Patent Publication Number: US-2021192348-A1

Title: Information processing method and information processing system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of PCT International Application No. PCT/JP2019/050480 filed on Dec. 24, 2019, designating the United States of America, which is based on and claims priority of U.S. Provisional Patent Application No. 62/813,348 filed on Mar. 4, 2019 and Japanese Patent Application No. 2019-168679 filed on Sep. 17, 2019. The entire disclosures of the above-identified applications, including the specifications, drawings and claims are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     This disclosure relates to an information processing method executed by a computer and an information processing system that executes the information processing method. 
     BACKGROUND 
     In order to stabilize the training of a discriminator in generative adversarial networks (GAN), a method using weight normalization has been proposed (Patent Literature (PTL) 1). 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: International Publication No. 2019/004350 
       
    
     Non Patent Literature 
     
         
         NPL 1: Jun-Yan Zhu, Taesung Park, Phillip Isola, and Alexei A. Efros. “Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks”, in IEEE International Conference on Computer Vision (ICCV), 2017 
       
    
     SUMMARY 
     Technical Problem 
     With the above method, it may be difficult to stabilize the training (learning) of the discriminator depending on the data used for training. 
     The present disclosure provides an information processing method or the like capable of more stably converging training of the discriminator in such a case. 
     Solution to Problem 
     The information processing method according to one aspect of the present disclosure is an information processing method executed by a computer, the information processing method including: obtaining first data and second data that is simulated data based on the first data; inputting the first data into a discriminator to obtain first discrimination result data; calculating a first difference between reference data in a discrimination process for the first data by the discriminator and the first discrimination result data; calculating a first squared error data and a first weight based on the first difference, the first weight being a weight of the first squared error data; inputting the second data into the discriminator to obtain second discrimination result data; calculating a second difference between reference data in a discrimination process for the second data by the discriminator and the second discrimination result data; calculating a second squared error data and a second weight based on the second difference, the second weight being a weight of the second squared error data; and training the discriminator based on the first squared error data, the second squared error data, the first weight, and the second weight; wherein the first discrimination result data and the second discrimination result data are data of a tensor having a rank of one or higher. 
     In addition, the information processing system according to one aspect of the present disclosure, includes: an obtainer that obtains first data and second data that is simulated data based on the first data; a weight calculator that calculates a first difference between first discrimination result data obtained by inputting the first data into a discriminator and reference data in a discrimination process for the first data, calculates a second difference between second discrimination result data obtained by inputting the second data into the discriminator and reference data in a discrimination process for the second data, calculates a first squared error data and a first weight, which is a weight of the first squared error data, based on the first difference, and calculates a second squared error data and a second weight, which is a weight of the second squared error data, based on the second difference; an error calculator that calculates error data used for training the discriminator based on the first squared error data, the second squared error data, the first weight, and the second weight; and a trainer that trains the discriminator using the error data, wherein the first discrimination result data and the second discrimination result data are data of a tensor having a rank of one or higher. 
     It should be noted that in addition to the above method and system, these comprehensive or specific aspects may be realized by a device, an integrated circuit, or a recording medium such as a computer-readable CD-ROM, and may be realized by any combination of a device, a system, an integrated circuit, a method, a computer program, and a recording medium. 
     Advantageous Effects 
     By the information processing method and the like according to the present disclosure, the training of the discriminator can be converged more stably even if the data by which it is conventionally difficult to converge the training is used. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       These and other advantages and features will become apparent from the following description thereof taken in conjunction with the accompanying Drawings, by way of non-limiting examples of embodiments disclosed herein. 
         FIG. 1  is a functional block diagram in the learning phase of the information processing system according to an embodiment. 
         FIG. 2  is a functional block diagram in the inference phase of the information processing system according to the embodiment. 
         FIG. 3  schematically shows a graph of a function indicating a weight set in the above learning phase. 
         FIG. 4  is a flow diagram showing a procedure example of the operations of the information processing method executed for training the discriminator in the above information processing system. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Underlying Knowledge Forming Basis of the Present Disclosure) 
     The inventors have found that the following problems arise with respect to the above-mentioned proposed conventional method. 
     In this conventional method, in order to prevent the weight of the discriminator from becoming excessive, the output value of the discriminator is prevented from becoming an outlier by normalizing the weight. More specifically, a singular value of the weight matrix having the weight of each layer of the discriminator as an element is calculated, and the weight matrix is normalized by using the norm of this singular value. Then, the weight matrix after normalization is updated based on the output error of the discriminator. 
     However, there are cases where it is difficult for the learning of the discriminator to converge with this conventional method. 
     There are GAN called CycleGAN, which are used, for example, for the purpose of conversion between different types of image sets. CycleGAN are GAN of a PatchGAN system and a least squares GAN (LSGAN) system. The output from the discriminator of a PatchGAN system is a matrix whose elements are not scalar values that take values of 0 or 1, but values indicating the determination results of whether each of the plurality of small areas (patches) obtained by dividing the entire input image is a simulated image output by the generator or an image not output from the generator. Then, the discriminator of the LSGAN system is trained based on the squared error of this matrix output by the discriminator and the matrix showing the correct answer in this discrimination (matrix in which 0s or 1s are lined up). Such CycleGAN show preferred conversion results even in a generator trained with a data set of unaligned images (see NPL 1). For that reason, for example, high practicality is expected in applications where it is practically difficult to obtain an aligned data set in an amount required for training. 
     However, there is a high possibility that the image data that can be obtained as an unaligned data set contains a larger amount of noise than the aligned data set. The noise referred to here is due to, for example, fluctuations in the image quality, the degree of focusing, or the color of the image. In addition, when the data set is a person image, the posture of the person in the image, the range of the body appearing in the image that changes depending on the occlusion or composition, or changes in objects other than the person such as the person&#39;s belongings or background, can also be included as an example of the cause of noise. Such noise affects the training of the discriminator of a PatchGAN system and a LSGAN system described above. Specifically, it destabilizes the training of the discriminator and thus makes it difficult to obtain generators that produce images in the desired quality. Then, there is a problem that the above-mentioned conventional method cannot cope with the stabilization of the training of the discriminator caused by such noise. 
     The information processing method according to one aspect of the present disclosure devised in view of such a problem is an information processing method executed by a computer, the information processing method including: obtaining first data and second data that is simulated data based on the first data; inputting the first data into a discriminator to obtain first discrimination result data; calculating a first difference between reference data in a discrimination process for the first data by the discriminator and the first discrimination result data; calculating a first squared error data and a first weight based on the first difference, the first weight being a weight of the first squared error data; inputting the second data into the discriminator to obtain second discrimination result data; calculating a second difference between reference data in a discrimination process for the second data by the discriminator and the second discrimination result data; calculating a second squared error data and a second weight based on the second difference, the second weight being a weight of the second squared error data; and training the discriminator based on the first squared error data, the second squared error data, the first weight, and the second weight; wherein the first discrimination result data and the second discrimination result data are data of a tensor having a rank of one or higher. 
     With this, when the noise contained in the training data of the discriminator is larger than a certain level, the influence on the training result can be suppressed to converge the training more stably. 
     In addition, as an absolute value of the first difference is larger, the first weight may be made smaller to reduce an influence rate (a degree of influence) of the first squared error data on the training of the discriminator, and as an absolute value of the second difference is larger, the second weight may be made smaller to reduce an influence rate of the second squared error data on the training of the discriminator. 
     In addition, when the absolute value of the first difference exceeds a threshold value, the first weight may be set to zero, and when the absolute value of the second difference exceeds a threshold value, the second weight may be set to zero. 
     In addition, the second data may be generated from the first data and output by a generator, and the generator may be trained based on the first squared error data, the second squared error data, the first weight, and the second weight. 
     With this, the training of the above-mentioned discriminator and the generator that is adversarial in the GAN converges more stably. 
     In addition, the first data may be image data. 
     In addition, the information processing system according to one aspect of the present disclosure, includes: an obtainer that obtains first data and second data that is simulated data based on the first data; a weight calculator that calculates a first difference between first discrimination result data obtained by inputting the first data into a discriminator and reference data in a discrimination process for the first data, calculates a second difference between second discrimination result data obtained by inputting the second data into the discriminator and reference data in a discrimination process for the second data, calculates a first squared error data and a first weight, which is a weight of the first squared error data, based on the first difference, and calculates a second squared error data and a second weight, which is a weight of the second squared error data, based on the second difference; an error calculator that calculates error data used for training the discriminator based on the first squared error data, the second squared error data, the first weight, and the second weight; and a trainer that trains the discriminator using the error data, wherein the first discrimination result data and the second discrimination result data are data of a tensor having a rank of one or higher. 
     With this, when the noise contained in the training data of the discriminator is larger than a certain level, the influence on the training result is suppressed to converge the training more stably. 
     It should be noted that in addition to the above method and system, these comprehensive or specific aspects may be realized by a device, an integrated circuit, or a recording medium such as a computer-readable CD-ROM, and may be realized by any combination of a device, a system, an integrated circuit, a method, a computer program, and a recording medium. 
     Hereinafter, an embodiment of the information processing method and the information processing system according to one aspect of the present disclosure will be described with reference to the drawings. The embodiment shown here show a specific example of the present disclosure. Therefore, the numerical values, shapes, components, arrangement and connection forms of the components, steps (processes), order of steps, and the like shown in the following embodiment are examples, and do not limit the present disclosure. In addition, among the components in the following embodiment, the components not described in the independent claims are components that can be arbitrarily added. In addition, each figure is a schematic diagram and is not necessarily a precise illustration. 
     EMBODIMENT 
     [1. Configuration] 
       FIG. 1  and  FIG. 2  are functional block diagrams showing a functional configuration example of the information processing system according to the embodiment. These information processing systems are configured by using one or more information processing devices (computers) each having a processor and a memory to execute a program, and implements CycleGAN. The functional configuration for the learning phase of this information processing system is shown in  FIG. 1 , and the functional configuration for the inference phase thereof is shown in  FIG. 2 , separately. The components of these functional configurations indicated by the respective blocks are realized, for example, by a part or all of the above-described processor executing one or more programs stored in a part or all of the memory. 
     [1-1. Configuration for Training Phase] 
     As shown in  FIG. 1 , information processing system  10 A according to the embodiment includes first converter  11 A, determiner  12 , weight calculator  13 , first error calculator  14 , trainer  15 , second converter  16 , and second error calculator  17 . 
     First converter  11 A performs a predetermined conversion on the real image obtained by information processing system  10 A to generate and output a fake image. The predetermined conversion is, for example, changing the image quality or the style of the image. Changing the style of the image means, for example, making an input real image look as if it is a painting of a predetermined painter or style, or vice versa, making an input oil painting image or an image by computer graphics (CG) look as if it is a real image. In addition, another example of a predetermined conversion is changing the colors contained in the image according to a predetermined policy, for example, making an input natural landscape photographic image look like an image taken in the same composition in different seasons. Another example similar to this includes making a specific subject included in an input image look like another subject mainly by changing the color or pattern. More specifically, it is a conversion that makes a brown horse in the image look like a zebra or an apple look like an orange. It can also be said that another expression for the conversions like these by first converter  11 A is generating and outputting a simulated image (fake image) in which different styles, different seasonal landscapes, different subject appearances, and the like are simulated, while retaining the basic composition of the input image (real image). Such first converter  11 A is one of two generators included in the CycleGAN implemented by information processing system  10 A, and is a generation model of a neural network used for the conversion applications as described above. In addition, the real image data is an example of the first data in the present embodiment, and the fake image data is an example of the second data in the present embodiment. 
     Determiner  12  performs a discrimination process for determining whether the input image is a real image or a fake image generated by first converter  11 A, and outputs the result. This discrimination process is performed by the PatchGAN system described above, and the result of the discrimination process is output in the form of a matrix whose elements are values indicating the likelihood of whether the image is a real image or a fake image for each small area. For example, it is a matrix that takes values of 1 for the element corresponding to the small area determined to be a real image, 0 for the element corresponding to the small area determined to be a fake image, and greater than 0 and less than 1 according to the determination result as to whether each small area is a fake image or a real image for the element corresponding to a small area other than these. Such determiner  12  is a discriminator in the CycleGAN implemented by information processing system  10 A, and is a discrimination model of a neural network used for the discrimination purposes as described above. In the following, among the data (hereinafter, also referred to as discrimination result data) indicating the result of this discrimination process output by determiner  12 , the discrimination result data output by receiving the input of the real image is also referred to as the first discrimination result data, and the discrimination result data output by receiving the input of the fake image is also referred to as the second discrimination result data. 
     Weight calculator  13  calculates a difference between the discrimination result data output by determiner  12  after executing the discrimination process and the data (hereinafter, also referred to as reference data) indicating the correct answer in the discrimination process of this discrimination process. In addition, weight calculator  13  calculates the weight and the squared error of each element of the matrix which is the discrimination result data output by determiner  12  based on this difference. The reference data is a matrix having the same size as the discrimination result data and having 1 for all elements or 0 for all elements. According to the example used in the above description of determiner  12 , it is a matrix having 1 for all elements that indicates the correct answer of the matrix output by determiner  12  when the real image is input. In addition, it is a matrix having 0 for all elements that indicates the correct answer of the matrix output by determiner  12  when the fake image is input. It should be noted that hereinafter, the weight and the squared error calculated by weight calculator  13  with respect to the discrimination result output by determiner  12  into which the real image is input are also referred to as the first weight and the first squared error, respectively. In addition, hereinafter, the weight and the squared error calculated by weight calculator  13  with respect to the discrimination result output by determiner  12  into which the fake image is input are also referred to as the second weight and the second squared error, respectively. 
     First error calculator  14  calculates the error of determiner  12  based on the first weight, the first squared error, the second weight, and the second squared error. 
     It should be noted that the above-mentioned weight calculation by weight calculator  13  and the error calculation of determiner  12  using this weight by first error calculator  14  will be described later using an example. 
     Trainer  15  trains determiner  12  using the error calculated by first error calculator  14 . 
     Second converter  16  is the other generator that is the generation model of the neural network in the CycleGAN implemented by information processing system  10 A. Second converter  16  receives the input of the fake image generated and output by first converter  11 A. Then, such a conversion as to restore the real image before being converted into the fake image is implemented to output the image generated by the conversion. 
     Second error calculator  17  calculates the error based on the difference between the image output by second converter  16  and the image of the correct answer corresponding to this image, that is, the real image before being converted into the fake image output by first converter  11 A. This error is input to trainer  15  and used for the training of first converter  11 A. 
     In information processing system  10 A, each of these components is realized by one or more information processing devices configuring information processing system  10 A. 
     It should be noted that the real image set is a set of images that have not undergone any conversion processing for simulation as described above by first converter  11 A, and includes a plurality of still images or a moving image including a plurality of frames. Information processing system  10 A may read out and obtain the data of the real image set, for example, the data recorded on a non-temporary recording medium such as a digital versatile disc (DVD) or a semiconductor memory, by using a reading device, or may obtain the data by receiving the input of the image signal from the camera. Alternatively, information processing system  10 A may further include a communication device and obtain the data of the real image set via the signal received by this communication device. 
     [1-2. Configuration for Inference Phase] 
     As shown in  FIG. 2 , information processing system  10 B according to the embodiment includes converter  11 B which is a generation model obtained by machine learning. Specifically, converter  11 B is first converter  11 A in which the above-mentioned training for a predetermined conversion is repeatedly performed in information processing system  10 A, and for example, when the evaluation regarding such conversion performance reaches a desired standard, it can be treated as converter  11 B. Converter  11 B executes a predetermined conversion on the unconverted image and outputs the converted image. For example, when converter  11 B receives an input of a real image as an unconverted image, converter  11 B converts the real image to generate and output a converted image that looks as if it is a painting in a predetermined style. 
     In information processing system  10 B, converter  11 B is realized by one or more information processing devices configuring information processing system  10 B. The information processing devices configuring information processing system  10 B may be common to those configuring information processing system  10 A, and converter  11 B may be first converter  11 A itself whose training has converged to some extent or more. In addition, the information processing devices configuring information processing system  10 B may be different from those configuring information processing system  10 A. For example, first converter  11 A may be on a plurality of stationary computers configuring information processing system  10 A, and converter  11 B may be on a microcontroller provided in a mobile body such as an automobile, a personal digital assistant, a household electric appliance, or the like. Converter  11 B in this case may be obtained by reducing the weight of (quantizing) first converter  11 A. 
     [2. Suppression of the Influence of Outliers] 
     In the training phase of the conventional GAN, the squared error calculated based on the difference between the output of the discriminator and the reference data indicating the correct answer is used for training the discriminator. On the other hand, in the training phase by information processing system  10 A according to the present embodiment, a process for suppressing the influence of outliers included in the data to be discriminated in the training of determiner  12  which is the discriminator is further performed. A specific example of this process will be described below. In this example, Tukey&#39;s biweight estimation method, which is one of the robust estimation methods, is used to set the weight. 
     In information processing system  10 A, the difference between the discrimination result data output by determiner  12  after executing the discrimination process and the reference data in this discrimination process is calculated by weight calculator  13  as described above. Furthermore, weight calculator  13  calculates the weight (first weight, second weight) and squared error (first squared error, second squared error) of each element of the matrix output by determiner  12  based on this difference as follows. 
     When each element of the first discrimination result data output by determiner  12  is D 1 (x) and each element of the reference data is R 1  when real image x is input to determiner  12  as a discrimination target, weight calculator  13  obtains first difference d 1 , which is the difference between the first identification result data and the reference data, by an operation represented by the following formula: 
         d   1   =D   1 ( x )− R   1  
 
     It should be noted that since the reference data in this case is a matrix in which the values of all the elements are 1, R 1 =1. 
     Here, when the magnitude of first difference d 1 , that is, the threshold value indicating the boundary of whether the absolute value is acceptable (hereinafter referred to as the error tolerance value) is T, weight calculator  13  calculates following function t(d 1 ) indicating the first weight corresponding to first difference d 1 . 
       When  d   1   &lt;−T:t ( d   1 )=0 
       When − T≤d   1   T:t ( d   1 )={1−( d   1   /T ) 2 } 2  
 
       When  T&lt;d   1   :t ( d   1 )=0  [Math. 1]
 
       FIG. 3  schematically represents a graph of function t(d 1 ) showing the first weight. As can be seen from  FIG. 3 , the first weight is set so as to decrease from 1 and approach 0 as the absolute value of first difference d 1  increases from 0, and become zero in the range where the absolute value of first difference d 1  exceeds error tolerance value T. 
     Similarly, when each element of the second discrimination result data output by determiner  12  is D 2 (G(z)) and each element of the reference data is R 2  when fake image G(z) output by first converter  11 A, which is a generator that has received the input of real image z, is input to determiner  12  as a discrimination target, weight calculator  13  obtains second difference d 2 , which is the difference between the second identification result data and the reference data, by an operation represented by the following formula: 
         d   2   =D   2 ( G ( z ))− R   2  
 
     It should be noted that since the reference data in this case is a matrix in which the values of all the elements are 0, R 2 =0. 
     In addition, when the error tolerance value of the absolute value of second difference d 2  is T, following function t(d 2 ) indicating the second weight corresponding to second difference d 2  is also calculated in the same manner as function t(d 1 ). 
       When  d   2   &lt;−T:t ( d   2 )=0 
       When − T≤d   2   ≤T:t ( d   2 )={1−( d   2   /T   2 } 2  
 
       When  T&lt;d   2   :t ( d   2 )=0 
     The graph of function t(d 2 ) showing the second weight is also schematically represented as shown in  FIG. 3 . That is, the second weight is set so as to decrease from 1 and approach 0 as the absolute value of second difference d 2  increases from 0, and become zero in the range where the absolute value of second difference d 2  exceeds error tolerance value T. 
     Weight calculator  13  further calculates the squared error of the discrimination result of determiner  12 . Specifically, first squared error (D 1 (x) −1) 2  is calculated based on first difference D 1 (x)−1 obtained above for each element of the matrix which is the discrimination result data, and the second squared error (D 2 (G(z))−0) 2  is calculated based on second difference D 2 (G(z))−0. 
     Next, first error calculator  14  calculates the error of determiner  12  based on the first weight, the first squared error, the second weight, and the second squared error calculated as described above. Specifically, each element of the first squared error is multiplied by first weight (t(d 1 )) corresponding to the value of d 1 . This result is also referred to as real image error below. In addition, each element of the second squared error is multiplied by second weight (t(d 2 )) corresponding to the value of d 2 . This result is also referred to as fake image error below. Then, the result of adding the real image error and the fake image error is obtained as the error of determiner  12 . The error of determiner  12  is used by trainer  15  for the training of determiner  12 . 
     The meaning of applying the weight set as described above to the squared error is as follows. The magnitude (absolute value) of the first difference or the second difference indicates the magnitude of the deviation from the correct answer of the determination for each part (small area in the above image example) of the data to be discriminated. Then, each weight set as described above is smaller as the deviation from the correct answer of the determination is larger. When such a weight is applied to the squared error used for the training of the discriminator, for each part of the data input to determiner  12  for the training, the larger the deviation from the correct answer of the determination, the smaller the addition to the error in this training. In other words, the larger the deviation from the correct answer of the determination, the less the influence on the training. Here, the portion including the outliers of the data input to determiner  12  for the training can be determined to deviate more from the correct answer. Therefore, it is possible to suppress the influence of outliers contained in the data to be discriminated on the training of the discriminator. In addition, the greater the degree of deviation of outliers, the stronger the suppression. In the above example, the weight is set to zero for the portion where the deviation from the correct answer of the determination exceeds a threshold value, so that the influence rate on the training of the discriminator becomes zero. 
     It should be noted that Tukey&#39;s biweight estimation method was used to suppress the influence of outliers in the above example, but the method of suppressing the influence of outliers is not limited thereto. Other M estimation methods, which are robust estimation methods capable of setting the squared error as described above, may be used. 
     [3. Operation of Information Processing System] 
     The operation of the information processing method for the training of determiner  12 , which is the discriminator, executed in information processing system  10 A will be described with reference to a procedure example thereof.  FIG. 4  is a flow chart showing a procedure example of the operation of information processing system  10 A in which this information processing method is executed. 
     (Step S 10 ) Determiner  12 , which is a discriminator, receives an input of an image obtained by information processing system  10 A from a set of real images. 
     (Step S 11 ) Determiner  12  performs a discrimination process for determining whether the image is a real image or a fake image for each small area of the input image, and calculates and outputs a matrix based on the result. Here, assuming that the image to be discriminated is a real image, the calculated matrix is referred to as a first output matrix for convenience. 
     (Step S 12 ) Weight calculator  13  calculates the first weight, which is the weight of each element, using the first output matrix calculated in step S 11 . For the method of calculating the first weight, refer to the example given in “2. Suppression of the influence of outliers” mentioned above. 
     (Step S 13 ) Weight calculator  13  calculates the first squared error, which is the squared error of each element of the first output matrix calculated in step S 11 . For the calculation method of the first squared error, refer to “2. Suppression of the influence of outliers” mentioned above. 
     (Step S 20 ) Determiner  12  receives the input of the fake image generated by first converter  11 A, which is a generator, converting the real image. 
     (Step S 21 ) Determiner  12  performs a discrimination process for determining whether the image is a real image or a fake image for each small area of the input image, and calculates and outputs a matrix based on the result. Here, assuming that the image to be discriminated is a fake image, the calculated matrix is referred to as a second output matrix for convenience. 
     (Step S 22 ) Weight calculator  13  calculates the second weight, which is the weight of each element, using the second output matrix calculated in step S 21 . For the method of calculating the second weight, refer to the example given in “2. Suppression of the influence of outliers” mentioned above. 
     (Step S 23 ) Weight calculator  13  calculates the second squared error, which is the squared error of each element of the second output matrix calculated in step S 21 . For the calculation method of the second squared error, refer to “2. Suppression of the influence of outliers” mentioned above. 
     (Step S 30 ) First error calculator  14  calculates the real image error by multiplying the first weight calculated in step S 12  by the first squared error calculated in step S 13 . 
     (Step S 31 ) First error calculator  14  calculates the fake image error by multiplying the second weight calculated in step S 22  by the second squared error calculated in step S 23 . 
     (Step S 32 ) First error calculator  14  calculates the error of determiner  12  by adding the real image error calculated in step S 30  and the fake image error calculated in step S 31 . 
     (Step S 33 ) Trainer  15  implements training of determiner  12 , which is a discriminator, using the error calculated in step S 32 . 
     It should be noted that the content of the information processing method performed by information processing system  10 A is not limited to the above. For example, training of first converter  11 A, which is a generator, is also performed by trainer  15 . This training is performed using, for example, the above-mentioned error calculated by second error calculator  17 . In addition, the first weight, the first squared error data, the second weight, and the second squared error data may be used for the training of first converter  11 A. 
     [4. Supplementary Notes] 
     The information processing method and information processing system according to one or more aspects of the present disclosure are not limited to the description of the above-described embodiment. Various modifications conceived by those skilled in the art may be included in the embodiment of the present disclosure without departing from the spirit of the present disclosure. Examples of such modifications and other supplementary notes to the description of embodiment are given below. 
     (1) The information processing system according to the above embodiment has been described by using a system that implements CycleGAN as an example, but the information processing system is not limited thereto. The information processing system according to one aspect of the present disclosure is also applicable to other types of GANs of the Patch GAN system and the LSGAN system, such as Combo GAN. 
     (2) The information processing system according to the above embodiment has been described by using a system, in which image conversion and discrimination are performed, as an example, but the processing target by the information processing system is not limited to image data. Other examples of processing targets include voice, distance point cloud, pressure, temperature, humidity, sensor data such as odor, and language data. 
     (3) The information processing system according to the above embodiment has been described with reference to an example in which the discrimination result is in a matrix format, but the present invention is not limited thereto. The information processing system in the present disclosure can be applied to information processing that handles discrimination result data, which is data of a tensor having a rank of one or higher. 
     (4) A part or all of the functional components included in each of the above-mentioned information processing systems may be configured by one system large scale integration (LSI). A system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on a single chip, and it is specifically a computer system configured by including a microprocessor, a read-only memory (ROM), a random access memory (RAM), and the like. A computer program is stored in the ROM. The system LSI achieves the function of each component by the microprocessor operating according to this computer program. 
     It should be noted that although it is referred to as a system LSI here, it may be referred to as an IC, an LSI, a super LSI, or an ultra LSI due to the difference in the degree of integration. In addition, the method of making an integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and settings of circuit cells inside the LSI may be used. 
     Furthermore, if an integrated circuit technology that replaces an LSI appears due to advances in semiconductor technology or another technology derived therefrom, functional blocks may be integrated using that technology. The application of biotechnology or the like may be one possibility among others. 
     (5) One aspect of the present disclosure is not limited to each of the above-mentioned information processing systems, but may be an information processing method in which a process by characteristic components included in the information processing system is a step. This information processing method is, for example, the information processing method described with reference to the flow chart in  FIG. 4 . In addition, one aspect of the present disclosure may be a computer program that causes a computer to execute each characteristic step included in this information processing method. In addition, one aspect of the present disclosure may be a computer-readable, non-temporary recording medium on which such a computer program is recorded. 
     INDUSTRIAL APPLICABILITY 
     This disclosure can be used for training the discriminator in GAN.