Image processing device, imaging device, control method, and program

Abstract

Provided is an image processing device characterized by including an associating means for associating first authenticity assurance information including information for assuring the authenticity of a first image with the first image when the first image is either a first type image or a second type image, where the first type image is a non-combined image captured with a single exposure, and the second type image is a combined image generated by combining a plurality of non-combined images captured with a single common exposure.

Description

Image processing apparatus, imaging device, control method, and program

[0001] The present disclosure relates to an image processing apparatus, an imaging device, a control method, and a program.

[0002] Conventionally, in order to guarantee that an image captured by a digital camera has not been tampered with, a digital camera having a function of adding (associating) authentic guarantee information as verification data has been proposed.

[0003] For example, Patent Document 1 discloses a technique of embedding information (hash and signature value) for prohibiting tampering in an image file when shooting is performed in an image tampering prohibition mode.

[0004] In recent years, a technical standardization organization called C2PA has been established for the purpose of developing technical specifications that can guarantee the origin and reliability of content and enabling publishers, creators, and consumers to track the origin of media. The need for authentic guarantee has been attracting renewed attention. In the C2PA standard, a Manifest can be saved in an image generated at the time of shooting or editing as C2PA data. In the Manifest, an Actor (the name of the camera or software that generated the image), a hash value, a claim signature (digital signature), a thumbnail image, etc. can be stored.

[0005] In addition, an imaging device having two column circuits for an output signal from a unit pixel and making the gain of an amplification unit in the column circuit different between the column circuits is known, and two images with different gains can be output. In this specification, such an imaging device is called a Dual Gain Output (DGO) imaging device. The DGO imaging device can output two images (High gain image and Low gain image) to which different gains are applied by performing shooting with a single exposure.

[0006] Japanese Unexamined Patent Application Publication No. 2008-005421

[0007] Some recent smartphones and other imaging devices have a function that captures multiple images, combines them according to some algorithm to generate a composite image, and records the composite image as a single photograph. Examples of such functions include HDR multi-shot, panoramic shooting, and multiplex shooting.

[0008] While such composite images are not necessarily tampered with, they may contain scenes that would be impossible to capture in a single exposure. Therefore, conventional technology does not provide authenticity assurance information for composite images.

[0009] Furthermore, a technique is known for generating a composite image with an expanded dynamic range by combining two images with different gains, captured in a single exposure using a DGO image sensor. A composite image with an expanded dynamic range, generated by combining two images with different gains, captured in a single exposure using a DGO image sensor (sometimes referred to as a "DGO composite image"), is a type of composite image. Therefore, conventional techniques do not add authenticity assurance information to DGO composite images.

[0010] However, the exposure involved in a DGO composite image is only one exposure common to the two images used to generate the DGO composite image. Therefore, unlike composite images obtained by multiple exposures, etc. (sometimes referred to as "multiple exposure composite images"), the possibility of the phenomenon where "scenes that could not be captured in an image taken with a single exposure are recorded in the composite image" is low in DGO composite images. More generally speaking, not limited to DGO images, the possibility of the phenomenon where "scenes that could not be captured in an image taken with a single exposure are recorded in the composite image" is low in composite images generated by combining multiple non-composite images taken with a common single exposure (sometimes referred to as "single exposure composite images") is low.

[0011] In at least some embodiments thereof, this disclosure provides a technique that enables the association of appropriate authenticity assurance information with a single-exposure composite image.

[0012] According to one aspect of the present disclosure, an image processing device is provided, comprising association means for associating a first authenticity assurance information, which includes information for ensuring the authenticity of the first image, with the first image when the first image is either a first type image or a second type image, wherein the first type image is a non-composite image captured in a single exposure, and the second type image is a composite image generated by combining a plurality of non-composite images captured in a common single exposure.

[0013] According to at least some aspects of this disclosure, it is possible to associate appropriate authenticity assurance information with a single-exposure composite image.

[0014] Features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is provided as an example.

[0015] A block diagram showing an example configuration of the digital camera 100. A diagram showing the configuration of the image sensor 13. A conceptual diagram of a circuit with one column extracted from the column AMP 124. A diagram showing an example configuration of a multi-exposure composite image file. A diagram showing another example configuration of a multi-exposure composite image file. A diagram showing another example configuration of a multi-exposure composite image file. A diagram showing another example configuration of a multi-exposure composite image file. A diagram showing an example configuration of a non-composite image file captured in a single exposure. A diagram showing an example configuration of a DGO composite image file. A flowchart of the process for adding authenticity assurance information to an image.

[0016] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are necessary, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0017] [First Embodiment] Figure 1A is a block diagram showing an example configuration of a digital camera 100. The digital camera 100 is an example of an imaging device equipped with an image processing device. The imaging device may be, for example, a smartphone. Furthermore, a personal computer (PC) without a camera can perform the role of the image processing device in this embodiment.

[0018] The barrier 10 is a protective member that covers the imaging unit of the digital camera 100, including the photographic lens 11, to prevent dirt and damage to the imaging unit, and its operation is controlled by the barrier control unit 43. The photographic lens 11 forms an optical image on the imaging surface of the image sensor 13. The shutter 12 has an aperture function. The image sensor 13 is composed of, for example, a CCD or a CMOS sensor, and converts the optical image formed on the imaging surface by the photographic lens 11 via the shutter 12 into an electrical signal.

[0019] The A / D converter 15 converts the analog image signal output from the image sensor 13 into a digital image signal. The digital image signal converted by the A / D converter 15 is written to the memory 25 as so-called RAW image data. At the same time, development parameters corresponding to each RAW image data are generated based on the shooting information and written to the memory 25. The development parameters consist of various parameters used in image processing for recording images in formats such as JPEG, such as exposure settings, white balance, color space, and contrast.

[0020] The timing generator 14 is controlled by the memory control unit 22 and the system control unit 50, and supplies clock signals and control signals to the image sensor 13, A / D converter 15, and D / A converter 21.

[0021] The image processing unit 20 performs various image processing operations on data from the A / D converter 15 or data from the memory control unit 22, such as predetermined pixel interpolation, color conversion, correction, resizing, and image synthesis. The image processing unit 20 also performs predetermined image processing and calculations using the image data obtained from the image capture, and provides the obtained calculation results to the system control unit 50. The system control unit 50 controls the exposure control unit 40 and the focus control unit 41 based on the provided calculation results to realize autofocus (AF), automatic exposure (AE), and flash pre-flash (EF) processing.

[0022] Furthermore, the image processing unit 20 performs predetermined calculations using the image data obtained from the capture, and also performs auto white balance (AWB) processing based on the obtained calculation results. In addition, the image processing unit 20 reads the image data stored in the memory 25 and performs compression or decompression processing using the JPEG format, MPEG-4 AVC format, High Efficiency Video Coding (HEVC) format, or a lossless compression method for uncompressed RAW data. Finally, the image processing unit 20 writes the processed image data to the memory 25.

[0023] Furthermore, the image processing unit 20 performs predetermined calculations using the image data obtained by capturing, and performs various image data editing processes. Specifically, it can perform cropping, which adjusts the display range and size of the image by hiding unnecessary parts around the image data, and resizing, which changes the size of the image data or screen display elements by enlarging or reducing them. In addition, the image processing unit 20 can perform RAW development, which adds image processing such as color conversion to data that has been compressed or decompressed using a lossless compression method for uncompressed RAW data, and converts it into JPEG or HEVC format data to create image data. Furthermore, the image processing unit 20 can perform video extraction, which extracts a specified frame from a video format such as MPEG-4, converts it into JPEG format data, and saves it.

[0024] Furthermore, the image processing unit 20 performs predetermined calculations using the image data and performs image comparison processing of various image data. Specifically, it performs decompression processing according to the compression method of the image data to be compared and compares the decompressed images. The image processing unit 20 can determine whether the images match or not, and how much the difference is.

[0025] Furthermore, the image processing unit 20 also performs processes such as overlaying On-Screen Display (OSD) elements, such as menus and arbitrary characters, onto the display unit 23 along with the image data for display.

[0026] Furthermore, the image processing unit 20 uses the input image data and distance information to the subject obtained from the image sensor 13 during shooting to detect subjects present in the image data and performs subject detection processing to detect the subject's region. The detectable information includes region information such as position and size within the image, as well as detection information such as tilt and certainty.

[0027] Furthermore, the image processing unit 20 includes a synthesis processing circuit for synthesizing multiple image data. In this embodiment, the image processing unit 20 may synthesize images by overwriting pixels, or by weighted addition. Weighted addition can produce an image in which the background is transparent. The image processing unit 20 can also perform a comparative light synthesis process or a comparative dark synthesis process, which selects the brightest or darkest image in each region of the image data to be synthesized, and synthesizes the selected images pixel by pixel to generate a single image data.

[0028] The memory control unit 22 controls the A / D converter 15, timing generator 14, image processing unit 20, image display memory 24, D / A converter 21, and memory 25. RAW image data generated by the A / D converter 15 is written to the image display memory 24 or memory 25 via the image processing unit 20 and the memory control unit 22, or directly via the memory control unit 22.

[0029] Image data for display written to the image display memory 24 is displayed on the display unit 23, which is composed of a TFT LCD or the like, via the D / A converter 21. By sequentially displaying the image data obtained by imaging using the display unit 23, it is possible to realize an electronic viewfinder function that displays live images.

[0030] The memory 25 has sufficient storage capacity to store a predetermined number of still images and a predetermined amount of video footage, and stores the captured still images and video footage. Furthermore, the memory 25 can also be used as a workspace for the system control unit 50.

[0031] The exposure control unit 40 controls the shutter 12, which has an aperture function. The exposure control unit 40 also has a flash metering function by working in conjunction with the flash 44. The focus control unit 41 adjusts the focus by driving a focus lens (not shown) included in the photographic lens 11 based on instructions from the system control unit 50. The zoom control unit 42 controls zooming by driving a zoom lens (not shown) included in the photographic lens 11. The flash 44 has an AF assist light projection function and a flash metering function.

[0032] The system control unit 50 controls the entire digital camera 100. The non-volatile memory 51 is an electrically erasable and recordable non-volatile memory, such as an EEPROM. In addition to the program, map information and other data are also stored in the non-volatile memory 51.

[0033] The shutter switch 61 (SW1) turns ON during the operation of the shutter button 60 and instructs the start of operations such as AF processing, AE processing, AWB processing, and EF processing. The shutter switch 62 (SW2) turns ON when the operation of the shutter button 60 is completed and instructs the start of a series of shooting operations including exposure processing, development processing, and recording processing. In the exposure processing, the system control unit 50 controls the system to write the signal read from the image sensor 13 to the memory 25 as RAW image data via the A / D converter 15 and the memory control unit 22. In the development processing, the system control unit 50 uses calculations in the image processing unit 20 and the memory control unit 22 to develop the RAW image data written to the memory 25 and controls the system to write it to the memory 25 as image data. In the recording processing, the system control unit 50 reads the image data from the memory 25, compresses it using the image processing unit 20, stores the compressed image data in the memory 25, and then writes it to the external recording medium 91 via the card controller 90.

[0034] The control unit 63 is equipped with various buttons and touch panel controls. For example, the control unit 63 includes a power button, a menu button, a mode switch for switching between shooting mode, playback mode, and other special shooting modes, a directional pad, a set button, a macro button, and a multi-screen playback page change button. Additionally, the control unit 63 may include a flash setting button, a single-shot / continuous-shot / self-timer switch button, a menu navigation + (plus) button, a menu navigation - (minus) button, a shooting quality selection button, an exposure compensation button, and a date / time setting button.

[0035] The metadata generation and analysis unit 70 generates various metadata, such as Exchangeable image file format (Exif) information, to be attached to the image data when recording image data to the external recording medium 91, based on the information at the time of shooting. Furthermore, when reading image data recorded on the external recording medium 91, the metadata generation and analysis unit 70 analyzes the metadata attached to the image data. Examples of metadata include various setting information at the time of shooting, image data information related to the image data, and characteristic information of the subject contained in the image data. Additionally, when recording moving image data, the metadata generation and analysis unit 70 can generate and attach metadata to each frame.

[0036] The power supply 80 consists of a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li battery, or an AC adapter, etc. The power control unit 81 supplies power from the power supply 80 to each part of the digital camera 100.

[0037] The card controller 90 transmits and receives data to and from an external recording medium 91, such as a memory card. The external recording medium 91 is, for example, a memory card, and records images (still images, videos) taken by the digital camera 100.

[0038] The communication unit 71 has a communication circuit for transmitting and receiving data. Specifically, the communication circuit may be configured to perform wireless communication such as Wi-Fi or Bluetooth®, or it may be configured to perform wired communication such as Ethernet or USB.

[0039] The hash value generation unit 72 generates (calculates) hash values ​​by executing a hash function on various data (e.g., image data or metadata) input via the system control unit 50. Algorithms for generating hash values ​​include SHA256, SHA384, and SHA512. Note that the system control unit 50 may generate the hash values ​​instead of the hash value generation unit 72. Furthermore, the hash value generation unit 72 may generate hash values ​​by executing a hash function on the entire image file, rather than just the image data.

[0040] The signature generation / verification unit 73 generates and verifies signature information necessary for determining authenticity. When an image is created, the signature generation / verification unit 73 generates signature information using the hash value of the image data generated by the hash value generation unit 72 and the signature generation key (private key), and records it in the image file as authenticity guarantee information. When image tampering is detected, the signature generation / verification unit 73 determines whether or not the image has been tampered with by verifying the hash value of the image data to be verified, generated by the hash value generation unit 72, and the signature recorded as authenticity guarantee information using the public key. Examples of algorithms for generating and verifying signature information include ECDSA, RSASSA-PSS, and EdDSA. Note that the system control unit 50 may perform the role of the signature generation / verification unit 73 instead of the signature generation / verification unit 73.

[0041] The configuration of the image sensor 13 will now be explained with reference to Figure 1B. The image sensor 13 is configured to generate multiple images with different gains applied in a single common exposure. In Figure 1B, the timing pulse control unit 121 controls the operation of the image sensor 13 by supplying an operating clock (CLK) to each block of the image sensor 13 and supplying timing signals to each block.

[0042] The vertical scanning circuit 122 performs timing control to sequentially read out the pixel signal voltages of the pixel section 123, in which multiple pixels are arranged in two dimensions, within one frame. Generally, the video signal is read out sequentially row by row within one frame, from the top row to the bottom row.

[0043] The pixel unit 123 is a photoelectric conversion element that photoelectrically converts incident light and outputs a voltage corresponding to the amount of incident light. The pixel unit 123 converts the captured light into charges and accumulates the charges in the capacitance Floating Diffusion (FD). The size of the capacitance of the FD can be changed, and by changing the capacitance according to the ISO sensitivity, the signal-to-noise ratio (SN ratio) can be improved. Generally, at low ISO sensitivity, the capacitance is set to "large", and at high ISO sensitivity, the capacitance is set to "small". When outputting two images with different gains described later, the capacitance for accumulating charges is common for the two gains. Also, the size of the configurable capacitance is not limited to two types, "large" and "small", and a configuration that can set three or more levels of capacitance may be adopted.

[0044] The column AMP 124 is used to electrically amplify the signal read from the pixel unit 123. By amplifying the signal with the column AMP 124, the signal level of the pixel with respect to the noise output by the subsequent column ADC 125 can be amplified, and equivalently, the SN ratio can be improved. Also, it is possible to change the gain of the column AMP from the timing pulse control unit 121.

[0045] The imaging device 13 includes two input memories in the column AMP 124, and by changing the gain of the column AMP 124, it is possible to output signals with two types of gains for generating a DGO composite image. As described above, the DGO composite image means a composite image with an expanded dynamic range generated by synthesizing two images with different gains captured in a single common exposure using a DGO imaging device (here, the imaging device 13). By having two input memories, two types of gains can be separately applied to the signal at a specific time read from the FD and output. Therefore, although the data amount increases, two types of images with different gains and simultaneity can be obtained. As the configuration of the imaging device 13, a configuration that outputs three or more types of images with different gains and simultaneity may also be adopted.

[0046] Column ADC125 performs AD conversion on the read signal from column AMP124. The digitized signal is sequentially read by the horizontal transfer circuit 126. The output of the horizontal transfer circuit 126 is input to the signal processing circuit 127.

[0047] The signal processing circuit 127 is a circuit that performs digital signal processing. The signal processing circuit 127 can easily perform a gain operation by adding a certain amount of offset value through digital processing of the signal and performing shift operations and multiplications. Also, a pixel region that is intentionally shaded may be provided in the pixel section 123. In this case, the signal processing circuit 127 can perform a digital black level clamping operation using the shaded pixel region. The output of the signal processing circuit 127 is passed to the external output circuit 128.

[0048] The external output circuit 128 has a serializer function and converts the multi-bit input parallel signal from the signal processing circuit 127 into a serial signal. Also, the external output circuit 128 converts this serial signal into, for example, a Low voltage differential signaling (LVDS) signal or the like and outputs it to the outside of the imaging device 13.

[0049] Next, referring to FIG. 1C, the operation of the imaging device 13 when generating the DGO composite image will be described. FIG. 1C is a conceptual diagram of a circuit in which one column of the column AMP124 is extracted. As described above, the imaging device 13 can change the gain of the column AMP124 in order to generate a DGO composite image.

[0050] OP135 is an operational amplifier, and an input capacitor and a feedback capacitor are connected to OP135. C133 and C134 are input capacitors, and SW131 and SW132 are switches. The signal read from the pixel section 123 is connected to C133 and C134 via SW131 and SW132.

[0051] C136 and C138 are feedback capacitors, and SW137 is a switch. The connection of C138 can be controlled by SW137. Since the column AMP124 uses a capacitor, the amplification factor is (input capacitor / feedback capacitor).

[0052] As described above, the column AMP 124 has two input capacitors. First, by turning SW 131 ON and SW 132 and SW 137 OFF, the column AMP 124 applies a gain based on C 133 and C 136 to the input signal and outputs it to the column ADC 125. Next, by turning SW 131 OFF and SW 132 and SW 137 ON, the column AMP 124 applies a gain based on C 134, C 136, and C 138 to the input signal and outputs it. This makes it possible to output two images with different gains.

[0053] Thus, the digital camera 100 is equipped with an image sensor 13 which is a DGO image sensor, and has a function to generate two images with different gains by taking a picture with a single exposure, and to generate a DGO composite image (second type image) by combining these two images. The digital camera 100 also has a function to generate a captured image (first type image) by taking a picture with a single exposure. In this case, the digital camera 100 controls the image sensor 13 to output a single image to which a single gain is applied. Furthermore, the digital camera 100 has a function to generate a multi-exposure composite image (third type image) by combining multiple captured images corresponding to multiple exposures. In this case, the digital camera 100 controls the image sensor 13 to output a single image to which a single gain is applied in each exposure. The image synthesis processing for generating the DGO composite image and the multi-exposure composite image is performed using the image processing unit 20.

[0054] The image sensor 13 may be configured to output signals with three or more different gains for a single exposure. In this case, the digital camera 100 can generate a composite image as a second type of image, based on three or more images with different gains captured in a single exposure. Even in this case, since the exposure involved in the composite image is only one common exposure, it is considered unlikely that a scene that could not be captured in a single exposure will be recorded in the composite image. Therefore, when describing DGO composite images below, the description also applies to composite images based on three or more images with different gains captured in a single exposure, as long as it is not technically contradictory.

[0055] Figure 2A shows an example of the configuration of a multi-exposure composite image file. The image file 200A recorded in this embodiment includes an area for recording metadata (Exif data 201) in accordance with the Exif standard, an area for recording compressed main image data 206, and an area for recording authenticity assurance information 223 (authenticity assurance information area 207).

[0056] For example, if the user instructs the image to be recorded in JPEG format, the thumbnail image data 205 and the main image data 206 are recorded in JPEG format in the image file 200A. In addition, Exif data 201 is recorded in an APP1 marker, and authenticity assurance information area 207 is recorded in an APP11 marker, etc.

[0057] Furthermore, if the user instructs recording in High Efficiency Image File Format (HEIF), the image file 200A is recorded in HEIF file format, and the Exif data 201 and authenticity assurance information area 207 are recorded in a MetaDataBox or the like. Similarly, if the user instructs recording in RAW format, the Exif data 201 and authenticity assurance information area 207 are recorded in a predetermined area such as a MetaDataBox.

[0058] Image file 200A may be recorded in formats other than those described above.

[0059] The Exif data 201 may also record information 202 indicating the presence or absence of authenticity assurance information and a link 203 to the authenticity assurance information. Furthermore, the ManufacturerNote 204 included in the Exif data 201 may contain manufacturer-specific metadata generated using the metadata generation and analysis unit 70, which is generally kept confidential.

[0060] The authenticity assurance information area 207 includes authenticity assurance information 223 (first authenticity assurance information) which includes information to guarantee the authenticity of the image data 206. The authenticity assurance information 223 includes an action, an Actor (name of the camera or software that generated the image), various hash values, thumbnail image data 224, and a signature.

[0061] The action indicates (identifies) whether the image data 206 is a multi-exposure composite image, a non-composite image (an image captured in a single exposure), or a DGO composite image. If the image data 206 is a multi-exposure composite image, the action has the value "Edit" (first information) as shown in Figure 2A. If the image data 206 is a non-composite image or a DGO composite image, the action has the value "Generate" (second information).

[0062] The thumbnail image data 224 is the thumbnail image data corresponding to the main image data 206 at the time when the authenticity assurance information 223 is added to the image file 200A.

[0063] The various hash values ​​include the hash value of the main image data 206, the hash value of the thumbnail image data 224, and the hash value of the metadata (Exif data 201 in the example in Figure 2A).

[0064] Thus, the authenticity assurance information 223 includes the hash values ​​of the main image data 206 and the thumbnail image data 224, and the hash values ​​are signed. Therefore, the authenticity assurance information 223 can be used to guarantee the authenticity of the main image data 206 and the thumbnail image data 224 (if the authenticity is compromised, the signature verification will fail, so if the signature verification is successful, it is guaranteed that the main image data 206 and the thumbnail image data 224 are authentic).

[0065] Figures 2B-1 to 2B-3 show other examples of the configuration of a multi-exposure composite image file. In the example of Figure 2A, the authenticity assurance information area 207 contains only one authenticity assurance information 223 (first authenticity assurance information), but as shown in Figures 2B-1 to 2B-3, the authenticity assurance information area 207 may contain multiple authenticity assurance information (multiple second authenticity assurance information). In the examples of Figures 2B-1 to 2B-3, the authenticity assurance information area 207 contains not only authenticity assurance information 223 to guarantee the authenticity of the main image data 206, which is a multi-exposure composite image, but also three authenticity assurance information pieces 217, 219, and 221 corresponding to the three source images used to generate the multi-exposure composite image. The thumbnail image data pieces 218, 220, and 222 stored in the authenticity assurance information pieces 217, 219, and 221 are thumbnail image data corresponding to each source image at the time the authenticity assurance information was added to each captured source image. The thumbnail image data 224 stored in the authenticity assurance information 223 is, as in Figure 2A, thumbnail image data corresponding to the multi-exposure composite image (main image data 206). Since the source image is a non-composite image, the action stored in the authenticity assurance information 217, 219, and 221 has the value "Generate".

[0066] In the examples shown in Figures 2B-1 to 2B-3, the latest authenticity assurance information for the multi-exposure composite image is the fourth (bottommost) authenticity assurance information 223. When the system control unit 50 records multiple authenticity assurance information in the authenticity assurance information area 207, it may store management information at the beginning of the authenticity assurance information area 207, such as a link to each authenticity assurance information, the number of authenticity assurance information items, and information indicating which is the latest authenticity assurance information. Alternatively, the system control unit 50 may record multiple authenticity assurance information sequentially without recording management information in the authenticity assurance information area 207, and treat the last recorded authenticity assurance information as the latest authenticity assurance information. Alternatively, the system control unit 50 may store information in the authenticity assurance information area 207 indicating which authenticity assurance information was added when the non-composite image was captured.

[0067] Authenticity assurance information 217 includes information to guarantee the authenticity of the source image and the thumbnail image (thumbnail image data 218) corresponding to the source image. The structure of authenticity assurance information 217 is the same as that of authenticity assurance information 223. However, the hash value of the main image data included in authenticity assurance information 217 is not the hash value of the main image data 206 of the image file 200B, but the hash value of the source image data (main image data 206 in Figure 2C, described later) used to generate the main image data 206. Also, the hash value of the thumbnail image data included in authenticity assurance information 217 is the hash value of the thumbnail image data 218 corresponding to the source image data. The structure of authenticity assurance information 219 and 221 is the same as that of authenticity assurance information 217.

[0068] Since the image file 200B contains authenticity assurance information 217, 219, and 221, the digital camera 100 can verify the authentic origin of the main image data 206, which is a composite image of multiple exposures. For example, the digital camera 100 can verify the authenticity of the thumbnail image data 218 corresponding to the source image data by verifying the signature of the hash value of the thumbnail image data in the authenticity assurance information 217.

[0069] Figure 2C shows an example of the structure of a non-composite image file. As shown in Figure 2C, the structure of image file 200C may be the same as the structure of image file 200A in Figure 2A. In the example in Figure 2C, it is assumed that image file 200C is an image file that stores the source image corresponding to the authenticity assurance information 217 in Figures 2B-1 to 2B-3 as the main image.

[0070] Figure 2D shows an example of the structure of a DGO composite image file. As shown in Figure 2D, the structure of image file 200D may be the same as the structure of image file 200A in Figure 2A. In the example of Figure 2D, the authenticity assurance information area 207 includes authenticity assurance information 208 to guarantee the authenticity of the main image data 206, which is a DGO composite image. The thumbnail image data 209 stored in the authenticity assurance information 208 is thumbnail image data corresponding to the main image data 206, which is a DGO composite image. The number of exposures involved in the DGO composite image is only one, and it is unlikely that a scene that could not be captured in an image taken with a single exposure will be recorded in the DGO composite image. Therefore, the action stored in the authenticity assurance information 208 has the value "Generate," just as in the case of a non-composite image.

[0071] Figure 3 is a flowchart of the process for adding authenticity assurance information to an image. Here, we will explain the case where a DGO composite image is generated, and the case where a multi-exposure composite image is generated by multiplexing three exposure images (non-composite images). Unless otherwise specified, the processing of each step in this flowchart is realized by the system control unit 50 executing a program stored in the non-volatile memory 51. In this embodiment, the number of source images used to generate a multi-exposure composite image is not limited to three. Also, the method of combining multiple source images (exposure images) is not limited to multiplexing, but may be other combining methods (for example, multi-shot HDR combining, multi-shot NR combining, multi-shot panoramic combining, etc.).

[0072] The user can display the HDR shooting menu on the display unit 23 by operating the operation unit 63. The user can then set the HDR shooting menu to generate a DGO composite image using DGO compositing (a process that combines two images with different gains captured in a single exposure). After that, when the user gives a single shooting (exposure) command to the digital camera 100, the digital camera 100 takes a single exposure. As a result of the single exposure, two images with different gains are generated, and the digital camera 100 generates a DGO composite image by combining these two images. Each time a DGO composite image is generated in the digital camera 100, the processing in this flowchart is performed on the generated DGO composite image. The two images with different gains used to generate the DGO composite image are, for example, a properly exposed image and an underexposed image, but are not limited to these. Also, in the above description, the DGO composite image is assumed to be a composite image with an expanded dynamic range, but it may also be a composite image with reduced noise. In this case, the digital camera 100 controls the image sensor 13 to generate both a properly exposed image and an overexposed image by taking a picture with a single exposure. The digital camera 100 then generates a composite image with reduced noise in the dark areas by darkening the overexposed image by the number of stops of difference between it and the properly exposed image, and then compositing this image into the dark areas of the properly exposed image.

[0073] Furthermore, the user can operate the control unit 63 to display the multiple image composition setting menu on the display unit 23, and set the number of images (source images) to be used for composition to three on the multiple image composition setting menu. After that, when the user takes three shots (exposures) with the digital camera 100, three source images (non-composite images) are generated, and a multi-exposure composite image based on the three source images is generated. Each time an image (non-composite image or multi-exposure composite image) is generated by the digital camera 100, the processing of this flowchart is performed on the generated image.

[0074] In S301, the system control unit 50 determines whether the setting for adding authenticity guarantee information is ON. If the setting for adding authenticity guarantee information is ON, the process proceeds to S302; otherwise, the process proceeds to S305.

[0075] It should be assumed that the user has previously configured the authenticity guarantee information setting. For example, the user can display the setting menu on the display unit 23 by operating the operation unit 63, and on the setting menu, select ON (enable) or OFF (disable) as the additional setting.

[0076] In S302, the system control unit 50 determines whether the image to be processed (the first image) is either a non-composite image or a DGO composite image. If the image to be processed is either a non-composite image or a DGO composite image, the process proceeds to S303; otherwise (if the image to be processed is a multi-exposure composite image), the process proceeds to S304.

[0077] In S303, the system control unit 50 generates authenticity assurance information for the image to be processed (in this case, a non-composite image or a DGO composite image) using the hash value generation unit 72 and the signature generation / verification unit 73, and adds (associates) the generated authenticity assurance information to the image to be processed. In this case, an image file such as the image file 200C shown in Figure 2C or the image file 200D shown in Figure 2D is generated. Since the image to be processed is a non-composite image or a DGO composite image, the value "Generate" is set for the action stored in the authenticity assurance information 217 or authenticity assurance information 208, as shown in Figure 2C or Figure 2D. In addition, the hash value generation unit 72 calculates the hash value of the main image data 206, the hash value of the thumbnail image data 218 or 209, and the hash value (not shown) of the metadata (Exif data 201), and these hash values ​​are stored in the authenticity assurance information 217 or 208.

[0078] In the case of multiple image synthesis, it is assumed that three source images will be captured, so the process in S303 will be executed three times, and three source image files will be generated. For example, the second source image file has the file structure shown in Figure 2C, and its authenticity assurance information is the authenticity assurance information 219 shown in Figure 2B-2. Also, for example, the third source image file has the file structure shown in Figure 2C, and its authenticity assurance information is the authenticity assurance information 221 shown in Figure 2B-3.

[0079] In S304, the system control unit 50 generates authenticity assurance information for the image to be processed (in this case, a multi-exposure composite image) using the hash value generation unit 72 and the signature generation / verification unit 73, and adds (associates) the generated authenticity assurance information to the image to be processed. In this case, an image file like the image file 200A shown in Figure 2A is generated. Since the image to be processed is a multi-exposure composite image, the value "edit" is set for the action stored in the authenticity assurance information 223, as shown in Figure 2A. In addition, the hash value generation unit 72 calculates the hash value of the main image data 206, the hash value of the thumbnail image data 224, and the hash value (not shown) of the metadata (Exif data 201), and these hash values ​​are stored in the authenticity assurance information 223.

[0080] In S305, the system control unit 50 refrains from adding authenticity assurance information to the image to be processed.

[0081] In S306, the system control unit 50 saves an image file containing either an image with authenticity assurance information attached (if S303 or S304 is passed) or an image without authenticity assurance information attached (if S305 is passed) to the external recording medium 91.

[0082] In the above explanation, it was assumed that the action in authenticity assurance information 223 has the value "edit" (first information), and the action in authenticity assurance information 217, 219, 221, and 208 has the value "generate" (second information). Authenticity assurance information 217, 219, 221, 223, and 208 identify whether the image whose authenticity should be guaranteed is either a non-composite image, a DGO composite image, or a multi-exposure composite image, based on the value of the action. However, the method of configuring authenticity assurance information to identify whether an image is either a non-composite image, a DGO composite image, or a multi-exposure composite image is not limited to using the value of the action ("edit" or "generate"). For example, the action in authenticity assurance information 217, 219, 221, and 208 may have the value "generate," while authenticity assurance information 223 may be configured not to include an action. In this case, the absence of an action in the authenticity assurance information means that the image is a multi-exposure composite image.

[0083] Furthermore, in the above explanation, when the image to be processed is a multi-exposure composite image, authenticity assurance information with an "edit" action (for example, authenticity assurance information 223 in Figure 2A) is associated with the multi-exposure composite image (S304). However, when the image to be processed is a multi-exposure composite image, the digital camera 100 may be configured to refrain from associating the authenticity assurance information with the image to be processed (multi-exposure composite image). In this case, it is possible to identify whether the image is a non-composite image or a DGO composite image based on whether or not the authenticity assurance information is associated with the image.

[0084] As described above, according to the first embodiment, when the first image (for example, the main image data 206 in Figure 2A, Figure 2C, or Figure 2D) is either a first type image (for example, the main image data 206 in Figure 2C) or a second type image (for example, the main image data 206 in Figure 2D), the digital camera 100 associates the first image with first authenticity assurance information (for example, authenticity assurance information 217 in Figure 2C, or authenticity assurance information 208 in Figure 2D), which includes information to guarantee the authenticity of the first image. Here, the first type image is a non-composite image (captured image) taken in a single exposure. The second type image is a composite image (single exposure composite image) generated by combining multiple non-composite images (captured images) taken in a common single exposure.

[0085] A single-exposure composite image is, for example, the DGO composite image described above, but is not limited to this. In composite images generated by combining multiple non-composite images taken in a common single exposure, the possibility of the phenomenon where "scenes that could not exist in images taken in a single exposure are recorded in the composite image" is low. Therefore, any composite image generated by combining multiple non-composite images taken in a common single exposure is included in the single-exposure composite image of this embodiment.

[0086] Therefore, according to this embodiment, it is possible to associate appropriate authenticity assurance information with a single-exposure composite image, which is unlikely to contain scenes that would not be possible in an image taken with a single exposure.

[0087] [Second Embodiment] In the first embodiment, in the explanation of S304 in Figure 3, it was assumed that an image file having the structure shown in Figure 2A was generated. In other words, in the first embodiment, only one authenticity assurance information 223 corresponding to the main image data 206 of the multiple exposure composite image was added to the multiple exposure composite image. In contrast, the second embodiment describes a case in which authenticity assurance information corresponding to the source image is also recorded as the origin for the multiple exposure composite image.

[0088] In the second embodiment, the basic configuration of the digital camera 100 is the same as in the first embodiment. The following will mainly describe the differences from the first embodiment.

[0089] In the second embodiment, at S304 in Figure 3, the system control unit 50 acquires multiple authenticity assurance pieces of information (multiple second authenticity assurance pieces of information) corresponding to multiple captured images (non-composite images) used as source images. Each of the multiple authenticity assurance pieces of information acquired here is associated with one of the multiple captured images. Here, the number of source images (captured images) is assumed to be three. The system control unit 50 adds the three authenticity assurance pieces of information corresponding to the three captured images (non-composite images) as authenticity assurance pieces of information 217, 219, and 221 (multiple second authenticity assurance pieces of information) to the multi-exposure composite image. Since the source images are non-composite images, the action stored in the authenticity assurance pieces of information 217, 219, and 221 has the value "generate". The system control unit 50 also adds authenticity assurance piece of information 223 (first authenticity assurance piece of information) corresponding to the main image data 206 of the multi-exposure composite image to the multi-exposure composite image.

[0090] Thus, according to the second embodiment, it is possible to add authenticity assurance information 223 to the multiple exposure composite image, which includes the history of what source images were used to generate the multiple exposure composite image (authenticity assurance information 217, 219, 221), and which has an action with the value "edit".

[0091] [Third Embodiment] In the first and second embodiments, three source images were taken when generating a multi-exposure composite image. However, the source images may be selected from pre-exposed image files. In the third embodiment, a case in which a multi-exposure composite image is generated by using images from a pre-exposed image file as source images will be described.

[0092] In the third embodiment, the basic configuration of the digital camera 100 is the same as in the first embodiment. The following will mainly describe the differences from the first embodiment.

[0093] The external recording medium 91 is assumed to contain two or more image files, each containing a captured image (non-composite image). The user can select multiple image files (multiple source image files) to be used to generate a multi-exposure composite image from the two or more image files stored on the external recording medium 91 by operating the operation unit 63. Here, it is assumed that three image files are selected. The system control unit 50 controls the image processing unit 20 to generate a multi-exposure composite image from the captured images in the three image files. Once the multi-exposure composite image is generated, the flowchart in Figure 3 is performed on the multi-exposure composite image.

[0094] In the third embodiment, at S304 in Figure 3, the system control unit 50 determines whether or not authenticity assurance information has been added to the source image file.

[0095] If the source image file has authenticity assurance information attached to it to guarantee the authenticity of the source image, the system control unit 50 inherits the authenticity assurance information from the source image file and also attaches the authenticity assurance information to the multi-exposure composite image. As a result, an image file like the image file 200B shown in Figures 2B-1 to 2B-3 is generated. Alternatively, the system control unit 50 may not attach the authenticity assurance information from the source image file to the multi-exposure composite image, but instead attach only the authenticity assurance information corresponding to the main image data of the multi-exposure composite image to the multi-exposure composite image. In this case, an image file like the image file 200A shown in Figure 2A is generated.

[0096] If authenticity assurance information is not attached to the source image file, the system control unit 50 refrains from attaching authenticity assurance information to the multi-exposure composite image.

[0097] Thus, according to the third embodiment, authenticity assurance information for guaranteeing the authenticity of the multiple exposure composite image is added to the multiple exposure composite image only when authenticity assurance information for guaranteeing the authenticity of the source image (non-composite image) is added to the source image. Therefore, according to this embodiment, it is possible to correctly record the history information of the authenticity assurance information of the multiple exposure composite image.

[0098] [Other Embodiments] The present invention can also be realized by supplying a program that implements one or more of the functions of the above embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (for example, an ASIC) that implements one or more functions.

[0099] The technical ideas derived from this disclosure are not limited to the exemplary embodiments disclosed, but are intended to encompass various modifications of the exemplary embodiments, or substitutions with equivalent structures or functions. The scope of the following claims should be interpreted in the broadest way to encompass all such modifications and equivalent structures and functions.

[0100] This application claims priority based on Japanese Patent Application No. 2024-196046, filed on 8 November 2024, and all of its contents are incorporated herein by reference.

[0101] 13...Image sensor, 20...Image processing unit, 25...Memory, 50...System control unit, 51...Non-volatile memory, 63...Operation unit, 72...Hash value generation unit, 73...Signature generation / verification unit

Claims

1. An image processing apparatus comprising association means for associating a first authenticity assurance information, which includes information for guaranteeing the authenticity of the first image, with the first image when the first image is either a first type image or a second type image, wherein the first type image is a non-composite image captured in a single exposure, and the second type image is a composite image generated by combining a plurality of non-composite images captured in a common single exposure.

2. The image processing apparatus according to claim 1, wherein, if the first image is a third type image, the association means associates the first authenticity assurance information with the first image, the third type image is a composite image generated by combining multiple captured images corresponding to multiple exposures, and the first authenticity assurance information is configured to identify whether the first image is either a first type image or a second type image, or whether the first image is a third type image.

3. The image processing apparatus according to claim 2, wherein, if the first image is an image of the third type, the first authenticity assurance information includes first information indicating that the first image is an image of the third type, and if the first image is either an image of the first type or an image of the second type, the first authenticity assurance information includes second information indicating that the first image is either an image of the first type or an image of the second type.

4. The image processing apparatus according to claim 2 or 3, wherein, when the first image is an image of the third type, the association means associates a plurality of second authenticity assurance information with the first image, and the plurality of second authenticity assurance information includes a plurality of thumbnail images corresponding to the plurality of captured images, and information for guaranteeing the authenticity of the plurality of thumbnail images.

5. The image processing apparatus according to claim 4, characterized in that the plurality of second authenticity assurance information includes information for ensuring the authenticity of the plurality of captured images.

6. The image processing apparatus according to claim 2, further comprising a synthesis means for generating the first image which is the third type of image by synthesizing the plurality of captured images, wherein when each of the plurality of second authenticity assurance information is associated with a separate one of the plurality of captured images, and each of the plurality of second authenticity assurance information includes information for guaranteeing the authenticity of the corresponding captured image, the association means associates the first authenticity assurance information with the first image which is the third type of image, and when each of the plurality of second authenticity assurance information is not associated with a separate one of the plurality of captured images, the association means refrains from associating the first authenticity assurance information with the first image which is the third type of image.

7. The image processing apparatus according to claim 6, wherein, when each of the plurality of second authenticity assurance information is associated with a separate one of the plurality of captured images, the association means associates the plurality of second authenticity assurance information with the first image which is the third type image, and the plurality of second authenticity assurance information includes a plurality of thumbnail images corresponding to the plurality of captured images, and information for guaranteeing the authenticity of the plurality of thumbnail images.

8. The image processing apparatus according to claim 6 or 7, further comprising a selection means for selecting a plurality of image files from a recording medium that stores two or more image files, each containing a captured image, in accordance with the user's instructions, wherein the synthesis means generates the first image, which is the third type of image, by synthesizing a plurality of captured images contained in the plurality of image files.

9. The image processing apparatus according to claim 1, wherein, if the first image is a third type image, the association means refrains from associating the first authenticity assurance information with the first image, and the third type image is a composite image generated by combining multiple captured images corresponding to multiple exposures.

10. The image processing apparatus according to any one of claims 1 to 9, characterized in that the plurality of non-composite images captured in a common single exposure are plurality of images captured using an image sensor configured to generate plurality of images with different gains applied in a common single exposure.

11. An imaging device comprising: an image processing device according to any one of claims 1 to 10; and a shooting means for capturing a non-composite image captured in a single exposure and a non-composite image captured without exposure.

12. A control method performed by an image processing device, comprising an association step of associating a first image with a first authenticity assurance information that includes information for guaranteeing the authenticity of the first image, when the first image is either a first type image or a second type image, wherein the first type image is a non-composite image captured in a single exposure, and the second type image is a composite image generated by combining a plurality of non-composite images captured in a common single exposure.

13. A program for causing a computer to function as one of the means of an image processing apparatus according to any one of claims 1 to 10.

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