Patent Publication Number: US-2023162474-A1

Title: Method of processing image, method of training model, and electronic device

Description:
This application claims priority to Chinese Patent Application No. 202111635804.5, filed on Dec. 29, 2021, the entire content of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a field of an automatic driving technology, in particular to a field of a high-definition map technology, and more specifically, to a method of processing an image, a method of training a multi-task processing model, an electronic device, and a storage medium. 
     BACKGROUND 
     A high-definition positioning and navigation technology plays an indispensable role in a safe driving of an autonomous vehicle, and plays an important role in a lateral and longitudinal precise positioning, an obstacle detection and a collision avoidance, an intelligent speed control, a path planning and a behavioral decision of the autonomous vehicle. A high-definition map, also known as a HD map, is applied in the autonomous vehicle. The high-definition map, which has a precise location information of a vehicle and a rich road element data information, may help the vehicle predict a complex road information, such as slope, curvature, heading, etc., in order to better avoid a potential risk. 
     SUMMARY 
     The present disclosure provides a method of processing an image, a method of training a multi-task processing model, an electronic device, and a storage medium. 
     According to an aspect of the present disclosure, a method of processing an image is provided, including: processing a to-be-processed image to obtain a feature point of the to-be-processed image, a feature point descriptor map of the to-be-processed image, and a dense descriptor map of the to-be-processed image; determining a pair of matched feature points between the to-be-processed image and a reference image based on the feature point and the feature point descriptor map; and determining a pair of matched pixels between the to-be-processed image and the reference image based on the dense descriptor map. 
     According to another aspect of the present disclosure, a method of training a multi-task processing model is provided, including: training an initial multi-task processing model by using a training sample, so as to obtain the multi-task processing model, wherein the training sample includes a first sample image, a second sample image, a label for a pair of matched feature points between the first sample image and the second sample image, and a label for a pair of matched pixels between the first sample image and the second sample image, and wherein the label for the pair of matched feature points is configured to represent a matching relationship between a feature point of the first sample image and a feature point of the second sample image, and the label for the pair of matched pixels is configured to represent a matching relationship between a pixel point of the first sample image and a pixel point of the second sample image. 
     According to another aspect of the present disclosure, an electronic device is provided, including: at least one processor; and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions, when executed by the at least one processor, are configured to cause the at least one processor to implement the methods as described in the present disclosure. 
     According to another aspect of the present disclosure, a non-transitory computer-readable storage medium having computer instructions therein is provided, wherein the computer instructions are configured to cause a computer system to implement the methods as described in the present disclosure. 
     According to another aspect of the present disclosure, an autonomous vehicle is provided, including the electronic device as described in the present disclosure. 
     It should be understood that content described in this section is not intended to identify key or important features in embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will be easily understood through the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are used for better understanding of the solution and do not constitute a limitation to the present disclosure, wherein: 
         FIG.  1    schematically shows an exemplary system architecture in which a method and an apparatus of processing an image may be applied according to an embodiment of the present disclosure; 
         FIG.  2    schematically shows a flowchart of a method of processing an image according to an embodiment of the present disclosure; 
         FIG.  3    schematically shows a network architecture diagram of a multi-task processing model according to an embodiment of the present disclosure; 
         FIG.  4 A  schematically shows a network architecture diagram of a multi-task processing model according to another embodiment of the present disclosure; 
         FIG.  4 B  schematically shows a network architecture diagram of a first self-attention module according to another embodiment of the present disclosure; 
         FIG.  4 C  schematically shows a network architecture diagram of a fusion module according to another embodiment of the present disclosure; 
         FIG.  4 D  schematically shows a network architecture diagram of a second self-attention module according to another embodiment of the present disclosure; 
         FIG.  5    schematically shows a network architecture diagram of a graph network according to an embodiment of the present disclosure; 
         FIG.  6    schematically shows a flowchart of determining a pair of matched pixels according to an embodiment of the present disclosure; 
         FIG.  7    schematically shows a flowchart of a method of training a multi-task processing model according to another embodiment of the present disclosure; 
         FIG.  8    schematically shows a block diagram of an apparatus of processing an image according to an embodiment of the present disclosure; 
         FIG.  9    schematically shows a block diagram of an apparatus of training a multi-task processing model according to another embodiment of the present disclosure; and 
         FIG.  10    schematically shows a block diagram of an electronic device suitable for implementing a method of processing an image according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, which include various details of embodiments of the present disclosure to facilitate understanding and should be considered as merely exemplary. Therefore, those of ordinary skilled in the art should realize that various changes and modifications may be made to embodiments described herein without departing from the scope and spirit of the present disclosure. Likewise, for clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description. 
     The present disclosure provides a method and an apparatus of processing an image, a method and an apparatus of training a multi-task processing model, an electronic device, a storage medium, and a program product. 
     According to embodiments of the present disclosure, a method of processing an image is provided, including: processing a to-be-processed image to obtain a feature point of the to-be-processed image, a feature point descriptor map of the to-be-processed image, and a dense descriptor map of the to-be-processed image; determining a pair of matched feature points between the to-be-processed image and a reference image based on the feature point and the feature point descriptor map; and determining a pair of matched pixels between the to-be-processed image and the reference image based on the dense descriptor map. 
     In the technical solution of the present disclosure, an acquisition, a storage, a use, a processing, a transmission, a provision and a disclosure of position information involved comply with provisions of relevant laws and regulations, and do not violate public order and good custom. 
       FIG.  1    schematically shows an exemplary system architecture in which a method and an apparatus of processing an image may be applied according to an embodiment of the present disclosure. 
     It should be noted that  FIG.  1    shows only an example of a system architecture in which embodiments of the present disclosure may be applied, so as to help those skilled in the art understand the technical content of the present disclosure, but it does not mean that embodiments of the present disclosure may not be applied to other devices, systems, environments or scenarios. 
     As shown in  FIG.  1   , a system architecture  100  according to the embodiment may include an autonomous vehicle  101 , a network  102 , and a server  103 . The network  102  is used to provide a medium of a communication link between the autonomous vehicle  101  and the server  103 . The network  102  may include various connection types, such as a wireless communication link. 
     The autonomous vehicle  101  may be used by a user to interact with the server  103  through the network  102 , so as to receive or send video stream data, positioning information, etc. 
     The server  103  may be a server providing various services, such as a background management server (for example only) that provides a support for a user to utilize the to-be-processed image processed by the autonomous vehicle  101 , a navigation of the selected target location. The background management server may analyze and process received data such as a user request, etc., and feedback a processing result (such as a web page, information, or data, etc. obtained or generated according to the user request) to the autonomous vehicle  101 . 
     The autonomous vehicle  101  may be installed with an information acquisition device for an image acquisition, such as a fish-eye camera, and/or a gun camera. The autonomous vehicle  101  may acquire the to-be-processed image by using the information acquisition device. 
     It should be noted that the method of processing the image provided in embodiments of the present disclosure may generally be performed by the autonomous vehicle  101 . Accordingly, the apparatus of processing the image provided by the embodiment of the present disclosure may also be provided in the autonomous vehicle  101 . 
     Alternatively, the method of processing the image provided in embodiments of the present disclosure may be generally performed by the server  103 . Accordingly, the apparatus of processing the image provided in embodiments of the present disclosure may be generally provided in the server  103 . The method of processing the image provided in embodiments of the present disclosure may also be performed by a server or a server cluster that is different from the server  103  and capable of communicating with the autonomous vehicle  101  and/or the server  103 . Accordingly, the apparatus of processing the image provided in embodiments of the present disclosure may also be provided in the server or server cluster that is different from the server  103  and capable of communicating with the autonomous vehicle  101  and/or the server  103 . 
     It should be understood that the number of autonomous vehicles, networks and image acquisition devices shown in  FIG.  1    is only schematic. According to implementation needs, any number of terminal devices, networks and servers may be provided. 
     It should be noted that the sequence numbers of the respective operations in the following methods are only used as representations of the operations for the ease of description, and should not be regarded as representing an execution order of the operations. Unless explicitly indicated, the methods do not need to be performed exactly in the orders shown. 
       FIG.  2    schematically shows a flowchart of a method of processing an image according to an embodiment of the present disclosure. 
     As shown in  FIG.  2   , the method includes operations S 210  to S 230 . 
     In operation S 210 , a to-be-processed image is processed to obtain a feature point of the to-be-processed image, a feature point descriptor map of the to-be-processed image, and a dense descriptor map of the to-be-processed image. 
     In operation S 220 , a pair of matched feature points between the to-be-processed image and a reference image is determined based on the feature point and the feature point descriptor map. 
     In operation S 230 , a pair of matched pixels between the to-be-processed image and the reference image is determined based on the dense descriptor map. 
     According to embodiments of the present disclosure, the feature point may refer to a set of feature points, which may be a recognizable and representative point or a set of points in an image, such as a corner point, an edge, a block, etc. The feature point may remain unchanged even if a camera angle of view changes a little. 
     According to embodiments of the present disclosure, the feature point may include a position information. However, the present disclosure is not limited to this. The feature point may also include an information such as an orientation, a size, etc. The feature point may be used to perform matching and correlation between respective target objects of at least two images. 
     According to embodiments of the present disclosure, the feature point descriptor map may refer to a vector, and a feature point descriptor describes information associated with the feature point, for example, information of a pixel around the feature point. If the feature point descriptors of two images, such as the to-be-processed image and the reference image, are close to each other in distance in a vector space or matched with each other, it may be determined that two feature points corresponding to the two feature point descriptors one by one are matched with each other, and may form the pair of matched feature points. 
     According to embodiments of the present disclosure, the to-be-processed image may refer to a video frame image at a current time instant, and the reference image may refer to a video frame image at a historical time instant, for example, the reference image is a previous video frame image of the video frame image at the current time instant. However, the present disclosure is not limited to this. The reference image may also be a historical video frame image spaced from the video frame image at the current time instant by a predetermined number of video frame images. 
     According to embodiments of the present disclosure, the pair of matched feature points between the to-be-processed image and the reference image may be determined based on the feature point of the to-be-processed image and the feature point descriptor map of the to-be-processed image and a reference feature point of the reference image and a reference feature point descriptor map of the reference image. 
     According to embodiments of the present disclosure, an operation such as a visual odometer or visual inertial odometer may be performed based on the pair of matched feature points. However, the present disclosure is not limited to this. An operation such as a sparse reconstruction or cloud mapping may also be performed based on the pair of matched feature points. 
     According to embodiments of the present disclosure, the dense descriptor map may refer to a descriptor map corresponding to a set of dense and discrete pixel points, relative to the feature point descriptor map, such as a descriptor map of a set of sparse and key feature points. 
     According to embodiments of the present disclosure, the pair of matched pixels between the to-be-processed image and the reference image may be determined based on the dense descriptor map of the to-be-processed image and a reference dense descriptor map of the reference image. 
     According to embodiments of the present disclosure, an operation such as a three-dimensional reconstruction of a set of scene objects, etc. may be performed based on the pair of matched pixels. 
     The to-be-processed image may be directly processed by using the method of processing the image provided in embodiments of the present disclosure, so as to obtain the feature point, the feature point descriptor map and the dense descriptor map of the to-be-processed image, so that the dense descriptor map used to perform the three-dimensional reconstruction of the set of scene objects may be obtained, and the matched feature points used to perform operations such as a visual odometer, a visual inertial odometer, a sparse reconstruction or cloud mapping, etc. may be obtained. Therefore, a plurality of tasks may be simultaneously processed to improve a timeliness of processing the plurality of tasks. 
     According to embodiments of the present disclosure, for operation S 210 , a multi-task processing model may be designed to process the to-be-processed image. For example, the to-be-processed image may be input into the multi-task processing model to obtain the feature point, the feature point descriptor map and the dense descriptor map of the to-be-processed image. 
     According to embodiments of the present disclosure, the reference image may also be input into the multi-task processing model to obtain the reference feature point, the reference feature point descriptor map and the reference dense descriptor map, so as to determine the pair of matched feature points between the to-be-processed image and the reference image based on the feature point, the feature point descriptor map, the reference feature point and the reference feature point descriptor map, and determine the pair of matched pixels between the to-be-processed image and the reference image based on the dense descriptor map and the reference dense descriptor map. 
       FIG.  3    schematically shows a network architecture diagram of a multi-task processing model according to an embodiment of the present disclosure. 
     As shown in  FIG.  3   , a multi-task processing model  300  includes a feature point extraction branch  310 , a feature point descriptor map calculation branch  320 , a dense descriptor map calculation branch  330 , and a feature point classification branch  340 . 
     A to-be-processed image  350  may be input into the feature point extraction branch  310  to obtain a feature point  361 . The to-be-processed image  350  is input into the feature point descriptor map calculation branch  320  to obtain a feature point descriptor map  362 . The to-be-processed image  350  is input into the dense descriptor map calculation branch  330  to obtain a dense descriptor map  363 . The to-be-processed image  350  is input into the feature point classification branch  340  to obtain a feature point category result  364 . 
     According to embodiments of the present disclosure, the multi-task processing model may be designed to include a feature point extraction branch, a feature point descriptor map calculation branch, a dense descriptor map calculation branch and a feature point classification branch. However, the present disclosure is not limited to this. The multi-task processing model may also be designed to include the feature point extraction branch, the feature point descriptor map calculation branch, and the dense descriptor map calculation branch. 
     With the method of processing the image provided by embodiments of the present disclosure, the to-be-processed image may be processed by using the multi-task processing model, so that a plurality of processing results for executing the plurality of tasks may be obtained, and a real-time performance of a multi-task operation may be improved. In addition, based on the feature point classification branch in the multi-task processing model, a foreground feature point and a background feature point may be effectively distinguished by using the feature point category result, and the background feature point applied to a visual positioning and a sparse reconstruction task may be effectively screened out, so that an effectiveness of the pair of matched feature points between the to-be-processed image and the reference image may be increased. 
     According to embodiments of the present disclosure, the feature point extraction branch may include a plurality of feature point extraction sub branches, and each feature point extraction sub branch may include at least one feature extraction module and a convolution layer that are cascaded. 
     According to embodiments of the present disclosure, the feature point descriptor map calculation branch may include at least one feature extraction module and a convolution layer that are cascaded. 
     According to embodiments of the present disclosure, a high-resolution dense descriptor map calculation sub branch or a low-resolution dense descriptor map calculation sub branch may include at least one feature extraction module and a fully convolution module that are cascaded. 
     According to embodiments of the present disclosure, the feature extraction module in the feature point extraction sub branch, the feature point descriptor map calculation branch, the high-resolution dense descriptor map calculation sub branch or the low-resolution dense descriptor map calculation sub branch may include a convolution layer, a pooling layer, or a convolution layer and a pooling layer that are cascaded. 
     According to embodiments of the present disclosure, the fully convolution module in the high-resolution dense descriptor map calculation sub branch or the low-resolution dense descriptor map calculation sub branch includes a plurality of stacked fully convolution layers. 
     According to embodiments of the present disclosure, the feature point classification branch includes a plurality of feature point classification sub branches, a fusion module, and a classifier, and each of the plurality of feature point classification sub branches includes a feature point classification extraction module, an encoder, and a fusion module. 
     According to embodiments of the present disclosure, the inputting the to-be-processed image into the feature point classification branch to obtain a feature point category result may include the following operations. 
     For example, the to-be-processed image is input into the plurality of feature point classification extraction modules, respectively, so as to obtain a plurality of feature point category feature maps, where the plurality of feature point category feature maps correspond to the plurality of feature point classification extraction modules one by one; for each feature point category feature map of the plurality of feature point category feature maps, the feature point category feature map is input into the encoder so as to obtain a plurality of encoded sub feature point category feature maps, where the plurality of encoded sub feature point category feature maps correspond to a plurality of encoders one by one; the plurality of encoded sub feature point category feature maps are processed by using the fusion module, so as to obtain a fused feature point category map; and the fused feature point category map is processed by using the classifier, so as to obtain the feature point category result. 
       FIG.  4 A  schematically shows a network architecture diagram of a multi-task processing model according to another embodiment of the present disclosure. 
     As shown in  FIG.  4 A , the feature point extraction branch may include a first feature point extraction sub branch, a second feature point extraction sub branch, and a third feature point extraction sub branch. The first feature point extraction sub branch may include a first feature extraction module and a first feature point extraction head  421  (Score Map Head 1) that are cascaded. The first feature extraction module includes a first convolution layer  411 , and the first feature point extraction head  421  includes a convolution layer. The second feature point extraction sub branch may include the first feature extraction module, a second feature extraction module and a second feature point extraction head  422  (Score Map Head 2) that are cascaded. The second feature extraction module may include a first pooling layer  412  and a second convolution layer  413  that are cascaded, and the second feature point extraction head  422  may include a convolution layer. The third feature point extraction sub branch may include the first feature extraction module, the second feature extraction module, a third feature extraction module and a third feature point extraction head  423  (Descriptors Head) that are cascaded. The third feature extraction module may include a second pooling layer  414  and a third convolution layer  415  that are cascaded. The third feature point extraction head  423  may include cascaded five fully convolution layers with  128  channels. 
     Inputs of the first feature point extraction sub branch, the second feature point extraction sub branch and the third feature point extraction sub branch are the to-be-processed image. Outputs of the first feature point extraction sub branch, the second feature point extraction sub branch and the third feature point extraction sub branch are feature point scoring maps, respectively, such as a first feature point scoring map  431 , a second feature point scoring map  432  and a third feature point scoring map  433 . The first feature point scoring map  431 , the second feature point scoring map  432  and the third feature point scoring map  433  have different feature scales from each other. 
     As shown in  FIG.  4 A , the feature point descriptor map calculation branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module, and the third feature point extraction head  423  (Descriptors Head). An input of the feature point descriptor map calculation branch may be the to-be-processed image, and an output of the feature point descriptor map calculation branch may be a 128-dimensional dense feature point descriptor map  441 . 
     As shown in  FIG.  4 A , the high-resolution dense descriptor map calculation sub branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module, and a local dense network head  451  (Spare to Dense Fine Descriptors Head). The local dense network head  451  includes a plurality of convolution layers that are cascaded. The low-resolution dense descriptor map calculation sub branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module, a fourth feature extraction module, a fifth feature extraction module, and a semantic dense network head  452  (Sparse to Dense Coarse Descriptors Head). The fourth feature extraction module may include a third pooling layer  416  and a fourth convolution layer  417  that are cascaded. The fifth feature extraction module may include a fourth pooling layer  418  and a fifth convolution layer  419  that are cascaded. The semantic dense network head  452  may include the plurality of convolutional layers that are cascaded. 
     Inputs of the high-resolution dense descriptor map calculation sub branch and the low-resolution dense descriptor map calculation sub branch may be the to-be-processed image, and outputs of the high-resolution dense descriptor map calculation sub branch and the low-resolution dense descriptor map calculation sub branch may be the high-resolution dense descriptor map and the low-resolution dense descriptor map, respectively. A resolution of the high-resolution dense descriptor map is greater than a resolution of the low-resolution dense descriptor map. 
     As shown in  FIG.  4 A , the feature point classification branch may include a first feature point classification sub branch, a second feature point classification sub branch, a third feature point classification sub branch and a fourth feature point classification sub branch, a fusion module, and a classifier. The first feature point classification sub branch, the second feature point classification sub branch, the third feature point classification sub branch and the fourth feature point classification sub branch are connected in parallel. The first feature point classification sub branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module and an encoder  461  (Encoder 1) that are cascaded. The second feature point classification sub branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module, the fourth feature extraction module and an encoder  462  (Encoder 2) that are cascaded. The third feature point classification sub branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module, the fourth feature extraction module, the fifth feature extraction module and an encoder  463  (Encoder 3) that are cascaded. The fourth feature point classification sub branch may include the first feature extraction module, the second feature extraction module, the third feature extraction module, the fourth feature extraction module, the fifth feature extraction module, a sixth feature extraction module and an encoder  464  (Encoder 4) that are cascaded. The sixth feature extraction module may include a fifth pooling layer  4100 . 
     As shown in  FIG.  4 A , inputs of the first feature point classification sub branch, the second feature point classification sub branch, the third feature point classification sub branch and the fourth feature point classification sub branch may be the to-be-processed image. Outputs of the first feature point classification sub branch, the second feature point classification sub branch, the third feature point classification sub branch and the fourth feature point classification sub branch may be a first encoded sub feature point category feature map, a second encoded sub feature point category feature map, a third encoded sub feature point category feature map, and a fourth encoded sub feature point category feature map, respectively. 
     The third encoded sub feature point category feature map may be processed by designing a first self-attention module  465  (Feature Attention), so as to obtain a first high-level feature map that is weighted and adjusted. The fourth encoded sub feature point category feature map may be processed by using a second self-attention module  466  (FAAP, Feature Attention and Projection), so as to obtain a second high-level feature map that is weighted and adjusted. The first high-level feature map and the second high-level feature map may be fused by using an Add fusion module  4671 , so as to obtain a first fused feature point category feature map. The first fused feature point category feature map and the second encoded sub feature point category feature map may be fused by using a first fusion module  4672  (Feature Fusion), so as to obtain a second fused feature point category feature map. The second fused feature point category feature map and the first encoded sub feature point category feature map may be fused by using a second fusion module  4673 , so as to obtain a fused feature point category feature map. The fused feature point category feature map may be processed by using a classifier  468 , so as to obtain a feature point category result  469 . It may be determined whether the feature point belongs to a foreground feature point or a background feature point based on the feature point category result. 
     According to embodiments of the present disclosure, a backbone network module may be obtained by cascading the first feature extraction module, the second feature extraction module, the third feature extraction module, the fourth feature extraction module, the fifth feature extraction module, and the sixth feature extraction module. The backbone network module may adopt a VGG network structure. The backbone network module may be used to extract feature maps of six different scales, which is convenient for the feature point extraction branch, the feature point descriptor map calculation branch, the dense descriptor map calculation branch and the feature point classification branch to reuse. The feature point extraction branch, the feature point descriptor map calculation branch, the dense descriptor map calculation branch and the feature point classification branch reuse the backbone network module, which may improve an operation efficiency of the multi-task processing model. 
       FIG.  4 B  schematically shows a network architecture diagram of a first self-attention module according to another embodiment of the present disclosure. 
     As shown in  FIG.  4 B , the first self-attention module  465  may include a classification pooling layer  4651 , a first classification convolution layer  4652 , a second classification convolution layer  4653 , an activation layer  4654 , and a first classification fusion layer  4655  that are cascaded. The third encoded sub feature point category feature map may be input into the first sub attention module  465  and processed by a classification pooling layer  4651 , a first classification convolution layer  4652 , a second classification convolution layer  4653 , and an activation layer  4654 , respectively, so as to obtain an activation feature map. Then, the activation feature map and the third encoded sub feature point category feature map may be fused by using the first classification fusion layer  4655 , so as to obtain the first high-level feature map. 
       FIG.  4 C  schematically shows a network architecture diagram of a fusion module according to another embodiment of the present disclosure. 
     As shown in  FIG.  4 C , the first fusion module  4672  or the second fusion module  4673  may include a concatenating layer (Concatenate)  4674 , a third classification convolution layer  4675  and a second classification fusion layer  4676  that are cascaded. The first fusion module  4672  or the second fusion module  4673  also includes a third self-attention module  4677 . The concatenating layer  4674  may fuse two inputs, and the third classification convolution layer  4675  may process the fused result, so as to obtain a classification feature extraction result. The classification feature extraction result is input into the third self-attention module  4677  to obtain an output result. The output result and the classification feature extraction result may be fused by using the second classification fusion layer  4676 , so as to obtain the fused feature point category feature map, for example. 
       FIG.  4 D  schematically shows a network architecture diagram of a second self-attention module according to another embodiment of the present disclosure. 
     As shown in  FIG.  4 D , the second self-attention module  466  may include a fourth self-attention module  4661  and a fourth classification convolution layer  4662  that are cascaded. An input of the second self-attention module  466  may be the fourth encoded sub feature point category feature map, and an output of the second self-attention module  466  may be the second high-level feature map. 
     According to embodiments of the present disclosure, the inputting the to-be-processed image into the feature point extraction branch to obtain the feature point may include the following operations. 
     For example, the to-be-processed image is input into the plurality of feature point extraction sub branches, respectively, so as to obtain a plurality of feature point scoring maps, where the plurality of feature point scoring maps correspond to the plurality of feature point extraction sub branches one by one. For example, the number of feature point extraction sub branches may be three. The plurality of feature point scoring maps of different scales, such as three feature point scoring maps s 0 ,  s 1 and  S 2 of different scales, may be extracted by using the plurality of feature point extraction sub branches. 
     A weighted summation may be performed on the plurality of feature point scoring maps, as shown in Equation (1): 
     
       
         
           
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      so as to obtain a target feature point scoring map S. 
     An interpolation processing may be performed on the target feature point scoring map to obtain the feature point. For example, extracted feature points may be prevented from clustering together by using a non-maximum suppression method, and then a sparse feature point may be extracted from the target feature point scoring map. 
     For example, the target feature point scoring map may be processed by difference methods shown in Equations (2) and (3), so as to obtain a position information of a feature point with a sub-pixel precision. The Equation (2) is expressed as: 
     
       
         
           
             
               
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                                 ∂ 
                                 x 
                                 ∂ 
                                 y 
                               
                             
                           
                         
                         
                           
                             
                               
                                 
                                   ∂ 
                                   2 
                                 
                                 s 
                               
                               
                                 ∂ 
                                 
                                   y 
                                   2 
                                 
                               
                             
                           
                         
                       
                     
                   
                 
                 
                   
                     
                       
                         
                           
                             
                               x 
                             
                           
                           
                             
                               y 
                             
                           
                         
                       
                     
                     − 
                     
                       
                         
                           
                             
                               
                                 
                                   x 
                                   0 
                                 
                               
                             
                           
                           
                             
                               
                                 
                                   y 
                                   0 
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
             
           
         
       
     
     The position information of the feature point with the sub-pixel precision may be obtained by derivation of the above-mentioned Equation (2). 
     The Equation (3) is expressed as: 
     
       
         
           
             
               
                 
                   
                     
                       x 
                     
                   
                   
                     
                       y 
                     
                   
                 
               
             
             = 
             − 
             
               
                 
                   
                     
                       
                         
                           
                             
                               
                                 
                                   ∂ 
                                   2 
                                 
                                 s 
                               
                               
                                 ∂ 
                                 
                                   x 
                                   2 
                                 
                               
                             
                           
                         
                         
                           
                             
                               
                                 
                                   ∂ 
                                   2 
                                 
                                 s 
                               
                               
                                 ∂ 
                                 x 
                                 ∂ 
                                 y 
                               
                             
                           
                         
                       
                       
                         
                           
                             
                               
                                 
                                   ∂ 
                                   2 
                                 
                                 s 
                               
                               
                                 ∂ 
                                 x 
                                 ∂ 
                                 y 
                               
                             
                           
                         
                         
                           
                             
                               
                                 
                                   ∂ 
                                   2 
                                 
                                 s 
                               
                               
                                 ∂ 
                                 
                                   y 
                                   2 
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 − 
                 1 
               
             
             
               
                 
                   
                     
                       
                         
                           
                             ∂ 
                             s 
                           
                           x 
                         
                       
                     
                   
                   
                     
                       
                         
                           
                             ∂ 
                             s 
                           
                           y 
                         
                       
                     
                   
                 
               
             
             + 
             
               
                 
                   
                     
                       
                         
                           x 
                           0 
                         
                       
                     
                   
                   
                     
                       
                         
                           y 
                           0 
                         
                       
                     
                   
                 
               
             
           
         
       
     
     where, (x, y) is a position information of the feature point with the sub-pixel precision, and (xo, yo) is a position information of a feature point with an integer precision. 
     According to embodiments of the present disclosure, based on a scoring result of each feature point in the feature point scoring map, the scores may be sorted in descending order, and at least one key pixel point ranked at top may be obtained as the feature point according to the target number. However, the present disclosure is not limited to this. A threshold value may also be predetermined, and at least one key pixel point whose scoring result is greater than the threshold value may be used as the feature point. 
     According to embodiments of the present disclosure, for operation S 220 , the pair of matched feature points between the to-be-processed image and the reference image may be determined based on the feature point and the feature point descriptor map. However, the present disclosure is not limited to this. The pair of matched feature points between the to-be-processed image and the reference image may also be determined based on the target feature point and the feature point descriptor map. 
     According to other embodiments of the present disclosure, the feature point may be screened based on the feature point category result, so as to determine a target feature point. The pair of matched feature points between the to-be-processed image and the reference image may be determined based on the target feature point and the feature point descriptor map. 
     According to embodiments of the present disclosure, the target feature point may be a feature point of a target object in a stationary state, such as a background feature point of a background target object. For example, a dynamic foreground feature point of a foreground target object may be filtered out by using the feature point category result, and the target feature point may be retained, so as to solve a problem of poor accuracy and robustness of tasks such as a visual positioning and a sparse reconstruction caused by extracting the foreground feature point of the foreground target object. 
     According to other embodiments of the present disclosure, the target feature point scoring map may also be screened by using the feature point category result, so as to determine a second target feature point scoring map. Difference processing is performed on the second target feature point scoring map to obtain the target feature point. Thus, the pair of matched feature points between the to-be-processed image and the reference image may be determined based on the target feature point and the feature point descriptor map. 
     According to embodiments of the present disclosure, the feature point descriptor matched with the target feature point may be extracted from the feature point descriptor map based on the target feature point. Based on the target feature point and the feature point descriptor matched with the target feature point, the pair of matched feature points between the to-be-processed image and the reference image may be determined by using a feature point matching method. 
     According to embodiments of the present disclosure, according to a position information of the target feature point, a feature vector of the target feature point may be extracted from the feature point descriptor map by using a bilinear interpolation method, so as to obtain the feature point descriptor. However, the present disclosure is not limited to this. The extracted feature vector may also be normalized, and the normalized result may be used as the feature point descriptor. 
     According to embodiments of the present disclosure, the pair of matched feature points between the to-be-processed image and the reference image may be determined by using the feature point matching method. The feature point matching method include at least one selected from: a nearest neighbor matching method, a cross matching method, and/or a graph-network-based matching method. 
     According to embodiments of the present disclosure, when an angle of view between the to-be-processed image and the reference image does not change greatly, the pair of matched feature points may have a good matching effect and a fast matching speed by using the nearest neighbor matching method (KNN, K-Nearest Neighbor), and thus the pair of matched feature points may be better applied to a task of performing a visual odometer or visual inertial odometer. 
     According to embodiments of the present disclosure, in a complex scene, for example, when there are many dynamic foreground objects, the graph-network-based matching method may be used to achieve a high matching accuracy of the pair of matched feature points, and thus the pair of matched feature points may be better applied to sparse reconstruction and cloud mapping tasks. 
       FIG.  5    schematically shows a network architecture diagram of a graph network according to an embodiment of the present disclosure. 
     As shown in  FIG.  5   , the graph network may include a structure of a codec (Transform). A feature point descriptor  511  of the to-be-processed image, a target feature point  512  of the to-be-processed image, a reference feature point descriptor  521  of the reference image, and a reference feature point  522  of the reference image may be input into the graph network. A position encoder in the graph network may encode the position information of the target feature point and a scoring result of the target feature point into a 128-dimensional encoded feature vector. Then, the feature point descriptor and the encoded feature vector may be fused together by using a matching fusion module  513  (Add fusion module), so as to obtain a fused feature vector  514 . Similarly, a reference position encoder connected in parallel with the position encoder in the graph network may encode a position information of the reference feature point and a scoring result of the reference feature point into a 128-dimensional reference encoded feature vector. Then, the reference feature point descriptor and the reference encoded feature vector may be fused by using the reference fusion module  523  (Add fusion module), so as to obtain a fused reference feature vector  524 . The fused reference feature vector  524  and the fused feature vector  514  may be input into a self-attention module  530  and a cross attention module  540 , and a target feature vector that fuses the to-be-processed image and the reference image may be output. A matching score (Match Score)  560  between the feature point of the to-be-processed image and the feature point of the reference image may be obtained by solving iteratively with a Sinkhorn Algorithm (optimal transmission)  550 . For each feature point of the to-be-processed image, a feature point with the maximum matching score may be selected from the reference image as a matching point, so as to form the pair of matched feature points. 
     According to embodiments of the present disclosure, for operation S 230 , the determining a pair of matched pixels between the to-be-processed image and the reference image is determined based on the dense descriptor map may include the following operations. 
     For example, a candidate pair of matched pixels between the to-be-processed image and the reference image is determined based on a low-resolution dense descriptor map. The pair of matched pixels between the to-be-processed image and the reference image is determined from the candidate pixel pair based on a high-resolution dense descriptor map. 
     According to embodiments of the present disclosure, the dense descriptor map calculation branch may include a high-resolution dense descriptor map calculation sub branch and a low-resolution dense descriptor map calculation sub branch. The dense descriptor map may include a high-resolution dense descriptor map and a low-resolution dense descriptor map. The low-resolution dense descriptor map is obtained by processing the to-be-processed image using the low-resolution dense descriptor map calculation sub branch. The high-resolution dense descriptor map is obtained by processing the to-be-processed image using the high-resolution dense descriptor map calculation sub branch. 
     According to embodiments of the present disclosure, the low-resolution dense descriptor map, which may be referred to as a coarse feature map, may be a low-resolution descriptor map, for example, the resolution may be 1/16 of a resolution of the to-be-processed image. The high-resolution dense descriptor map, which may be referred to as a fine feature map, may be a high-resolution descriptor map, for example, the resolution may be ¼ of the resolution of the to-be-processed image. A coarse-grained correlation may be performed on the pixel point by using the low-resolution dense descriptor map of the to-be-processed image and a reference low-resolution dense descriptor map of the reference image, so as to obtain the candidate pair of matched pixels between the to-be-processed image and the reference image. Then, a fine-grained correlation may be performed in the candidate pair of matched pixels by using the high-resolution dense descriptor map of the to-be-processed image and the reference high-resolution dense descriptor map of the reference image, so as obtain the pair of matched pixels between the to-be-processed image and the reference image and obtain an accurate position information of the pair of matched pixels. 
     Based on the method of determining the pair of matched pixels provided in embodiments of the present disclosure, a search range may be expanded by using the low-resolution dense descriptor map, so as to ensure a full matching, and an accurate positioning may be performed by using the high-resolution dense descriptor map, so as to ensure a matching accuracy. Then, the pair of matched pixels obtained by combining the low-resolution dense descriptor map with the high-resolution dense descriptor map is applied in a subsequent three-dimensional reconstruction task of the set of scene objects, which may achieve a good effect. 
       FIG.  6    schematically shows a flowchart of determining a pair of matched pixels according to an embodiment of the present disclosure. 
     As shown in  FIG.  6   , the candidate pair of matched pixels between the to-be-processed image and the reference image may be determined by using a correlation module. A low-resolution dense descriptor map  611  of the to-be-processed image and a reference low-resolution dense descriptor map  621  of the reference image may be input into a correlation module  630 . The correlation module  630  is used to perform calculations such as Equations (4) and (5), so as to determine a candidate pair of matched pixels  640 . 
     For example, a low-resolution dense descriptor map F o c of the to-be-processed image and a reference low-resolution dense descriptor map F 1 c of the reference image. A position p 0  (x, y) of a pixel point to be correlated in the to-be-processed image may be determined, a corresponding semantic dense descriptor ƒ  0 c= F 0 c(p 0 ) may be determined in the to-be-processed image, a correlation probability P 1   c (x) between the pixel point and each pixel point of the reference image may be determined by using the semantic dense descriptor. An expected value p 1   c  of the position of the pixel point is obtained based on the correlation probability, so that a candidate correlation position information on the low-resolution dense descriptor map may be obtained, that is, the candidate pair of pixels may be obtained. Then, a high-resolution dense descriptor map  612  of the to-be-processed image and a reference high-resolution dense descriptor map  622  of the reference image are input into a correlation module  650 , and a region of interesting (ROI) is delimited in the high-resolution dense descriptor map  612  of the to-be-processed image by the candidate correlation position information in the candidate pair of pixels  640 . A local dense descriptor F 0 ƒ of the pixel point to be associated in the high-resolution dense descriptor map  612  of the to-be-processed image is determined by using the above-mentioned matching method, and a correlation probability between the pixel point and each pixel point in a candidate region of the reference high-resolution dense descriptor map  622  of the reference image is calculated. The expected value is calculated based on the correlation probability, so that a final correlation position information may be obtained to determine a pair of matched pixels  660 . Equations (4) and (5) may be expressed as: 
     
       
         
           
             
               P 
               c 
               1 
             
             
               x 
             
             = 
             
               
                 exp 
                 
                   
                     
                       F 
                       c 
                       0 
                     
                     
                       
                         
                           
                             
                               p 
                               0 
                             
                           
                         
                       
                       T 
                     
                     
                       F 
                       c 
                       1 
                     
                     
                       x 
                     
                   
                 
               
               
                 
                   
                     ∑ 
                     y 
                   
                   
                     exp 
                     
                       
                         
                           F 
                           c 
                           0 
                         
                         
                           
                             
                               
                                 
                                   p 
                                   0 
                                 
                               
                             
                           
                           T 
                         
                         
                           F 
                           c 
                           1 
                         
                         
                           y 
                         
                       
                     
                   
                 
               
             
           
         
       
     
     
       
         
           
             
               p 
               c 
               1 
             
             = 
             
               
                 ∑ 
                 x 
               
               
                 x 
                 
                   P 
                   c 
                   1 
                 
                 
                   x 
                 
               
             
           
         
       
     
       FIG.  7    schematically shows a flowchart of a method of training a multi-task processing model according to another embodiment of the present disclosure. 
     As shown in  FIG.  7   , the method includes operations S 710  to S 720 . 
     In operation S 710 , a training sample is acquired. 
     In operation S 720 , an initial multi-task processing model is trained by using the training sample, so as to obtain the multi-task processing model, where the training sample includes a first sample image, a second sample image, a label for a pair of matched feature points between the first sample image and the second sample image, and a label for a pair of matched pixels between the first sample image and the second sample image, and where the label for the pair of matched feature points is used to represent a matching relationship between a feature point of the first sample image and a feature point of the second sample image, and the label for the pair of matched pixels is used to represent a matching relationship between a pixel point of the first sample image and a pixel point of the second sample image. 
     According to embodiments of the present disclosure, the method of training the multi-task processing model may include operation S 710  and operation S 720 . However, the present disclosure is not limited to this. The method may also include only operation S 720 . 
     According to embodiments of the present disclosure, the initial multi-task processing model includes an initial feature point extraction branch and an initial feature point descriptor map calculation branch. 
     According to embodiments of the present disclosure, for operation S 720 , the training an initial multi-task processing model by using a training sample so as to obtain the multi-task processing model may include the following operations. 
     For example, the initial feature point extraction branch and the initial feature point descriptor map calculation branch are trained by using the first sample image, the second sample image, and the label for the pair of matched feature points between the first sample image and the second sample image, so as to obtain a feature point extraction branch and a feature point descriptor map calculation branch of the multi-task processing model. 
     According to embodiments of the present disclosure, the initial feature point extraction branch and the initial feature point descriptor map calculation branch may be trained together by using a training sample in a set of training samples of a 3D model reconstructed from images. A loss function loss (I1, I 2 ) shown in Equation (6) may be used for training. The Equation (6) may be expressed as: 
     
       
         
           
             
               
                 l 
                 o 
                 s 
                 s 
                 
                   
                     
                       I 
                       1 
                     
                     , 
                     
                       I 
                       2 
                     
                   
                 
                 = 
                 
                   1 
                   
                     
                       Ω 
                     
                   
                 
                 
                   
                     ∑ 
                     
                       c 
                       ∈ 
                       Ω 
                     
                   
                   
                     
                       
                         
                           s 
                           1 
                           c 
                         
                         
                           s 
                           2 
                           c 
                         
                       
                       
                         
                           
                             ∑ 
                             
                               q 
                               ∈ 
                               Ω 
                             
                           
                           
                             
                               s 
                               1 
                               q 
                             
                             
                               s 
                               2 
                               q 
                             
                           
                         
                       
                     
                   
                 
                 
                   
                     
                       
                         
                           
                             D 
                             
                               
                                 
                                   f 
                                   1 
                                   c 
                                 
                                 , 
                                 
                                   f 
                                   2 
                                   c 
                                 
                               
                             
                             − 
                             
                               m 
                               p 
                             
                           
                         
                       
                       + 
                     
                     + 
                     
                       
                         
                           m 
                           n 
                         
                         − 
                       
                     
                   
                 
               
             
             
               
                 
                   
                     
                       
                         
                           
                             min 
                             
                               
                                 
                                   
                                     min 
                                   
                                   
                                     k 
                                     ≠ 
                                     c 
                                   
                                 
                                 D 
                                 
                                   
                                     
                                       f 
                                       1 
                                       c 
                                     
                                     , 
                                     
                                       f 
                                       2 
                                       k 
                                     
                                   
                                 
                                 , 
                                 
                                   
                                     min 
                                   
                                   
                                     k 
                                     ≠ 
                                     c 
                                   
                                 
                                 D 
                                 
                                   
                                     
                                       f 
                                       1 
                                       k 
                                     
                                     , 
                                     
                                       f 
                                       2 
                                       c 
                                     
                                   
                                 
                               
                             
                           
                         
                       
                       + 
                     
                   
                 
               
             
           
         
       
     
      where, s c 1 represents a calculated feature point score of a c th  pixel point on a first sample image, ƒ  c 1 represents a feature point descriptor of the c th  pixel on the first sample image, D(.,.) represents a distance function of the feature point descriptor, m p  and m n  respectively represent constants,  Ω represents the number of sets of pixel points, q represents a q th  pixel point, [ ] represents being greater than or equal to 0, and I 1  and I 2  represent a first sample image and a second sample image respectively. 
     According to embodiments of the present disclosure, the initial multi-task processing model may include an initial dense descriptor map calculation branch. 
     According to embodiments of the present disclosure, for operation S 720 , the training an initial multi-task processing model by using a training sample so as to obtain the multi-task processing model may include the following operations. 
     For example, the initial dense descriptor map calculation branch is trained by using the first sample image, the second sample image, and the label for the pair of matched pixels between the first sample image and the second sample image, so as obtain a dense descriptor map calculation branch of the multi-task processing model. 
     According to embodiments of the present disclosure, the initial dense descriptor map calculation branch may be trained by using the training sample in the set of training samples of the 3D model reconstructed from the images. A loss function loss shown in Equation (7) may be used for training. The Equation (7) may be expressed as: 
     
       
         
           
             l 
             o 
             s 
             s 
             = 
             
               
                 
                   
                     
                       
                         
                           x 
                           0 
                         
                         − 
                         x 
                       
                     
                   
                   2 
                 
                 + 
                 
                   
                     
                       
                         
                           y 
                           0 
                         
                         − 
                         y 
                       
                     
                   
                   2 
                 
               
               2 
             
           
         
       
     
     where, (x, y) is a predicted position information of a pixel point in the second sample image that forms a pair of matched pixels with a target pixel point of the first sample image, and (x 0 , y0) is a real position information of the pixel point in the second sample image that forms the pair of matched pixels with the target pixel point. 
     According to embodiments of the present disclosure, the initial multi-task processing model may further include an initial feature point classification branch. 
     According to embodiments of the present disclosure, for operation S 720 , the training an initial multi-task processing model by using a training sample so as to obtain the multi-task processing model may include the following operations. 
     For example, the initial feature point classification branch is trained by using a target sample image, a feature point label of the target sample image, and a category label of the target sample image, so as to obtain a feature point classification branch of the multi-task processing model, where the target sample image includes the first sample image and/or the second sample image; the feature point label of the target sample image is used to represent a probability value that a pixel point of the target sample image is a feature point; and the category label of the target sample image is used to represent a category of the pixel point. 
     According to embodiments of the present disclosure, the initial feature point classification branch may be trained by using a training sample in a set of training samples labeled with category labels. A loss function loss (I) may use a cross entropy loss function shown in Equation (8), for example. The Equation (8) is expressed as: 
     
       
         
           
             l 
             o 
             s 
             s 
             
               I 
             
             = 
             − 
             
               
                 ∑ 
                 
                   k 
                   ∈ 
                   N 
                 
               
               
                 
                   
                     exp 
                     
                       
                         
                           s 
                           k 
                         
                       
                     
                   
                   
                     
                       
                         ∑ 
                         
                           q 
                           ∈ 
                           Ω 
                         
                       
                       
                         exp 
                         
                           
                             
                               s 
                               q 
                             
                           
                         
                       
                     
                   
                 
               
             
             
               
                 
                   y 
                   k 
                 
                 log 
                 
                   
                     
                       p 
                       k 
                     
                   
                 
                 + 
                 
                   
                     1 
                     − 
                     
                       y 
                       k 
                     
                   
                 
                 log 
                 
                   
                     1 
                     − 
                     
                       p 
                       k 
                     
                   
                 
               
             
           
         
       
     
      where, s k  represents a feature point score of a k th  pixel point,  Yk  ∈ {0,1} represents a category label of a pixel point, p k  represents a prediction probability that the pixel point belongs to a foreground point, and q represents a q th  pixel point. 
     According to embodiments of the present disclosure, the multi-task processing model may include a feature point extraction branch, a feature point descriptor map calculation branch, a dense descriptor map calculation branch, and a feature point classification branch. However, the present disclosure is not limited to this. The multi-task processing model may also include only the feature point extraction branch, the feature point descriptor map calculation branch, and the dense descriptor map calculation branch. 
     According to embodiments of the present disclosure, the feature point extraction branch may include a plurality of feature point extraction sub branches, and each feature point extraction sub branch may include at least one feature extraction module and a convolution layer that are cascaded. 
     According to embodiments of the present disclosure, the feature point descriptor map calculation branch may include at least one feature extraction module and a convolution layer that are cascaded. 
     According to embodiments of the present disclosure, the dense descriptor map calculation branch may include a high-resolution dense descriptor map calculation sub branch and a low-resolution dense descriptor map calculation sub branch. The high-resolution dense descriptor map calculation sub branch or the low-resolution dense descriptor map calculation sub branch may include at least one feature extraction module and a fully convolution module that are cascaded. 
     According to embodiments of the present disclosure, the feature extraction module in the feature point extraction sub branch, the feature point descriptor map calculation branch, the high-resolution dense descriptor map calculation sub branch or the low-resolution dense descriptor map calculation sub branch may include a convolution layer, a pooling layer, or a convolution layer and a pooling layer that are cascaded. 
     According to embodiments of the present disclosure, the fully convolution module in the high-resolution dense descriptor map calculation sub branch or the low-resolution dense descriptor map calculation sub branch includes a plurality of fully convolution layers that are cascaded. 
     According to the embodiment of the present disclosure, the feature point classification branch includes a plurality of feature point classification sub branches, a fusion module, and a classifier, and each of the plurality of feature point classification sub branches includes a feature point classification extraction module, an encoder, and the fusion module. 
     According to embodiments of the present disclosure, the feature point extraction branch, the feature point descriptor map calculation branch, the dense descriptor map calculation branch and the feature point classification branch may reuse a backbone network module. The backbone network module may use a VGG network structure. Before the backbone network module is used, a pre-training may be performed by using an ImageNet training set. When the initial multi-task processing model is trained, parameters of the backbone network module may be fixed, and parameters of the initial feature point extraction branch, the initial feature point descriptor map calculation branch, the initial dense descriptor map calculation branch and the initial feature point classification branch may be trained sequentially. 
       FIG.  8    schematically shows a block diagram of an apparatus of processing an image according to an embodiment of the present disclosure. 
     As shown in  FIG.  8   , an apparatus  800  of processing an image may include a processing module  810 , a first determination module  820 , and a second determination module  830 . 
     The processing module  810  is used to process a to-be-processed image to obtain a feature point of the to-be-processed image, a feature point descriptor map of the to-be-processed image, and a dense descriptor map of the to-be-processed image. 
     The first determination module  820  is used to determine a pair of matched feature points between the to-be-processed image and a reference image based on the feature point and the feature point descriptor map. 
     The second determination module  830  is used to determine a pair of matched pixels between the to-be-processed image and the reference image based on the dense descriptor map. 
     According to embodiments of the present disclosure, the processing module may include a processing sub module. 
     The processing sub module is used to input the to-be-processed image into a multi-task processing model to obtain the feature point of the to-be-processed image, the feature point descriptor map of the to-be-processed image, and the dense descriptor map of the to-be-processed image. 
     According to embodiments of the present disclosure, the multi-task processing model includes a feature point extraction branch, a feature point descriptor map calculation branch and a dense descriptor map calculation branch. 
     According to embodiments of the present disclosure, the processing sub module may include a first processing unit, a second processing unit, and a third processing unit. 
     The first processing unit is used to input the to-be-processed image into the feature point extraction branch to obtain the feature point. 
     The second processing unit is used to input the to-be-processed image into the feature point descriptor map calculation branch to obtain the feature point descriptor map. 
     The third processing unit is used to input the to-be-processed image into the dense descriptor map calculation branch to obtain the dense descriptor map. 
     According to embodiments of the present disclosure, the multi-task processing model further includes a feature point classification branch. 
     According to embodiments of the present disclosure, the apparatus of processing the image may further include a fourth processing unit. 
     The fourth processing unit is used to input the to-be-processed image into the feature point classification branch to obtain a feature point category result, so as to determine the pair of matched feature points between the to-be-processed image and the reference image based on the feature point, the feature point descriptor map and the feature point category result. 
     According to embodiments of the present disclosure, the first determination module may include a screening unit and a determination unit. 
     The screening unit is used to screen the feature point based on the feature point category result, so as to determine a target feature point. 
     The determination unit is used to determine the pair of matched feature points between the to-be-processed image and the reference image based on the target feature point and the feature point descriptor map. 
     According to embodiments of the present disclosure, the determination unit may include an extraction sub unit and a first matching sub unit. 
     The extraction sub unit is used to extract, from the feature point descriptor map, a feature point descriptor matched with the target feature point based on the target feature point. 
     The first matching sub unit is used to determine, by using a feature point matching method, the pair of matched feature points between the to-be-processed image and the reference image based on the target feature point and the feature point descriptor matched with the target feature point. 
     According to embodiments of the present disclosure, the feature point extraction branch includes a plurality of feature point extraction sub branches. 
     According to embodiments of the present disclosure, the first processing unit may include a first input sub unit, a weighting sub unit, and an interpolation sub unit. 
     The first input sub unit is used to input the to-be-processed image into the plurality of feature point extraction sub branches respectively, so as to obtain a plurality of feature point scoring maps, where the plurality of feature point scoring maps correspond to the plurality of feature point extraction sub branches one by one. 
     The weighted sub unit is used to perform a weighted summation on the plurality of feature point scoring maps to obtain a target feature point scoring map. 
     The interpolation sub unit is used to perform an interpolation processing on the target feature point scoring map to obtain the feature point. 
     According to embodiments of the present disclosure, the dense descriptor map includes a high-resolution dense descriptor map and a low-resolution dense descriptor map. 
     According to embodiments of the present disclosure, the dense descriptor map calculation branch includes a high-resolution dense descriptor map calculation sub branch and a low-resolution dense descriptor map calculation sub branch. 
     According to embodiments of the present disclosure, the third processing unit may include a second matching sub unit and a third matching sub unit. 
     The second matching sub unit is used to determine a candidate pair of matched pixels between the to-be-processed image and the reference image based on the low-resolution dense descriptor map, where the low-resolution dense descriptor map is obtained by processing the to-be-processed image using the low-resolution dense descriptor map calculation sub branch. 
     The third matching sub unit is used to determine the pair of matched pixels between the to-be-processed image and the reference image from the candidate pair of matched pixels based on the high-resolution dense descriptor map, where the high-resolution dense descriptor map is obtained by processing the to-be-processed image using the high-resolution dense descriptor map calculation sub branch. 
     According to embodiments of the present disclosure, the feature point classification branch includes a plurality of feature point classification sub branches, a fusion module, and a classifier, and each of the plurality of feature point classification sub branches includes a feature point classification extraction module, an encoder, and a fusion module. 
     According to embodiments of the present disclosure, the fourth processing unit may include a second input sub unit, an encoding sub unit, a fusion sub unit, and a classification sub unit. 
     The second input subunit is used to input the to-be-processed image into the plurality of feature point classification extraction modules respectively, so as to obtain a plurality of feature point category feature maps, where the plurality of feature point category feature maps correspond to the plurality of feature point classification extraction modules one by one. 
     The encoding sub unit is used to input, for each of the plurality of feature point category feature maps, the feature point category feature map into the encoder, so as to obtain a plurality of encoded sub feature point category feature maps, where the plurality of encoded sub feature point category feature maps correspond to a plurality of encoders one by one. 
     The fusion sub unit is used to process the plurality of encoded sub feature point category feature maps by using the fusion module, so as to obtain a fused feature point category map. 
     The classification sub unit is used to process the fused feature point category map by using the classifier, so as to obtain the feature point category result. 
     According to embodiments of the present disclosure, the apparatus of processing the image may further include an input module. 
     The input module is used to input the reference image into the multi-task processing model to obtain a reference feature point, a reference feature point descriptor map and a reference dense descriptor map, so as to determine the pair of matched feature points between the to-be-processed image and the reference image based on the feature point, the feature point descriptor map, the reference feature point and the reference feature point descriptor map, and determine the pair of matched pixels between the to-be-processed image and the reference image based on the dense descriptor map and the reference dense descriptor map. 
     According to embodiments of the present disclosure, the high-resolution dense descriptor map calculation sub branch or the low-resolution dense descriptor map calculation sub branch includes: at least one feature extraction module and a fully convolution module that are cascaded. 
     The feature extraction module includes: a convolution layer, a pooling layer, or a convolution layer and a pooling layer that are cascaded. The fully convolution module includes a plurality of full convolution layers that are cascaded. 
     According to embodiments of the present disclosure, at least one of the plurality of feature point extraction sub branches includes: at least one feature extraction module and a convolution layer that are cascaded. The feature extraction module includes: a convolution layer, a pooling layer, or a convolution layer and a pooling layer that are cascaded. 
     According to embodiments of the present disclosure, the feature point descriptor map calculation branch includes: at least one feature extraction module and a convolution layer that are cascaded. The feature extraction module includes: a convolution layer, a pooling layer, or a convolution layer and a pooling layer that are cascaded. 
     According to embodiments of the present disclosure, the feature point matching method includes at least one selected from: a nearest neighbor matching method, a cross matching method, or a graph-network-based matching method. 
       FIG.  9    schematically shows a block diagram of an apparatus of training a multi-task processing model according to an embodiment of the present disclosure. 
     As shown in  FIG.  9   , an apparatus  900  of training a multi-task processing model may include an acquisition module  910  and a training module  920 . 
     The acquisition module  910  is used to acquire a training sample. 
     The training module  920  is used to train an initial multi-task processing model by using the training sample, so as to obtain the multi-task processing model. 
     According to embodiments of the present disclosure, the training sample includes a first sample image, a second sample image, a label for a pair of matched feature points between the first sample image and the second sample image, and a label for a pair of matched pixels between the first sample image and the second sample image, and where the label for the pair of matched feature points is used to represent a matching relationship between a feature point of the first sample image and a feature point of the second sample image, and the label for the pair of matched pixels is used to represent a matching relationship between a pixel point of the first sample image and a pixel point of the second sample image. 
     According to embodiments of the present disclosure, the apparatus  900  of training the multi-task processing model may include an acquisition module  910  and a training module  920 . However, the present disclosure is not limited to this. The apparatus may further include only the training module  920 . 
     According to embodiments of the present disclosure, the initial multi-task processing model may include an initial feature point extraction branch and an initial feature point descriptor map calculation branch. 
     According to embodiments of the present disclosure, the training module may include a first training unit. 
     The first training unit is used to train the initial feature point extraction branch and the initial feature point descriptor map calculation branch by using the first sample image, the second sample image, and the label for the pair of matched feature points between the first sample image and the second sample image, so as to obtain a feature point extraction branch and a feature point descriptor map calculation branch in the multi-task processing model. 
     According to embodiments of the present disclosure, the initial multi-task processing model includes an initial dense descriptor map calculation branch. 
     According to embodiments of the present disclosure, the training module may include a second training unit. 
     The second training unit is used to train the initial dense descriptor map calculation branch by using the first sample image, the second sample image, and the label for the pair of matched pixels between the first sample image and the second sample image, so as obtain a dense descriptor map calculation branch in the multi-task processing model. 
     According to embodiments of the present disclosure, the initial multi-task processing model further includes an initial feature point classification branch. 
     According to embodiments of the present disclosure, the training module may include a third training unit. 
     The third training unit is used to train the initial feature point classification branch by using a target sample image, a feature point label of the target sample image, and a category label of the target sample image, so as to obtain a feature point classification branch of the multi-task processing model, where the target sample image includes the first sample image and/or the second sample image; the feature point label of the target sample image is used to represent a probability value that a pixel point of the target sample image is a feature point; and the category label of the target sample image is used to represent a category of the pixel point. 
     According to embodiments of the present disclosure, the present disclosure further provides an electronic device, a readable storage medium, an autonomous vehicle and a computer program product. 
     According to embodiments of the present disclosure, an electronic device is provided, including: at least one processor; and a memory communicatively connected to the at least one processor; where the memory stores instructions executable by the at least one processor, and the instructions, when executed by the at least one processor, are configured to cause the at least one processor to implement the methods according to embodiments of the present disclosure. 
     According to an embodiment of the present disclosure, a non-transitory computer-readable storage medium having computer instructions therein is provided, where computer instructions are used to cause a computer system to implement the methods according to embodiments of the present disclosure. 
     According to embodiments of the present disclosure, a computer program product containing a computer program is provided, where the computer program, when executed by a processor, is configured to cause the processor to implement the methods according to embodiments of the present disclosure. 
       FIG.  10    shows a schematic block diagram of an exemplary electronic device  1000  for implementing embodiments of the present disclosure. The electronic device is intended to represent various forms of digital computers, such as a laptop computer, a desktop computer, a workstation, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device may further represent various forms of mobile devices, such as a personal digital assistant, a cellular phone, a smart phone, a wearable device, and other similar computing devices. The components as illustrated herein, and connections, relationships, and functions thereof are merely examples, and are not intended to limit the implementation of the present disclosure described and/or required herein. 
     As shown in  FIG.  10   , the electronic device  1000  includes a computing unit  1001  which may perform various appropriate actions and processes according to a computer program stored in a read only memory (ROM)  1002  or a computer program loaded from a storage unit  1008  into a random access memory (RAM)  1003 . In the RAM  1003 , various programs and data necessary for an operation of the electronic device  1000  may also be stored. The computing unit  1001 , the ROM  1002  and the RAM  1003  are connected to each other through a bus  1004 . An input/output (I/O) interface  1005  is also connected to the bus  1004 . 
     A plurality of components in the electronic device  1000  are connected to the I/O interface  1005 , including: an input unit  1006 , such as a keyboard, or a mouse; an output unit  1007 , such as displays or speakers of various types; a storage unit  1008 , such as a disk, or an optical disc; and a communication unit  1009 , such as a network card, a modem, or a wireless communication transceiver. The communication unit  1009  allows the electronic device  1000  to exchange information/data with other devices through a computer network such as Internet and/or various telecommunication networks. 
     The computing unit  1001  may be various general-purpose and/or dedicated processing assemblies having processing and computing capabilities. Some examples of the computing units  1001  include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units that run machine learning model algorithms, a digital signal processing processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit  1001  executes various methods and steps described above, such as the method of processing the image or the method of training the multi-task processing model. For example, in some embodiments, the method of processing the image or the method of training the multi-task processing model may be implemented as a computer software program which is tangibly embodied in a machine-readable medium, such as the storage unit  1008 . In some embodiments, the computer program may be partially or entirely loaded and/or installed in the electronic device  1000  via the ROM  1002  and/or the communication unit  1009 . The computer program, when loaded in the RAM  1003  and executed by the computing unit  1001 , may execute one or more steps in the method of processing the image or the method of training the multi-task processing model described above. Alternatively, in other embodiments, the computing unit  1001  may be configured to perform the method of processing the image or the method of training the multi-task processing model by any other suitable means (e.g., by means of firmware). 
     According to embodiments of the present disclosure, the present disclosure further provides an autonomous vehicle, which may include an electronic device, a communication device, an image acquisition device, etc. 
     According to embodiments of the present disclosure, the electronic device may be integrated with the communication device and an information acquisition device, or set separately with the communication device and the information acquisition device. 
     Various embodiments of the systems and technologies described herein may be implemented in a digital electronic circuit system, an integrated circuit system, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), an application specific standard product (ASSP), a system on chip (SOC), a complex programmable logic device (CPLD), a computer hardware, firmware, software, and/or combinations thereof. These various embodiments may be implemented by one or more computer programs executable and/or interpretable on a programmable system including at least one programmable processor. The programmable processor may be a dedicated or general-purpose programmable processor, which may receive data and instructions from a storage system, at least one input device and at least one output device, and may transmit the data and instructions to the storage system, the at least one input device, and the at least one output device. 
     Program codes for implementing the methods of the present disclosure may be written in one programming language or any combination of more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a dedicated computer or other programmable data processing apparatus, so that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program codes may be executed entirely on a machine, partially on a machine, partially on a machine and partially on a remote machine as a stand-alone software package or entirely on a remote machine or server. 
     In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in connection with an instruction execution system, an apparatus or a device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any suitable combination of the above. More specific examples of the machine-readable storage medium may include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read only memory (ROM), an erasable programmable read only memory (EPROM or a flash memory), an optical fiber, a compact disk read only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. 
     In order to provide interaction with the user, the systems and technologies described here may be implemented on a computer including a display device (for example, a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user, and a keyboard and a pointing device (for example, a mouse or a trackball) through which the user may provide the input to the computer. Other types of devices may also be used to provide interaction with the user. For example, a feedback provided to the user may be any form of sensory feedback (for example, visual feedback, auditory feedback, or tactile feedback), and the input from the user may be received in any form (including acoustic input, voice input or tactile input). 
     The systems and technologies described herein may be implemented in a computing system including back-end components (for example, a data server), or a computing system including middleware components (for example, an application server), or a computing system including front-end components (for example, a user computer having a graphical user interface or web browser through which the user may interact with the implementation of the system and technology described herein), or a computing system including any combination of such back-end components, middleware components or front-end components. The components of the system may be connected to each other by digital data communication (for example, a communication network) in any form or through any medium. Examples of the communication network include a local area network (LAN), a wide area network (WAN), and the Internet. 
     The computer system may include a client and a server. The client and the server are generally far away from each other and usually interact through a communication network. The relationship between the client and the server is generated through computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, a server of a distributed system, or a server combined with a block-chain. 
     It should be understood that steps of the processes illustrated above may be reordered, added or deleted in various manners. For example, the steps described in the present disclosure may be performed in parallel, sequentially, or in a different order, as long as a desired result of the technical solution of the present disclosure may be achieved. This is not limited in the present disclosure. 
     The above-mentioned specific embodiments do not constitute a limitation on the scope of protection of the present disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions may be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present disclosure shall be contained in the scope of protection of the present disclosure.