CN117689951A - Open set identification method and system based on training-free open set simulator - Google Patents

Open set identification method and system based on training-free open set simulator Download PDF

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CN117689951A
CN117689951A CN202311730143.3A CN202311730143A CN117689951A CN 117689951 A CN117689951 A CN 117689951A CN 202311730143 A CN202311730143 A CN 202311730143A CN 117689951 A CN117689951 A CN 117689951A
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unknown
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王嘉晨
宋怀波
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Northwest A&F University
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Abstract

The invention discloses an open set identification method and system based on a training-free open set simulator, which relate to the technical field of image classification and comprise the steps of collecting original pictures, constructing the training-free open set simulator, carrying out local degradation operation on known images, and simulating to generate unknown samples; constructing a multi-transformation feature extraction model, and extracting the discriminant features of the known class images in the training set and the generated unknown class samples; the discriminant features are input into a feature extractor and classifier based on prototype learning for training. According to the open set identification method based on the training-free open set simulator, high-frequency information of an image is removed through low-pass filtering, the characteristic of the low-frequency information representing the content of the image is used as a part of the variable characteristic, the identification accuracy is enhanced, an unknown sample is constructed, the image overturning is not carried out, the larger image difference is avoided, the generalization capability of the model is improved, and the model is enabled to be more stable when facing variable and unknown data in the real world.

Description

Open set identification method and system based on training-free open set simulator
Technical Field
The invention relates to the technical field of image classification, in particular to an open set identification method and system based on a training-free open set simulator.
Background
Machine learning, one of the important branches of the explosive developments in the fields of computer science and artificial intelligence, is an advanced calculation method using experience. By continuously improving the algorithm performance, machine learning can achieve accurate prediction, and meanwhile meaningful modes existing in data can be automatically found. As large-scale data continue to emerge in various fields of social life and industrial production, machine learning is a mainstream artificial intelligence technology, and has become a core means for realizing large-scale data intelligent processing. Over the past few decades, machine learning has become a common technique in almost all tasks that require information to be extracted from big data. In recent years, machine learning techniques typified by deep learning have greatly promoted the development of artificial intelligence. Deep learning, by virtue of its strong fitting ability, stands out from many tasks such as classification, detection and segmentation, and is gradually applied in business scenes such as face recognition, automatic driving, robots, intelligent conversations, machine translation, etc., greatly improving the quality of life of people, and becoming an indispensable part of human life.
In general, most existing methods follow the assumption of a closed set of data, i.e., the data categories encountered by the model in the test set are exactly identical to those in the training set. However, in practical applications, the model is often in an open environment, i.e., the test set data includes both known classes that have appeared in the training set and unknown classes that have not appeared in the training set, and the appearance of unknown class samples can cause degradation of the model performance. For example, in the vehicle recognition procedure, only data information of various vehicle categories is provided for the model in the training process, the model may encounter other categories of data, such as human beings, animals and the like, in the actual recognition scene, and the model can also recognize the categories outside the range of the training set as a certain vehicle due to the sealing property of the training set data; in another example, in the face recognition task, when a model trained by a certain face data set is required to recognize a specific face, if the faces all exist in the training set, the model can easily recognize each known face. However, when faces that do not belong to the training set appear, the model may still misinterpret them as a known face in the training set.
Although the influence of unknown class samples on the model can be alleviated by collecting data of various classes in large quantities, it is difficult to include all data classes in the training set because the classes in nature are difficult to exhaust. Even large-scale datasets like ImageNet can cover only a small part of the real world categories, not all the possible categories. In the face of the Open environment existing in practical applications, the model needs a more reasonable way to process unknown class samples, namely Open-Set Recognition (OSR). The main goal of open set identification is to accurately identify samples from unknown classes while correctly classifying the known classes.
Disclosure of Invention
The present invention has been made in view of the above-described problems.
Therefore, the technical problems solved by the invention are as follows: the existing deep learning model has the problems of poor stability, high calculation cost, high required resources and how to generate high-quality unknown class samples under the condition of not introducing the generation of the countermeasure network by using the method for generating the additional samples of the countermeasure network.
In order to solve the technical problems, the invention provides the following technical scheme: an open set identification method based on a training-free open set simulator comprises the steps of collecting an original picture, constructing the training-free open set simulator, carrying out local degradation operation on a known image, and simulating to generate an unknown sample; constructing a multi-transformation feature extraction model, and extracting the discriminant features of the known class images in the training set and the generated unknown class samples; the discriminant features are input into a feature extractor and classifier based on prototype learning for training.
As a preferable scheme of the open set identification method based on the training-free open set simulator, the invention comprises the following steps: the simulation generation of the unknown sample comprises the steps of collecting an original picture, and then simulating the generation of the unknown sample, wherein the simulation generation of the unknown sample comprises an unknown sample generation method based on local noise addition, an unknown sample generation method based on local erasure and an unknown sample generation method based on local mosaic; the unknown sample generation method based on local noise addition comprises the steps of taking a center point of an original input image as a center, selecting a square area with a side length of R on the image, wherein H/R, W/R is a random number between 1.1 and 1.2, generating a noise value of Gaussian distribution with a mean value of 0 and a variance of 1 in the square area, setting the value of other areas except the square area to be 0, superposing local noise on the original input image, and generating an unknown sample based on local noise addition, wherein the unknown sample generation method based on local noise addition is represented as follows:
wherein x is i Representing the original input image, size H, W, noise local(R) The method comprises the steps of representing local noise superimposed on an original image, wherein K represents the total category number of known categories, and K+1 represents the unknown category of labels corresponding to generated samples; the unknown sample generation method based on local erasure comprises the steps of setting the side length of a local square area to be erased as R, setting the pixel of the square area as 0 and the pixels of the other areas as 1, multiplying the pixels with an original input image element by element, wherein H/R, W/R is a random number ranging from 1.5 to 2, and the method is expressed as follows:
wherein, mask local (R) Indicating an erasure mask, as would be the case if the element-wise multiplication; the unknown sample generation method based on local mosaic comprises the steps of generating a local square area with a side length of R on an original image, uniformly generating grids with a side length of G in the local square area, setting the value of each pixel point in each grid as the average value of the pixels in the grids, generating a local mosaic mask, adding the generated local mosaic mask and the unknown sample based on local erasure to form the unknown sample based on the local mosaic mask, wherein the unknown sample based on local mosaic mask is expressed as follows:
wherein, the Mosaic local(R,G) Representing the partial mosaic mask superimposed on the original image.
As a preferable scheme of the open set identification method based on the training-free open set simulator, the invention comprises the following steps: the step of extracting the distinguishing characteristics of the known class image in the training set and the generated unknown class sample comprises the step of carrying out frequency domain transformation on the unknown sample, and carrying out frequency domain transformation by adopting low-pass filtering based on discrete cosine transformation, wherein the distinguishing characteristics are expressed as follows:
wherein C (u, v) represents an array element of the DCT transform coefficient, u, v are coordinates of the transform domain, f (x, y) represents a numerical value of the two-dimensional image signal in the spatial domain, and x, y are coordinates of the spatial domain.
As a preferable scheme of the open set identification method based on the training-free open set simulator, the invention comprises the following steps: the method comprises the steps of extracting the distinguishing characteristics of the known type images in the training set and the generated unknown type samples, and further comprises the steps of carrying out position transformation on the unknown samples, horizontally overturning the image pixels along the vertical central axis, wherein objects in the images are mirror symmetry in the horizontal direction, and the image pixels are overturned along the horizontal central axis by the vertical overturning, so that an up-down symmetrical viewing angle is created.
As a preferable scheme of the open set identification method based on the training-free open set simulator, the invention comprises the following steps: the feature extractor and the classifier for inputting the discriminant features based on prototype learning are used for training, wherein the training comprises the steps of utilizing an unknown sample and known class data generated by a training-free open-set simulator to train class prototypes and network parameters together, and converting closed-set training into open-set training by introducing the unknown class sample in the training process, wherein a loss function is expressed as follows:
L first_step =L close +α·L open
wherein L is close And L open The method comprises the steps of respectively representing the closed set classification loss and the open set classification loss, wherein alpha represents the proportion of the open set classification loss in a loss function, and the distances between sample features and prototypes of different categories reflect the probability of the samples belonging to the current category, so that the distribution probability is calculated.
As a preferable scheme of the open set identification method based on the training-free open set simulator, the invention comprises the following steps: the probability that the distribution probability calculation includes that the sample x belongs to the category k is expressed as:
where f (·) represents a feature extractor network extracting features from the input sample x, P represents a trainable class prototype, P + Representing a prototype corresponding to the input sample x class, K being the total number of classes of known class, d (·) representing a dot product distance calculation formula;
will L close The classification loss set to the negative logarithmic probability based on the true class k is expressed as:
L close =-logS k
L open expressed as:
wherein,representing the probability that an unknown class feature belongs to class k.
As a preferable scheme of the open set identification method based on the training-free open set simulator, the invention comprises the following steps: the step of inputting the discriminant features into the feature extractor and classifier based on prototype learning to train further comprises the step of reserving the classification capacity of a closed set of the model in the training process, and the step of using the known class samples to carry out fine adjustment expression on the parameters of the model is as follows:
L second_step =L close
after the fine tuning is completed, a data set is prepared for training.
It is another object of the present invention to provide an open set identification system based on a training-free open set simulator, which can reduce the attribute of the original image belonging to a known class by degrading specific key features of the original image by using local transformation, and simultaneously retain the other features to maintain the similarity with the known class, so as to solve the problem that the existing assumption method of the data closed set contains the training set and has the known class.
As a preferred scheme of the open set identification system based on the untrained open set simulator, the invention comprises the following steps: the device comprises a local degradation module, a multi-transformation feature extraction module and a feature extraction classification module; the local degradation module is used for collecting an original picture, constructing a training-free open-set simulator, carrying out local degradation operation on a known image, and simulating to generate an unknown sample; the multi-transformation feature extraction module is used for constructing a multi-transformation feature extraction model and extracting distinguishing features of known class images in a training set and generated unknown class samples; the feature extraction and classification module is used for inputting the discriminant features into a feature extractor and classifier based on prototype learning for training.
A computer device comprising a memory storing a computer program and a processor executing the computer program is the step of implementing an open set identification method based on a training-free open set simulator.
A computer readable storage medium having stored thereon a computer program which when executed by a processor implements the steps of an open set identification method based on a training-free open set simulator.
The invention has the beneficial effects that: according to the open set identification method based on the training-free open set simulator, high-frequency information of an image is removed through low-pass filtering, the characteristic of the low-frequency information representing the content of the image is used as a part of the variable characteristic, the identification accuracy is enhanced, an unknown sample is constructed, the image overturning is not carried out, the larger image difference is avoided, the generalization capability of the model is improved, and the model is enabled to be more stable when facing variable and unknown data in the real world. The distinguishing characteristics are extracted, the diversity of data is increased, the model can identify the same object from different view angles and directions, the identification accuracy of the model to known categories is improved, and the identification capability to the unknown categories is enhanced. The invention has better effect in stability, accuracy and universality.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is an overall flowchart of an open set identification method based on a training-free open set simulator according to a first embodiment of the present invention.
Fig. 2 is a network structure diagram of an open set identification method based on a training-free open set simulator according to a first embodiment of the present invention.
Fig. 3 is an overall flowchart of an open set identification system based on a training-free open set simulator according to a third embodiment of the present invention.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Example 1
Referring to fig. 1-2, for one embodiment of the present invention, there is provided an open set identification method based on a training-free open set simulator, including:
s1: and acquiring an original picture, constructing a training-free open-set simulator, performing local degradation operation on the known class image, and simulating to generate an unknown sample.
Further, the core idea of the on-set simulator is to degrade certain key features of the original image using local transformations without introducing additional generative models to reduce their homing properties to known classes, while preserving the remaining features to preserve their similarity to the known classes. Additional open set samples obtained by the simulator are labeled as unknown classes participating in training of the model, helping the classifier model class boundaries between known classes and unknown classes.
The simulation generation of the unknown sample comprises a local noise adding-based unknown sample generation method, a local erasure-based unknown sample generation method and a local mosaic-based unknown sample generation method after the original picture is acquired; the unknown sample generation method based on local noise addition comprises the steps of taking the center point of an original input image as the center, selecting a square area with a side length of R on the image, wherein H/R, W/R takes random numbers between 1.1 and 1.2, generating noise values of Gaussian distribution with a mean value of 0 and a variance of 1 in the square area, setting the values of other areas except the square area to be 0, adding local noise to the original input image, and generating unknown samples based on local noise addition, wherein the unknown samples are expressed as:
wherein x is i Representing the original input image, size H, W, noise local(R) The method comprises the steps of representing local noise superimposed on an original image, wherein K represents the total category number of known categories, and K+1 represents the unknown category of labels corresponding to generated samples; the unknown sample generation method based on local erasure comprises the following steps of waiting forThe side length of the erased local square area is R, H/R, W/R is a random number between 1.5 and 2, the pixels of the square area are set to 0, the pixels of the other areas are set to 1, and the pixels are multiplied by the original input image element by element, which is expressed as follows:
wherein, mask local(R) Representing erasure masks, +.represents element-wise multiplication, which is designed to account for the fact that too large erasure areas may result in loss of useful information, and thus the training of the model by the generated samples is rather disadvantageous. The method comprises the steps of carrying out a first treatment on the surface of the The unknown sample generation method based on local mosaic comprises the steps of generating a local square area with a side length of R on an original image, uniformly generating grids with a side length of G in the local square area, setting the value of each pixel point in each grid as the average value of the pixels in the grids, generating the local mosaic, adding the generated local mosaic and the unknown sample based on local erasure to form the unknown sample based on the local mosaic, wherein the unknown sample based on the local mosaic is expressed as:
wherein, the Mosaic local(R,G) Representing the partial mosaic mask superimposed on the original image.
S2: and constructing a multi-transformation feature extraction model, and extracting the discriminant features of the known class images and the generated unknown class samples in the training set.
Furthermore, for the frequency domain transformation, from the viewpoint of human vision, low-pass filtering is used to process the image. Since the human eye can recognize the difference in content between the known class image and the unknown class image, the known class image and the unknown class image can be distinguished. Inspired by this phenomenon, the present step removes the high frequency information of the image by low pass filtering, and takes the feature of the low frequency information representing the image content as a part of the multiple transformation feature. For the position change, a flipping operation is employed. For known class samples, the flipping operation does not change the semantic information of the image, while for unknown class images, there is a relatively large difference in the features extracted by the model before and after image flipping. .
It should be noted that, extracting the distinguishing features of the known class image and the generated unknown class sample in the training set includes performing frequency domain transformation on the unknown sample, and performing frequency domain transformation by adopting low-pass filtering based on discrete cosine transformation, which is expressed as:
wherein C (u, v) represents an array element of the DCT transform coefficient, u, v are coordinates of the transform domain, f (x, y) represents a numerical value of the two-dimensional image signal in the spatial domain, and x, y are coordinates of the spatial domain.
It should also be noted that this processing method of DCT transformation can introduce less information loss while preserving the full information of the original signal. Because DCT transformation can effectively distinguish high-frequency parts and low-frequency parts in data, the invention designs a low-pass filtering method based on DCT transformation, after the image is subjected to DCT transformation, the high-frequency parts are set to 0, and then the image is subjected to DCT inverse transformation to a space domain, thereby realizing low-pass filtering of the image.
Furthermore, extracting the distinguishing characteristics of the known type image and the generated unknown type sample in the training set further comprises performing position transformation on the unknown sample, wherein the horizontal overturning is used for overturning the image pixels along the vertical central axis, objects in the image are mirror symmetry in the horizontal direction, and the vertical overturning is used for overturning the image pixels along the horizontal central axis to create an up-down symmetrical viewing angle.
It should be noted that the multiple transformation feature extraction module adopts the idea of integrated learning, extracts the features of each transformed sample through a convolution layer after performing multiple transformations on the input sample, and splices the extracted discriminant features in the channel dimension, so that the integrated multiple transformation features are used to jointly represent the input sample. Thus, the model will erroneously identify an unknown class sample as a known class sample only if the known class sample and the unknown class sample are similar in multiple transformation dimensions.
S3: the discriminant features are input into a feature extractor and classifier based on prototype learning for training.
Furthermore, inputting the discriminant features into the feature extractor and classifier based on prototype learning to train includes training the class prototype and the network parameters by using the unknown sample and the known class data generated by the untrained open-set simulator, and converting the closed-set training into the open-set training by introducing the unknown class sample in the training process, wherein the loss function is expressed as:
L ftrst_step =L close +α·L open
wherein L is close And L open The method comprises the steps of respectively representing the closed set classification loss and the open set classification loss, wherein alpha represents the proportion of the open set classification loss in a loss function, and the distances between sample features and prototypes of different categories reflect the probability of the samples belonging to the current category, so that the distribution probability is calculated. The smaller the distance between a sample feature and a prototype of a certain class, the greater the probability that the sample belongs to that class.
It should be noted that the probability of performing the assignment probability calculation includes that the probability that the sample x belongs to the category k is expressed as:
where f (·) represents a feature extractor network extracting features from the input sample x, P represents a trainable class prototype, p+ represents a prototype corresponding to the input sample x class, K is the total number of classes of known classes, d (·) represents a dot product distance calculation formula;
will L close The classification loss set to the negative logarithmic probability based on the true class k is expressed as:
L close =-logS k
L open expressed as:
wherein,representing the probability that an unknown class feature belongs to class k. The larger the dot product calculation value, the smaller the distance between the two features
It should also be noted that, the feature extractor and classifier training based on prototype learning of the discriminative feature input further includes preserving the closed set classification capability of the model during training, and fine tuning the model parameters using the known class samples is expressed as:
Lsecond_step=Lclose
after the fine tuning is completed, a data set is prepared for training.
Example 2
In order to verify the beneficial effects of the invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.
First, six data sets of MNIST, SVHN, CIFAR, cifar+10, cifar+50 and TinyImageNet were selected according to the present invention and tested with reference to table 1. Wherein MNIST, SVHN and CIFAR10 datasets contain ten categories of images, respectively. Six categories are randomly selected as known categories respectively, and then the remaining four categories are used as unknown categories. For the CIFAR+10 and CIFAR+50 data sets, four categories of the CIFAR+10 data set are randomly selected as known categories, and 10 and 50 non-overlapping categories are randomly selected as unknown categories from the CIFAR100 data set. The TinyImageNet dataset contains two hundred categories in total, twenty of which are randomly sampled by the present invention as known categories, while the remaining one hundred eighty categories are considered as unknown categories. In order to evaluate the performance of the proposed algorithm, AUROC (Area under theROC curve) was used as an evaluation index in the present invention. Among these, ROC curves are an efficient way to demonstrate the relationship between true and false positive rates. AUROC represents the area under the ROC curve, the value range is between 0.1 and 1, the advantages and disadvantages of the classifier can be evaluated as an intuitive index, and the larger the value is, the better the performance of the classifier is represented.
Table 1 Performance comparison Table of the inventive algorithm and existing open set recognition algorithm based on deep learning
Example 3
Referring to fig. 3, for one embodiment of the present invention, an open set identification system based on a training-free open set simulator is provided, which includes a local degradation module, a multiple transformation feature extraction module, and a feature extraction classification module.
The local degradation module is used for collecting an original picture, constructing a training-free open-set simulator, carrying out local degradation operation on a known class image, and simulating to generate an unknown sample; the multi-transformation feature extraction module is used for constructing a multi-transformation feature extraction model and extracting distinguishing features of known class images in a training set and the generated unknown class samples; the feature extraction and classification module is used for inputting the discriminant features into a feature extractor and classifier based on prototype learning for training.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method of the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium may even be paper or other suitable medium upon which the program is printed, as the program may be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.
It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like. It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.

Claims (10)

1. An open set identification method based on a training-free open set simulator is characterized by comprising the following steps:
collecting an original picture, constructing a training-free open-set simulator, performing local degradation operation on a known class image, and simulating to generate an unknown sample;
constructing a multi-transformation feature extraction model, and extracting the discriminant features of the known class images in the training set and the generated unknown class samples;
the discriminant features are input into a feature extractor and classifier based on prototype learning for training.
2. The open set identification method based on the training-free open set simulator as claimed in claim 1, wherein: the simulation generation of the unknown sample comprises the steps of collecting an original picture, and then simulating the generation of the unknown sample, wherein the simulation generation of the unknown sample comprises an unknown sample generation method based on local noise addition, an unknown sample generation method based on local erasure and an unknown sample generation method based on local mosaic;
the unknown sample generation method based on local noise addition comprises the steps of taking a center point of an original input image as a center, selecting a square area with a side length of R on the image, wherein H/R, W/R is a random number between 1.1 and 1.2, generating a noise value of Gaussian distribution with a mean value of 0 and a variance of 1 in the square area, setting the value of other areas except the square area to be 0, superposing local noise on the original input image, and generating an unknown sample based on local noise addition, wherein the unknown sample generation method based on local noise addition is represented as follows:
wherein x is i Representing the original input image, size H, W, noise local(R) The method comprises the steps of representing local noise superimposed on an original image, wherein K represents the total category number of known categories, and K+1 represents the unknown category of labels corresponding to generated samples;
the unknown sample generation method based on local erasure comprises the steps of setting the side length of a local square area to be erased as R, setting the pixel of the square area as 0 and the pixels of the other areas as 1, multiplying the pixels with an original input image element by element, wherein H/R, W/R is a random number ranging from 1.5 to 2, and the method is expressed as follows:
wherein, mask local(R) Indicating an erasure mask, as would be the case if the element-wise multiplication;
the unknown sample generation method based on local mosaic comprises the steps of generating a local square area with a side length of R on an original image, uniformly generating grids with a side length of G in the local square area, setting the value of each pixel point in each grid as the average value of the pixels in the grids, generating a local mosaic mask, adding the generated local mosaic mask and the unknown sample based on local erasure to form the unknown sample based on the local mosaic mask, wherein the unknown sample based on local mosaic mask is expressed as follows:
wherein, the Mosaic local(R,G) Representing the partial mosaic mask superimposed on the original image.
3. The open set identification method based on the training-free open set simulator as claimed in claim 2, wherein: the step of extracting the distinguishing characteristics of the known class image in the training set and the generated unknown class sample comprises the step of carrying out frequency domain transformation on the unknown sample, and carrying out frequency domain transformation by adopting low-pass filtering based on discrete cosine transformation, wherein the distinguishing characteristics are expressed as follows:
wherein C (u, v) represents an array element of the DCT transform coefficient, u, v are coordinates of the transform domain, f (x, y) represents a numerical value of the two-dimensional image signal in the spatial domain, and x, y are coordinates of the spatial domain.
4. The open set identification method based on a training-free open set simulator as claimed in claim 3, wherein: the method comprises the steps of extracting the distinguishing characteristics of the known type images in the training set and the generated unknown type samples, and further comprises the steps of carrying out position transformation on the unknown samples, horizontally overturning the image pixels along the vertical central axis, wherein objects in the images are mirror symmetry in the horizontal direction, and the image pixels are overturned along the horizontal central axis by the vertical overturning, so that an up-down symmetrical viewing angle is created.
5. The open set identification method based on the training-free open set simulator as claimed in claim 4, wherein: the feature extractor and the classifier for inputting the discriminant features based on prototype learning are used for training, wherein the training comprises the steps of utilizing an unknown sample and known class data generated by a training-free open-set simulator to train class prototypes and network parameters together, and converting closed-set training into open-set training by introducing the unknown class sample in the training process, wherein a loss function is expressed as follows:
L first_step =L close +α·L open
wherein L is close And L open The method comprises the steps of respectively representing the closed set classification loss and the open set classification loss, wherein alpha represents the proportion of the open set classification loss in a loss function, and the distances between sample features and prototypes of different categories reflect the probability of the samples belonging to the current category, so that the distribution probability is calculated.
6. The open set identification method based on the training-free open set simulator as claimed in claim 5, wherein: the probability that the distribution probability calculation includes that the sample x belongs to the category k is expressed as:
where f (·) represents a feature extractor network extracting features from the input sample x, P represents a trainable class prototype, P + Representing a prototype corresponding to the input sample x class, K being the total number of classes of known class, d (·) representing a dot product distance calculation formula;
will L close The classification loss set to the negative logarithmic probability based on the true class k is expressed as:
L close =-logS k
L open expressed as:
wherein,representing the probability that an unknown class feature belongs to class k.
7. The open set identification method based on the training-free open set simulator as claimed in claim 6, wherein: the step of inputting the discriminant features into the feature extractor and classifier based on prototype learning to train further comprises the step of reserving the classification capacity of a closed set of the model in the training process, and the step of using the known class samples to carry out fine adjustment expression on the parameters of the model is as follows:
L second_step =L close
after the fine tuning is completed, a data set is prepared for training.
8. A system employing the training-free open set simulator-based open set identification method of any of claims 1-7, characterized by: the device comprises a local degradation module, a multi-transformation feature extraction module and a feature extraction classification module;
the local degradation module is used for collecting an original picture, constructing a training-free open-set simulator, carrying out local degradation operation on a known image, and simulating to generate an unknown sample;
the multi-transformation feature extraction module is used for constructing a multi-transformation feature extraction model and extracting distinguishing features of known class images in a training set and generated unknown class samples;
the feature extraction and classification module is used for inputting the discriminant features into a feature extractor and classifier based on prototype learning for training.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the training-free open set simulator-based open set identification method of any of claims 1 to 7 when the computer program is executed.
10. A computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor implements the steps of the open set identification method based on a training-free open set simulator of any of claims 1 to 7.
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