JP2017069914A - Image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing apparatus, an image processing system, an image processing method and a program, capable of expressing a gradation of high resolution with the small number of bits.SOLUTION: The image processing apparatus includes a gradation converter unit which converts an image signal having each pixel value expressed with a first bit number into an image signal which is expressed with a second bit number smaller than the first bit number. The gradation converter unit performs a plurality of types of conversion on an image signal expressed with the first bit number to generate a plurality of types of image signals which are expressed with the second bit number.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image processing apparatus, an image processing system, an image processing method, and a program.

  An image processing apparatus such as a digital camera or a digital video camera performs image signal processing by performing photoelectric conversion on a pixel-by-pixel basis using an image sensor such as a CMOS sensor or a CCD to generate an image signal corresponding to the intensity of light. In recent years, the performance of an image sensor has been improved, and image data with a high dynamic range can be generated. However, since the range width supported by the display device is also limited, there are many display devices that cannot display image data of a high dynamic range as it is. Therefore, when displaying image data on such a display device, it is necessary to reduce the range to, for example, 8-bit image data having a standard range width and output the image data to the display device.

  Patent Document 1 discloses an image recording apparatus that generates range-reduced image data by gradation-compressing high-gradation image data and generates additional data based on data lost by gradation compression by range reduction. Yes. The image recording apparatus records range-reduced image data and additional data in association with each other.

JP 2014-220546 A

  However, in Patent Document 1, the gradation of the high-gradation image data is compressed to generate the range-reduced image data, and therefore the gradation of the image data is detailed in a display device that cannot display the image data of the high dynamic range as it is. There is a problem that cannot be confirmed.

  An object of the present invention is to provide an image processing apparatus, an image processing system, an image processing method, and a program capable of expressing a high-resolution gradation with a small number of bits.

  The image processing apparatus of the present invention converts an image signal in which each pixel value is represented by a first number of bits into an image signal in which each pixel value is represented by a second number of bits that is less than the first number of bits. A gradation converter, wherein the gradation converter performs a plurality of types of conversion on the image signal represented by the first number of bits, and a plurality of types represented by the second number of bits. The image signal is generated.

  According to the present invention, it is possible to express a high-resolution gradation by generating a plurality of types of image signals expressed by the second number of bits.

It is a block diagram which shows the structural example of the image processing apparatus by this embodiment. It is a block diagram which shows the structural example of the image process part by this embodiment. It is a figure which shows operation | movement of the gradation conversion part by this embodiment. It is a flowchart which shows the process of the image processing apparatus by this embodiment. It is a figure which shows the conversion table of the gradation conversion part by this embodiment. It is a figure which shows the management information linked | related with compressed video data. It is a figure which shows the structural example of the image processing system by this embodiment. It is a flowchart which shows transmission of the compression video data of an image processing apparatus. It is a figure explaining conversion of the gradation conversion part by this embodiment. It is a block diagram which shows the structural example of the portable terminal by this embodiment. It is a flowchart which shows the compression video data display of a portable terminal. It is a figure which shows UI of the portable terminal by this embodiment.

  FIG. 1 is a block diagram illustrating a configuration example of an image processing apparatus 100 according to an embodiment of the present invention. The image processing apparatus 100 is, for example, a digital camera or a digital video camera. The image processing apparatus 100 includes a lens unit 101, an image sensor 102, an image processing unit 103, compression / decompression circuits 104 and 105, an on-screen display unit 106, a liquid crystal panel 107, a microcomputer 108, an operation switch group 109, a ROM 110, and a RAM 111. . The image processing apparatus 100 further includes memory card controllers 112 and 113, memory cards 114 and 115, an external output unit 116, a bus 117, and a wireless module 118.

  The lens unit 101 is a correction lens group that has both a function of correcting the imaging position moved by the movement of the fixed lens group, the variable power lens group, the stop, and the variable power lens group for focusing, and the function of performing focus adjustment. And subject images are formed on the imaging surface of the image sensor 102. The image sensor 102 is a CMOS sensor, a CCD, or the like, and generates an image signal by photoelectric conversion. The image processing unit 103 performs image processing on the image signal output from the image sensor 102 and outputs digital image data to the RAM 111.

  FIG. 2 is a block diagram illustrating a configuration example of the image processing unit 103 in FIG. The image processing unit 103 includes an image processing unit 201 and a gradation conversion unit 205 and is connected to the RAM 111. The image processing unit 201 calculates a white balance gain value suitable for the image signal output from the image sensor 102, and multiplies the image signal output from the image sensor 102 by the gain value. Thereafter, the image processing unit 201 converts the image signal from an RGB signal to a YCbCr signal, and outputs a 12-bit Y signal, a 12-bit Cb signal, and a 12-bit Cr signal. The luminance information calculation unit 202 calculates, as luminance information, an average value of pixel values of the Y signal obtained by dividing the sum of the pixel values of the 12-bit Y signal (luminance signal) output from the image processing unit 201 by the number of pixels. That is, the luminance information calculation unit 202 calculates, as luminance information, an average luminance value obtained by dividing the total luminance value of each pixel of the image signal output from the image processing unit 201 by the number of pixels.

  FIG. 3A is a diagram of a luminance distribution 301 indicating the number of pixels having each pixel value (luminance value) of the image signal output from the image processing unit 201. The luminance value is a 12-bit Y signal and can take a value of 0 to 4095. The luminance distribution 301 indicates how the luminance values (Y signal) of the image signal are distributed. The vertical axis is the number of pixels, and the horizontal axis is the pixel value (pixel value of Y signal = luminance value). It can be seen that the image signal of the luminance distribution 301 has many pixels having luminance values of 2048 or more. Therefore, the average pixel value of the image signal of the luminance distribution 301 is a value of 2048 or more. In this case, the luminance information (luminance average value) calculated by the luminance information calculation unit 202 is also a value of 2048 or more.

  The gradation conversion unit 205 outputs a high dynamic range (HDR) image signal in which each pixel value is expressed by a first number of bits (12 bits) to a second bit in which each pixel value is smaller than the first number of bits. The image signal is converted into a standard dynamic range (SDR) image signal expressed by a number (8 bits). For example, the gradation conversion unit 205 receives the 12-bit Y signal, the 12-bit Cb signal, and the 12-bit Cr signal output from the image processing unit 201, performs gradation conversion, and converts the 8-bit Y signal, the 8-bit Cb signal, and 8 The bit Cr signal is output. The image processing unit 201 outputs each 12-bit YCbCr signal before gradation conversion to the RAM 111, and the gradation conversion unit 205 outputs each 8-bit YCbCr signal after gradation conversion to the RAM 111. In the RAM 111, 12-bit YCbCr signals before gradation conversion and 8-bit YCbCr signals after gradation conversion are written.

  FIG. 3B is a diagram illustrating input / output characteristics of the gradation conversion unit 205. The horizontal axis indicates an input 12-bit pixel value (luminance value) before gradation conversion, and can take a value of 0 to 4095. The vertical axis represents the output 8-bit pixel value (luminance value) after gradation conversion, and can take a value of 0-255. The gradation conversion unit 205 converts a 12-bit pixel value into an 8-bit pixel value. The 12-bit pixel value can take a value from 0 to 4095, and the 8-bit pixel value can take only a value from 0 to 255. The gradation converting unit 205 can control how a 12-bit pixel value is mapped to an 8-bit pixel value. For example, as illustrated in FIG. 3C, the gradation conversion unit 205 converts a 12-bit pixel value “0 to 15” into an 8-bit pixel value “0” and a 12-bit “16 to 31”. The pixel value is converted into an 8-bit pixel value of “1”. Thereby, the gradation conversion unit 205 can perform gradation conversion of the pixel value from 12 bits to 8 bits. This gradation conversion is performed with reference to a gradation conversion table set by the microcomputer 108.

  FIG. 3C is a diagram illustrating an example of an all gradation conversion table. The gradation conversion unit 205 refers to the entire gradation conversion table of FIG. 3C, and changes the pixel value “0 to 15” before gradation conversion to the pixel value “0” after gradation conversion as described above. The pixel value “16 to 31” before gradation conversion is converted into the pixel value “1” after gradation conversion. The all gradation conversion table in FIG. 3C is a table in which the gradation conversion unit 205 increases the pixel value after gradation conversion by 1 every time the image value before gradation conversion increases by 16. The gradation conversion unit 205 reads the entire gradation conversion table in FIG. 3C and converts the 12-bit pixel value before gradation conversion into the 8-bit pixel value after gradation conversion. Note that the gradation conversion unit 205 performs gradation conversion on the Cb signal and the Cr signal in the same manner as the Y signal. That is, the gradation conversion unit 205 converts each 12-bit YCbCr signal into an 8-bit YCbCr signal with reference to the all gradation conversion table of FIG.

  This gradation conversion makes it possible to confirm all gradations even on the liquid crystal panel 107 having a narrow dynamic range. However, since the gradation skip at the time of gradation conversion is large, a pseudo contour or the like occurs when a fine gradation pattern such as gradation is displayed, and the image quality is greatly deteriorated. Hereinafter, a method for solving this problem will be described.

  In FIG. 1, compression / decompression circuits 104 and 105 are compression units, which respectively compress the digital image signal stored in the RAM 111 into MPEG, generate (encode) compressed video data, and output the compressed video data to the RAM 111. To do. The compression / decompression circuits 104 and 105 are decompression units, and each also has a function (decode) for inputting and decompressing MPEG compressed video data.

  The on-screen display unit (OSD unit) 106 superimposes information such as various setting menus, titles, or time on the digital image signal after gradation conversion. The OSD unit 106 outputs a superimposed digital image signal or the like to the liquid crystal panel 107 as a display unit to display a digital image. The liquid crystal panel 107 displays a digital image under the control of the OSD unit 106.

  The microcomputer 108 is a microcomputer and controls the entire image processing apparatus 100. The operation switch group 109 is a switch group for a user to input an operation. Further, the operation switch group 109 includes switches for selecting a camera mode mainly for photographing with a camera, a reproduction mode for mainly reproducing, and a power-off mode for turning off the power. The ROM 110 is a flash ROM, for example, and stores a program executed by the microcomputer 108. In addition, a partial area of the ROM 110 is used for backup, for holding the state of the image processing apparatus 100 and the like. A RAM 111 is a volatile memory used as a work area by the microcomputer 108, the image processing unit 103, the compression / decompression circuits 104 and 105, and the like.

  The memory card controllers 112 and 113 record the compressed video data (moving image data) written in the RAM 111 in the memory cards 114 and 115 in accordance with a format compatible with a computer such as a FAT file system, respectively. The memory cards 114 and 115 are recording media for recording the compressed video data generated by the compression / decompression circuits 104 and 105 and the management information written in the RAM 111 by the microcomputer 108, respectively. Further, the memory cards 114 and 115 record according to a predetermined format compatible with a computer such as a FAT file system. Each of the memory cards 114 and 115 is a detachable recording medium that is removable from the image processing apparatus 100, and can be mounted on a personal computer or the like in addition to the image processing apparatus 100. The external output unit 116 outputs the digital image written in the RAM 111 by the image processing unit 103 to the outside. The wireless module 118 is a transmission unit, and transmits the moving image data stored in the RAM 111 to the outside by wireless communication such as WiFi (registered trademark) or Bluetooth (registered trademark). Each of the above blocks exchanges data via the bus 117. Although not particularly illustrated, the image processing apparatus 100 includes a microphone unit and a speaker for audio, and the compression / decompression circuits 104 and 105 perform compression / expansion of the audio signal together with the image signal. Audio data is also multiplexed with the compressed video data.

  5A to 5F are diagrams showing a gradation conversion table set in the gradation conversion unit 205 of FIG. 5A and 5B show a gradation conversion table in the intermediate gradation range of “1024 to 3071”. 5C and 5D show a gradation conversion table in the high gradation range of “2048 to 4095”. FIGS. 5E and 5F show tone conversion tables in the low tone range of “0 to 2047”.

  FIG. 5A is a diagram illustrating input / output characteristics of the gradation conversion unit 205 using the intermediate gradation conversion table. The horizontal axis indicates an input 12-bit pixel value (luminance value) before gradation conversion, and can take a value of 0 to 4095. The vertical axis represents the output 8-bit pixel value (luminance value) after gradation conversion, and can take a value of 0-255. As shown in FIG. 5B, the intermediate gradation conversion table indicates that the pixel value before gradation conversion of “1024 to 3071” is a gradation of “0 to 255” in the dynamic range of 8 bits (256). The pixel value after conversion is converted. The intermediate gradation conversion table converts pixel values before gradation conversion of “0 to 1023” into pixel values after gradation conversion of “0”, and pixels before gradation conversion of “3072 to 4095”. The value is converted into a pixel value after gradation conversion of “255”.

  FIG. 5B is a diagram illustrating an example of the intermediate gradation conversion table in FIG. In the pixel value before gradation conversion of “1024 to 3071”, the pixel value after gradation conversion increases by 1 each time the pixel value before gradation conversion increases by 8. Further, the pixel value before gradation conversion of “1023” or less is converted into a pixel value after gradation conversion of “0”. Further, the pixel value before gradation conversion of “3072” or more is converted into the pixel value after gradation conversion of “255”. As a result, the pixel values before gradation conversion of “0 to 1023” are blacked out after gradation conversion. Further, the pixel values before gradation conversion of “3072 to 4095” are overexposed after gradation conversion. However, the pixel values before gradation conversion of “1024 to 3071” in the intermediate gradation conversion tables in FIGS. 5A and 5B are “the pixel values before gradation conversion in FIGS. 3B and 3C”. The resolution after gradation conversion is higher than the pixel value before gradation conversion of 1024 to 3071 ". That is, the intermediate gradation conversion table can increase the resolution of the intermediate gradation range of “1024 to 3071”.

  Note that the gradation conversion unit 205 performs gradation conversion on the Cb signal and the Cr signal in the same manner as the Y signal. That is, the gradation conversion unit 205 converts each 12-bit YCbCr signal into an 8-bit YCbCr signal with reference to the intermediate gradation conversion tables in FIGS.

  FIG. 5C is a diagram illustrating input / output characteristics of the gradation conversion unit 205 using the high gradation conversion table. The horizontal axis indicates an input 12-bit pixel value (luminance value) before gradation conversion, and can take a value of 0 to 4095. The vertical axis represents the output 8-bit pixel value (luminance value) after gradation conversion, and can take a value of 0-255. As shown in FIG. 5D, the high gradation conversion table is configured to convert the pixel values before gradation conversion of “2048 to 4095” into “0 to 255” with an 8-bit (256) dynamic range. Convert to a later pixel value. The high gradation conversion table converts a pixel value before gradation conversion of “0 to 2047” into a pixel value after gradation conversion of “0”.

  FIG. 5D is a diagram illustrating an example of the high gradation conversion table in FIG. In the pixel value before gradation conversion of “2048 to 4095”, the pixel value after gradation conversion increases by 1 every time the pixel value before gradation conversion increases by 8. Also, the pixel value before gradation conversion of “2047” or less is converted into a pixel value after gradation conversion of “0”. As a result, the pixel values before gradation conversion of “0 to 2047” are blacked out after gradation conversion. However, the pixel values before gradation conversion of “2048 to 4095” in the high gradation conversion tables in FIGS. 5C and 5D are “2048” in the all gradation conversion tables in FIGS. 3B and 3C. The resolution after gradation conversion is higher than the pixel value before gradation conversion of “˜4095”. That is, the high gradation conversion table can increase the resolution of the high gradation range of “2048 to 4095”.

  Note that the gradation conversion unit 205 performs gradation conversion on the Cb signal and the Cr signal in the same manner as the Y signal. That is, the gradation conversion unit 205 converts each 12-bit YCbCr signal into each 8-bit YCbCr signal with reference to the high gradation conversion tables in FIGS.

  FIG. 5E is a diagram illustrating input / output characteristics of the gradation conversion unit 205 using the low gradation conversion table. The horizontal axis indicates an input 12-bit pixel value (luminance value) before gradation conversion, and can take a value of 0 to 4095. The vertical axis represents the output 8-bit pixel value (luminance value) after gradation conversion, and can take a value of 0-255. As shown in FIG. 5F, in the low gradation conversion table, the pixel value before gradation conversion of “0 to 2047” is the gradation of “0 to 255” in the dynamic range of 8 bits (256). The pixel value after conversion is converted. The third gradation conversion table converts a pixel value before gradation conversion of “2048 to 4095” into a pixel value after gradation conversion of “255”.

  FIG. 5F is a diagram illustrating an example of the low gradation conversion table in FIG. In the pixel value before gradation conversion of “0 to 2047”, the pixel value after gradation conversion increases by 1 every time the pixel value before gradation conversion increases by 8. Also, the pixel value before gradation conversion of “2048” or more is converted to the pixel value after gradation conversion of “255”. As a result, the pixel values before gradation conversion of “2048 to 4095” become overexposed after gradation conversion. However, the pixel values before gradation conversion of “0 to 2047” in the low gradation conversion tables in FIGS. 5E and 5F are “0” in the all gradation conversion tables in FIGS. The resolution after gradation conversion is higher than the pixel value before gradation conversion of “0-2047”. That is, the low gradation conversion table can increase the resolution of the low gradation range of “0 to 2047”.

  Note that the gradation conversion unit 205 performs gradation conversion on the Cb signal and the Cr signal in the same manner as the Y signal. In other words, the gradation conversion unit 205 converts each 12-bit YCbCr signal into each 8-bit YCbCr signal with reference to the low gradation conversion tables in FIGS.

  FIG. 4 is a flowchart illustrating the image processing method of the image processing apparatus 100 according to the present embodiment. Each process in the flowchart of FIG. 4 is realized by the microcomputer 108 configuring the image processing apparatus 100 executing a program stored in the ROM 111. Each time the image sensor 102 generates a frame image, the image signal after gradation conversion and the image signal before gradation conversion are written into the RAM 111.

  In step S <b> 401, the microcomputer 108 sets a gradation conversion table in the intermediate gradation range of FIGS. 5A and 5B for the gradation conversion unit 205 of the image processing unit 103. The gradation conversion unit 205 refers to the gradation conversion table of the intermediate gradation range in FIGS. 5A and 5B, and converts the 12-bit pixel value to the 8-bit pixel so that the intermediate gradation range has high resolution. Convert to value. Specifically, the gradation conversion unit 205 converts each 12-bit YCbCr signal into an 8-bit YCbCr signal with reference to the gradation conversion table in the intermediate gradation range of FIGS. To do. As a result, the 12-bit YCbCr signal output from the image processing unit 201 and the 8-bit YCbCr signal output from the gradation conversion unit 205 are written in the RAM 111.

  In step S <b> 402, the microcomputer 108 determines whether the user has instructed the image processing apparatus 100 to start recording using the operation switch group 109. The microcomputer 108 waits until a recording start instruction is given, and proceeds to step S403 if it determines that a recording start instruction has been given.

  In step S403, under the control of the microcomputer 108, the compression / decompression circuit 104 compresses each 12-bit 1-frame YCbCr signal before gradation conversion stored in the RAM 111 as compressed video data, and the compression / decompression circuit 104 of the RAM 111. Write to the buffer area. Similarly, under the control of the microcomputer 108, the compression / decompression circuit 105 compresses each 8-bit 1-frame YCbCr signal after gradation conversion stored in the RAM 111 as compressed video data, and is used for the compression / decompression circuit 105 of the RAM 111. Write to the buffer area.

  Next, in step S404, the luminance information calculation unit 202 calculates the luminance average value of the frame image before gradation conversion as luminance information under the control of the microcomputer 108, and stores the calculated luminance information in the luminance information in the RAM 111. Write to the area. In the luminance information storage area of the RAM 111, luminance information is written in a form added for each frame.

  In step S <b> 405, the microcomputer 108 determines whether compressed video data is stored in the buffer area for the compression / decompression circuit 104 of the RAM 111. If it is stored in the buffer area for the compression / expansion circuit 104 of the RAM 111, the microcomputer 108 proceeds to step S406. If not stored in the buffer area for the compression / expansion circuit 104 of the RAM 111, the microcomputer 108 proceeds to step S407. Proceed with the process. In step S406, under the control of the microcomputer 108, the memory card controller 112 writes the compressed video data before gradation conversion stored in the RAM 111 to the memory card 114, and deletes the compressed video data from the buffer area. Thereafter, the microcomputer 108 proceeds to step S407.

  Similarly, in step S <b> 405, the microcomputer 108 determines whether or not compressed video data is stored in the buffer area for the compression / decompression circuit 105 of the RAM 111. If it is stored in the buffer area for the compression / decompression circuit 105 of the RAM 111, the microcomputer 108 proceeds to step S406. If not stored in the buffer area for the compression / decompression circuit 105 of the RAM 111, the microcomputer 108 proceeds to step S407. Proceed with the process. In step S406, under the control of the microcomputer 108, the memory card controller 113 writes the compressed video data after gradation conversion stored in the RAM 111 into the memory card 115, and deletes the compressed video data from the buffer area. Thereafter, the microcomputer 108 proceeds to step S407.

  In step S <b> 407, the microcomputer 108 determines whether the user instructs the image processing apparatus 100 to stop recording using the operation switch group 109. If the microcomputer 108 determines that a recording stop instruction has been given, the process proceeds to step S408. If the microcomputer 108 determines that a recording start instruction has not been given, the process returns to step S403 to repeat the process for the next frame.

  In step S <b> 408, the microcomputer 108 determines whether compressed video data is stored in the buffer area for the compression / decompression circuit 104 of the RAM 111. If it is stored in the buffer area for the compression / decompression circuit 104 of the RAM 111, the microcomputer 108 proceeds to step S409. If not stored in the buffer area for the compression / decompression circuit 104 of the RAM 111, the microcomputer 108 proceeds to step S410. Proceed with the process. In step S409, under the control of the microcomputer 108, the memory card controller 112 writes the compressed video data before gradation conversion stored in the RAM 111 to the memory card 114, and deletes the compressed video data from the buffer area. Thereafter, the microcomputer 108 proceeds to step S410.

  Similarly, in step S <b> 408, the microcomputer 108 determines whether or not compressed video data is stored in the buffer area for the compression / decompression circuit 105 of the RAM 111. If it is stored in the buffer area for the compression / decompression circuit 105 of the RAM 111, the microcomputer 108 proceeds to step S409. If not stored in the buffer area for the compression / decompression circuit 105 of the RAM 111, the microcomputer 108 proceeds to step S410. Proceed with the process. In step S409, the memory card controller 113 writes the compressed video data after gradation conversion stored in the RAM 111 to the memory card 115 under the control of the microcomputer 108, and deletes the compressed video data from the buffer area. Thereafter, the microcomputer 108 proceeds to step S410.

  In step S410, the microcomputer 108 generates management information 601 of compressed video data before gradation conversion on the RAM 111, as shown in FIG. The memory card controller 112 writes the management information 601 to the memory card 114 under the control of the microcomputer 108. The management information 601 of the compressed video data before gradation conversion includes a resolution 611 indicating the image size of the compressed video data, a bit rate 612 indicating the data size of the compressed video data, a frame rate 613 of the compressed video data, and an average luminance value 614. including. The microcomputer 108 writes the value obtained by dividing the sum of the luminance information written in the luminance information storage area of the RAM 111 in step S404 by the number of frames as the luminance average value (metadata) 614.

  Further, the microcomputer 108 generates management information 602 of compressed video data after gradation conversion on the RAM 111 as shown in FIG. The memory card controller 113 writes the management information 602 to the memory card 115 under the control of the microcomputer 108. The compressed video data management information 602 after gradation conversion includes a resolution 621 indicating the image size of the compressed video data, a bit rate 622 indicating the data size of the compressed video data, a frame rate 623 of the compressed video data, and a gradation range 624. including. The microcomputer 108 writes the middle gradation range set in step S 401 as a gradation range (metadata) 624. Thereafter, the microcomputer 108 ends the processing of the flowchart of FIG.

  FIG. 7 is a diagram illustrating a configuration example of an image processing system. The image processing system includes an image processing apparatus 100 and a portable terminal 702. The portable terminal 702 is a display device, and can display each 8-bit YCbCr signal after gradation conversion, but cannot display each 12-bit YCbCr signal before gradation conversion. The image processing apparatus 100 and the portable terminal 702 are connected by wireless communication 703. The image processing apparatus 100 transmits the compressed video data after gradation conversion stored in the memory card 115 to the portable terminal 702 by wireless communication 703. The portable terminal 702 can receive and expand the compressed video data after gradation conversion, and display each 8-bit YCbCr signal on the internal liquid crystal panel. The user can check the moving image recorded by the image processing apparatus 100 in FIG.

  FIG. 10 is a block diagram illustrating a configuration example of the mobile terminal 702. A portable terminal 702 includes a microcomputer 1001, an operation switch group 1002, a ROM 1003, a RAM 1004, a recording medium 1005, a bus 1006, a wireless module 1007, a compression / decompression circuit 1008, an OSD unit 1009, and a liquid crystal panel 1010. The microcomputer 1001 is the same as the microcomputer 108 in FIG. The operation switch group 1002 is the same as the operation switch group 109 in FIG. The ROM 1003 is the same as the ROM 110 in FIG. The RAM 1004 is the same as the RAM 111 in FIG. The bus 1006 is the same as the bus 117 in FIG. The wireless module 1007 is the same as the wireless module 118 in FIG. The compression / decompression circuit 1008 is the same as the compression / decompression circuit 104 of FIG. 1, and is a compression unit and a decompression unit. The OSD unit 1009 is the same as the OSD unit 106 in FIG. The liquid crystal panel 1010 is a display unit similar to the liquid crystal panel 107 of FIG. 1, and displays any YCbCr signal among a plurality of types of 8-bit YCbCr signals generated by the image processing apparatus 100. The recording medium 1005 is an SSD, a flash memory, or the like, and can record data. The wireless module 1007 receives compressed video data from the image processing apparatus 100. Then, the microcomputer 1001 writes the received compressed video data in the RAM 1004 and then writes it in the recording medium 1005. When displaying the compressed video data, the microcomputer 1001 reads the compressed video data from the recording medium 1005 to the RAM 1004. The compression / decompression circuit 1008 decompresses the compressed video data in the RAM 1004 under the control of the microcomputer 1001 to generate each 8-bit YCbCr signal. The OSD unit 1009 superimposes display information on each 8-bit YCbCr signal and outputs it to the liquid crystal panel 1010. The liquid crystal panel 1010 displays each 8-bit YCbCr signal.

  FIG. 8 is a flowchart illustrating an image processing method of the image processing apparatus 100, and illustrates a process in which the image processing apparatus 100 transmits the compressed video data after gradation conversion to the portable terminal 702. Before the flowchart of FIG. 9 is executed, the image processing apparatus 100 and the portable terminal 702 are connected via the wireless module 118 and the wireless module 1007.

  In step S <b> 801, the microcomputer 108 determines whether the user has instructed the image processing apparatus 100 to transmit compressed video data using the operation switch group 109. The microcomputer 108 waits until the compressed video data transmission is instructed, and proceeds to step S802 when determining that the compressed video data transmission is instructed.

  In step S <b> 802, the memory card controller 113 reads the compressed video data after gradation conversion of the intermediate gradation range stored in the memory card 115 into the RAM 111 under the control of the microcomputer 108. Next, under the control of the microcomputer 108, the wireless module 118 transmits the compressed video data after gradation conversion in the intermediate gradation range in the RAM 111 to the portable terminal 702.

  Next, in step S <b> 803, the microcomputer 108 reads the management information 601 of the compressed video data before gradation conversion stored in the memory card 114 into the RAM 111. Then, the microcomputer 108 determines whether or not the average luminance value 614 in the management information 601 is equal to or greater than the median value. Here, since the pixel value of the 12-bit Y signal before gradation conversion can take a value of 4096 steps of “0 to 4095”, the above-mentioned median value is fixed to “2048”. If the microcomputer 108 determines that the average brightness value 614 is greater than or equal to the median value, the microcomputer 108 proceeds to step S804. If the microcomputer 108 determines that the average brightness value 614 is less than the median value, the microcomputer 108 proceeds to step S808. The meaning of this determination will be described. When the average luminance value 614 is equal to or higher than the median value, it can be determined that the pixel values before gradation conversion are many pixel values equal to or higher than the median value, and an image having a high resolution in the gradation range equal to or higher than the median value can be obtained. It can be determined that there is a high possibility that the user wants to confirm. On the other hand, when the average luminance value 614 is less than the median value, it can be determined that the pixel values before the tone conversion have many pixel values less than the median value, and high resolution is given to the tone range less than the median value. It can be determined that there is a high possibility that the user wants to check the image. Thus, by analyzing the luminance average value 614, the compressed video data in the gradation range that is highly likely to be desired by the user is transmitted first, and the gradation range that is unlikely to be desired by the user is as follows. The compressed video data is transmitted later.

  In step S804, the microcomputer 108 sets the gradation conversion table in the high gradation range of FIGS. 5C and 5D for the gradation conversion unit 205. Next, the microcomputer 108 controls the memory card controller 112, reads the compressed video data before gradation conversion stored in the memory card 114, and outputs the compressed video data before gradation conversion to the compression / decompression circuit 104. . The compression / decompression circuit 104 decompresses the input compressed video data before gradation conversion, and generates 12-bit YCbCr signals before gradation conversion. Next, the microcomputer 108 writes each 12-bit YCbCr signal before gradation conversion in the RAM 111. Next, the gradation conversion unit 205 refers to the gradation conversion table in the high gradation range shown in FIGS. 5C and 5D under the control of the microcomputer 108, and each 12 bits before gradation conversion in the RAM 111. YCbCr signals are converted into 8-bit YCbCr signals. Next, under the control of the microcomputer 108, the compression / decompression circuit 105 compresses each 8-bit YCbCr signal after gradation conversion to generate compressed video data. Next, the memory card controller 113 writes the compressed video data after gradation conversion into the memory card 115 under the control of the microcomputer 108. At this time, the microcomputer 108 writes the management information 602 in which the high gradation range is set as the gradation range 624 to the memory card 115 as in step S410.

  Next, in step S805, the microcomputer 108 controls the memory card controller 113 to read out the compressed video data after gradation conversion of the high gradation range written in step S804 stored in the memory card 115 to the RAM 111. Next, under the control of the microcomputer 108, the wireless module 118 transmits the compressed video data after gradation conversion of the high gradation range read out to the RAM 111 to the portable terminal 702. Similarly, the microcomputer 108 reads the management information 602 of the compressed video data after gradation conversion from the memory card 115 to the RAM 111, and the wireless module 118 transmits the management information 602 to the portable terminal 702.

  Next, in step S806, as in step S804, the gradation conversion unit 205 refers to the gradation conversion table in the low gradation range of FIGS. 5E and 5F, and before gradation conversion in the RAM 111. Each 12-bit YCbCr signal is converted into an 8-bit YCbCr signal. Next, under the control of the microcomputer 108, the compression / decompression circuit 105 compresses each 8-bit YCbCr signal after gradation conversion to generate compressed video data. Next, the memory card controller 113 writes the compressed video data after gradation conversion into the memory card 115 under the control of the microcomputer 108. At this time, the microcomputer 108 writes the management information 602 in which the low gradation range is set as the gradation range 624 to the memory card 115.

  Next, in step S807, the microcomputer 108 controls the memory card controller 113 to read out the compressed video data after gradation conversion of the low gradation range written in step S806 stored in the memory card 115 to the RAM 111. . Next, under the control of the microcomputer 108, the wireless module 118 transmits the compressed video data after gradation conversion in the low gradation range read out to the RAM 111 to the portable terminal 702. Similarly, the microcomputer 108 reads the management information 602 of the compressed video data after gradation conversion from the memory card 115 to the RAM 111, and the wireless module 118 transmits the management information 602 to the portable terminal 702. Thereafter, the microcomputer 108 ends the processing of the flowchart of FIG.

  In step S808, as in step S804, the gradation conversion unit 205 refers to the gradation conversion table in the low gradation range shown in FIGS. 5E and 5F, and each 12 before gradation conversion in the RAM 111. The bit YCbCr signal is converted into an 8-bit YCbCr signal. Next, under the control of the microcomputer 108, the compression / decompression circuit 105 compresses each 8-bit YCbCr signal after gradation conversion to generate compressed video data. Next, the memory card controller 113 writes the compressed video data after gradation conversion into the memory card 115 under the control of the microcomputer 108. At this time, the microcomputer 108 writes the management information 602 in which the low gradation range is set as the gradation range 624 to the memory card 115.

  Next, in step S809, the microcomputer 108 controls the memory card controller 113, and reads out the compressed video data after gradation conversion of the low gradation range written in step S808 stored in the memory card 115 to the RAM 111. . Next, under the control of the microcomputer 108, the wireless module 118 transmits the compressed video data after gradation conversion in the low gradation range read out to the RAM 111 to the portable terminal 702. Similarly, the microcomputer 108 reads the management information 602 of the compressed video data after gradation conversion from the memory card 115 to the RAM 111, and the wireless module 118 transmits the management information 602 to the portable terminal 702.

  Next, in step S810, as in step S804, the gradation conversion unit 205 refers to the gradation conversion table in the high gradation range shown in FIGS. 5C and 5D, and before gradation conversion in the RAM 111. Each 12-bit YCbCr signal is converted into an 8-bit YCbCr signal. Next, under the control of the microcomputer 108, the compression / decompression circuit 105 compresses each 8-bit YCbCr signal after gradation conversion to generate compressed video data. Next, the memory card controller 113 writes the compressed video data after gradation conversion into the memory card 115 under the control of the microcomputer 108. At this time, the microcomputer 108 writes the management information 602 in which the high gradation range is set as the gradation range 624 to the memory card 115.

  Next, in step S811, the microcomputer 108 controls the memory card controller 113, and reads the compressed video data after gradation conversion of the high gradation range written in step S810 stored in the memory card 115 into the RAM 111. Next, under the control of the microcomputer 108, the wireless module 118 transmits the compressed video data after gradation conversion of the high gradation range read out to the RAM 111 to the portable terminal 702. Similarly, the microcomputer 108 reads the management information 602 of the compressed video data after gradation conversion from the memory card 115 to the RAM 111, and the wireless module 118 transmits the management information 602 to the portable terminal 702. Thereafter, the microcomputer 108 ends the processing of the flowchart of FIG.

  As described above, the gradation conversion unit 205 includes at least the image signal obtained by converting the pixel value in the high gradation range (first gradation range) and the pixel value in the low gradation range (second gradation range). And an image signal obtained by converting the pixel value in the middle gradation range (third gradation range). The low gradation range has a smaller pixel value than the high gradation range. The middle gradation range includes pixel values between the high gradation range and the low gradation range.

  The wireless module 118 differs between the case where the average brightness value 614 is equal to or greater than the median value (reference value) (first case) and the case where the average brightness value 614 is less than the median value (reference value) (second case). In order, the compressed video data in the high gradation range and the compressed video data in the low gradation range are transmitted.

  In step S803, the microcomputer 108 determines whether the average value 614 of the pixel values of the image signal expressed by 12 bits before gradation conversion is equal to or greater than the median value. The average value 614 is, for example, an average value of luminance values of each pixel. When the average value 614 is larger than the median value, the wireless module 118 transmits an image signal obtained by converting the pixel value in the middle gradation range, and then transmits an image signal obtained by converting the pixel value in the high gradation range. Thereafter, an image signal obtained by converting the pixel value in the low gradation range is transmitted. In addition, when the average value 614 is smaller than the median value, the wireless module 118 transmits an image signal obtained by converting the pixel value in the middle gradation range, and then the image signal obtained by converting the pixel value in the low gradation range. Then, an image signal obtained by converting pixel values in the high gradation range is transmitted.

  When transmitting the image signal obtained by converting the pixel value in the high gradation range, the wireless module 118 transmits the management information 602 including the information 624 in the high gradation range together with the image signal obtained by converting the pixel value in the high gradation range. When the wireless module 118 transmits an image signal obtained by converting a pixel value in the low gradation range, the wireless module 118 includes management information including the information 624 in the low gradation range together with the image signal obtained by converting the pixel value in the low gradation range. 602 is transmitted. When the wireless module 118 transmits an image signal obtained by converting the pixel value in the middle gradation range, the wireless module 118 includes management information including information 624 on the middle gradation range together with the image signal obtained by converting the pixel value in the middle gradation range. 602 is transmitted.

  FIG. 11 is a flowchart illustrating an image processing method of the mobile terminal 702. The microcomputer 1001 monitors whether or not the image processing apparatus 100 has transmitted the compressed video data via the wireless module 1007. When the microcomputer 1001 determines that the compressed video data has been transmitted, the microcomputer 1001 starts the process of the flowchart of FIG.

  In step S <b> 1101, the microcomputer 1001 receives compressed video data and management information 602 from the image processing apparatus 100 via the wireless module 1007. Next, the microcomputer 1001 writes the received compressed video data and management information 602 to the RAM 1004, and writes the compressed video data and management information 602 in the RAM 1004 to the recording medium 1005.

  Next, in step S1102, the microcomputer 1001 reads the management information 602 stored in the recording medium 1005. Next, as shown in FIG. 12A, the microcomputer 1001 causes the OSD unit 1009 to generate a list 1201 of the compressed video data received in step S1101 stored in the recording medium 1005 based on the read management information. The list 1201 is displayed on the liquid crystal panel 1010. The liquid crystal panel 1010 displays file names and file descriptions as a list 1201. The description of the file includes gradation range information after gradation conversion as the gradation range 624 in the management information 602. This display is updated every time it is received in step S1101.

  This display update will be described with reference to FIG. When the image processing apparatus 100 transmits the compressed video data in the middle gradation range in step S802 in FIG. 8, the portable terminal 702 receives the compressed video data in the middle gradation range in step S1101, and displays the list 1202 in step S1102. Display on panel 1010. The list 1202 displays that only compressed video data that has been subjected to gradation conversion in the middle gradation range can be displayed.

  Next, when the image processing apparatus 100 transmits the compressed video data in the high gradation range in step S805 in FIG. 8, the portable terminal 702 receives the compressed video data in the high gradation range in step S1101, and displays the list 1203 in step S1102. Displayed on the liquid crystal panel 1010. The list 1203 displays that the compressed video data subjected to gradation conversion in the middle gradation range and the compressed video data subjected to gradation conversion in the high gradation range can be displayed.

  Next, when the image processing apparatus 100 transmits the compressed video data in the low gradation range in step S807 in FIG. 8, the portable terminal 702 receives the compressed video data in the low gradation range in step S1101, and the list is displayed in step S1102. 1204 is displayed on the liquid crystal panel 1010. The list 1204 indicates that compressed video data that has undergone gradation conversion in the middle gradation range, compressed video data that has undergone gradation conversion in the high gradation range, and compressed video data that has undergone gradation conversion in the low gradation range can be displayed. Is displayed. Thereafter, the microcomputer 1001 advances the process to step S1103.

  In step S1103, the microcomputer 1001 determines whether or not the user has operated the operation switch group 1002 to instruct display of compressed video data in a specific gradation range from the list displayed in step S1102. . The microcomputer 10001 is a selection unit, and selects any one of the compressed video data of a plurality of types of gradation ranges according to the instruction. The microcomputer 1001 advances the process to step S1104 when the display is instructed, and advances the process to step S1105 when the display is not instructed.

  In step S1104, the microcomputer 1001 reads compressed video data in the gradation range selected in step S1103 from the recording medium 1005 to the RAM 1004. Next, the compression / decompression circuit 1008 decompresses the compressed video data in the RAM 1004 and generates an 8-bit YCbCr signal. Next, the microcomputer 1001 outputs each 8-bit YCbCr signal to the liquid crystal panel 1010 via the OSD unit 1009. The liquid crystal panel 1010 displays each 8-bit YCbCr signal. Thereafter, the microcomputer 1001 advances the process to step S1105.

  In step S <b> 1105, the microcomputer 1001 determines whether the user has issued an end instruction to the portable terminal 702 using the operation switch group 1002. The microcomputer 1001 returns the process to step S1101 when determining that the end instruction is not given, and ends the process when determining that the end instruction is given.

  As described above, the image processing apparatus 100 transmits, to the portable terminal 702, compressed video data obtained by performing gradation conversion on a gradation conversion table in a plurality of gradation ranges with respect to an image signal that has not been subjected to gradation conversion. As a result, even with the portable terminal 702 that can display only compressed video data after gradation conversion, a high-resolution gradation can be confirmed within the designated gradation range. Furthermore, the image processing apparatus 100 changes the transmission order of the compressed video data after gradation conversion according to the luminance average value 614 before gradation conversion. This increases the possibility that the portable terminal 702 can confirm the gradation of the image in the gradation range desired by the user before the transmission of the compressed video data in the entire gradation range is completed.

  The liquid crystal panel 1010 of the portable terminal 702 cannot display each 12-bit YCbCr signal as it is, and can display only each 8-bit YCbCr signal. Therefore, the image processing apparatus 100 generates a plurality of 8-bit YCbCr signals obtained by gradation-converting a plurality of gradation ranges so as to cover the entire gradation range of each 12-bit YCbCr signal. The portable terminal 702 can check the gradation of each 12-bit YCbCr signal by switching a plurality of 8-bit YCbCr signals to display on the liquid crystal panel 1010.

  In the above description, compressed video data having three types of tone conversion is generated by switching the tone conversion table of the three types of high tone range, medium tone range, and low tone range. It is not limited. As shown in FIG. 9A, by performing three types of gradation conversion on the 12-bit image data 901 before gradation conversion, 8-bit image data 902 to 904 after three types of gradation conversion are performed. May be generated. The 8-bit image data 902 is generated by deleting the lower 4 bits of the 12-bit image data 901. The 8-bit image data 903 is generated by deleting the upper 2 bits and the lower 2 bits of the 12-bit image data 901. The 8-bit image data 904 is generated by deleting the upper 4 bits of the 12-bit image data 901. As a result, the image processing apparatus 100 may generate three types of compressed video data subjected to gradation conversion, and may transmit the three types of compressed video data to the mobile terminal 702.

  FIG. 9B is a diagram showing a gradation conversion table for generating 8-bit image data 902, and shows the relationship between pixel values before gradation conversion and pixel values after gradation conversion. The pixel value after gradation conversion is a value obtained by cutting off the remainder from the value obtained by dividing the pixel value before gradation conversion by 16. Therefore, the range of pixel values that had 16 steps before gradation conversion becomes the range of one-step pixel values after gradation conversion, and the gradation is 1/16. However, since the entire range of pixel values “0 to 4095” before gradation conversion can be covered by the range of pixel values “0 to 255” after gradation conversion, the entire image data is grasped. Suitable for cases.

  FIG. 9C is a diagram showing a gradation conversion table for generating 8-bit image data 903, and shows the relationship between pixel values before gradation conversion and pixel values after gradation conversion. The range of pixel values that had four steps before gradation conversion becomes the range of one-step pixel values after gradation conversion, and the gradation is ¼. However, only a range of ¼ of the pixel value of “0 to 4095” before gradation conversion can be covered by the range of pixel value of “0 to 255” after gradation conversion. For this reason, the gradation conversion in FIG. 9C can confirm only a partial gradation range of the image data as compared with the gradation conversion in FIG. The resolution gradation can be confirmed.

  FIG. 9D is a diagram showing a gradation conversion table for generating 8-bit image data 904, and shows the relationship between pixel values before gradation conversion and pixel values after gradation conversion. Before gradation conversion, the range of one-step pixel values becomes the range of one-step pixel values even after gradation conversion, and the gradation is maintained even after conversion. However, only the range of 1/16 of the pixel value of “0-4095” before gradation conversion can be covered by the range of the pixel value of “0-255” after gradation conversion. For this reason, the gradation conversion in FIG. 9D can confirm only a partial gradation range of the image data compared with the gradation conversion in FIG. The resolution gradation can be confirmed.

  That is, when it is desired to grasp the entire gradation range of the image, it becomes advantageous in the order of “gradation conversion in FIG. 9B> gradation conversion in FIG. 9C> gradation conversion in FIG. 9”. On the other hand, when it is desired to confirm the high-resolution gradation of the image, the order of “gradation conversion in FIG. 9D> gradation conversion in FIG. 9C> gradation conversion in FIG. 9B”. Will be advantageous.

  Therefore, at the time of recording described with reference to the flowchart of FIG. 4, compressed video data subjected to the gradation conversion of FIG. 9B is generated. When transmitting the compressed video data described with reference to the flowchart of FIG. 8, first, the compressed video data subjected to the gradation conversion of FIG. 9B generated at the time of recording is transmitted to the portable terminal 702, and then, FIG. ) Is sent to the portable terminal 702. Finally, the compressed video data subjected to the gradation conversion of FIG. 9D is transmitted to the portable terminal 702. Thus, the user can first confirm the entire gradation range of the image and gradually confirm the high-resolution gradation of the image.

  As described above, the gradation conversion unit 205 performs a plurality of types of conversion on the image signal represented by the first number of bits (12 bits), and is represented by the second number of bits (8 bits). A plurality of types of image signals are generated.

  In the case of FIGS. 5A to 5F, the gradation conversion unit 205 has a plurality of different gradation ranges within the entire gradation range of each pixel value of the image signal represented by the first number of bits. The pixel value is converted into a pixel value of an image signal expressed by the second number of bits with a dynamic range of the second number of bits. Thereby, the gradation conversion unit 205 can generate a plurality of types of image signals expressed by the second number of bits.

  In the case of FIGS. 9A to 9D, the gradation converting unit 205 deletes different bits from the image signal expressed by the first number of bits, and thereby a plurality of numbers expressed by the second number of bits. Generate different types of image signals.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 100 Image processing apparatus, 101 Lens unit, 102 Image sensor, 103 Image processing part, 104 Compression / decompression circuit, 105 Compression / decompression circuit, 106 OSD part, 107 Liquid crystal panel, 108 Microcomputer, 109 Operation switch group, 110 ROM, 111 RAM, 112 memory card controller, 113 memory card controller, 114 memory card, 115 memory card, 116 external output unit, 118 wireless module

Claims (17)

A gradation conversion unit that converts an image signal in which each pixel value is represented by a first number of bits into an image signal in which each pixel value is represented by a second number of bits that is less than the first number of bits;
The gradation conversion unit performs a plurality of types of conversion on the image signal expressed by the first number of bits, and generates a plurality of types of image signals expressed by the second number of bits. A featured image processing apparatus.   The gradation conversion unit converts pixel values of a plurality of different gradation ranges within the entire gradation range of each pixel value of the image signal expressed by the first number of bits to the second number of bits. A plurality of types of image signals expressed by the second number of bits are generated by converting the pixel values of the image signal expressed by the second number of bits in a dynamic range. The image processing apparatus according to 1.   The gradation converting unit generates a plurality of types of image signals represented by the second number of bits by deleting different bits of the image signal represented by the first number of bits. The image processing apparatus according to claim 1.   The image processing apparatus according to claim 1, further comprising a transmission unit that transmits a plurality of types of image signals represented by the second number of bits. And a compression unit that compresses a plurality of types of image signals represented by the second number of bits,
The image processing apparatus according to claim 4, wherein the transmission unit transmits a plurality of types of image signals expressed by the second number of bits compressed by the compression unit.   6. The transmission unit according to claim 4, wherein the transmission unit transmits a plurality of types of image signals expressed by the second number of bits in different orders in the first case and the second case. Image processing apparatus. And a transmitter that transmits a plurality of types of image signals represented by the second number of bits,
The gradation conversion unit converts at least an image signal obtained by converting a pixel value in a first gradation range and an image signal obtained by converting a pixel value in a second gradation range having a pixel value smaller than the first gradation range. Signal and generate
The transmitter is
When the average value of the pixel values of the image signal expressed by the first number of bits is larger than a reference value, the image signal obtained by converting the pixel value of the first gradation range is transmitted, and then the first An image signal obtained by converting the pixel value of the gradation range of 2 is transmitted,
When the average value of the pixel values of the image signal represented by the first number of bits is smaller than the reference value, the image signal obtained by converting the pixel value of the second gradation range is transmitted, The image processing apparatus according to claim 2, wherein an image signal obtained by converting a pixel value in the first gradation range is transmitted. The gradation conversion unit includes at least an image signal obtained by converting a pixel value in the first gradation range, an image signal obtained by converting a pixel value in the second gradation range, and the first gradation range. And an image signal obtained by converting the pixel value of the third gradation range including the pixel value between the second gradation range,
The transmitter is
When the average value of each pixel value of the image signal expressed by the first number of bits is larger than the reference value, an image signal obtained by converting the pixel value of the third gradation range is transmitted, and thereafter , Transmitting an image signal converted from the pixel value of the first gradation range, and then transmitting an image signal converted from the pixel value of the second gradation range,
When the average value of the pixel values of the image signal represented by the first number of bits is smaller than the reference value, an image signal obtained by converting the pixel value of the third gradation range is transmitted, and thereafter 8. The image signal obtained by converting the pixel value in the second gradation range is transmitted, and then the image signal obtained by converting the pixel value in the first gradation range is transmitted. Image processing apparatus. The transmitter is
When the average value of the luminance values of the pixels of the image signal represented by the first number of bits is larger than the reference value, after transmitting the image signal obtained by converting the pixel value of the first gradation range , Transmitting an image signal obtained by converting the pixel value of the second gradation range,
When the average luminance value of each pixel of the image signal represented by the first number of bits is smaller than the reference value, after transmitting the image signal converted from the pixel value of the second gradation range 9. The image processing apparatus according to claim 7, wherein an image signal obtained by converting a pixel value in the first gradation range is transmitted. The transmitter is
When transmitting an image signal obtained by converting the pixel value of the first gradation range, information on the first gradation range is transmitted together with the image signal obtained by converting the pixel value of the first gradation range. ,
When transmitting an image signal obtained by converting the pixel value in the second gradation range, information on the second gradation range is transmitted together with the image signal obtained by converting the pixel value in the second gradation range. The image processing apparatus according to claim 7, wherein the image processing apparatus is an image processing apparatus.   11. The image signal represented by the first number of bits and the image signal represented by the second number of bits are each a YCbCr signal. 11. Image processing apparatus. Furthermore, it has an image sensor that generates an image signal by photoelectric conversion,
The image processing apparatus according to claim 1, wherein the image signal expressed by the first number of bits is a signal based on an image signal generated by the imaging element. The image processing apparatus according to any one of claims 1 to 12,
A display device,
The display device includes a display unit that displays any one of a plurality of types of image signals represented by the second number of bits generated by the image processing device. . The display device includes a selection unit that selects any one of a plurality of types of image signals represented by the second number of bits,
The image processing system according to claim 13, wherein the display unit displays the image signal selected by the selection unit. The display device includes an expansion unit that expands the image signal selected by the selection unit,
15. The image processing system according to claim 14, wherein the display unit displays the image signal expanded by the expansion unit. A gradation for converting an image signal in which each pixel value is expressed by a first number of bits into an image signal in which each pixel value is expressed by a second number of bits smaller than the first number of bits by a gradation conversion unit. A conversion step,
In the gradation conversion step, a plurality of types of conversion are performed on the image signal represented by the first number of bits to generate a plurality of types of image signals represented by the second number of bits. A featured image processing method. A computer executes a gradation conversion step for converting an image signal in which each pixel value is represented by a first number of bits into an image signal in which each pixel value is represented by a second number of bits that is smaller than the first number of bits. A program for
In the gradation conversion step, a plurality of types of conversion are performed on the image signal represented by the first number of bits to generate a plurality of types of image signals represented by the second number of bits. A featured program.

Images