Display system, display method, display controller, and video signal processing method for display controller

Abstract

This display system comprises: a first decoding unit that decodes a first video signal and outputs a second video signal; an analysis unit that analyzes the second video signal and obtains a luminance distribution in at least a portion of an analysis range; a first determination unit that determines a first gamma curve on the basis of the luminance distribution; an encoding unit that outputs a third video signal obtained by encoding the second video signal by using the first gamma curve; a second determination unit that determines a second gamma curve on the basis of the third video signal and gamma curve information; a second decoding unit that outputs a fourth video signal obtained by decoding the third video signal by using the second gamma curve; and a display unit that displays video on the basis of the fourth video signal.

Description

Display system, display method, display controller, and video signal processing method for display controller

[0001] The present invention relates to a display system, a display method, a display controller, and a video signal processing method for a display controller.

[0002] In conventional LED (Light Emitting Diode) display systems, an LED controller unit and an LED panel unit are typically configured in separate housings, allowing for cases where the housings are installed in different locations. The LED controller unit and the LED panel unit are often connected by a cable such as a LAN (Local Area Network) cable, and the transmission rate is typically 1 Gbps. Therefore, there is a limit to the amount of data that can be transmitted over a single cable between the LED controller unit and the LED panel unit.

[0003] While LED display systems are capable of high-contrast display due to the high brightness of their elements, they can sometimes cause perceived degradation in image quality in low-brightness areas. In displays that involve transmission between a controller and a panel, including not only LED display systems but also LCD (Liquid Crystal Display) displays and OLED (Organic Light-Emitting Diode) displays, degradation in image quality can be perceived in low-brightness areas. This degradation in image quality can be prevented by increasing the amount of data (number of bits) per pixel. However, as mentioned above, transmission paths such as cables have a limited amount of data that can be transmitted. Therefore, increasing the amount of data per pixel reduces the image display area that can be covered by a single cable. Therefore, increasing the amount of data per pixel to prevent degradation in image quality requires increasing the number of cable connections, which ultimately increases product costs and reduces usability.

[0004] Japanese Patent Application Laid-Open No. 2006-124993 discloses a technique for performing gamma processing on an image signal generated by an imaging device before image processing, and then performing inverse gamma processing on the image signal after image processing before transmitting the image signal to a display. In this technique, the gamma processing converts the image signal using a conversion characteristic represented by a straight line rather than a curve for low-brightness areas. This reduces data loss in low-brightness areas, making it possible to suppress degradation of image quality in low-brightness areas without increasing the amount of data per pixel.

[0005] JP 2017-156721 A

[0006] However, the technology of Patent Document 1 takes into consideration data loss in processing (gamma processing) performed before image processing of the image signal, but does not take into consideration data loss in processing (inverse gamma processing) performed after image processing. Therefore, there is room for improvement in processing performed after image processing of the image signal in order to suppress degradation of image quality.

[0007] In view of the above-mentioned problems, an object of the present invention is to provide a display system, a display method, a display controller, and a video signal processing method for a display controller that can suppress degradation of image quality caused by the data capacity of a transmission path.

[0008] In order to solve the above-mentioned problems, a display system according to one aspect of the present invention is a display system including: a first decoding unit that decodes an input first video signal and outputs a second video signal; an analysis unit that analyzes the second video signal and acquires a luminance distribution in at least a portion of an analysis range of the second video signal; a first determination unit that determines a first gamma curve to be used in encoding the second video signal based on the luminance distribution; an encoding unit that outputs a third video signal obtained by encoding the second video signal using the determined first gamma curve; a second determination unit that determines a second gamma curve to be used in decoding the third video signal based on the third video signal and gamma curve information indicating the first gamma curve used for encoding; a second decoding unit that outputs a fourth video signal obtained by decoding the third video signal using the determined second gamma curve; and a display unit that displays an image based on the fourth video signal.

[0009] A display method according to one aspect of the present invention is a computer-executed display method including: a first decoding step of decoding an input first video signal to output a second video signal; an analysis step of analyzing the second video signal and acquiring a luminance distribution in at least a portion of an analysis range of the second video signal; a first determination step of determining a first gamma curve to be used in encoding the second video signal based on the luminance distribution; an encoding step of outputting a third video signal obtained by encoding the second video signal using the determined first gamma curve; a second determination step of determining a second gamma curve to be used in decoding the third video signal based on the third video signal and gamma curve information indicating the first gamma curve used for encoding; a second decoding step of outputting a fourth video signal obtained by decoding the third video signal using the determined second gamma curve; and a display step of displaying an image based on the fourth video signal.

[0010] A display controller according to one embodiment of the present invention comprises a decoding unit that decodes an input first video signal and outputs a second video signal; an analysis unit that analyzes the second video signal and obtains a luminance distribution in at least a portion of an analysis range of the second video signal; a determination unit that determines a gamma curve to be used in encoding the second video signal based on the luminance distribution; and an encoding unit that outputs a third video signal obtained by encoding the second video signal using the determined gamma curve.

[0011] A video signal processing method for a display controller according to one embodiment of the present invention is a computer-executed video signal processing method for a display controller, including: a decoding process for decoding an input first video signal and outputting a second video signal; an analysis process for analyzing the second video signal and obtaining a luminance distribution in at least a portion of an analysis range of the second video signal; a determination process for determining a gamma curve to be used in encoding the second video signal based on the luminance distribution; and an encoding process for outputting a third video signal obtained by encoding the second video signal using the determined gamma curve.

[0012] According to the present invention, it is possible to suppress deterioration in image quality caused by the data capacity of a transmission path.

[0013] 1 is a block diagram showing an example of a configuration of a display system according to a first embodiment. FIG. 2 is a block diagram showing an example of a functional configuration of a display controller according to the first embodiment. FIG. 3 is a diagram showing an example of a gamma curve used in encoding a video signal according to the first embodiment. FIG. 4 is a block diagram showing an example of a functional configuration of a display module according to the first embodiment. FIG. 5 is a diagram showing an example of a gamma curve used in decoding a video signal according to the first embodiment. FIG. 6 is a sequence diagram showing an example of a processing flow in a display system according to the first embodiment. FIG. 7 is a flowchart showing an example of a detailed flow of an analysis process and a determination process according to the first embodiment. FIG. 8 is a flowchart showing an example of a detailed flow of an analysis process and a determination process in a modified example according to the first embodiment. FIG. 9 is a diagram showing an example of a histogram in a modified example according to the first embodiment. FIG. 10 is a block diagram showing an example of a configuration of a display system according to a second embodiment. FIG. 11 is a diagram showing an example of a configuration of a display according to the second embodiment. FIG. 12 is a diagram showing an example of an image displayed on a display according to the second embodiment. FIG. 13 is a block diagram showing an example of a functional configuration of an analysis unit according to the second embodiment. FIG. 14 is a block diagram showing an example of a functional configuration of an analysis unit in a modified example according to the second embodiment. FIG. 15 is a block diagram showing an example of a functional configuration of a display controller according to a third embodiment. FIG. 16 is a block diagram showing an example of a functional configuration of a display module according to the third embodiment. FIG. 17 is a block diagram showing an example of a functional configuration of a display controller according to a fourth embodiment. FIG. 18 is a block diagram showing an example of a functional configuration of a display module according to the fourth embodiment. FIG. 19 is a block diagram showing an example of a configuration of a display system according to a fifth embodiment.

[0014] An embodiment of the present invention will be described in detail with reference to the drawings. A display system for displaying an image on a display will be described below. The display system is a system (display system) in which data is transmitted between a display unit (e.g., a panel) of a display that displays the image and a controller of the display. Examples of the display include an LCD (Liquid Crystal Display) display, an OLED (Organic Light-Emitting Diode) display, and an LED (Light Emitting Diode) display. In the display system, the display unit and the controller may be provided in a single housing, or may be provided in different housings. Furthermore, in the display system, another device, such as a module, may be interposed between the display unit and the controller. In this case, the display unit, the controller, and the other devices may all be provided in a single housing, or may be provided in different housings, or may be provided in any combination in any number of housings. That is, the configuration of the display system is not particularly limited as long as transmission occurs between the video signal input to the controller and the display unit. Furthermore, transmission between the display unit and the controller may be performed by a wired connection in which the display unit and the controller are connected by a cable such as a LAN (Local Area Network) cable, or by a wireless connection in which the display unit and the controller are connected by wireless communication.

[0015] <<1. First Embodiment>> A first embodiment will be described with reference to FIGS. 1 to 9 . In the first embodiment, an example will be described in which one image is displayed on a display having one display unit. For example, this is a case in which only one display such as an LCD display or an OLED display is used. In addition, in the first embodiment, an example will be described in which the display unit and the controller are provided in different housings, and another device is interposed between the display unit and the controller, and the other device is provided in the same housing as the display unit.

[0016] <1-1. Configuration of the Display System> The configuration of the display system according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the configuration of the display system according to the first embodiment. As shown in Fig. 1, the display system 1 according to the first embodiment includes a control terminal 10, a source device 20, a display controller 30, a display 40, and a display module 50.

[0017] (1) Control Terminal 10 The control terminal 10 is a terminal for controlling the display of images on the display 40. The control terminal 10 is, for example, a personal computer (PC), a smartphone, or a tablet terminal. The control terminal 10 is communicably connected to the display controller 30 via a wired or wireless connection. When a user inputs information for controlling the display of images, the control terminal 10 outputs (transmits) the input information to the display controller 30.

[0018] (2) Source Device 20 The source device 20 is a device that outputs a video signal. The source device 20 is, for example, a PC or a video output device. The source device 20 is communicably connected to the display controller 30 via a wired or wireless connection. The source device 20 and the display controller 30 are wiredly connected by a cable such as an HDMI (High Definition Multimedia Interface) (registered trademark) cable. The source device 20 outputs (transmits) a video signal to the display controller 30.

[0019] (3) Display Controller 30 The display controller 30 is a device that converts an input video signal into a video signal for displaying an image on the display 40. The display controller 30 is communicably connected to the control terminal 10, the source device 20, and the display 40 via a wired or wireless connection. The display controller 30 processes the video signal based on information received from the control terminal 10 and the video signal received from the source device 20, and outputs (transmits) the processed video signal to the display 40.

[0020] (4) Display 40 The display 40 is a display device that displays an image based on an input video signal. The display 40 is communicably connected to the display controller 30 via a wired or wireless connection. The display 40 displays an image based on the video signal received from the display controller 30. As shown in FIG. 1 , the display 40 includes a display module 50.

[0021] (5) Display Module 50 The display module 50 incorporates a display unit such as a panel or screen that constitutes a display, and a processing unit such as a driver or controller that performs processing to display images. The display module 50 is communicably connected to the display controller 30 via a wired or wireless connection. The display module 50 performs processing for displaying a video signal received from the display controller 30 in the processing unit, and displays the processed image on the display unit.

[0022] <1-2. Functional Configuration of Display Controller> The configuration of the display system 1 according to the first embodiment has been described above. Next, the functional configuration of the display controller 30 according to the first embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a block diagram showing an example of the functional configuration of the display controller 30 according to the first embodiment. As shown in FIG. 2, the display controller 30 includes a decoding unit 310 (first decoding unit), a signal processing unit 320, an analyzing unit 330, a determining unit 340 (first determining unit), an encoding unit 350, a switching unit 360, and a formatter unit 370.

[0023] (1) Decoding Unit 310 The decoding unit 310 has a function of decoding a video signal. The decoding unit 310 decodes a video signal (first video signal) input from the source device 20 and outputs a video signal (second video signal). The decoding unit 310 decodes the input video signal to match the gamma curve of the video signal and return it to a video signal (linear data) with linear characteristics. In decoding, the decoding unit 310 converts the input video signal into a video signal with a bit precision greater than the bit width of the video signal. For example, the decoding unit 310 converts a 10-bit video signal into a 16-bit video signal. After decoding, the decoding unit 310 outputs the video signal to the signal processing unit 320.

[0024] (2) Signal Processing Unit 320 The signal processing unit 320 has a function of performing signal processing on the video signal. The signal processing unit 320 performs signal processing such as color adjustment on the video signal (second video signal) input from the decoding unit 310. In the signal processing, the bit width of the video signal may be changed. For example, the signal processing unit 320 may convert a 16-bit video signal input from the decoding unit 310 into a 14-bit video signal or an 18-bit video signal. The number of bits after the change is not particularly limited. After the signal processing, the signal processing unit 320 outputs the processed video signal (second video signal) to the analysis unit 330.

[0025] (3) Analysis Unit 330 The analysis unit 330 has a function of analyzing a video signal. The analysis unit 330 analyzes the video signal (second video signal) input from the signal processing unit 320 and acquires a luminance distribution in at least a part of the analysis range of the video signal. In the first embodiment, since one video based on the input video signal is displayed on the display 40 having one panel, the analysis range is the entire video signal (entire frame). After the analysis, the analysis unit 330 outputs the acquired luminance distribution to the determination unit 340.

[0026] In the analysis, the analysis unit 330 first acquires a luminance value for each pixel of the input video signal. After acquisition, the analysis unit 330 determines the luminance level of each pixel based on the acquired luminance value. Specifically, the analysis unit 330 compares the acquired luminance value with a preset reference luminance value to assign each pixel to a corresponding luminance level. At this time, the analysis unit 330 counts and records the number of pixels assigned to each luminance level (hereinafter also referred to as the "number of pixels"). By assigning luminance levels to all pixels, the analysis unit 330 can acquire the luminance distribution within the analysis range of the video signal. The luminance distribution is represented, for example, by the number of pixels assigned to each luminance level.

[0027] The reference value is set, for example, by dividing the range of values ​​that the luminance value can take into multiple regions. In the first embodiment, as an example, when the number of bits is 10, the range of values ​​that the luminance value can take is set to 0 to 1023, and the reference luminance value is set by dividing this range into three regions. For example, the reference luminance value is set to 0 to 255 as a value that determines that the luminance level is level 1, 256 to 511 as a value that determines that the luminance level is level 2, and 512 to 1023 as a value that determines that the luminance level is level 3. Note that the number of bits, the range of values ​​that the luminance value can take, the number of regions into which the range is divided, and the value of the reference luminance value are not limited to the above-mentioned example. For example, the number of bits is not limited to 10 bits, and the reference luminance value is set in the same way for bit numbers such as 8 bits and 12 bits.

[0028] (4) Determination Unit 340 The determination unit 340 has a function of determining a gamma curve to be used for encoding a video signal. The determination unit 340 determines a gamma curve (first gamma curve) to be used for encoding a video signal (second video signal) based on the luminance distribution acquired by the analysis unit 330. After determination, the determination unit 340 outputs the video signal to the encoding unit 350, and outputs gamma curve information to the switching unit 360 and the formatter unit 370. The gamma curve information output here is information indicating the gamma curve determined by the determination unit 340 to be used for encoding the video signal.

[0029] The gamma curves used for encoding are prepared in accordance with the proportion of low-luminance pixels in the analysis range. For example, in the first embodiment, three types of gamma curves are prepared for encoding. The first type is an encoding gamma curve used for encoding when the proportion of low-luminance pixels in the analysis range is high (i.e., the number of level 1 pixels is large). The second type is an encoding gamma curve used for encoding when the proportion of low-luminance pixels in the analysis range is medium (i.e., the number of level 2 pixels is large). The third type is an encoding gamma curve used for encoding when the proportion of low-luminance pixels in the analysis range is low (i.e., the number of level 3 pixels is large).

[0030] Here, gamma curves used for encoding video signals will be described with reference to FIG. 3. FIG. 3 is a diagram showing an example of a gamma curve used for encoding video signals according to the first embodiment. A gamma curve GC1 shown in the graph (a) of FIG. 3 is a gamma curve for encoding corresponding to level 1. The gamma value of the gamma curve GC1 is set smaller than those of the other gamma curves. A gamma curve GC2 shown in the graph (b) of FIG. 3 is a gamma curve for encoding corresponding to level 2. The gamma value of the gamma curve GC2 is set larger than those of the gamma curve GC1 and smaller than those of the gamma curve GC3. A gamma curve GC3 shown in the graph (c) of FIG. 3 is a gamma curve for encoding corresponding to level 3. The gamma value of the gamma curve GC3 is set larger than those of the other gamma curves.

[0031] The determination unit 340 determines a gamma curve to be used for encoding the video signal based on the acquired luminance distribution and the proportion of low-luminance pixels in the analysis range. The determination unit 340 compares the number of pixels at each luminance level indicated by the acquired luminance distribution with a reference number of pixels (hereinafter also referred to as the "reference pixel number") to determine the proportion of low-luminance pixels in the analysis range. For example, in the first embodiment, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range is high if the number of pixels at either luminance level 1 or level 2 is equal to or greater than the reference pixel number, and the number of level 1 pixels is equal to or greater than the level 2 pixel number. Furthermore, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range is medium if the number of pixels at either luminance level 1 or level 2 is equal to or greater than the reference pixel number, and the number of level 1 pixels is less than the level 2 pixel number. Furthermore, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range is low if the number of pixels at luminance level 1 or level 2 is less than the reference pixel number.

[0032] When the proportion of pixels in the analysis range that are low-luminance is high, the determination unit 340 determines to use a gamma curve (gamma curve GC1 in FIG. 3 ) in which the gamma value is set smaller than when the proportion of pixels in the analysis range that are not low-luminance is high. Furthermore, when the proportion of pixels in the analysis range that are low-luminance is medium, the determination unit 340 determines to use a gamma curve (gamma curve GC2 in FIG. 3 ) in which the gamma value is set larger than when the proportion of pixels in the analysis range that are low-luminance is high and smaller than when the proportion of pixels in the analysis range that are low-luminance is low. Furthermore, when the proportion of pixels in the analysis range that are low-luminance is low, the determination unit 340 determines to use a gamma curve (gamma curve GC3 in FIG. 3 ) in which the gamma value is set larger than when the proportion of pixels in the analysis range that are low-luminance is medium.

[0033] (5) Encoding Unit 350 The encoding unit 350 has a function of encoding a video signal. The encoding unit 350 uses the gamma curve (first gamma curve) determined by the determination unit 340 to encode the video signal (second video signal) input from the determination unit 340, and outputs a video signal (third video signal). In encoding, the encoding unit 350 converts the input video signal into a video signal with a smaller bit precision than the bit width of the video signal. For example, the encoding unit 350 converts a 16-bit video signal into a 10-bit video signal. After encoding, the encoding unit 350 outputs the video signal to the switching unit 360.

[0034] In the first embodiment, encoding is performed in parallel using not only the gamma curve determined by the determination unit 340, but also other prepared gamma curves. For this reason, as shown in FIG. 2 , the encoding unit 350 includes multiple processing units 351. For example, the number of processing units 351 is equal to the number of gamma curves used for encoding. In the encoding unit 350, each of the multiple processing units 351-1, 351-2, ... performs encoding using a different gamma curve for the same video signal. In the first embodiment, three gamma curves GC1 to GC3 are prepared, and therefore three processing units 351 are provided. The first processing unit 351 performs encoding using the gamma curve GC1. The second processing unit 351 performs encoding using the gamma curve GC2. The third processing unit 351 performs encoding using the gamma curve GC3.

[0035] (6) Switching Unit 360 The switching unit 360 has a function of switching between multiple video signals. Based on the gamma curve information input from the determining unit 340, the switching unit 360 switches which of the multiple video signals output from each processing unit 351 of the encoding unit 350 is to be output to a subsequent block. After switching, the switching unit 360 outputs the video signal to the formatter unit 370.

[0036] For example, in the first embodiment, if the gamma curve information indicates gamma curve GC1, the switching unit 360 switches to output a video signal encoded using gamma curve GC1. If the gamma curve information indicates gamma curve GC2, the switching unit 360 switches to output a video signal encoded using gamma curve GC2. If the gamma curve information indicates gamma curve GC3, the switching unit 360 switches to output a video signal encoded using gamma curve GC3.

[0037] (7) Formatter Unit 370 The formatter unit 370 has a function of processing the video signal to match the format of the transmission path between the display controller 30 and the display module 50. The formatter unit 370 processes the video signal input from the switching unit 360 to match the format of the transmission path. Furthermore, the formatter unit 370 performs a process of embedding the gamma curve information input from the determination unit 340 into the video signal input from the switching unit 360 in order to convey to the display module 50 information on the gamma curve used in encoding the video signal to be output. After processing, the formatter unit 370 outputs the video signal to the display module 50.

[0038] <1-3. Functional Configuration of Display Module> The functional configuration of the display controller 30 according to the first embodiment has been described above. Next, the functional configuration of the display module 50 according to the first embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing an example of the functional configuration of the display module 50 according to the first embodiment. As shown in FIG. 4, the display module 50 includes a format decoding unit 510, a determination unit 520 (second determination unit), a decoding unit 530 (second decoding unit), a switching unit 540, and a display unit 550.

[0039] (1) Format Decoding Unit 510 The format decoding unit 510 has a function of decoding the format of a video signal. The format decoding unit 510 decodes the format of the video signal (third video signal) input from the display controller 30. As a result, the format decoding unit 510 acquires the video signal and gamma curve information indicating the gamma curve (first gamma curve) used to encode the video signal. After decoding the format, the format decoding unit 510 outputs the video signal and the gamma curve information to the determination unit 520.

[0040] (2) Determination Unit 520 The determination unit 520 has a function of determining a gamma curve to be used for decoding a video signal. The determination unit 520 determines a gamma curve (second gamma curve) to be used for decoding a video signal based on the video signal (third video signal) and gamma curve information acquired by the format decoding unit 510. After determination, the determination unit 520 outputs the video signal to the decoding unit 530 and outputs the gamma curve information to the switching unit 540. The gamma curve information output here is the gamma curve information input from the format decoding unit 510.

[0041] The gamma curves used for decoding are prepared in a manner corresponding to the gamma curves used for encoding in the display controller 30. For example, in the first embodiment, three types of gamma curves are prepared for decoding. The first type is a gamma curve for decoding that corresponds to the gamma curve used for encoding when the proportion of low-luminance pixels in the analysis range is high (i.e., the number of level 1 pixels is large). The second type is a gamma curve for decoding that corresponds to the gamma curve used for encoding when the proportion of low-luminance pixels in the analysis range is medium (i.e., the number of level 2 pixels is large). The third type is a gamma curve for decoding that corresponds to the gamma curve used for encoding when the proportion of low-luminance pixels in the analysis range is low (i.e., the number of level 3 pixels is large).

[0042] Here, gamma curves used for decoding video signals will be described with reference to FIG. 5 . FIG. 5 is a diagram showing an example of a gamma curve used for decoding video signals according to the first embodiment. The gamma curve GC4 shown in the graph (d) of FIG. 5 is a gamma curve for decoding corresponding to level 1. The gamma value of the gamma curve GC4 is set to be larger than that of the other gamma curves for decoding. The gamma curve GC5 shown in the graph (e) of FIG. 5 is a gamma curve for decoding corresponding to level 2. The gamma value of the gamma curve GC5 is set to be smaller than that of the gamma curve GC4 and larger than that of the gamma curve GC6. The gamma curve GC6 shown in the graph (f) of FIG. 5 is a gamma curve for decoding corresponding to level 3. The gamma value of the gamma curve GC6 is set to be smaller than that of the other gamma curves for decoding.

[0043] Based on a gamma value (first gamma value) set in the gamma curve indicated by the acquired gamma curve information, the determination unit 520 determines to use a gamma curve in which a gamma value (second gamma value) that is the reciprocal of the gamma value is set. For example, in the first embodiment, if the gamma value indicated by the gamma curve information is that of gamma curve GC1, the determination unit 520 determines to use gamma curve GC4, which is the gamma value that is the reciprocal of that gamma value, for decoding. Furthermore, if the gamma value indicated by the gamma curve information is that of gamma curve GC2, the determination unit 520 determines to use gamma curve GC5, which is the gamma value that is the reciprocal of that gamma value, for decoding. Furthermore, if the gamma value indicated by the gamma curve information is that of gamma curve GC3, the determination unit 520 determines to use gamma curve GC6, which is the gamma value that is the reciprocal of that gamma value, for decoding.

[0044] (3) Decoding Unit 530 The decoding unit 530 has a function of decoding a video signal. The decoding unit 530 outputs a video signal (fourth video signal) obtained by decoding the video signal (third video signal) input from the determination unit 520 using the gamma curve (second gamma curve) determined by the determination unit 520. After decoding, the decoding unit 530 outputs the video signal to the switching unit 540.

[0045] In the first embodiment, decoding is performed in parallel not only using the gamma curve determined by the determination unit 520, but also using other prepared gamma curves. For this reason, as shown in FIG. 4 , the decoding unit 530 includes multiple processing units 531. For example, the number of processing units 531 is equal to the number of gamma curves used for decoding. In the decoding unit 530, each of the multiple processing units 531-1, 531-2, ... performs decoding using a different gamma curve for the same video signal. In the first embodiment, three gamma curves GC4 to GC6 are prepared, and therefore three processing units 351 are provided. The first processing unit 351 performs decoding using the gamma curve GC4. The second processing unit 351 performs decoding using the gamma curve GC5. The third processing unit 351 performs decoding using the gamma curve GC6.

[0046] (4) Switching Unit 540 The switching unit 540 has a function of switching between a plurality of video signals. The switching unit 540 switches which of the plurality of video signals (fourth video signals) output from each processing unit 531 of the decoding unit 530 is to be output to a subsequent block, based on the gamma curve information input from the determining unit 520. After switching, the switching unit 540 outputs the video signal to the display unit 550.

[0047] For example, in the first embodiment, if the gamma curve information indicates that gamma curve GC1 was used in encoding by the display controller 30, the switching unit 540 switches to output a video signal decoded using gamma curve GC4. If the gamma curve information indicates that gamma curve GC2 was used in encoding by the display controller 30, the switching unit 540 switches to output a video signal decoded using gamma curve GC5. If the gamma curve information indicates that gamma curve GC3 was used in encoding by the display controller 30, the switching unit 540 switches to output a video signal encoded using gamma curve GC6.

[0048] (5) Display Unit 550 The display unit 550 has a function of displaying an image. The display unit 550 displays an image based on the image signal (fourth image signal) input from the switching unit 540.

[0049] 1-4. Processing Flow The functional configuration of the display module 50 according to the first embodiment has been described above. Next, the processing flow according to the first embodiment will be described with reference to FIGS.

[0050] (1) Processing Flow in Display System 1 The processing flow in the display system 1 will be described with reference to Fig. 6. Fig. 6 is a sequence diagram showing an example of the processing flow in the display system 1 according to the first embodiment. The processing shown in Fig. 6 is executed when, for example, an operation to display an image on the display 40 is performed on the control terminal 10 as a trigger.

[0051] As shown in FIG. 6, first, the source device 20 transmits a video signal to the display controller 30 (step S101).

[0052] The decoding unit 310 of the display controller 30 performs a decoding process when a video signal is input from the source device 20 (step S102). In the decoding process, the decoding unit 310 decodes the video signal input from the source device 20 and outputs the decoded video signal. Next, the signal processing unit 320 of the display controller 30 performs signal processing (step S103). In the signal processing, the signal processing unit 320 performs color adjustment and the like on the video signal input from the decoding unit 310 and outputs the processed video signal. Next, the analysis unit 330 of the display controller 30 performs an analysis process (step S104). In the analysis process, the analysis unit 330 analyzes the video signal input from the signal processing unit 320, obtains and outputs the luminance distribution of the video signal. Next, the determination unit 340 of the display controller 30 performs a determination process (step S105). In the determination process, the determination unit 340 determines a gamma curve to be used for encoding the video signal based on the luminance distribution input from the analysis unit 330, and outputs the video signal and gamma curve information. Next, the encoding unit 350 of the display controller 30 performs an encoding process (step S106). In the encoding process, the encoding unit 350 encodes the video signal input from the determination unit 340 using different gamma curves in each processing unit 351, and outputs multiple encoded video signals. Next, the switching unit 360 of the display controller 30 performs a switching process (step S107). In the switching process, the switching unit 360 switches the video signal to be output to the subsequent block from among the multiple video signals output from each processing unit 351 of the encoding unit 350 based on the gamma curve information input from the determination unit 340, and outputs one video signal. Next, the formatter unit 370 of the display controller 30 performs a formatting process (step S108). In the formatting process, the formatter unit 370 processes the video signal input from the switching unit 360 and embeds the gamma curve information input from the determination unit 340 into the video signal. Next, the formatter unit 370 transmits the formatted video signal to the display module 50 (step S109).

[0053] When a video signal is input from the display controller 30, the format decoding unit 510 of the display module 50 performs a format decoding process (step S110). In the format decoding process, the format decoding unit 510 decodes the format of the video signal input from the display controller 30, obtains and outputs the video signal and gamma curve information. Next, the determination unit 520 of the display module 50 performs a determination process (step S111). In the determination process, the determination unit 520 determines a gamma curve to be used for decoding the video signal based on the video signal and gamma curve information input from the format decoding unit 510, and outputs the video signal and gamma curve information. Next, the decoding unit 530 of the display module 50 performs a decoding process (step S112). In the decoding process, the decoding unit 530 decodes the video signal input from the determination unit 520 using different gamma curves in each processing unit 531, and outputs multiple decoded video signals. Next, the switching unit 540 of the display module 50 performs a switching process (step S113). In the switching process, the switching unit 540 switches the video signal to be output to the subsequent block from among the multiple video signals output from each processing unit 531 of the decoding unit 530 based on the gamma curve information input from the determination unit 520, and outputs one video signal. Next, the display unit 550 of the display module 50 performs a display process (step S114). In the display process, the display unit 550 displays an image based on the video signal input from the switching unit 540.

[0054] (2) Detailed Flow of Analysis Processing and Determination Processing A detailed flow of the analysis processing and determination processing will be described with reference to FIG. 7. FIG. 7 is a flowchart showing an example of a detailed flow of the analysis processing and determination processing according to the first embodiment. In the processing shown in FIG. 7, the luminance level of pixels having a luminance value of 0 to 255 is determined as level 1, the luminance level of pixels having a luminance value of 256 to 511 as level 2, and the luminance level of pixels having a luminance value of 512 to 1023 as level 3. Furthermore, the number of pixels having a luminance level of level 1 is denoted as c1, the number of pixels having a luminance level of level 2 as c2, and the reference number of pixels as T1.

[0055] As shown in FIG. 7 , first, the analysis unit 330 of the display controller 30 performs initialization (step S201). During initialization, the analysis unit 330 sets c1 = 0 and c2 = 0. Next, the analysis unit 330 acquires a luminance value for each pixel of the video signal input from the signal processing unit 320 (step S202). Next, the analysis unit 330 determines the luminance level for each pixel of the video signal based on the acquired luminance value for each pixel (step S203). If the luminance level is level 1 (step S203 / level 1), the analysis unit 330 counts up the number of pixels c1 at level 1 (c1 = c1 + 1) (step S204). After counting up, the process proceeds to step S206. If the luminance level is level 2 (step S203 / level 2), the analysis unit 330 counts up the number of pixels c2 at level 2 (c2 = c2 + 1) (step S205). After counting up, the process proceeds to step S206. If the luminance level is level 3 (step S203 / level 3), the analysis unit 330 proceeds to step S206. If the process proceeds to step S206, the analysis unit 330 determines whether or not the determination of the luminance level for all pixels has been completed (step S206). If the determination has been completed (step S206 / YES), the process proceeds to step S207. On the other hand, if the determination has not been completed (step S206 / NO), the process is repeated from step S202.

[0056] If the process proceeds to step S207, the determination unit 340 of the display controller 30 determines the proportion of pixels with low brightness within the analysis range of the video signal (step S207). Specifically, the determination unit 340 first determines whether either the number of pixels c1 whose brightness level is level 1 or the number of pixels c2 whose brightness level is level 2 is equal to or greater than the reference pixel number T1 (c1≧T1 or c2≧T1) (step S208). If either c1 or c2 is equal to or greater than T1 (step S208 / YES), the process proceeds to step S209. On the other hand, if both c1 and c2 are less than T1 (step S208 / NO), the process proceeds to step S212. If the process proceeds to step S209, the determination unit 340 determines whether the number of pixels c1 whose brightness level is level 1 is equal to or greater than the number of pixels c2 whose brightness level is level 2 (c1≧c2) (step S209). If c1 is equal to or greater than c2 (step S209 / YES), the process proceeds to step S210. On the other hand, if c1 is less than c2 (step S209 / NO), the process proceeds to step S211. If the process proceeds to step S210, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range of the video signal is high, and determines to use gamma curve GC1 (step S210). If the process proceeds to step S211, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range of the video signal is medium, and determines to use gamma curve GC2 (step S211). If the process proceeds to step S212, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range of the video signal is low, and determines to use gamma curve GC3 (step S212). After the gamma curve is determined, the process shown in FIG. 7 ends.

[0057] 1-5. Modifications The processing flow according to the first embodiment has been described above. Next, modifications of the first embodiment will be described.

[0058] In the first embodiment described above, an example has been described in which the proportion of pixels in a video signal that are low in luminance is determined based on the number of pixels at each luminance level, and a gamma curve to be used for encoding is determined, but the present invention is not limited to such an example. For example, the gamma curve to be used for encoding may be determined by determining the proportion of pixels in a video signal that are low in luminance based on the area of ​​each luminance level in a histogram.

[0059] Here, with reference to FIGS. 8 and 9 , a process flow for determining the proportion of pixels of a video signal that are low brightness based on the area of ​​each brightness level in a histogram and determining a gamma curve to be used for encoding will be described. FIG. 8 is a flowchart showing an example of the detailed flow of the analysis process and the determination process in a modified example of the first embodiment. In the process shown in FIG. 8 , the area in the histogram where the brightness level is level 1 is indicated as AR1, the area where the brightness level is level 2 is indicated as AR2, and the reference area is indicated as T2. FIG. 9 is a diagram showing an example of a histogram in a modified example of the first embodiment. The horizontal axis of the histogram shown in FIG. 9 represents the brightness value, and the vertical axis represents the frequency. Furthermore, area A1 shown in FIG. 9 represents an area including a histogram of pixels with a brightness level of level 1, and area A2 represents an area including a histogram of pixels with a brightness level of level 2.

[0060] As shown in FIG. 8 , first, the analysis unit 330 of the display controller 30 performs initialization (step S301). During initialization, the analysis unit 330 resets the determination result of the previous frame. Next, the analysis unit 330 acquires a luminance value for each pixel of the video signal input from the signal processing unit 320 (step S302). Next, the analysis unit 330 generates a histogram based on the acquired luminance value for each pixel (step S303). The analysis unit 330 generates a histogram, for example, as shown in FIG. 9 . Next, the analysis unit 330 determines whether generation of histograms for all pixels has been completed (step S304). If it has been completed (step S304 / YES), the process proceeds to step S305. On the other hand, if it has not been completed (step S304 / NO), the process repeats from step S302.

[0061] When the process proceeds to step S305, the determination unit 340 of the display controller 30 calculates an area AR1 where the brightness level is level 1 and an area AR2 where the brightness level is level 2 in the histogram generated by the analysis unit 330 (step S305). When the analysis unit 330 generates the histogram shown in FIG. 9 , the determination unit 340 calculates the area of ​​the histogram within region A1 as the area AR1 where the brightness level is level 1, and calculates the area of ​​the histogram within region A2 as the area AR2 where the brightness level is level 2. Next, the determination unit 340 determines the proportion of low-brightness pixels in the analysis range of the video signal (step S306). Specifically, the determination unit 340 first determines whether either the area AR1 where the brightness level is level 1 or the area AR2 where the brightness level is level 2 is equal to or greater than a reference area T2 (AR1≧T2 or AR2≧T2) (step S307). If either AR1 or AR2 is equal to or greater than T2 (step S307 / YES), the process proceeds to step S308. On the other hand, if both AR1 and AR2 are less than T2 (step S307 / NO), the process proceeds to step S311. If the process proceeds to step S308, the determination unit 340 determines whether the area AR1 where the luminance level is Level 1 is equal to or greater than the area AR2 where the luminance level is Level 2 (AR1≧AR2) (step S308). If AR1 is equal to or greater than AR2 (step S308 / YES), the process proceeds to step S309. On the other hand, if AR1 is less than AR2 (step S308 / NO), the process proceeds to step S310. If the process proceeds to step S309, the determination unit 340 determines that the proportion of pixels with low luminance in the analysis range of the video signal is high, and determines to use the gamma curve GC1 (step S309). If the process proceeds to step S310, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range of the video signal is medium, and determines to use gamma curve GC2 (step S310). If the process proceeds to step S311, the determination unit 340 determines that the proportion of low-luminance pixels in the analysis range of the video signal is low, and determines to use gamma curve GC3 (step S311). After the gamma curve is determined, the process shown in FIG. 8 ends.

[0062] In the first embodiment described above, the determination unit 340 of the display controller 30 and the determination unit 520 of the display module 50 determine the gamma curve to be used for decoding or encoding by selecting one gamma curve from a plurality of gamma curves prepared in advance. However, the present invention is not limited to this example. For example, the determination unit 340 and the determination unit 520 may each calculate a gamma curve each time decoding or encoding is performed and determine that the calculated gamma curve is to be used for decoding or encoding. In this case, the determination unit 340 calculates the gamma curve to be used for encoding based on the results of analysis by the analysis unit 330. Furthermore, the determination unit 520 calculates the gamma curve to be used for decoding based on gamma curve information acquired by the format decoding unit 510.

[0063] The above has described the modified examples according to the first embodiment. As described above, the display system 1 according to the first embodiment includes a decoding unit 310 (first decoding unit) that decodes an input first video signal and outputs a second video signal, an analyzing unit 330 that analyzes the second video signal and acquires a luminance distribution in at least a part of the analysis range of the second video signal, a determining unit 340 (first determining unit) that determines a first gamma curve to be used for encoding the second video signal based on the luminance distribution, and a determining unit 340 (first determining unit) that encodes the second video signal using the determined first gamma curve. The video signal decoding device includes an encoding unit 350 that outputs a third video signal encoded therefrom, a determination unit 520 (second determination unit) that determines a second gamma curve to be used in decoding the third video signal based on the third video signal and gamma curve information indicating the first gamma curve used for encoding, a decoding unit 530 (second decoding unit) that outputs a fourth video signal obtained by decoding the third video signal using the determined second gamma curve, and a display unit 550 that displays an image based on the fourth video signal.

[0064] With this configuration, the display system 1 according to the first embodiment decodes an input video signal, analyzes the characteristics of the video signal, determines an optimal gamma curve to use for decoding based on the analysis results, and transmits the image-processed video signal to a display unit after encoding it using the determined gamma curve. This reduces data loss not only in the decoding process (gamma processing) performed on the video signal before image processing, but also in the encoding process (inverse gamma processing) performed on the video signal after image processing. Therefore, the display system 1 according to the first embodiment makes it possible to suppress degradation of image quality caused by the data capacity of the transmission path.

[0065] <<2. Second Embodiment>> The first embodiment has been described above. Next, the second embodiment will be described with reference to Fig. 10 to Fig. 14. Note that, in the following, descriptions that overlap with the first embodiment will be omitted as appropriate.

[0066] In the first embodiment described above, an example in which one video is displayed on a display having one display unit has been described, but the present invention is not limited to such an example. In the second embodiment, an example in which one video is displayed on a display having multiple display units will be described. For example, a multi-display combining multiple LED displays is used. In this case, one video is displayed on the display by displaying multiple split videos obtained by splitting one video on the corresponding display units.

[0067] 2-1. Configuration of the Display System The configuration of a display system according to the second embodiment will be described with reference to Fig. 10 to Fig. 12. Fig. 10 is a block diagram showing an example of the configuration of the display system according to the second embodiment. As shown in Fig. 10, the display system 1a according to the second embodiment includes a control terminal 10, a source device 20, a display controller 30a, a display 40a, a plurality of display modules 50a, and a plurality of cabinets 60.

[0068] 10, in the display system 1a, the display 40a includes a plurality of display modules 50a and a plurality of cabinets 60. That is, the display system 1a includes a plurality of display units. The display 40a is realized by physically connecting a plurality of display modules 50a-11, 50a-12, etc. Each of the plurality of display modules 50a-11, 50a-12, etc. is housed in and connected to a respective one of a plurality of cabinets 60-11, 60-12, etc.

[0069] Here, the configuration of the display 40a will be described with reference to Fig. 11. Fig. 11 is a diagram showing an example of the configuration of the display 40a according to the second embodiment. As shown in Fig. 11, the display 40a has m cabinets 60 arranged vertically and n cabinets 60 arranged horizontally in a matrix. That is, m x n cabinets 60 are arranged. Each cabinet 60 houses a display module 50a. That is, one display 40a is configured by arranging m x n display modules 50 in a matrix, similar to the cabinets 60.

[0070] Here, with reference to FIG. 12 , an image displayed on the display 40a will be described. FIG. 12 is a diagram showing an example of an image displayed on the display 40a according to the second embodiment. In the second embodiment, the image displayed on the display 40a is divided into a plurality of split images according to the number of display units (display modules 50a) included in the display 40a. FIG. 12 shows an example of splitting an image displayed on the display 40a shown in FIG. 11. The display 40a shown in FIG. 11 is composed of m×n display modules 50 and therefore has m×n display units. Therefore, the image 70 displayed on the display 40a shown in FIG. 11 is split into m split images vertically and n split images horizontally, as shown in FIG. 12 . That is, the image 70 is split into m×n split images. In this case, the display 40a displays each split image 71 on the corresponding display unit of the display module 50a. For example, the display module 50a-11 displays the divided image 71-11, the display module 50a-12 displays the divided image 71-12, the display module 50a-1n displays the divided image 71-1n, the display module 50a-m1 displays the divided image 71-m1, and the display module 50a-mn displays the divided image 71-mn.

[0071] <2-2. Functional Configuration of Display Controller> The configuration of the display system 1a according to the second embodiment has been described above. Next, the functional configuration of the display controller 30a according to the second embodiment will be described with reference to Fig. 13. The functional configuration of the display controller 30a according to the second embodiment is similar to that of the display controller 30 according to the first embodiment shown in Fig. 2, but the function of the analysis unit is different.

[0072] Here, the functional configuration of the analysis unit of the display controller 30a according to the second embodiment will be described with reference to Fig. 13. Fig. 13 is a block diagram showing an example of the functional configuration of the analysis unit according to the second embodiment. As shown in Fig. 13, the analysis unit 330a according to the second embodiment includes a processing unit determination unit 3301, an analysis processing unit 3302, a memory unit 3303, a memory controller unit 3304, and an image memory unit 3305.

[0073] (1) Processing Unit Determination Unit 3301 The processing unit determination unit 3301 has a function of determining the processing unit of the video signal. The processing unit determination unit 3301 determines, based on control signals such as a vertical synchronization signal and a horizontal synchronization signal, which display module 50a the data of the video signal (second video signal) input from the signal processing unit 320 corresponds to in the divided video 71 to be displayed on. After the determination, the processing unit determination unit 3301 outputs the video signal together with the determination result to the analysis processing unit 3302.

[0074] (2) Analysis Processing Unit 3302 The analysis processing unit 3302 has a function of analyzing a video signal. The analysis processing unit 3302 performs analysis processing for each divided video, similar to the analysis unit 330 according to the first embodiment. The analysis processing unit 3302 uses the memory unit 3303 to store count values ​​during analysis, generated histograms, and the like. After analysis, the analysis processing unit 3302 outputs the analyzed video signal and the acquired luminance distribution to the memory controller unit 3304.

[0075] (3) Memory Unit 3303 The memory unit 3303 has a function of storing data generated by the analysis processing of the analysis processing unit 3302. For example, the memory unit 3303 stores count values ​​generated during analysis by the analysis processing unit 3302, generated histograms, and the like.

[0076] (4) Memory Controller Unit 3304 The memory controller unit 3304 has a function of controlling the output of various information. The memory controller unit 3304 temporarily stores the video signals and luminance distributions in the image memory unit 3305 in order to rearrange the video signals input from the analysis processing unit 3302 in the transmission order when they are transmitted from the display controller 30a to the display module 50a. The memory controller unit 3304 then reads out the video signals and luminance distributions from the image memory unit 3305 in the transmission order and outputs them to the determination unit 340 at the subsequent stage.

[0077] (5) Image Memory Unit 3305 The image memory unit 3305 has a function of temporarily storing a video signal input from the memory controller unit 3304. When a request is made by the memory controller unit 3304, the image memory unit 3305 outputs the requested video signal.

[0078] With the above-described configuration, the analysis unit 330a of the display controller 30a can analyze the video signal (second video signal) for each portion corresponding to a divided image and obtain multiple luminance distributions. This allows the determination unit 340 (first determination unit) to determine a gamma curve (first gamma curve) to be used for encoding the video signal for each portion of the video signal (second video signal) corresponding to a divided image, based on the multiple luminance distributions.

[0079] <2-3. Functional Configuration of Display Module> The functional configuration of the display controller 30a according to the second embodiment has been described above. Next, the functional configuration of the display module 50a according to the second embodiment will be described. The display 40a according to the second embodiment includes a plurality of display modules 50a. Each of the plurality of display modules 50a includes a format decoding unit 510, a determination unit 520 (second determination unit), a decoding unit 530 (second decoding unit), a switching unit 540, and a display unit 550, similar to the display module 50 according to the first embodiment shown in FIG. 4.

[0080] A video signal input from the display controller 30a to the display 40a is processed by a display module 50a including a display unit 550 on which a divided image indicated by the video signal is displayed. When a video signal is input from the display controller 30, each format decoding unit 510 acquires the video signal and gamma curve information of the divided image portion through format decoding processing and outputs the acquired video signal and gamma curve information to a determination unit 520. Each determination unit 520 determines a gamma curve (second gamma curve) to be used in decoding the video signal (third video signal) based on a video signal (third video signal) obtained by encoding a part (divided image portion) of a video signal (second video signal) corresponding to the divided image displayed on the corresponding display unit 550 and gamma curve information indicating the gamma curve (first gamma curve) used for encoding. Each decoding unit 530 outputs a video signal (fourth video signal) obtained by decoding the video signal (third video signal) using the determined gamma curve (second gamma curve). The switching unit 540 switches which of the multiple video signals (fourth video signals) output from each processing unit 531 of the decoding unit 530 is to be output to a subsequent block, based on the gamma curve information input from the determination unit 520. The display unit 550 displays a divided video based on the video signal (fourth video signal) input from the switching unit 540.

[0081] <2-4. Processing Flow> The functional configuration of the display module 50a according to the second embodiment has been described above. Next, the processing flow according to the second embodiment will be described. In the second embodiment, processing is performed in the same manner as the processing flow according to the first embodiment shown in FIG. 6, but some processing is different. In the second embodiment, before the analysis processing of step S104, a determination processing is performed by the processing unit determination unit 3301. After the determination processing, the analysis processing unit 3302 performs the analysis processing of step S104. After the analysis processing, a rearrangement processing is performed by the memory controller unit 3304. After the rearrangement processing, the determination processing of step S105 is performed by the determination unit 340.

[0082] 2-5. Modifications The processing flow according to the second embodiment has been described above. Next, modifications of the second embodiment will be described.

[0083] In the second embodiment described above, an example in which the analysis unit 330a determines the processing unit before performing the analysis process has been described, but the present invention is not limited to this example. For example, the analysis process may be performed after rearranging the video signals. This eliminates the need for the process of determining the processing unit, and also eliminates the need for a configuration for this purpose.

[0084] Here, the functional configuration of the analysis unit of the display controller 30a in the modified example according to the second embodiment will be described with reference to Fig. 14. Fig. 14 is a block diagram showing an example of the functional configuration of the analysis unit in the modified example according to the second embodiment. As shown in Fig. 14, the analysis unit 330b in the modified example according to the second embodiment includes a memory controller unit 3306, an image memory unit 3307, an analysis processing unit 3308, and a memory unit 3309.

[0085] (1) Memory Controller Unit 3306 The memory controller unit 3306 rearranges the video signals input from the signal processing unit 320, in the same manner as the memory controller unit 3304 according to the second embodiment described above. Note that the image memory unit 3307 is used to temporarily store the video signals. After rearrangement, the memory controller unit 3306 reads out the video signals from the image memory unit 3307 in the order of transmission, and outputs them to the analysis processing unit 3308.

[0086] (2) Image Memory Unit 3307 Similar to the image memory unit 3305 according to the second embodiment described above, the image memory unit 3307 temporarily holds the video signal input from the memory controller unit 3306, and outputs the requested video signal when requested by the memory controller unit 3306.

[0087] (3) Analysis Processing Unit 3308 The analysis processing unit 3308 performs analysis processing for each divided video, similar to the analysis processing unit 3302 according to the second embodiment described above. The analysis processing unit 3308 uses a memory unit 3309 to store count values ​​during analysis, generated histograms, and the like. After analysis, the analysis processing unit 3308 outputs the analyzed video signal and the acquired luminance distribution to the determination unit 340 at the subsequent stage.

[0088] (4) Memory Unit 3309 The memory unit 3309 has a function of storing data generated by the analysis processing of the analysis processing unit 3302. For example, the memory unit 3303 stores count values ​​generated during analysis by the analysis processing unit 3302, generated histograms, and the like.

[0089] In this modified example, before the analysis process of step S104, the memory controller unit 3306 performs the rearrangement process. After the rearrangement process, the analysis process of step S104 is performed by the analysis processing unit 3308. After the analysis process, the determination unit 340 performs the determination process of step S105.

[0090] <<3. Third Embodiment>> The second embodiment has been described above. Next, the third embodiment will be described with reference to FIGS. 15 and 16. Note that, hereinafter, descriptions that overlap with the first and second embodiments will be omitted as appropriate. In the first and second embodiments described above, the display controller 30 processes the video signal input from the source device 20 as is, but this is not limited to this example. For example, the display controller 30 may divide the input video signal into three video signals, R (Red), G (Green), and B (Blue), and process each video signal separately.

[0091] Here, the functional configuration of a display controller according to the third embodiment will be described with reference to FIG. 15 . FIG. 15 is a block diagram showing an example of the functional configuration of a display controller according to the third embodiment. As shown in FIG. 15 , a display controller 30 b according to the third embodiment includes a format decoding unit 305, a decoding unit 310, a signal processing unit 320, an analysis unit 330, a determination unit 340, an encoding unit 350, a switching unit 360, and a formatter unit 370. The decoding unit 310, the signal processing unit 320, the analysis unit 330, the determination unit 340, the encoding unit 350, and the switching unit 360 each include a processing block for an R video signal (a block marked with an R symbol), a processing block for a G video signal (a block marked with a G symbol), and a processing block for a B video signal (a block marked with a B symbol).

[0092] The format decoding unit 305 performs a process of dividing the video signal input from the source device 20 into an R video signal, a G video signal, and a B video signal. After the division, the format decoding unit 305 outputs the R video signal to the decoding unit 310R, the G video signal to the decoding unit 310G, and the B video signal to the decoding unit 310B. When the video signal is input as YUV data, the format decoding unit 305 converts the YUV data to RGB data. The decoding unit 310, signal processing unit 320, analysis unit 330, determination unit 340, encoding unit 350, and switching unit 360 for each of the R, G, and B video signals perform their respective processes in the same manner as in the first or second embodiment described above. The formatter unit 370 performs formatting processing on the video signals input from the switching unit 360 for each of the R, G, and B video signals, and transmits the processed video signals to the display module 50b.

[0093] Here, the functional configuration of a display module according to the third embodiment will be described with reference to Fig. 16 . Fig. 16 is a block diagram showing an example of the functional configuration of a display module according to the third embodiment. As shown in Fig. 16 , a display module 50b according to the third embodiment includes a format decoding unit 510, a determination unit 520, a decoding unit 530, a switching unit 540, and a display unit 550. The determination unit 520, the decoding unit 530, and the switching unit 540 each include a processing block for an R video signal (a block marked with R), a processing block for a G video signal (a block marked with G), and a processing block for a B video signal (a block marked with B).

[0094] When a video signal is input from the display controller 30b, the format decoding unit 510 performs format decoding processing for each of the R, G, and B video signals. After processing, the format decoding unit 510 outputs the R video signal and gamma curve information to the determination unit 520R, the G video signal and gamma curve information to the determination unit 520G, and the B video signal and gamma curve information to the determination unit 520B. The determination unit 520, decoding unit 530, and switching unit 540 for each of the R, G, and B video signals perform their respective processes in the same manner as in the first or second embodiment described above. The display unit 550 displays an image based on the video signals input from the switching unit 540 for each of the R, G, and B video signals.

[0095] <<4. Fourth Embodiment>> The third embodiment has been described above. Next, the fourth embodiment will be described with reference to FIGS. 17 to 18 . Note that, hereinafter, descriptions that overlap with the first to third embodiments will be omitted as appropriate. In each of the above-described embodiments, an example has been described in which the encoding unit of the display controller and the decoding unit of the display module each include multiple processing units, but the present invention is not limited to such an example. For example, the encoding unit of the display controller and the decoding unit of the display module may each include only one processing unit.

[0096] Here, the functional configuration of a display controller in which the encoding unit of the display controller includes only one processing unit will be described with reference to Fig. 17. Fig. 17 is a block diagram showing an example of the functional configuration of a display controller according to the fourth embodiment. As shown in Fig. 17, a display controller 30c according to the fourth embodiment includes a decoding unit 310, a signal processing unit 320, an analyzing unit 330, a determining unit 340, an encoding unit 350c, a formatter unit 370, and a gamma table generating unit 380.

[0097] After the determination process, the determination unit 340 outputs the video signal to the encoding unit 350c and outputs gamma curve information to the formatter unit 370 and the gamma table generation unit 380. The gamma table generation unit 380 generates a table (gamma table) indicating the gamma curve to be used for encoding the video signal based on the gamma curve information input from the determination unit 340. The processing unit 351 of the encoding unit 350c encodes the video signal input from the determination unit 340 using the gamma curve indicated by the gamma table generated by the gamma table generation unit 380. Each time the determination unit 340 determines a gamma curve to be used for encoding, the gamma table generation unit 380 updates the gamma table based on the gamma curve information input from the determination unit 340. The processing unit 351 then performs encoding based on the updated gamma table. The gamma table generation unit 380 quickly rewrites the gamma table, making it possible to perform encoding using multiple gamma curves.

[0098] Here, the functional configuration of a display module in which the decoding unit of the display module includes only one processing unit will be described with reference to Fig. 18. Fig. 18 is a block diagram showing an example of the functional configuration of a display module according to the fourth embodiment. As shown in Fig. 18, a display module 50c according to the fourth embodiment includes a format decoding unit 510, a determination unit 520, a decoding unit 530c, a display unit 550, and a gamma table generation unit 560.

[0099] After the determination process, the determination unit 520 outputs the video signal to the decoding unit 530c and outputs gamma curve information to the gamma table generation unit 560. The gamma table generation unit 560 generates a table (gamma table) indicating a gamma curve to be used for decoding the video signal based on the gamma curve information input from the determination unit 520. The processing unit 531 of the decoding unit 530c decodes the video signal input from the determination unit 520 using the gamma curve indicated by the gamma table generated by the gamma table generation unit 560. Each time the determination unit 520 determines a gamma curve to be used for decoding, the gamma table generation unit 560 updates the gamma table based on the gamma curve information input from the determination unit 520. The processing unit 531 then performs decoding based on the updated gamma table. The gamma table generation unit 560 quickly rewrites the gamma table, making it possible to execute decoding processes using multiple gamma curves.

[0100] <<5. Fifth Embodiment>> The fourth embodiment has been described above. Next, the fifth embodiment will be described with reference to FIG. 19 . FIG. 19 is a block diagram showing an example of the configuration of a display system according to the fifth embodiment. As shown in FIG. 19 , a display system 90 according to the fifth embodiment includes a first decoding unit 910, an analyzing unit 920, a first determining unit 930, an encoding unit 940, a second determining unit 950, a second encoding unit 960, and a display unit 970.

[0101] The first decoding unit 910 decodes the input first video signal and outputs a second video signal.

[0102] The analysis unit 920 analyzes the second video signal and obtains the luminance distribution in at least a part of the analysis range of the second video signal.

[0103] The first determination unit 930 determines a first gamma curve to be used for encoding the second video signal based on the luminance distribution.

[0104] The encoding unit 940 outputs a third video signal obtained by encoding the second video signal using the determined first gamma curve.

[0105] The second determination unit 950 determines a second gamma curve to be used for decoding the third video signal based on the third video signal and gamma curve information indicating the first gamma curve used for encoding.

[0106] The second encoding unit 960 outputs a fourth video signal obtained by decoding the third video signal using the determined second gamma curve.

[0107] The display unit 970 displays an image based on the fourth image signal.

[0108] With this configuration, in the display system 90 according to the fifth embodiment, after an input video signal is decoded, the characteristics of the video signal are analyzed, an optimal gamma curve to be used for decoding is determined based on the analysis results, and the image-processed video signal is encoded using the determined gamma curve before being transmitted to the display unit. This alleviates data loss not only in the decoding process (gamma processing) performed on the video signal before image processing, but also in the encoding process (inverse gamma processing) performed on the video signal after image processing. Therefore, the display system 90 according to the fifth embodiment makes it possible to suppress degradation of image quality due to the data capacity of the transmission path.

[0109] The above describes each embodiment of the present invention. Note that all or part of the functions of the display system, control terminal, source device, display controller, display, and display module in each of the above-described embodiments may be implemented by a computer. In this case, a program for implementing these functions may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Furthermore, the term "computer-readable recording medium" may also include media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and media that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as the server or client in such cases. Furthermore, the above program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in a computer system, or may be one that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0110] The embodiments of the present invention have been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope of the gist of the present invention.

[0111] 1, 1a, 90...display system, 10...control terminal, 20...source device, 30, 30a, 30b, 30c...display controller, 40, 40a...display, 50, 50a, 50b, 50c...display module, 60...cabinet, 305...format decoding unit, 310, 310B, 310G, 310R...decoding unit, 320...signal processing unit, 330, 330a, 330b...analysis unit, 340...determination unit, 350, 350c...encoding unit, 351...processing unit, 360...switching unit, 370...formatter unit, 380...gamma table generation unit, 510...format decoding unit , 520, 520B, 520G, 520R...determination unit, 530, 530c...decoding unit, 531...processing unit, 540...switching unit, 550...display unit, 560...gamma table generation unit, 910...first decoding unit, 920...analysis unit, 930...first determination unit, 940...encoding unit, 950...second determination unit, 960...second encoding unit, 970...display unit, 3301...processing unit determination unit, 3302...analysis processing unit, 3303...memory unit, 3304...memory controller unit, 3305...image memory unit, 3306...memory controller unit, 3307...image memory unit, 3308...analysis processing unit, 3309...memory unit

Claims

1. A display system comprising: a first decoding unit that decodes an input first video signal and outputs a second video signal; an analysis unit that analyzes the second video signal and obtains a luminance distribution in at least a portion of an analysis range of the second video signal; a first determination unit that determines a first gamma curve to be used in encoding the second video signal based on the luminance distribution; an encoding unit that outputs a third video signal obtained by encoding the second video signal using the determined first gamma curve; a second determination unit that determines a second gamma curve to be used in decoding the third video signal based on the third video signal and gamma curve information indicating the first gamma curve used for encoding; a second decoding unit that outputs a fourth video signal obtained by decoded the third video signal using the determined second gamma curve; and a display unit that displays an image based on the fourth video signal.

2. The display system according to claim 1, wherein the first determination unit determines the first gamma curve to be used in encoding the second video signal based on the luminance distribution and in accordance with the proportion of pixels in the analysis range that have low luminance.

3. The display system of claim 2, wherein the first determination unit determines to use the first gamma curve having a gamma value set smaller when the proportion of pixels in the analysis range that are low luminance is high than when the proportion of pixels in the analysis range that are other than low luminance is high.

4. The display system of claim 1, wherein the display system comprises a plurality of the display units, and when one image is displayed by dividing one image and displaying a plurality of split images on each of the corresponding display units, the analysis unit analyzes the second image signal for each portion corresponding to the split images to obtain a plurality of the luminance distributions, and the first determination unit determines the first gamma curve to be used in encoding the second image signal for each portion of the second image signal corresponding to the split images based on the plurality of the luminance distributions.

5. The display system according to claim 4, further comprising: a second determination unit and a second decoding unit for each of a plurality of display units; each of the second determination units determines a second gamma curve to be used in decoding the third video signal based on the third video signal obtained by encoding a portion of the second video signal corresponding to the divided image displayed on the corresponding display unit and on gamma curve information indicating the first gamma curve used for encoding; and each of the second decoding units outputs a fourth video signal obtained by decoding the third video signal using the determined second gamma curve.

6. A display system as described in claim 1 or claim 5, wherein the second determination unit determines to use a second gamma curve in which a second gamma value that is the reciprocal of the first gamma value is set based on a first gamma value set in the first gamma curve indicated by the gamma curve information.

7. The display system according to claim 1, further comprising a signal processing unit that performs signal processing on the second video signal input from the first decoding unit and outputs the signal-processed second video signal to the analysis unit.

8. A display method executed by a computer, comprising: a first decoding process for decoding an input first video signal to output a second video signal; an analysis process for analyzing the second video signal and acquiring a luminance distribution in at least a portion of an analysis range of the second video signal; a first determination process for determining a first gamma curve to be used in encoding the second video signal based on the luminance distribution; an encoding process for outputting a third video signal obtained by encoding the second video signal using the determined first gamma curve; a second determination process for determining a second gamma curve to be used in decoding the third video signal based on the third video signal and gamma curve information indicating the first gamma curve used for encoding; a second decoding process for outputting a fourth video signal obtained by decoding the third video signal using the determined second gamma curve; and a display process for displaying an image based on the fourth video signal.

9. A display controller comprising: a decoding unit that decodes an input first video signal and outputs a second video signal; an analysis unit that analyzes the second video signal and obtains a luminance distribution in at least a portion of an analysis range of the second video signal; a determination unit that determines a gamma curve to be used in encoding the second video signal based on the luminance distribution; and an encoding unit that outputs a third video signal obtained by encoding the second video signal using the determined gamma curve.

10. The display controller according to claim 9, wherein the determination unit determines the gamma curve to be used for encoding the second video signal based on the luminance distribution and in accordance with a ratio of pixels in the analysis range that have low luminance.

11. The display controller according to claim 10, wherein the determination unit determines to use the gamma curve with a gamma value set smaller when a proportion of pixels in the analysis range that are low luminance is high than when a proportion of pixels in the analysis range that are not low luminance is high.

12. A display controller as described in claim 9, wherein, in a case where a single image is displayed by dividing a single image into a plurality of split images, each of the split images being displayed on a corresponding one of a plurality of display units, the analysis unit analyzes the second image signal for each portion corresponding to the split image to obtain a plurality of the luminance distributions, and the determination unit determines the gamma curve to be used in encoding the second image signal for each portion of the second image signal corresponding to the split image based on the plurality of the luminance distributions.

13. The display controller according to claim 9, further comprising a signal processing unit that performs signal processing on the second video signal input from the decoding unit and outputs the signal-processed second video signal to the analysis unit.

14. A video signal processing method for a display controller executed by a computer, comprising: a decoding process for decoding an input first video signal and outputting a second video signal; an analysis process for analyzing the second video signal and obtaining a luminance distribution in at least a portion of an analysis range of the second video signal; a determination process for determining a gamma curve to be used in encoding the second video signal based on the luminance distribution; and an encoding process for outputting a third video signal obtained by encoding the second video signal using the determined gamma curve.

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