whiteboard detection device 600 can access a wireless network based on communication standards, such as WiFi, 2G or 3G, or a combination thereof. In one exemplary embodiment, the communication component 660 receives a broadcast signal or broadcast related information from an external broadcast management system via a broadcast channel.

In an exemplary embodiment, the whiteboard detection device 600 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field A Programmable Gate Array (FPGA), controller, microcontroller, microprocessor or other electronic component implementation for performing the methods described above.

In an exemplary embodiment, there is also provided a non-transitory computer-readable storage medium including instructions, such as the memory 604 including instructions, which can be executed by the processor 620 of the whiteboard detection device 600 to complete the above method. For example, the non-transitory computer readable storage medium may be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, optical data storage device, and the like.

A non-transitory computer-readable storage medium, when the instructions in the storage medium are executed by the processor of the whiteboard detection device, the whiteboard detection device can execute a whiteboard detection method, the whiteboard detection method includes:

Obtain the image to be detected;

Determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image based on the length of the straight line segment.

Regarding the whiteboard detection device in the above embodiments, the specific manner in which the processor executes operations has been described in detail in the embodiment of the whiteboard detection method, and will not be described in detail here.

Other embodiments of the present disclosure will be readily apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, and these modifications, uses or adaptations follow the general principles of the present disclosure and include common knowledge or conventional technical means in the technical field not disclosed in the present disclosure . The specification and examples are to be considered exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It should be understood that the present disclosure is not limited to the precise constructions which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (21)

1. A whiteboard detection method, is characterized in that, comprises the following steps: Obtain the image to be detected; Determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment. 2. The method of claim 1, further comprising: Acquiring a preset area in the image; Detecting the line segments contained in the preset area based on the least significant difference algorithm LSD; Clustering the line segments in the preset area, and determining a straight line segment in the preset area according to the line segments in the preset area. 3. The method according to claim 2, wherein said determining the straight line segment in the preset area according to the line segment in the preset area comprises: Obtain the straight line equation of the line segment in the preset area; Calculate the slope difference between every two described line segments and the intercept difference between every two described line segments according to the straight line equation; When the slope difference between at least two line segments is less than a first threshold and the intercept difference between the at least two line segments is less than a second threshold, the at least two line segments are clustered to generate first line segment; The first line segment is determined as the straight line segment. 4. The method according to any one of claims 1-3, wherein the determining the edge of the whiteboard area in the image according to the length of the straight line segment comprises: When the length of the straight line segment is greater than a preset length, it is determined that the straight line segment is an edge corresponding to the whiteboard area. 5. The method according to any one of claims 1-3, wherein the preset area includes at least one of an upper area, a lower area, a left area, a right area and the image itself. 6. The method according to claim 4, wherein determining that the straight line segment is an edge corresponding to the whiteboard area comprises: When there are multiple straight line segments greater than the preset length, the straight line segment with the longest length is determined as the corresponding edge of the whiteboard area. 7. The method according to claim 4, wherein when there are multiple straight line segments greater than a preset length, determining the edge of the whiteboard area comprises: When the preset area is the upper area, intercept area blocks of the same size on the lower side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than a preset threshold, determine that the straight line segment at the upper end is the upper edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the lower end is the upper edge of the whiteboard area. 8. The method according to claim 4, wherein when there are multiple straight line segments greater than a preset length, generating the corresponding edge of the whiteboard area comprises: When the preset area is the lower area, intercept area blocks of the same size on the upper side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than the preset threshold, determine that the straight line segment at the lower end is the lower edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the upper end is the lower edge of the whiteboard area. 9. The method according to claim 4, wherein when there are multiple straight line segments greater than a preset length, generating the corresponding edge of the whiteboard area comprises: When the preset area is the left area, intercept area blocks of the same size on the right side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than the preset threshold, determine that the straight line segment at the left end is the left edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the right end is the left edge of the whiteboard area. 10. The method according to claim 4, wherein when there are multiple straight line segments greater than a preset length, generating the corresponding edge of the whiteboard area comprises: When the preset area is the right area, intercept area blocks of the same size on the left side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than a preset threshold, determine that the straight line segment at the right end is the right edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the left end is the right edge of the whiteboard area. 11. A whiteboard detection device, characterized in that it comprises: The first acquisition module is used to acquire the image to be detected; The first determination module is configured to determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment. 12. The device of claim 11, further comprising: a second acquiring module, configured to acquire a preset area in the image; A detection module, configured to detect the line segments contained in the preset area based on the least significant difference algorithm LSD; The second determination module is configured to cluster the line segments in the preset area, and determine the straight line segments in the preset area according to the line segments in the preset area. 13. The device according to claim 12, wherein the second determination module is configured to: Obtain the straight line equation of the line segment in the preset area; Calculate the slope difference between every two described line segments and the intercept difference between every two described line segments according to the straight line equation; When the slope difference between at least two line segments is less than a first threshold and the intercept difference between the at least two line segments is less than a second threshold, the at least two line segments are clustered to generate first line segment; The first line segment is determined as the straight line segment. 14. The device according to any one of claims 11-13, wherein the first determining module is configured to: When the length of the straight line segment is greater than a preset length, it is determined that the straight line segment is an edge corresponding to the whiteboard area. 15. The device according to any one of claims 11-13, wherein the preset area includes at least one of an upper area, a lower area, a left area, a right area, and the image itself. 16. The device according to claim 14, wherein the first determining module is configured to: When there are multiple straight line segments greater than the preset length, the straight line segment with the longest length is determined as the corresponding edge of the whiteboard area. 17. The device according to claim 14, wherein when there are multiple straight line segments greater than a preset length, the first determination module is configured to: When the preset area is the upper area, intercept area blocks of the same size on the lower side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than a preset threshold, determine that the straight line segment at the upper end is the upper edge of the whiteboard area; When the gray value difference is greater than the preset threshold, the straight line segment at the lower end is determined as the upper edge of the whiteboard area. 18. The device according to claim 14, wherein when there are multiple straight line segments greater than a preset length, the first determination module is configured to: When the preset area is the lower area, intercept area blocks of the same size on the upper side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than the preset threshold, determine that the straight line segment at the lower end is the lower edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the upper end is the lower edge of the whiteboard area. 19. The device according to claim 14, wherein when there are multiple straight line segments greater than a preset length, the first determination module is configured to: When the preset area is the left area, intercept area blocks of the same size on the right side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than the preset threshold, determine that the straight line segment at the left end is the left edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the right end is the left edge of the whiteboard area. 20. The device according to claim 14, wherein when there are multiple straight line segments greater than a preset length, the first determination module is configured to: When the preset area is the right area, intercept area blocks of the same size on the left side of the plurality of straight line segments; Calculate the difference between the gray value of each two area blocks; When the gray value difference is less than a preset threshold, determine that the straight line segment at the right end is the right edge of the whiteboard area; When the gray value difference is greater than the preset threshold, it is determined that the straight line segment at the left end is the right edge of the whiteboard area. 21. A whiteboard detection device, characterized in that it comprises: processor; memory for storing processor-executable instructions; Wherein, the processor is configured as: Obtain the image to be detected; Determine the length of the straight line segment in the image, and determine the edge of the whiteboard area in the image according to the length of the straight line segment.