Patent Publication Number: US-2023156348-A1

Title: Parameter optimization system, parameter optimization method, and computer program

Description:
TECHNICAL FIELD 
     The present disclosure relates to a technical field of a parameter optimization system, a parameter optimization method, and a computer program that optimize a parameter of an image sensor. 
     BACKGROUND ART 
     As a system of this type, there is known a system that adjusts various parameters related to image pickup. For example, Patent Reference 1 discloses a technique in which an estimated image of a target object is generated based on an image dataset obtained by associating captured images with lighting parameters, and the lighting parameters are optimized through machine learning using the estimated image. Patent Reference 2 discloses a technique that optimizes an imaging parameter estimator by performing regression learning using, for teacher values, imaging parameters that maximize a category determination score. Patent Reference 3 discloses a technique in which, from a parameter table updated by using a predetermined learning algorithm, a recognition control parameter corresponding to an image pickup environment where a camera device is installed is selected and used. 
     CITATION LIST 
     Patent Literature 
     Patent Reference 1 
     Japanese Patent Laid-Open No. 2020-077326 A 
     Patent Reference 2 
     Japanese Patent Laid-Open No. 2019-012426 A 
     Patent Reference 3 
     Japanese Patent Laid-Open No. 2016-015116 A 
     SUMMARY 
     Technical Problem 
     The present disclosure improves the related techniques described above. 
     Solution to Problem 
     A parameter optimization system according to an example aspect of the present invention includes: an image sensor having at least one sensing parameter; a parameter setting unit configured to be able to change the sensing parameter; a score calculation unit configured to calculate a score from an image acquired by the image sensor; and a parameter determination unit configured to determine a right parameter value that is a value of the sensing parameter at which the score is relatively high, based on a value of the sensing parameter and the score corresponding to the value of the sensing parameter. 
     A parameter optimization method in a parameter optimization system for an image sensor having at least one sensing parameter that can be changed, the parameter optimization method according to an example aspect of the present invention includes: calculating a score from an image acquired by the image sensor; and determining a right parameter value that is a value of the sensing parameter at which the score is relatively high, based on a value of the sensing parameter and the score corresponding to the value of the sensing parameter. 
     A computer program according to an example aspect of the present invention causing a computer to operate as a parameter optimization system for an image sensor having at least one sensing parameter that can be changed, and operate such as to: calculate a score from an image acquired by the image sensor; and determine a right parameter value that is a value of the sensing parameter at which the score is relatively high, based on a value of the sensing parameter and the score corresponding to the value of the sensing parameter. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a block diagram showing a hardware configuration of a parameter optimization system according to a first embodiment. 
         FIG.  2    is a block diagram showing a functional configuration of the parameter optimization system according to the first embodiment. 
         FIG.  3    is a flowchart showing a flow of operation of the parameter optimization system according to the first embodiment. 
         FIG.  4    is a block diagram showing a functional configuration of a parameter optimization system according to a second embodiment. 
         FIG.  5    is a table showing examples of sensing parameters handled in the parameter optimization system according to the second embodiment. 
         FIG.  6    is a block diagram showing a functional configuration of a parameter optimization system according to a third embodiment. 
         FIG.  7    is a flowchart showing a flow of operation of the parameter optimization system according to the third embodiment. 
         FIG.  8    is a block diagram showing a functional configuration of a parameter optimization system according to a fourth embodiment. 
         FIG.  9    is a flowchart showing a flow of operation of the parameter optimization system according to the fourth embodiment. 
         FIG.  10    is a block diagram showing a functional configuration of a parameter optimization system according to a fifth embodiment. 
         FIG.  11    is a flowchart showing a flow of operation of the parameter optimization system according to the fifth embodiment. 
         FIG.  12    is a block diagram showing a functional configuration of a parameter optimization system according to a sixth embodiment. 
         FIG.  13    is a flowchart showing a flow of operation of the parameter optimization system according to the sixth embodiment. 
         FIG.  14    is a block diagram showing a functional configuration of a parameter optimization system according to a seventh embodiment. 
         FIG.  15    is a flowchart showing a flow of operation of the parameter optimization system according to the seventh embodiment. 
         FIG.  16    is a conceptual diagram showing examples of differences between lighting environments, in the parameter optimization system according to the seventh embodiment. 
         FIG.  17    is a block diagram showing a functional configuration of a parameter optimization system according to an eighth embodiment. 
         FIG.  18    is a flowchart showing a flow of operation of the parameter optimization system according to the eighth embodiment. 
         FIG.  19    is a diagram (version 1) showing an example of presentation by the parameter optimization system according to the eighth embodiment. 
         FIG.  20    is a diagram (version 2) showing an example of presentation by the parameter optimization system according to the eighth embodiment. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Hereinafter, embodiments of a parameter optimization system, a parameter optimization method, and a computer program will be described with reference to drawings. 
     First Embodiment 
     A parameter optimization system according to a first embodiment is described with reference to  FIGS.  1  to  3   . 
     (Hardware Configuration) 
     First, a hardware configuration of the parameter optimization system according to the first embodiment is described with reference to  FIG.  1   .  FIG.  1    is a block diagram showing the hardware configuration of the parameter optimization system according to the first embodiment. 
     As shown in  FIG.  1   , the parameter optimization system  10  according to the first embodiment includes a processor  11 , a RAM (Random Access Memory)  12 , a ROM (Read Only Memory)  13 , and a storage device  14 . The parameter optimization system  10  may include an input device  15  and an output device  16 . The parameter optimization system  10  further includes a camera  20 . The processor  11 , the RAM  12 , the ROM  13 , the storage device  14 , the input device  15 , the output device  16 , and the camera  20  are connected to each other through a data bus  17 . 
     The processor  11  reads a computer program. For example, the processor  11  is configured to read the computer program stored in at least one of the RAM  12 , the ROM  13 , and the storage device  14 . Alternatively, the processor  11  may read the computer program stored in a computer-readable recording medium, by using an undepicted recording media reader. The processor  11  may acquire (that is, may read) the computer program, via a network interface, from an undepicted device disposed outside of the parameter optimization system  10 . The processor  11  controls the RAM  12 , the storage device  14 , the input device  15 , and the output device  16  by executing the read computer program. In the present embodiment in particular, when the processor  11  executes the read computer program, a functional block for optimizing a sensing parameter of an image sensor is implemented in the processor  11 . Examples of the processor  11  include CPU (Central Processing Unit), GPU (Graphics Processing Unit), FPGA (field-programmable gate array), DSP (Demand-Side platform), and ASIC (Application Specific Integrated Circuit). The processor  11  may use one of the examples mentioned above, or may use two or more thereof in parallel. 
     The RAM  12  transitorily stores the computer program to be executed by the processor  11 . The RAM  12  transitorily stores data transitorily used by the processor  11  when the processor  11  executes the computer program. The RAM  12  may be, for example, a D-RAM (Dynamic RAM). 
     The ROM  13  stores the computer program to be executed by the processor  11 . The ROM  13  may store other fixed data. The ROM  13  may be, for example, a P-ROM (Programmable ROM). 
     The storage device  14  stores data that the parameter optimization system  10  retains for a long time. The storage device  14  may operate as a transitory storage device for the processor  11 . The storage device  14  may include at least one of, for example, a hard disk device, a magneto-optical device, an SSD (Solid State Drive), and a disk array device. 
     The input device  15  is a device that receives an input instruction from a user of the parameter optimization system  10 . The input device  15  may include at least one of, for example, a keyboard, a mouse, and a touch panel. The input device  15  may be a dedicated controller (operation terminal). The input device  15  may include a terminal (for example, a smartphone, a tablet terminal, or the like) owned by the user. The input device  15  may be, for example, a device that includes a microphone and can receive voice inputs. 
     The output device  16  is a device that outputs information related to the parameter optimization system  10  to the outside. For example, the output device  16  may be a display device (for example, a display) capable of displaying the information related to the parameter optimization system  10 . The display device here may be a TV monitor, a PC monitor, a monitor on a smartphone, a monitor on a tablet terminal, or a monitor on any other mobile terminal. The display device may be a large-sized monitor, a digital signage, or the like installed in various facilities such as stores. The output device  16  may be a device that outputs information in a form other than image. For example, the output device  16  may be a speaker that outputs the information related to the parameter optimization system  10  via voice. 
     The camera  20  is configured as a device capable of picking up an image. The camera  20  may be a visible-light camera, or may be a camera that picks up an image by using light other than the visible light, such as infrared camera. The camera  20  may be a camera that picks up still images, or may be a camera that picks up moving images. The camera  20  includes an image sensor that has a sensing parameter. Details of the image sensor will be described later. 
     (Functional Configuration) 
     Next, a functional configuration of the parameter optimization system  10  according to the first embodiment is described with reference to  FIG.  2   .  FIG.  2    is a block diagram showing the functional configuration of the parameter optimization system according to the first embodiment. 
     As shown in  FIG.  2   , the parameter optimization system  10  according to the first embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , and a parameter determination unit  140 . The image sensor  110  is a sensor included in the above-described camera  20  (see  FIG.  1   ). Each of the parameter setting unit  120 , the score calculation unit  130 , and the parameter determination unit  140  may be implemented by the above-described processor  11  (see  FIG.  1   ). 
     The image sensor  110  is configured as a sensor capable of acquiring an image. Although a specific configuration of the image sensor  110  is not particularly limited, the image sensor  110  may be configured as, for example, CCD (Charge Coupled Devices), or CMOS (Complementary Metal Oxide Semiconductor). The image sensor  110  has at least one sensing parameter (that is, a parameter related to image pickup). Specific examples of the sensing parameter are described in detail in another embodiment, which will be described later. 
     The parameter setting unit  120  is configured to be able to set (that is, change) the sensing parameter of the image sensor  110 . When the image sensor  110  has a plurality of sensing parameters, the parameter setting unit  120  may be able to collectively set the sensing parameters, or may be able to individually set the sensing parameters one by one. The parameter setting unit  120  is configured to be able to output information related to a current setting of the sensing parameter to the parameter determination unit  140 . 
     The score calculation unit  130  is configured to be able to calculate a score from an image acquired by the image sensor  110 . The “score” here is a quantified state of the image. For example, the score may be a value indicating quality of the image, or may be a value indicating a result of detecting or a result of recognizing an image-pickup target in the image. More specifically, the score may be a face recognition score indicating a degree of matching (degree of similarity) of a face in face recognition. A detailed description of a specific method of calculating the score is omitted because an existing technique can be adopted as appropriate. A configuration is made such that the score calculated by the score calculation unit  130  is outputted to the parameter determination unit  140 . 
     The parameter determination unit  140  is configured to be able to determine a right parameter value at which the score becomes relatively high, by using information related to the sensing parameter acquired from the parameter setting unit  120 , and information related to the score calculated by the score calculation unit  130 . A specific method of determining the right parameter value is described in detail in other embodiments, which will be described later. The right parameter value may be such a value of the sensing parameter that maximizes the score of an image in a current shooting environment. Alternatively, the right parameter value may be such a value of the sensing parameter that makes the score of an image higher than a predetermined threshold value. When the image sensor  110  has a plurality of sensing parameters, the parameter determination unit  140  may determine right parameter values for all of the sensing parameters, or may determine a right parameter value or right parameter values for one or some of the sensing parameters. 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the first embodiment is described with reference to  FIG.  3   .  FIG.  3    is a flowchart showing the flow of the operation of the parameter optimization system according to the first embodiment. 
     As shown in  FIG.  3   , when the parameter optimization system  10  according to the first embodiment starts operation, first, the image sensor  110  acquires an image (step S 11 ). 
     Subsequently, the score calculation unit  130  calculates a score from the image acquired by the image sensor  110  (step S 12 ). The score calculated by the score calculation unit  130  is outputted to the parameter determination unit  140 . The parameter determination unit  140  acquires, from the parameter setting unit  120 , information related to the sensing parameter at the time of picking up the image from which the score is calculated (step S 13 ). 
     Subsequently, the parameter determination unit  140  determines a right parameter value, based on the score and the information related to the sensing parameter corresponding to the score (step S 14 ). A method of using the right parameter value determined here is described in detail in the other embodiments described later. 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the first embodiment are described. 
     As described in  FIGS.  1  to  3   , in the parameter optimization system  10  according to the first embodiment, a right parameter value is determined based on the sensing parameter of the image sensor  110  and a score calculated from an image. With the configuration thus made, the sensing parameter can be appropriately set, and an image with a high score can be picked up. Accordingly, even if an initial value of the sensing parameter is an improper value for score calculation (for example, a value set to pick up an image that is easily visible to the human eye), an appropriate image for score calculation can be picked up by resetting the sensing parameter. Moreover, an appropriate image can also be picked up, irrespective of an environment (particularly, a lighting environment) when the image is picked up. 
     Second Embodiment 
     A parameter optimization system  10  according to a second embodiment is described with reference to  FIGS.  4  and  5   . Note that the second embodiment is different from the above-described first embodiment only in part of the configuration, and, for example, a hardware configuration and a flow of entire operation may be similar to those of the first embodiment (see  FIGS.  1  and  3   ). Accordingly, in the following, the part different from the first embodiment is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the second embodiment is described with reference to  FIG.  4   .  FIG.  4    is a block diagram showing the functional configuration of the parameter optimization system according to the second embodiment. Note that in  FIG.  4   , elements similar to the constitutional elements shown in  FIG.  2    are denoted by the same reference numbers as in  FIG.  2   . 
     As shown in  FIG.  4   , the parameter optimization system  10  according to the second embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , and a parameter determination unit  140 . The score calculation unit  130  according to the second embodiment in particular includes a neural network  135 . 
     The neural network  135  is configured as a trained model that calculates a score from an image. The neural network  135  may be, for example, CNN (Convolution Neural Network), RNN (Recurrent Neural Network), LSTM (Long Short Term Memory), Transformer, or GAN (Generative Adversarial Network). The neural network  135  may be configured as a face recognition model that performs face recognition using a face image. Alternatively, the neural network  135  may be configured as an object recognition model that recognizes an object existing in an image. 
     (Sensing Parameters) 
     Next, sensing parameters handled in the parameter optimization system according to the second embodiment are described with reference to  FIG.  5   .  FIG.  5    is a table showing examples of the sensing parameters handled in the parameter optimization system according to the second embodiment. 
     The sensing parameters shown in  FIG.  5    are parameters related to set values of an image pickup device, and are parameters for which gradients cannot be calculated by error backpropagation in the neural network. The parameter optimization system according to the second embodiment determines right parameter values for such sensing parameters. Specifically, such parameters include exposure time, analog gain, F number (aperture value), focal length (field of view), flash, and the like that are analog parameters. Moreover, such parameters include white balance, brightness, digital gain, denoising, and the like that are digital parameters. Note that the parameters listed here are examples, and any other sensing parameter may be included as long as the sensing parameter is a parameter for which a gradient cannot be calculated by error backpropagation in the neural network. 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the second embodiment are described. 
     As described in  FIGS.  4  and  5   , in the parameter optimization system  10  according to the second embodiment, a right parameter value is determined for a parameter for which a gradient cannot be calculated by error backpropagation in the neural network. In such a case, even if a neural network is provided, a right parameter value cannot be determined by using the neural network. However, in the parameter optimization system  10  according to the second embodiment, a right parameter value is determined based on a value of a sensing parameter of the image sensor  110  and a score calculated from an image, as described already. Accordingly, a right parameter value can be determined without using the neural network. In other words, a right parameter value can be appropriately determined also for a parameter for which a gradient cannot be calculated by error backpropagation in the neural network. 
     Third Embodiment 
     A parameter optimization system  10  according to a third embodiment is described with reference to  FIGS.  6  and  7   . Note that the third embodiment is different from the above-described first and second embodiments only in part of the configuration and operation, and other part may be similar to those of the first and second embodiments. Accordingly, in the following, the part different from each embodiment described already is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the third embodiment is described with reference to  FIG.  6   .  FIG.  6    is a block diagram showing the functional configuration of the parameter optimization system according to the third embodiment. Note that in  FIG.  6   , elements similar to the constitutional elements shown in  FIG.  2    are denoted by the same reference numbers as in  FIG.  2   . 
     As shown in  FIG.  6   , the parameter optimization system  10  according to the third embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , a parameter determination unit  140 , and an information storage unit  150 . In other words, the parameter optimization system  10  according to the third embodiment further includes the information storage unit  150 , in addition to the constitutional elements in the first embodiment (see  FIG.  2   ). Note that the information storage unit  150  may be implemented by, for example, the above-described storage device  14  (see  FIG.  1   ). 
     The information storage unit  150  is configured to be able to store a pair of a score calculated by the score calculation unit  130  and information related to a sensing parameter acquired from the parameter setting unit  120  (hereinafter, referred to as “pair information” as appropriate). The information storage unit  150  stores pair information each time a new image is acquired and a score is calculated. Accordingly, in the information storage unit  150 , a plurality of pairs of pair information are accumulated. The pair information stored in the information storage unit  150  is configured to be able to be read by the parameter determination unit  140  when necessary. 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the third embodiment is described with reference to  FIG.  7   .  FIG.  7    is a flowchart showing the flow of the operation of the parameter optimization system according to the third embodiment. Note that in  FIG.  7   , processes similar to the processes shown in  FIG.  3    are denoted by the same reference numbers as in  FIG.  3   . 
     As shown in  FIG.  7   , when the parameter optimization system  10  according to the third embodiment starts operation, first, the image sensor  110  acquires an image (step S 11 ). The score calculation unit  130  calculates a score from the image acquired by the image sensor  110  (step S 12 ). 
     Subsequently, the information storage unit  150  stores a pair of the score calculated by the score calculation unit  130  and information related to the sensing parameter acquired from the parameter setting unit  120  (that is, pair information) (step S 31 ). 
     Thereafter, the parameter optimization system  10  determines whether or not to finish accumulating pair information (step S 32 ). It may be determined whether or not to finish accumulating pair information, for example, based on whether or not the number of accumulated pairs of pair information reaches a predetermined value The “predetermined value” in such a case may be a value preset through preliminary simulation or the like, as a sufficient number of pairs of pair information to determine a right parameter value in step S 33 , which will be described later. Alternatively, it may be determined whether or not to finish accumulating pair information, based on whether or not pair information corresponding to all prepared images is accumulated. 
     When it is determined not to finish accumulating pair information (step S 32 : NO), the parameter optimization system  10  according to the third embodiment repeats the processes from step S 11 . Thus, pair information is accumulated in the information storage unit  150 . When it is determined to finish accumulating pair information (step S 32 : YES), the parameter determination unit  140  determines a right parameter value, based on the pair information accumulated in the information storage unit  150  (step S 33 ). 
     Note that the above-described series of processes is performed beforehand, typically prior to actual operation of a system using the image sensor  110  (that is, execution of a process using a score, such as face recognition). The right parameter value determined by the parameter determination unit  140  may be reflected by the parameter setting unit  120  immediately after determined. In other words, when the right parameter value is determined, the sensing parameter of the image sensor  110  may be changed to the right parameter value. Alternatively, the right parameter value determined by the parameter determination unit  140  may be reflected by the parameter setting unit  120  at a time of the actual operation mentioned above. In other words, the determined right parameter value may be reflected in the sensing parameter of the image sensor  110  when necessary, without being immediately reflected. 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the third embodiment are described. 
     As described in  FIGS.  6  and  7   , in the parameter optimization system  10  according to the third embodiment, a right parameter value is determined based on pair information accumulated in the information storage unit  150 . With the configuration thus made, since a right parameter value can be determined by using a plurality of pairs of pair information (that is, a plurality of scores and a plurality of values of the sensing parameter) accumulated in the information storage unit  150 , the right parameter value can be determined as a more appropriate value than in cases where a right parameter value is determined from less information. 
     Fourth Embodiment 
     A parameter optimization system  10  according to a fourth embodiment is described with reference to  FIGS.  8  and  9   . Note that the fourth embodiment is different from the above-described first to third embodiments only in part of the configuration and operation, and other part may be similar to those of the first to third embodiments. Accordingly, in the following, the part different from each embodiment described already is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the fourth embodiment is described with reference to  FIG.  8   .  FIG.  8    is a block diagram showing the functional configuration of the parameter optimization system according to the fourth embodiment. Note that in  FIG.  8   , elements similar to the constitutional elements shown in  FIG.  2    are denoted by the same reference numbers as in  FIG.  2   . 
     As shown in  FIG.  8   , the parameter optimization system  10  according to the fourth embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , a parameter determination unit  140 , and a score storage unit  160 . In other words, the parameter optimization system  10  according to the fourth embodiment further includes the score storage unit  160 , in addition to the constitutional elements in the first embodiment (see  FIG.  2   ). Note that the score storage unit  160  may be implemented by, for example, the above-described storage device  14  (see  FIG.  1   ). Moreover, the parameter determination unit  140  according to the fourth embodiment includes a gradient calculation unit  145 . 
     The score storage unit  160  is configured to be able to store a score calculated by the score calculation unit  130  and a value of a sensing parameter (hereinafter, simply referred to as a “parameter value” in some cases) at a time of picking up an image from which the score is calculated. In the parameter optimization system  10  according to the fourth embodiment, since images are acquired by the image sensor  100  sequentially (for example, in real time), a score is calculated by the score calculation unit  130  each time a new image is acquired. The score storage unit  160  accumulates thus sequentially calculated scores and parameter values. However, the score storage unit  160  may be configured to be able to store only two consecutively calculated scores and two parameter values. In other words, the score storage unit  160  may be able to store at least two scores and two parameter values. Moreover, the score storage unit  160  may include a function of deleting a score and a parameter value that no longer need to be stored, as appropriate. The score and the parameter value stored in the score storage unit  160  are configured to be able to be read by the parameter determination unit  140  (more specifically, the gradient calculation unit  145 ) when necessary. 
     The gradient calculation unit  145  is configured to be able to calculate a parameter gradient from a plurality of scores and parameter values stored in the score storage unit  160 . The gradient calculation unit  145  may calculate the parameter gradient by calculating differences between the plurality of scores and between the plurality of parameter values, and dividing the score difference by an amount of change in the parameter values. The gradient calculation unit  145  may calculate the parameter gradient from two scores and two parameter values, or may calculate the parameter gradient from three or more scores and three or more parameter values. The parameter gradient calculated by the gradient calculation unit  145  is used in determination of a right parameter value by the parameter determination unit  140 . 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the fourth embodiment is described with reference to  FIG.  9   .  FIG.  9    is a flowchart showing the flow of the operation of the parameter optimization system according to the fourth embodiment. Note that in  FIG.  9   , processes similar to the processes shown in  FIG.  3    are denoted by the same reference numbers as in  FIG.  3   . 
     As shown in  FIG.  9   , when the parameter optimization system  10  according to the fourth embodiment starts operation, first, the image sensor  110  acquires an image (step S 11 ). Note that in the parameter optimization system  10  according to the fourth embodiment, the image sensor  110  sequentially acquires images. For example, the image sensor  110  is configured as an image sensor of a camera that picks up moving images, and consecutively acquires a plurality of frames of images. 
     Subsequently, the score calculation unit  130  calculates a score from each image acquired by the image sensor  110  (step S 12 ). The score storage unit  160  stores the score calculated by the score calculation unit  130  and a parameter value (step S 41 ). 
     Thereafter, the gradient calculation unit  145  in the parameter determination unit  140  calculates a parameter gradient from the plurality of scores and parameter values stored in the score storage unit  160  (step S 42 ). The parameter determination unit  140  determines a right parameter value, based on the parameter gradient calculated by the gradient calculation unit  145  (step S 43 ). 
     Subsequently, the parameter setting unit  120  updates (changes) the sensing parameter of the image sensor  110 , according to the right parameter value determined by the parameter determination unit  140  (step S 44 ). Accordingly, in the parameter optimization system  10  according to the fourth embodiment, the sensing parameter of the image sensor  110  is updated each time a new right parameter value is determined. 
     Subsequently, the parameter optimization system  10  according to the fourth embodiment determines whether or not acquisition of an image by the image sensor  110  is to be finished (step S 45 ). When acquisition of an image is to be finished (step S 45 : YES), the series of processes is terminated immediately. When acquisition of an image is not to be finished (step S 45 : NO), the parameter optimization system  10  according to the fourth embodiment repeats the processes again from step S 11 . Accordingly, while images are acquired by the image sensor  110  (that is, while it is continued to shoot images), the processes of determining a right parameter value from a parameter gradient and updating the sensing parameter of the image sensor  110  are executed repeatedly. 
     Note that the parameter optimization system  10  according to the fourth embodiment may be configured to stop the above-described series of processes when right parameter values converge to a specific value (in other words, when it becomes almost meaningless to update the sensing parameter) even if acquisition of images is not to be finished. The parameter optimization system  10  according to the fourth embodiment may be configured to start the series of processes again when a situation requires that the sensing parameter of the image sensor be updated again (for example, when a lighting environment around the image sensor  110  has changed, or the like) after the series of processes is stopped. 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the fourth embodiment are described. 
     As described in  FIGS.  8  and  9   , in the parameter optimization system  10  according to the fourth embodiment, a right parameter value is determined according to a sequentially calculated parameter gradient, and each time such a new right parameter value is determined, the sensing parameter of the image sensor  110  is updated. With the configuration thus made, an optimal right parameter value can be searched for while images are sequentially acquired. Accordingly, for example, when moving images are shot, appropriated shooting can be realized while the sensing parameter adapted to the then environment is reflected at all times. Such an effect works remarkably, for example, when images are consecutively picked up in a situation where a lighting environment around the image sensor  110  changes over time (for example, from afternoon to evening, from evening to night, or the like). 
     Fifth Embodiment 
     A parameter optimization system  10  according to a fifth embodiment is described with reference to  FIGS.  10  and  11   . The fifth embodiment is different from the above-described fourth embodiment only in part of the configuration and operation, and other part may be similar to those of the fourth embodiment. Accordingly, in the following, the part different from each embodiment described already is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the fifth embodiment is described with reference to  FIG.  10   .  FIG.  10    is a block diagram showing the functional configuration of the parameter optimization system according to the fifth embodiment. Note that in  FIG.  10   , elements similar to the constitutional elements shown in  FIG.  8    are denoted by the same reference numbers as in  FIG.  8   . 
     As shown in  FIG.  10   , the parameter optimization system  10  according to the fifth embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , a parameter determination unit  140 , a score storage unit  160 , and a noise amount calculation unit  170 . In other words, the parameter optimization system  10  according to the fifth embodiment further includes the noise amount calculation unit  170 , in addition to the constitutional elements in the fourth embodiment (see  FIG.  8   ). Note that the noise amount calculation unit  170  may be implemented by, for example, the above-described processor  11  (see  FIG.  1   ). 
     The noise amount calculation unit  170  is configured to be able to calculate an amount of noise included in a score calculated by the score calculation unit  130 . The “amount of noise” here is an amount of noise that is, due to a noise in an image acquired by the image sensor  110 , included in a score calculated from the image. Although a method of calculating the amount of noise is not particularly limited, for example, a plurality of images may be acquired by the image sensor  110  beforehand, and the amount of noise may be calculated by using a standard deviation or the like obtained from the plurality of images. A configuration is made such that the amount of noise calculated by the noise amount calculation unit  170  is outputted to the parameter determination unit  140 . 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the fifth embodiment is described with reference to  FIG.  11   .  FIG.  11    is a flowchart showing the flow of the operation of the parameter optimization system according to the fifth embodiment. Note that in  FIG.  11   , processes similar to the processes shown in  FIG.  9    are denoted by the same reference numbers as in  FIG.  9   . 
     As shown in  FIG.  11   , when the parameter optimization system  10  according to the fifth embodiment starts operation, first, the image sensor  110  acquires an image (step S 11 ). Note that in the parameter optimization system  10  according to the fifth embodiment, the image sensor  110  sequentially acquires images, as in the fourth embodiment. For example, the image sensor  110  is configured as an image sensor of a camera that picks up moving images, and consecutively acquires a plurality of frames of images. 
     Subsequently, the score calculation unit  130  calculates a score from each image acquired by the image sensor  110  (step S 12 ). The score storage unit  160  stores the score calculated by the score calculation unit  130  and a parameter value (step S 41 ). 
     Subsequently, the noise amount calculation unit  170  calculates an amount of noise in the score (step S 51 ). Note that the calculation of an amount of noise may be executed before the calculation of a score in step S 12 , or the storage of a score in step S 41 . When an amount of noise is calculated from a different image from an image acquired in step S 11 , the process of calculating an amount of noise may be executed before step S 11 . In other words, the process of calculating an amount of noise may be executed before the series of processes in  FIG.  11    is started. 
     Subsequently, the parameter determination unit  140  determines whether or not a score difference used when the gradient calculation unit  145  calculates a parameter gradient is larger than the amount of noise calculated by the noise amount calculation unit  170  (step S 52 ). 
     When the score difference is larger than the amount of noise (step S 52 : YES), the gradient calculation unit  145  in the parameter determination unit  140  calculates a parameter gradient from a plurality of scores and parameter values stored in the score storage unit  160  (step S 42 ). The parameter determination unit  140  determines a right parameter value, based on the parameter gradient calculated by the gradient calculation unit  145  (step S 43 ). Thereafter, the parameter setting unit  120  updates the sensing parameter of the image sensor  110 , according to the right parameter value determined by the parameter determination unit  140  (step S 44 ). 
     In contrast, when the score difference is smaller than the amount of noise (step S 52 : NO), the above-described processes in steps S 42  to S 44  are omitted. In other words, in such a case, the process of calculating a parameter gradient, the process of determining a right parameter value based on the parameter gradient, and the process of updating the sensing parameter according to the right parameter value are not executed. 
     Note that the process in step S 52  of determining whether or not the score difference is larger than the amount of noise may be executed after the calculation of a parameter gradient in step S 42  is executed. In such a case, when the score difference is smaller than the amount of noise, the processes in steps S 43  and S 44  are omitted. In other words, there are some cases where although a parameter gradient is calculated, the process of determining a right parameter value and the process of updating the sensing parameter are not executed. Moreover, the process in step S 52  of determining whether or not the score difference is larger than the amount of noise may be executed after the determination of a right parameter value in step S 43  is executed. In such a case, when the score difference is smaller than the amount of noise, only the process in step S 44  is omitted. In other words, there are some cases where although the process of calculating a parameter gradient and the process of determining a right parameter value are executed, the updating of the sensing parameter according to the right parameter value is not executed. 
     Subsequently, the parameter optimization system  10  according to the fifth embodiment determines whether or not acquisition of an image by the image sensor  110  is to be finished (step S 45 ). When acquisition of an image is to be finished (step S 45 : YES), the series of processes is terminated immediately. When acquisition of an image is not to be finished (step S 45 : NO), the parameter optimization system  10  according to the fifth embodiment repeats the processes again from step S 11 . 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the fifth embodiment are described. 
     As described in  FIGS.  10  and  11   , in the parameter optimization system  10  according to the fifth embodiment, a score difference and an amount of noise are compared, and it is determined, depending on a result of the comparison, whether or not to update the sensing parameter. With the configuration thus made, the sensing parameter can be updated after significance of the score difference is determined based on the amount of noise. Specifically, when the score difference is larger than the amount of noise, it can be determined that the score difference has significance (is not an error caused by noise), and the sensing parameter can be updated. When the score difference is smaller than the amount of noise, it can be determined that the score difference has no significance (is an error caused by noise), and the updating of the sensing parameter can be omitted. 
     Sixth Embodiment 
     A parameter optimization system  10  according to a sixth embodiment is described with reference to  FIGS.  12  and  13   . Note that the sixth embodiment is different from the above-described first to fifth embodiments only in part of the configuration and operation, and other part may be similar to those of the first to fifth embodiments. Accordingly, in the following, the part different from each embodiment described already is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the sixth embodiment is described with reference to  FIG.  12   .  FIG.  12    is a block diagram showing the functional configuration of the parameter optimization system according to the sixth embodiment. Note that in  FIG.  12   , elements similar to the constituent elements shown in  FIG.  2    are denoted by the same reference numbers as in  FIG.  2   . 
     As shown in  FIG.  12   , the parameter optimization system  10  according to the sixth embodiment includes, as constituent elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , and a parameter determination unit  140 . The parameter setting unit  120  according to the sixth embodiment in particular incudes a detection determination unit  125 . 
     The detection determination unit  125  is configured to be able to determine, based on a score calculated by the score calculation unit  130 , whether or not an image-pickup target is detected from an image. Specifically, the detection determination unit  125  is configured to be able to determine whether or not an image-pickup target is detected from an image, based on whether or not a score calculated by the score calculation unit  130  is a value corresponding to a state in which the image-pickup target is not detected. Note that the score calculated by the score calculation unit  130  according to the sixth embodiment is a value that changes according to an image-pickup target detected from an image. For example, the score calculation unit  130  detects a human face from an image, and calculates a score indicating whether or not the face is a registered face. In such a case, the score calculated by the score calculation unit  130  changes according to, for example, a degree of matching between the face detected from the image and the registered face. However, when no human face is detected, the score is “0”. In such an example, the detection determination unit  125  can determine whether or not a face is detected, based on whether the calculated score is “0” or “other”. 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the sixth embodiment is described with reference to  FIG.  13   .  FIG.  13    is a flowchart showing the flow of the operation of the parameter optimization system according to the sixth embodiment. Note that in  FIG.  13   , processes similar to the processes shown in  FIG.  3    are denoted by the same reference numbers as in  FIG.  3   . 
     As shown in  FIG.  13   , when the parameter optimization system  10  according to the sixth embodiment starts operation, first, the image sensor  110  acquires an image (step S 11 ). 
     Subsequently, the score calculation unit  130  calculates a score from the image acquired by the image sensor  110  (step S 12 ). The score calculated by the score calculation unit  130  is outputted to the parameter determination unit  140  and the detection determination unit  125 . 
     Subsequently, the detection determination unit  125  determines, based on the score calculated by the score calculation unit  130 , whether or not an image-pickup target is detected from the image (step S 61 ). When it is determined that an image-pickup target is not detected from the image (step S 61 : NO), the parameter setting unit  120  makes an adjustment, by changing a sensing parameter of the image sensor  110 , such that the image-pickup target can be detected from the image acquired by the image sensor  110  (step S 62 ). In other words, the parameter setting unit  120  adjusts the sensing parameter such that it becomes easy to detect the image-pickup target. For example, when the image is too dark to detect the image-pickup target, the parameter setting unit  120  may make an adjustment, by changing a parameter related to brightness among sensing parameters, such that the image acquired by the image sensor  110  becomes brighter. When the image is too bright to detect the image-pickup target, the parameter setting unit  120  may make an adjustment, by changing the parameter related to brightness among the sensing parameters, such that the image acquired by the image sensor  110  becomes darker. 
     Thereafter, the parameter optimization system  10  according to the sixth embodiment repeats the processes again from step S 11 . Accordingly, when a state continues in which the image-pickup target cannot be detected from an image, the sensing parameter is further changed. For example, when the sensing parameter is adjusted such that the image becomes brighter, the image is adjusted to be further brighter. Note that when the sensing parameter is further changed, the first changed sensing parameter may be changed to be greater, or a different sensing parameter from the first changed sensing parameter may be changed. 
     Incidentally, when no image-pickup target is ever included in an image, an image-pickup target will never be detected from the image even if the sensing parameter is adjusted in whatever manner. Accordingly, when an image-pickup target cannot be detected even after the sensing parameter is changed to a certain value or greater (for example, even after the image is made to have more brightness corresponding to the certain value or greater), the adjusted sensing parameter may be set back to an initial value, to shift to a state in which an external execution command or a periodical execution command is waited for. 
     In contrast, when it is determined that an image-pickup target is detected from the image (step S 61 : YES), the parameter determination unit  140  acquires, from the parameter setting unit  120 , information related to the sensing parameter at a time of picking up the image from which the score is calculated (step S 13 ). The parameter determination unit  140  determines a right parameter value, based on the score and the information related to the sensing parameter corresponding to the score (step S 14 ). 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the sixth embodiment are described. 
     As described in  FIGS.  12  and  13   , in the parameter optimization system  10  according to the sixth embodiment, when an image-pickup target is not detected from an image, an adjustment is made, by adjusting the sensing parameter, such that the image-pickup target can be detected from the image. With the configuration thus made, a situation can be prevented in which a right parameter value cannot be determined due to no image-pickup target being detected from an image. Specifically, when an image-pickup target is not detected from an image, the score is “0”, or the score substantially cannot be calculated. Accordingly, when an image-pickup target cannot be detected from an image, a parameter gradient cannot be calculated. In such a situation, it is difficult to determine an appropriate right parameter value. However, in the present embodiment, when an image-pickup target is not detected from an image, an adjustment is made to bring about a state in which it is easy to detect the image-pickup target from the image (for example, an adjustment is made such that the image becomes brighter). Accordingly, it can be assured that an image-pickup target is detected from an image, and an appropriate right parameter value can be determined. 
     Seventh Embodiment 
     A parameter optimization system  10  according to a seventh embodiment is described with reference to  FIGS.  14  to  16   . Note that the seventh embodiment is different from the above-described first to sixth embodiments only in part of the configuration and operation, and other part may be similar to those of the first to sixth embodiments. Accordingly, in the following, the part different from each embodiment described already is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the seventh embodiment is described with reference to  FIG.  14   .  FIG.  14    is a block diagram showing the functional configuration of the parameter optimization system according to the seventh embodiment. Note that in  FIG.  14   , elements similar to the constitutional elements shown in  FIG.  2    are denoted by the same reference numbers as in  FIG.  2   . 
     As shown in  FIG.  14   , the parameter optimization system  10  according to the seventh embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , a parameter determination unit  140 , and a parameter storage unit  180 . In other words, the parameter optimization system  10  according to the seventh embodiment further includes the parameter storage unit  180 , in addition to the constitutional elements in the first embodiment (see  FIG.  2   ). Note that the parameter storage unit  180  may be implemented by, for example, the above-described storage device  14  (see  FIG.  1   ). 
     The parameter storage unit  180  is configured to be able to store right parameter values determined by the parameter determination unit  140 , in a plurality of patterns. More specifically, the parameter storage unit  180  is configured to be able to store the plurality of patterns of right parameter values corresponding to light environments, respectively. The right parameter values stored in the parameter storage unit  180  may be in two patterns, or three or more patterns. 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the seventh embodiment is described with reference to  FIG.  15   .  FIG.  15    is a flowchart showing the flow of the operation of the parameter optimization system according to the seventh embodiment. Note that in  FIG.  15   , processes similar to the processes shown in  FIG.  3    are denoted by the same reference numbers as in  FIG.  3   . 
     As shown in  FIG.  15   , when the parameter optimization system  10  according to the seventh embodiment starts operation, first, the image sensor  110  acquires an image (step S 11 ). 
     Subsequently, the score calculation unit  130  calculates a score from the image acquired by the image sensor  110  (step S 12 ). The score calculated by the score calculation unit  130  is outputted to the parameter determination unit  140 . The parameter determination unit  140  acquires, from the parameter setting unit  120 , information related to a sensing parameter at a time of picking up the image from which the score is calculated (step S 13 ). 
     Subsequently, the parameter determination unit  140  determines a right parameter value, based on the score and the information related the sensing parameter corresponding to the score (step S 14 ). Thereafter, the parameter storage unit  180  stores the right parameter value determined by the parameter determination unit  140  (step S 71 ). In other words, the parameter storage unit  180  stores one pattern of the right parameter value corresponding to one lighting environment. 
     Subsequently, the parameter optimization system  10  according to the seventh embodiment determines whether or not patterns of right parameter values corresponding to all lighting environments are stored (step S 72 ). In other words, it is determined whether or not a preset number of right parameter values are stored. 
     When patterns of right parameter values corresponding to all lighting environments are stored (step S 72 : YES), the series of processes is terminated. When patterns of right parameter values corresponding to all lighting environments are not stored (step S 72 : NO), the lighting environment is changed to another one (step S 73 ), and the processes are repeated again from step S 11 . By repeating the processes in steps S 11  to S 18  in such a manner, a plurality of patterns of right parameter values corresponding to different lighting environments are stored in the parameter storage unit  180 . Note that the change of the lighting environment in step S 73  may be implemented, for example, by changing intensity of illumination, or with passage of time (for example, by waiting for time to pass from afternoon to night). 
     (Specific Examples of Lighting Environment) 
     Next, a right parameter value determined for each lighting environment is described specifically with reference to  FIG.  16   .  FIG.  16    is a conceptual diagram showing examples of differences among lighting environments, in the parameter optimization system according to the seventh embodiment. 
     As shown in  FIG.  16   , the parameter optimization system  10  according to the seventh embodiment may be configured such that the parameter storage unit  180  stores right parameter values corresponding to three lighting environments, namely, lighting environment A, lighting environment B, and lighting environment C. More specifically, the parameter storage unit  180  may store three patterns of: a right parameter value A corresponding to the lighting environment A that is sunny and bright; a right parameter value B corresponding to the lighting environment B that is cloudy and gray; and a right parameter value C corresponding to the lighting environment C that is dark at night. 
     Note that the above-described examples are only examples, and a plurality of patterns of right parameter values corresponding to other lighting environments may be determined. Although it is assumed in the above-described examples that images are picked up outdoors, when images are picked up indoors, a plurality of patterns of right parameter values may be determined, for example, according to intensities of illumination or the like. 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the seventh embodiment are described. 
     As described in  FIGS.  14  to  16   , in the parameter optimization system  10  according to the seventh embodiment, a plurality of patterns of right parameter values are stored according to different lighting environments. With the configuration thus made, an image can be appropriately picked up by selecting an appropriate right parameter value from the plurality of patterns, based on a lighting environment at a time of picking up the image. Accordingly, an appropriate image can be picked up relatively easily, without determining a new right parameter value at a timing of picking up an image. 
     Eighth Embodiment 
     A parameter optimization system  10  according to an eighth embodiment is described with reference to  FIGS.  17  to  20   . Note that the eighth embodiment is different from the above-described seventh embodiment only in part of the configuration and operation, and other part may be similar to those of the seventh embodiment. Accordingly, in the following, the part different from each embodiment described already is described in detail, and a description of other overlapping part is omitted as appropriate. 
     (Functional Configuration) 
     First, a functional configuration of the parameter optimization system  10  according to the eighth embodiment is described with reference to  FIG.  17   .  FIG.  17    is a block diagram showing the functional configuration of the parameter optimization system according to the eighth embodiment. Note that in  FIG.  17   , elements similar to the constitutional elements shown in  FIG.  14    are denoted by the same reference numbers as in  FIG.  14   . 
     As shown in  FIG.  17   , the parameter optimization system  10  according to the eighth embodiment includes, as constitutional elements for implementing functions of the parameter optimization system  10 , an image sensor  110 , a parameter setting unit  120 , a score calculation unit  130 , a parameter determination unit  140 , a parameter storage unit  180 , a pattern presentation unit  190 , and a selection operation detection unit  200 . In other words, the parameter optimization system  10  according to the eighth embodiment further includes the pattern presentation unit  190  and the selection operation detection unit  200 , in addition to the components in the seventh embodiment (see  FIG.  14   ). Each of the pattern presentation unit  190  and the selection operation detection unit  200  may be implemented by, for example, the above-described processor  11  (see  FIG.  1   ). The pattern presentation unit  190  may include the above-described output device  16  (see  FIG.  1   ). The selection operation detection unit  200  may include the above-described input device  15  (see  FIG.  1   ). 
     The pattern presentation unit  190  is configured to be able to present a plurality of patterns of right parameter values stored in the parameter storage unit  180 , to a user of the system. The pattern presentation unit  190  may present the plurality of patterns of right parameter values, for example, by displaying images on a display. Alternatively, the pattern presentation unit  190  may present the plurality of patterns of right parameter values by using voice through a speaker or the like. 
     The selection operation detection unit  200  is configured to be able to detect a selection operation (that is, an operation of selecting one pattern from among the presented patterns) made by a user to which the plurality of patterns of right parameter values are presented by the pattern presentation unit  190 . For example, the selection operation detection unit  200  may be configured to be able to detect an operation of a terminal performed by the user. A configuration is made such that information related to the selection operation detected by the selection operation detection unit  200  (for example, information related to a pattern selected by the user) is outputted to the parameter setting unit  120 . 
     (Flow of Operation) 
     Next, a flow of operation of the parameter optimization system  10  according to the eighth embodiment is described with reference to  FIG.  18   .  FIG.  18    is a flowchart showing the flow of the operation of the parameter optimization system according to the eighth embodiment. Note that a series of processes shown in  FIG.  18    is processes executed after a plurality of patterns of right parameter values are determined. Processes before the plurality of patterns of right parameter values are determined may be similar to the processes in the seventh embodiment (see  FIG.  15   ). 
     As shown in  FIG.  18   , when the parameter optimization system  10  according to the eighth embodiment starts operation, first, the pattern presentation unit  190  presents the plurality of patterns of right parameter values stored in the parameter storage unit  180  to a user of the system (step S 81 ). 
     Subsequently, the selection operation detection unit  200  detects a selection operation made by the user (step S 82 ). Note that when a selection operation made by the user is not detected (for example, no selection operation is detected when a predetermined time period has passed since the presentation), notification may be given to prompt the user to make a selection operation. Alternatively, any one pattern may be automatically selected, without waiting for the user to make a selection operation. 
     Subsequently, in response to the selection operation detected by the selection operation detection unit  200 , the parameter setting unit  120  changes the sensing parameter of the image sensor  110 . Specifically, the parameter setting unit  120  changes the sensing parameter of the image sensor  110  such that the sensing parameter has a right parameter value in the pattern selected through the selection operation by the user (step S 83 ). 
     Note that the selection operation detection unit  200  may continue to detect a selection operation also after the sensing parameter is changed in step S 83 . When a new selection operation made by the user is detected, the parameter setting unit  120  may change the sensing parameter again in response to the newly detected selection operation. As described above, the detection of a selection operation and the change of the sensing parameter may be executed a plurality of times. 
     (UI) 
     Next, UIs (User Interfaces) applicable to the parameter optimization system  10  according to the eighth embodiment are described specifically with reference to  FIGS.  19  and  20   .  FIG.  19    is a diagram (version 1) showing an example of presentation by the parameter optimization system according to the eighth embodiment.  FIG.  20    is a diagram (version 2) showing an example of presentation by the parameter optimization system according to the eighth embodiment. Note that  FIGS.  19  and  20    show examples of presentation in a case where a human face is detected from an image and a face recognition score is calculated. 
     In the example shown in  FIG.  19   , a shot image (moving image) is displayed in an area on a left side of a screen. On the image, a rectangular region including a detected face, and a calculated face recognition score are displayed in a superimposed manner. Moreover, buttons for setting the sensing parameter are provided in an area on a right side of the screen. Specifically, four buttons of “auto”, “lighting environment A”, “lighting environment B”, and “lighting environment C” are arranged in the same order from the top. A user can select one pattern from among a plurality of patterns of right parameter values (that is, make a selection operation) by clicking on any one of the four buttons. 
     Note that the example shown in  FIG.  19    is in a state where the user selects “lighting environment A” (a color of the button is different from those of the others). Accordingly, at a timing shown in  FIG.  19   , images are picked up with a right parameter value corresponding to the lighting environment A. When the user clicks on the button of “lighting environment B”, the sensing parameter of the image sensor  110  is changed to a right parameter value corresponding to the lighting environment B. Similarly, when the user clicks on the button of “lighting environment C”, the sensing parameter of the image sensor  110  is changed to a right parameter value corresponding to the lighting environment C. Note that when the user clicks on the button of “auto”, the sensing parameter of the image sensor  110  is automatically changed to the right parameter value corresponding to any one of the lighting environments A, B, and C, or another random value of the sensing parameter. 
     In the example shown in  FIG.  20   , a graph indicating changes over time in the score is displayed in a lower left area on a screen. When the graph is viewed in a time direction, it can be seen that a user first selects “auto”, next selects “lighting environment A (right parameter value A)”, then selects “lighting environment B (right parameter value B)”, and lastly selects “lighting environment C (right parameter value C)”. When score values in the individual patterns are compared to each other, it can be seen that the score is highest when the lighting environment A is selected. Accordingly, the user can easily find that the right parameter value A corresponding to the lighting environment A ought to be selected in order to make the score higher. 
     (Technical Effects) 
     Next, technical effects achieved by the parameter optimization system  10  according to the eighth embodiment are described. 
     As described in  FIGS.  17  to  20   , in the parameter optimization system  10  according to the eighth embodiment, a plurality of patterns of right parameter values are presented to a user, and the sensing parameter of the image sensor  110  is changed according to a selection operation made by the user. With the configuration thus made, since a right parameter value can be selected by the user, an image can be picked up with an appropriate value of the sensing parameter even in a case where, for example, it is difficult to automatically select a right parameter value. Moreover, if a configuration is made such that changes in images are presented to a user in real time as in the UIs shown in  FIGS.  19  and  20   , a right pattern can be selected more appropriately. 
     A processing method in which a program causing the components in each of the above-described embodiments to operate such as to implement the functions of the embodiment is recorded on a recording medium, and the program recorded on the recording medium is read as codes and executed on a computer, is also included in the scope of each embodiment. In other words, a computer-readable recording medium is also included in the scope of each embodiment. Moreover, needless to mention the recording medium on which the above-described program is recorded, the program itself is also included in each embodiment. 
     For the recording medium, for example, a Floppy® disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, or a ROM can be used. Moreover, the systems and the like are not limited to those that execute the processes based on the program alone recorded on the recording medium, but those that execute the processes by operating on an OS in cooperation with other software and functionality of an add-in board are also included in the scope of each embodiment. 
     Changes can be made to the present disclosure as appropriate within a scope that does not conflict with the gist or the principle of the invention that can be read from the claims and the specification in its entirety, and a parameter optimization system, a parameter optimization method, and a computer program with such changes are also incorporated within the technical idea of the present disclosure. 
     Supplementary Notes 
     The above-described embodiments can also be further described as, but are not limited to, the following supplements. 
     (Supplementary Note 1) 
     A parameter optimization system described in Supplementary Note 1 is a parameter optimization system including: an image sensor having at least one sensing parameter; a parameter setting unit configured to be able to change the sensing parameter; a score calculation unit configured to calculate a score from an image acquired by the image sensor; and a parameter determination unit configured to determine a right parameter value that is a value of the sensing parameter at which the score is relatively high, based on a value of the sensing parameter and the score corresponding to the value of the sensing parameter. 
     (Supplementary Note 2) 
     A parameter optimization system described in Supplementary Note 2 is the parameter optimization system described in Supplementary Note 1, wherein the score calculation unit includes a neural network, and the sensing parameter is a parameter related to a setting value of an image pickup device. 
     score corresponding to the value of the sensing parameter. 
     (Supplementary Note 3) 
     A parameter optimization system described in Supplementary Note 3 is the parameter optimization system described in Supplementary Note 1 or 2, further comprising an information storage unit configured to store, as pair information, the value of the sensing parameter and the score corresponding to the value of the sensing parameter in association with each other, wherein the parameter determination unit is configured to determine the right parameter value, based on the pair information stored in the information storage unit. 
     (Supplementary Note 4) 
     A parameter optimization system described in Supplementary Note 4 is the parameter optimization system described in any one of Supplementary Notes 1 to 3, wherein the score calculation unit is configured to calculate the score from each of a plurality of images sequentially acquired, the parameter determination unit is configured to determine the right parameter value, based on a gradient of the sensing parameter that is calculated from a difference between the scores for the plurality of images and a difference between values of the sensing parameter, and the parameter setting unit is configured to change the sensing parameter such that the sensing parameter has the right parameter value newly determined. 
     (Supplementary Note 5) 
     A parameter optimization system described in Supplementary Note 5 is the parameter optimization system described in Supplementary Note 4, further comprising a noise calculation unit configured to calculate an amount of noise included in the score, wherein the parameter determination unit is configured not to newly determine the right parameter value when the difference between the scores is smaller than the amount of noise, and to newly determine the right parameter value when the difference between the scores is larger than the amount of noise. 
     (Supplementary Note 6) 
     A parameter optimization system described in Supplementary Note 6 is the parameter optimization system described in any one of Supplementary Notes 1 to 5, wherein the score is related to an image-pickup target included in the image, and the parameter setting unit is configured to change the sensing parameter such that the image-pickup target can be detected from the image when the score is a value corresponding to a state in which the image-pickup target is not detected. 
     (Supplementary Note 7) 
     A parameter optimization system described in Supplementary Note 7 is the parameter optimization system described in any one of Supplementary Notes 1 to 6, wherein the parameter determination unit is configured to determine a plurality of patterns of the right parameter values, according to different lighting environments around the image sensor. 
     (Supplementary Note 8) 
     A parameter optimization system described in Supplementary Note 8 is the parameter optimization system described in Supplementary Note 7, further comprising a presentation unit configured to present the plurality of patterns of the right parameter values to a user, wherein the parameter setting unit is configured to change the sensing parameter, according to a pattern selected by the user. 
     (Supplementary Note 9) 
     A parameter optimization method described in Supplementary Note 9 is a parameter optimization method in a parameter optimization system for an image sensor having at least one sensing parameter that can be changed, the parameter optimization method including: calculating a score from an image acquired by the image sensor; and determining a right parameter value that is a value of the sensing parameter at which the score is relatively high, based on a value of the sensing parameter and the score corresponding to the value of the sensing parameter. 
     (Supplementary Note 10) 
     A computer program described in Supplementary Note 10 is a computer program that allows a computer to: calculate a score from an image acquired by the image sensor; and determine a right parameter value that is a value of the sensing parameter at which the score is relatively high, based on a value of the sensing parameter and the score corresponding to the value of the sensing parameter. 
     (Supplementary Note 11) 
     A recording medium described in Supplementary Note 11 is a recording medium on which the computer program described in Supplementary Note 10 is recorded. 
     DESCRIPTION OF REFERENCE CODES 
     
         
           10  Parameter optimization system 
           11  Processor 
           14  Storage device 
           15  Input device 
           16  Output device 
           20  Camera 
           50  Image-pickup target 
           110  Image sensor 
           120  Parameter setting unit 
           125  Detection determination unit 
           130  Score calculation unit 
           135  Neural network 
           140  Parameter determination unit 
           145  Gradient calculation unit 
           150  Information storage unit 
           160  Score storage unit 
           170  Noise amount calculation unit 
           180  Parameter storage unit 
           190  Pattern presentation unit 
           200  Selection operation detection unit