Patent Publication Number: US-9413974-B2

Title: Information processing apparatus, image sensing apparatus, control method, and recording medium for conversion processing

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an information processing apparatus, image sensing apparatus, control method, and recording medium, and particularly to generation of image data to which input response characteristic conversion processing complying with the Academy Color Encoding Specification is applied. 
     2. Description of the Related Art 
     Recently, images and moving images serving as digital data are presented to viewers in various scenes including a movie show. When an image to be presented is data imaged by an image sensing apparatus such as a digital camera, the image represents a color output corresponding to the characteristic of the image sensing apparatus. That is, the image represents a different color response under the influence of the model or individual difference of the image sensing apparatus, an optical member such as a lens mounted in imaging, applied conversion processing, or the like. In this manner, the color response of image data changes depending on conditions in imaging. Especially when image data are sequentially presented by using an image presentation apparatus such as a projector at a screening of a movie, different impressions may be given to viewers between images obtained under different conditions in imaging. 
     To solve this, in creation/editing of digital data of a movie to be screened, different color conversion processes are applied for respective image sensing apparatuses used in imaging so as to exhibit, for example, a uniform color response in the same scene. That is, processing of removing (or reducing) a change of the color response arising from the individual difference or settings of an image sensing apparatus or the like is applied. The Academy of Motion Picture Arts and Sciences of America (to be referred to as the Academy hereinafter) has proposed the Academy Color Encoding Specification (ACES) which defines an ideal color response function or the like by an image sensor. This specification includes implementation of a uniform color response independent of conditions in imaging. More specifically, conversion into a color balance complying with an ideal color response function is implemented by performing, on image data, Input Device Transform (IDT) processing considering various parameters in imaging. 
     ACES IDT processing requires parameters (imaging parameters) representing conditions in imaging for respective image data. Factors which deviate, from an ideal color response function, the color balance of image data obtained by imaging are, for example, the difference of the image sensor, the lens tint and applied color filter in imaging, and a correction parameter applied to image data. In IDT processing, an IDT conversion coefficient is decided in accordance with imaging parameters serving as these deviation factors. The decided IDT conversion coefficient is applied to image data to convert it into image data corresponding to an ideal color response function. 
     However, there has not been an image sensing apparatus which outputs, for IDT processing in an external apparatus, imaging parameters necessary to decide an IDT conversion coefficient. Japanese Patent Laid-Open No. 2002-010178 has disclosed a technique of adding, to image data, imaging parameters including attribute information such as exposure information. However, these imaging parameters cannot be used in IDT processing, unlike the above-mentioned parameters necessary to decide an IDT conversion coefficient. For example, when editing a video, the user needs to decide an IDT conversion coefficient by referring to conventional imaging parameters, and apply IDT processing to image data in an external apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention was made in view of such problems in the conventional technique. The present invention provides an information processing apparatus, image sensing apparatus, control method, and recording medium for generating image data capable of preferably implementing input response characteristic conversion processing. 
     According to one aspect of the present invention, there is provided an information processing apparatus comprising: an obtaining unit configured to obtain a sensed image, and information representing an imaging condition used when the image was sensed; a generation unit configured to generate, based on the information representing the imaging condition, conversion information corresponding to a conversion coefficient used in conversion processing of converting the sensed image into an image corresponding to a predetermined color response function independent of an image sensing apparatus; and a recording unit configured to record, in association with the sensed image, the conversion information generated by the generation unit, wherein the conversion processing includes at least one of de-gamma processing and color balance correction processing. 
     According to another aspect of the present invention, there is provided an image sensing apparatus comprising: an image sensing unit; an obtaining unit configured to, when the image sensing unit performs imaging, obtain information representing an imaging condition in imaging; a generation unit configured to generate, based on the information representing the imaging condition, conversion information corresponding to a conversion coefficient used in conversion processing of converting the sensed image into an image corresponding to a predetermined color response function independent of an image sensing apparatus; and a recording unit configured to record, in association with the sensed image, the conversion information generated by the generation unit, wherein the conversion processing includes at least one of de-gamma processing and color balance correction processing. 
     According to still another aspect of the present invention, there is provided an information processing apparatus control method, comprising: an obtaining step of obtaining a sensed image, and information representing an imaging condition used when the image was sensed; a generation step of generating, based on the information representing the imaging condition, conversion information corresponding to a conversion coefficient used in conversion processing of converting the sensed image into an image corresponding to a predetermined color response function independent of an image sensing apparatus; and a recording step of recording, in association with the sensed image, the conversion information generated in the generation step, wherein the conversion processing includes at least one of de-gamma processing and color balance correction processing. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing the functional arrangement of a digital video camera  100  according to an embodiment of the present invention; 
         FIG. 2  is a flowchart exemplifying recording processing to be executed in a digital video camera  100  according to the first embodiment of the present invention; 
         FIGS. 3A and 3B  are graphs for explaining imaging parameters necessary for IDT processing to be executed in a PC  700  according to the embodiment of the present invention; 
         FIG. 4  is a flowchart exemplifying information obtaining processing to be executed in the digital video camera  100  according to the embodiment of the present invention; 
         FIG. 5  shows an example of an XY chromaticity diagram used to specify the type of light source according to the embodiment of the present invention; 
         FIGS. 6A and 6B  are views exemplifying a color balance transformation matrix configuration method according to the first embodiment of the present invention; 
         FIG. 7  is a block diagram showing the functional arrangement of the PC  700  according to the embodiment of the present invention; 
         FIG. 8  is a flowchart exemplifying IDT processing to be executed in the PC  700  according to the embodiment of the present invention; 
         FIG. 9  is a flowchart exemplifying recording processing to be executed in a digital video camera  100  according to the second embodiment of the present invention; 
         FIG. 10  is a flowchart exemplifying recording processing to be executed in a digital video camera  100  according to the third embodiment of the present invention; and 
         FIG. 11  is a view exemplifying a color balance transformation matrix configuration method according to the third embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     [First Embodiment] 
     An exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings. An embodiment to be described below will explain an example in which the present invention is applied to, as an example of an information processing apparatus, a digital video camera configured to associate parameters (Input Device Transform (IDT) processing information) necessary for IDT processing with image data to be used in IDT processing, and record them. However, the present invention is applicable to an arbitrary apparatus capable of associating parameters necessary for IDT processing with image data to be used in IDT processing, and recording them. 
     &lt;&lt;Arrangement of Digital Video Camera&gt;&gt; 
       FIG. 1  is a block diagram showing the functional arrangement of a digital video camera  100  according to the embodiment of the present invention. 
     A system controller  101  is, for example, a CPU. The system controller  101  controls the operation of each block of the digital video camera  100 . More specifically, the system controller  101  controls the operation of each block by reading out the operation program of each block of the digital video camera  100  that is stored in, for example, a nonvolatile memory  102 , loading the program to a system memory  103 , and executing it. 
     The nonvolatile memory  102  is, for example, an electrically erasable/recordable memory such as an EEPROM. The nonvolatile memory  102  stores the operation program of each block of the digital video camera  100 , and in addition, parameters and the like necessary in the operation of each block. The system memory  103  is, for example, a volatile memory such as a RAM. In the embodiment, the nonvolatile memory  102  stores information necessary to generate IDT processing information (to be described later). The system memory  103  is used not only as a loading area for the operation program of each block, but also as a storage area for temporarily storing intermediate data and the like output in the operation of each block. 
     A system timer  105  is a timer incorporated in the digital video camera  100 . The system timer  105  is used for measurement of the elapsed time, the time stamp, and the like in each program or processing executed by the system controller  101 . 
     An image sensing unit  120  is a unit which images an object and outputs image data. The image sensing unit  120  includes an imaging lens  121 , shutter  122 , image sensor  123 , and A/D converter  124 . The imaging lens  121  is an imaging lens group of the digital video camera  100  including a focus lens, zoom lens, and color filter. The imaging lens  121  forms an optical image on the image sensor  123  via the shutter  122  having the diaphragm and ND filter functions. The image sensor  123  is, for example, an image sensor such as a CCD or CMOS sensor. The image sensor  123  converts an optical image formed via the imaging lens  121  into an analog image signal, and outputs the analog image signal to the A/D converter  124 . The A/D converter  124  applies A/D conversion processing to the analog image signal input from the image sensor  123 , converting the analog image signal into a digital image signal (image data/frame). 
     An image processor  104  applies various image conversion processes to image data output from the image sensing unit  120 , or image data read out from a memory  107  by a memory controller  106  (to be described later). These image conversion processes include predetermined pixel interpolation processing, resize processing such as reduction, and color conversion processing. The image processor  104  executes arithmetic processing regarding exposure control and distance measurement control by using image data input from the A/D converter  124  upon imaging. The image processor  104  outputs the arithmetic result to the system controller  101 . Based on the arithmetic result, the system controller  101  operates the imaging lens  121  and shutter  122  by a driving system (not shown) to perform exposure control and distance measurement control. 
     Assume that the digital video camera  100  according to the embodiment employs TTL (Through The Lens) AF (Auto Focus) processing and AE (Auto Exposure) processing. In AE processing, control of the shutter speed, diaphragm, and ND filter, and control of a gain applied to a digital image signal in the image processor  104  are performed. The image processor  104  performs predetermined arithmetic processing by using sensed image data, and executes even TTL AWB (Auto White Balance) processing based on the obtained arithmetic result. 
     In AWB processing, first, the image processor  104  divides image data output from the image sensing unit  120  into a plurality of subblock regions. The image processor  104  searches each divided subblock region for white, and decides the R, G, and B ratio coefficients of image data so that a subblock in which white has been detected becomes white in data. The R, G, and B ratio coefficients are stored as white balance detection values in the memory  107 . 
     In the following description, AF processing, AE processing, and AWB processing are executed in real time in use in a mode in which a normal moving image is sensed in the digital video camera  100 . However, when the auto execution setting is canceled, the user can manually set the parameter of each processing. 
     The memory controller  106  is a block which controls readout of information from the memory  107  and write of information in the memory  107 . The memory controller  106  writes, in the memory  107 , a digital image signal input from the A/D converter  124 , or an image signal output upon applying various processes by the image processor  104 . In addition to images regarding frames of a moving image during imaging, information of a sound during imaging is also written in the memory  107 . To store this information, the memory  107  is designed to have a sufficient storage capacity. 
     In addition to an image obtained by imaging, a display image to be displayed on a display unit  109  (to be described later) is also written in the memory  107 . When displaying the display image on the display unit  109 , the display image is read out from the memory  107 , and output to a D/A converter  108  (to be described later) in order to display the display image on the display unit  109 . 
     The D/A converter  108  applies D/A conversion processing to an input digital image signal, and outputs an obtained analog image signal to the display unit  109  to display it. The display unit  109  is, for example, a display device such as a compact LCD, and displays an analog image signal output from the D/A converter  108 . Note that the display unit  109  functions as an electronic viewfinder by inputting, to the D/A converter  108 , digital image signals sequentially output from the A/D converter  124  by imaging, converting again them into analog image signals, and displaying (live view-displaying) the analog image signals. 
     An operation input unit  115  is a user interface of the digital video camera  100 , including a power button, mode switching SW, and imaging button. When the operation input unit  115  detects that the user has operated each operation member, it transmits a control signal corresponding to this operation to the system controller  101 . 
     A recording medium I/F  111  is an interface for connecting the digital video camera  100  and a recording medium  112  such as a memory card or HDD, which is a recording device detachably connected to the digital video camera  100 . The recording medium  112  records, for example, via the recording medium I/F  111 , data and sound of a moving image which has been encoded by an encoding unit  110  in accordance with a predetermined encoding format such as MPEG. 
     An external output I/F  113  is, for example, an external output terminal and is an output interface for image data to an external device of the digital video camera  100 . Image data to be externally output is not limited to image data recorded on the recording medium  112 , but may be image data stored in the memory  107  or image data output from the image sensing unit  120 . An external input I/F  114  is, for example, an external input terminal and is an input interface for receiving, from an external device, various kinds of information and the like to be used in IDT processing. 
     &lt;&lt;Recording Processing&gt;&gt; 
     As for recording processing of recording a moving image in the digital video camera  100  having the above arrangement according to the embodiment, detailed processing will be explained with reference to the flowchart of  FIG. 2 . In the following description, this recording processing starts when, for example, a moving image sensing instruction is issued in the digital video camera  100 . 
     In step S 201 , the system controller  101  obtains the result of arithmetic processing by the image processor  104 , and decides an exposure value. The exposure value is a controlled variable regarding the image sensing unit  120 , including the shutter speed, the opening amount of the diaphragm, and the ISO sensitivity setting. 
     In step S 202 , the system controller  101  sets the decided exposure value in the image sensing unit  120 , and causes the image sensing unit  120  to output image data serving as a frame of a moving image by imaging. 
     In step S 203 , the system controller  101  executes information obtaining processing to obtain IDT processing information for the image data obtained by imaging. In the embodiment, in IDT processing to be executed in a PC (to be described later), three conversion processes, that is, de-gamma processing, ACES color balance correction processing, and ACES color space conversion processing are performed. In the information obtaining processing executed in this step, imaging parameters necessary to decide an IDT coefficient are obtained in these three conversion processes. 
     &lt;IDT Processing Information&gt; 
     The three conversion processes to be executed in IDT processing, and imaging parameters necessary for the respective processes will be explained with reference to the drawings. 
     De-gamma processing as one IDT processing is processing of removing, from image data, the influence of gamma correction processing applied to image data by the image processor  104  in the digital video camera  100 . In gamma correction processing, conversion is performed for easy visual recognition of the dark and bright portions of an image by, for example, mapping a pixel representing a low tone in a wide tone region and to the contrary, mapping a pixel representing a high tone in a lower, narrow tone region. More specifically, as shown in  FIG. 3A , the input and output of the tone value do not change generally, as indicated by a straight line  301 . However, correction is performed to decrease the output of a bright portion and increase that of a dark portion, as indicated by a curve  302 . As a result of gamma correction processing, the frame of a moving image to be recorded on the recording medium  112  exhibits a color output different from that of image data output from the image sensor  123 . To grasp the influence of the image sensor and optical system in conversion for adaptation to an ideal color response function of the ACES (Academy Color Encoding Specification), it is necessary to perform de-gamma processing of excluding the influence of gamma correction processing in IDT processing, and then perform another color conversion processing. IDT processing information regarding the applied gamma correction processing may be obtained from, for example, an LUT (Look Up Table) for converting the RGB value of image data after correction into a value before correction at which the input and output have a one-to-one correspondence. 
     In ACES color balance correction processing serving as another IDT processing, image data is corrected so that the color balance of image data comes close to a color balance which is defined by the ACES and is faithful to the visual characteristic. The color balance faithful to the visual characteristic is a color balance corresponding to an ideal color response function of the ACES. As described above, the color balance of image data deviates from a color balance faithful to the visual characteristic owing to light source information, camera settings (white balance, gamma, and clip), an imaging optical system used (lens tint and built-in color filter), and the like in imaging. More specifically, as shown in the XY chromaticity diagram of  FIG. 3B , the R, G, and B pixel values of image data to be recorded in the digital video camera  100  are originally points  310   a ,  310   b , and  310   c , but are changed to points  311   a ,  311   b , and  311   c  owing to the aforementioned factors. To execute ACES color balance correction processing in IDT processing and bring image data close to a color balance (target value) faithful to the visual characteristic, a transformation matrix to the target value is associated as IDT processing information with the image data in the embodiment. The transformation matrix is a matrix such as: 
               A   source     =     [           a   11           a   12           a   13               a   21           a   22           a   23               a   31           a   32           a   33           ]           
By multiplying the R, G, and B values of image data by the transformation matrix:
 
               [           R   ′               G   ′               B   ′           ]     =       A   source     ⁡     [         R           G           B         ]             
R′, G′, and B′ values close to an ideal color response can be obtained. It will readily occur that the color balance conversion information is not limited to the transformation matrix, and an LUT or the like is usable.
 
     In ACES color space conversion processing serving as the final IDT processing, the color space of image data is converted into a color space defined by the ACES. As described above, the ACES defines an ideal color response function by an image sensor. In addition to this aspect, the ACES defines a common format (ACES format) when performing corresponding processing. That is, in ACES color space conversion processing, the color space of image data is converted into a color space defined by the ACES format. For example, when image data has R, G, and B values (709RGB) in an ITU-R BT.709 color space, the R, G, and B values are converted once into those in the XYZ color space, and then converted from the R, G, and B values in the XYZ color space into R, G, and B values (ACES_RGB) in the ACES color space. In the embodiment, therefore, a transformation matrix M 709→RGB , which defines color space conversion in two stages: 
               [           R   ACES               G   ACES               B   ACES           ]     =       M     709   →   ACES       ⁡     [           R   709               G   709               B   709           ]             
is associated as IDT processing information with image data. The embodiment describes that the transformation matrix regarding conversion of the color space is associated as IDT processing information with image data. However, the practice of the present invention is not limited to this. If the color space of a conversion source is determined in color space conversion, the conversion is always constant, so information of the color space of image data may be associated as IDT processing information with the image data. Alternatively, when the color space of image data is turned out in advance, IDT processing information regarding ACES color space conversion processing may not be associated with image data.
 
     &lt;Information Obtaining Processing&gt; 
     Next, information obtaining processing to be executed in the digital video camera  100  according to the embodiment will be explained in detail with reference to the flowchart of  FIG. 4 . 
     In step S 401 , the system controller  101  obtains various imaging parameters regarding IDT processing information. These imaging parameters include camera setting data such as the white balance coefficient, gamma correction coefficient, gain, ISO sensitivity setting in imaging, frame rate, clip, diaphragm, and focal position which have been applied to image data. These parameters also include mounting data regarding the imaging optical system, such as the angle of field of a lens mounted in imaging, a color filter, and the color balance of the lens. 
     In step S 402 , the system controller  101  refers to information regarding gamma correction out of the obtained parameters, and obtains IDT processing information, that is, an LUT regarding de-gamma processing. The shape of a gamma curve to be converted by gamma correction is determined by the gamma correction coefficient, gain value, ISO sensitivity, and the like. By referring to these pieces of information, the system controller  101  specifies a gamma curve and obtains IDT processing information regarding de-gamma processing. 
     In step S 403 , the system controller  101  refers to information regarding the color balance out of the obtained parameters, and obtains IDT processing information, that is, a color balance transformation matrix regarding ACES color balance correction processing. 
     For example, an outline of processing of obtaining a color balance transformation matrix based on estimation of the type of light source and the type of color filter applied in the imaging optical system will be explained with reference to the drawings. 
     First, the system controller  101  specifies the type of light source by using a white balance coefficient (R, G, and B ratio coefficients) which has been decided by the image processor  104  based on analysis of obtained image data. In the digital video camera  100  according to the embodiment, a white balance coefficient in white balance coefficient information is determined in advance as a preset for a light source for which white balance adjustment is assumed. The type of light source is specified as follows: the white balance coefficient of image data is mapped in a two-dimensional space defined by an abscissa representing the R ratio coefficient/G ratio coefficient and an ordinate representing the B ratio coefficient/G ratio coefficient. Then, the white balance coefficient of a predetermined light source to which the mapped white balance coefficient is closer is determined.  FIG. 5  shows this two-dimensional space. In the example of  FIG. 5 , a light source A 1  (daylight) and light source A 2  (tungsten) represent the white balance coefficients of preset light sources. When a white balance coefficient decided based on analysis of image data is mapped at, for example, the position of a point  501  in  FIG. 5 , the type of light source in imaging is specified as the light source A 1 , that is, daylight. 
     Also, the system controller  101  specifies the type of color filter by referring to color filter information out of various obtained parameters. When color filter information cannot be mechanically obtained, this information may be information input by a user setting or the like. 
     Based on a combination of the type of light source and the type of color filter, the system controller  101  obtains a corresponding transformation matrix as IDT processing information out of predetermined color balance transformation matrices. For example, the color balance transformation matrix suffices to be determined in advance for each combination of the type of light source and the color filter, and stored as a table in the memory  107 , as shown in  FIG. 6A . For example, the transformation matrix suffices to be generated based on a conversion coefficient into an ideal ACES color balance target value for image data obtained by imaging in advance a color chart such as a Macbeth chart in the digital video camera  100 . 
     Note that the color balance transformation matrix may be determined not for the decoding condition of the above-mentioned factor which causes deviation from an ideal color balance, but for each factor. For example, a change of the color balance arising from the difference in the type of light source, and a change of the color balance arising from the difference in the type of color filter are generated independently. For this reason, transformation matrices may be defined separately for the type of light source and the type of color filter, as shown in  FIG. 6B . 
     After obtaining various kinds of IDT processing information in this manner, the system controller  101  terminates the information obtaining processing, and returns the process to recording processing. In the information obtaining processing, no detailed processing is described for IDT processing information regarding ACES color space conversion processing. However, IDT processing information suffices to contain a predetermined transformation matrix. 
     In step S 204 , the system controller  101  sets the IDT processing information obtained by information obtaining processing in the frame header of image data serving as a frame of a moving image, and records it on the recording medium  112  via the recording medium I/F  111 . The embodiment describes that IDT processing information is contained in the frame header and recorded. However, the practice of the present invention is not limited to this, and IDT processing information may be recorded as another file associated with moving image data. 
     In step S 205 , the system controller  101  determines whether a moving image sensing end instruction has been issued. If the system controller  101  determines that a moving image sensing end instruction has been issued, it terminates the recording processing. If the system controller  101  determines that no moving image sensing end instruction has been issued, it returns the process to step S 201 . 
     By this processing, the digital video camera  100  according to the embodiment can generate moving image data associated with IDT processing information necessary to execute IDT processing in an external apparatus. The IDT processing information contains pieces of information necessary for de-gamma processing, ACES color balance correction processing, and ACES color space conversion processing. By executing IDT processing using these pieces of information in the external apparatus, the moving image data can be converted into moving image data adapted to an ideal color response function defined by the ACES. 
     &lt;&lt;IDT Processing&gt;&gt; 
     Next, an operation when executing IDT processing on moving image data obtained as a result of recording processing in the digital video camera  100  in the above-described manner will be explained. The embodiment describes that a PC  700  serving as an external apparatus executes IDT processing. 
     &lt;Arrangement of PC  700 &gt; 
     First, the arrangement of the PC  700  which executes IDT processing will be explained with reference to  FIG. 7 . As shown in  FIG. 7 , the PC  700  is constructed by connecting a display  706 , in addition to a CPU  701 , RAM  702 , HDD  703 , communication unit  704 , display control unit  705 , and PC operation input unit  707  which are connected via an internal bus. 
     The CPU  701  controls the operation of each block of the PC  700 . More specifically, the CPU  701  controls the operation of each block by, for example, reading out an application program which is recorded in the HDD  703  and executes IDT processing, loading the application program to the RAM  702 , and executing it. 
     The RAM  702  is a rewritable volatile memory. The RAM  702  is used as a working memory for an application program, and also stores intermediate data and the like output in the operation of each block of the PC  700 . 
     The HDD  703  is a recording device of the PC  700 . In addition to an application program which executes IDT processing, the HDD  703  records image data and other data. The embodiment assumes that moving image data recorded by recording processing in the digital video camera  100  is recorded in the HDD  703 . Moving image data may be recorded in the HDD  703  by, for example, moving or copying the moving image data from the recording medium  112  connected to an interface (not shown), or receiving it from the digital video camera  100  via the communication unit  704 . Note that the communication unit  704  is a communication interface of the PC  700  and is configured to transmit/receive data by, for example, wireless communication. 
     The display control unit  705  outputs a display signal regarding a screen to be displayed on the display  706 . More specifically, the display control unit  705  receives a display control signal regarding a screen from the CPU  701 , generates a display signal based on this signal, and outputs it to the display  706 . For example, the display control unit  705  reads out various GUI (Graphical User Interface) data based on the display control signal, and composites these data in a video memory (not shown) to generate a GUI screen and output it as a display signal. The embodiment describes the PC  700  of a so-called laptop type which includes the display  706  as a building component. However, it will be understood that the practice of the present invention is not limited to this. 
     The PC operation input unit  707  is a user interface of the PC  700 , including a mouse and keyboard. When the PC operation input unit  707  detects an operation input from the user, it outputs a control signal corresponding to this operation to the CPU  701 . 
     IDT processing to be executed in the PC  700  having this arrangement will be explained in detail with reference to the flowchart of  FIG. 8 . In the following description, this recording processing starts when, for example, a corresponding application is executed in the PC  700  and moving image data to be adapted to an ideal color response function is selected. 
     In step S 801 , the CPU  701  obtains image data regarding an unprocessed frame (target frame) out of frames of moving image data. More specifically, the CPU  701  selects a frame of moving image data as a target frame sequentially from the start frame, and performs decoding processing on data of the frame, obtaining corresponding image data. The obtained image data is stored in the RAM  702 . 
     In step S 802 , the CPU  701  reads out IDT processing information from the frame header of the target frame, and stores it in the RAM  702 . 
     In step S 803 , the CPU  701  applies IDT processing to image data regarding the target frame by using the readout IDT processing information, and records the resultant image data as the frame of moving image data after conversion in, for example, the HDD  703 . The IDT processing applied in this step includes the above-described de-gamma processing, ACES color balance correction processing, and ACES color space conversion processing. In the IDT processing, not all the three processes, but at least some of these processes may be performed. In this case, image data suffices to be associated with IDT processing information regarding corresponding processing. 
     In step S 804 , the CPU  701  determines whether the IDT processing has been executed for all the frames of the moving image data. If the CPU  701  determines that the IDT processing has been executed for all the frames, it terminates the IDT processing. If the CPU  701  determines that there is an unprocessed frame, it returns the process to step S 801 . 
     By this processing, the PC  700  serving as an external apparatus can execute appropriate IDT processing after accurately recognizing imaging parameters regarding IDT processing. That is, conversion into image data corresponding to an ideal color response function can be implemented without requiring input of IDT processing information by the user. 
     The embodiment has described that concrete processing parameters such as a matrix used for conversion processing are recorded as IDT processing information. However, the practice of the present invention is not limited to this. For example, when the digital video camera  100  and an application to be executed in the PC  700  are associated, link information which designates predetermined processing parameters in the application may be recorded as IDT processing information. It is also possible to record, as IDT processing information, imaging parameters necessary for specifying or generating processing parameters, and specify or generate processing parameters from the information in an external apparatus, as described in information obtaining processing. 
     As described above, the information processing apparatus according to the embodiment can generate image data capable of preferably implementing input response characteristic conversion processing. More specifically, the information processing apparatus obtains a sensed image, and information representing imaging conditions used when this image was sensed. Based on the information representing the imaging conditions, the information processing apparatus generates conversion information corresponding to a conversion coefficient used in at least either de-gamma processing or color balance correction processing for converting a sensed image into an image corresponding to a predetermined color response function. The information processing apparatus records the generated conversion information in association with the sensed image. 
     [Second Embodiment] 
     The above-described embodiment has explained the method of deciding and associating IDT processing information for each frame during recording processing in the digital video camera  100 . The second embodiment will explain a method of associating IDT processing information with only a frame in which a change has occurred, instead of associating IDT processing information with the frame headers of all frames. Note that a digital video camera  100  and PC  700  in the embodiment have the same arrangements as those in the first embodiment, and a description thereof will not be repeated. 
     &lt;&lt;Recording Processing&gt;&gt; 
     Recording processing to be executed in the digital video camera  100  according to the embodiment will be explained in detail with reference to the flowchart of  FIG. 9 . In the recording processing according to the embodiment, the same reference numerals as those in the recording processing according to the first embodiment described above denote steps of performing the same processes, and a description thereof will not be repeated. Only steps of performing characteristic processing in the second embodiment will be explained. 
     After image data serving as a frame of a moving image is output in step S 202 , a system controller  101  determines in step S 901  whether there is the file header of moving image data to be recorded. If the system controller  101  determines that there is the file header of moving image data, it shifts the process to step S 903 . If the system controller  101  determines that there is no file header of moving image data, it shifts the process to step S 203 . 
     After executing information obtaining processing to obtain IDT processing information in step S 203 , the system controller  101  sets the obtained IDT processing information in the file header of moving image data to be recorded, and records it on a recording medium  112  via a recording medium I/F  111  in step S 902 . Then, the system controller  101  shifts the process to step S 205 . 
     If the system controller  101  determines in step S 901  that there is the file header, it determines in step S 903  whether various imaging parameters regarding IDT processing information have changed. More specifically, various imaging parameters corresponding to IDT processing information recorded in the file header or frame header immediately before current parameters are stored in the memory  107 . The system controller  101  compares these parameters with the current parameters to determine whether the parameters have changed. If the system controller  101  determines that various imaging parameters have changed, it shifts the process to step S 904 . If the system controller  101  determines that these parameters have not changed, it shifts the process to step S 205 . 
     In step S 904 , the system controller  101  executes information obtaining processing, obtaining IDT processing information corresponding to the changed imaging parameters. 
     In step S 905 , the system controller  101  determines whether the obtained IDT processing information has changed from IDT processing information recorded in the file header or frame header immediately before the obtained IDT processing information. For example, when the user performs imaging with the digital video camera  100  while moving outdoors from the inside of a room, the light source changes, the white balance coefficient thus changes, and IDT processing information regarding ACES color balance correction processing changes in some cases. At this time, when a coordinate value at which a detected white balance coefficient is mapped changes from a point  502  to a point  501 , as shown in  FIG. 5 , the Euclidean distance changes from a state close to a light source A 2  to a state close to a light source A 1 , so the IDT processing information needs to be changed. Note that a point  503  during transition is in a state close to the light source A 2  and does not change, and IDT processing information need not be changed. 
     If the system controller  101  determines that the obtained IDT processing information has changed from IDT processing information recorded immediately before the obtained IDT processing information, it shifts the process to step S 906 . If the system controller  101  determines that the obtained IDT processing information has not changed, it shifts the process to step S 205 . 
     In step S 906 , the system controller  101  sets the IDT processing information obtained by the information obtaining processing in a frame header corresponding to the image data, and records it on the recording medium  112  via the recording medium I/F  111 . Note that the IDT processing information contained in the frame header need not include all coefficients regarding de-gamma processing, ACES color balance correction processing, and ACES color space conversion processing, and may include only a changed coefficient or only the difference of a changed coefficient. 
     By this processing, the digital video camera  100  according to the embodiment can associate IDT processing information with only a frame in which a change has occurred, and can reduce the file size of moving image data. 
     When applying IDT processing to moving image data recorded in this way, IDT processing information recorded in a file header is used from the start frame up to a frame in which IDT processing information is recorded in the frame header. In subsequent frames, IDT processing information recorded in the frame header is used till the next frame in which IDT processing information is recorded in the frame header, and then processing is performed. 
     [Third Embodiment] 
     The above-described first and second embodiments have explained that the digital video camera  100  generates and records IDT processing information necessary for IDT processing, that is, the digital video camera  100  manages information necessary to generate IDT processing information. However, it is not practice to store, in the digital video camera  100 , information necessary to generate pieces of IDT processing information for all imaging conditions. An optical system and the like to be mounted in the digital video camera  100  may be commercialized later, and the digital video camera  100  is less likely to have in advance information capable of coping with such a product. The third embodiment will explain a form in which when a digital video camera  100  and PC  700  are connected to perform imaging, the PC  700  transmits, to the digital video camera  100 , information which is supplied from, for example, an application program and is necessary to generate IDT processing information. 
     &lt;&lt;Recording Processing&gt;&gt; 
     Recording processing to be executed in the digital video camera  100  according to the embodiment will be explained in detail with reference to the flowchart of  FIG. 10 . In the recording processing according to the embodiment, the same reference numerals as those in the recording processing according to the above-described first embodiment denote steps of performing the same processes, and a description thereof will not be repeated. Only steps of performing characteristic processing in the third embodiment will be explained. 
     After image data serving as a frame of a moving image is output in step S 202 , a system controller  101  receives, from the PC  700  via an external input I/F  114  in step S 1001 , information (reception information) necessary to generate IDT processing information. 
     In step S 1002 , the system controller  101  compares information which is stored in a nonvolatile memory  102  and is necessary to generate IDT processing information, with the reception information received from the PC  700 , and determines whether the reception information contains information of a condition not stored in the nonvolatile memory  102 . If the system controller  101  determines that the reception information contains information of a condition not stored in the nonvolatile memory  102 , it shifts the process to step S 1003 . If the system controller  101  determines that the reception information does not contain information of a condition not stored in the nonvolatile memory  102 , it shifts the process to step S 203 . 
     In step S 1003 , the system controller  101  stores, in the nonvolatile memory  102 , the information of the condition not stored in the nonvolatile memory  102 , out of the reception information, and shifts the process to step S 203 . For example, when the information which is stored in the nonvolatile memory  102  and is necessary to generate IDT processing information is information at a hatched portion in  1101  of  FIG. 11 , pieces of information  1102  and  1103  contained in the reception information are stored in the nonvolatile memory  102 . Note that the information to be stored may be information of a condition associated with the digital video camera  100 , out of the reception information. 
     By this processing, even if the digital video camera  100  according to the embodiment does not have in advance information necessary to generate IDT processing information, it can externally obtain information and record IDT processing information corresponding to an imaging condition in association with image data. 
     Although different aspects of the present invention have been described in detail in the first to third embodiments, all or some of these aspects may be combined, as a matter of course. 
     Other Embodiments 
     Embodiments of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions recorded on a storage medium (e.g., non-transitory computer-readable storage medium) to perform the functions of one or more of the above-described embodiment(s) of the present invention, and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more of a central processing unit (CPU), micro processing unit (MPU), or other circuitry, and may include a network of separate computers or separate computer processors. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2013-152099, filed Jul. 22, 2013, which is hereby incorporated by reference herein in its entirety.