Image processing device, display device, and control method

Abstract

Provided are an image processing device, a display device, and a control method whereby the luminance of an overlapping region in a projection image can be suppressed from decreasing non-linearly according to the position in the overlapping region by edge blending. This image processing device comprises an arithmetic circuit and a storage device, and transmits an output video signal to a display device. The arithmetic circuit performs gamma correction on a received input video signal using a first gamma characteristic and a second gamma characteristic, performs edge blending for adjusting the luminance of a predetermined region in an image according to the position in the predetermined region using the second gamma characteristic, and generates an output video signal. The second gamma characteristic is the inverse function of a third gamma characteristic of the display device. The third gamma characteristic has a gamma curve expressed by an exponential function. The predetermined region is a region in which the image displayed by the display device and another image displayed by another display device overlap.

Description

Image processing device, display device, and control method

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

[0002] Conventionally, multi-projection systems have been known in which multiple display devices each project an image, projecting the multiple images as a single virtual image content. In the multi-projection system, adjacent images are displayed so that at least a portion of each image overlaps. The brightness of each image's overlapping region is adjusted by edge blending to reduce the visibility of the overlapping region. The edge blending process adjusts the brightness of the overlapping region of each image so that the brightness decreases proportionally with the distance from one edge of the overlapping region closer to the center of the image to the other edge of the overlapping region closer to the edge of the image. By linearly reducing the brightness of each image according to its position within the overlapping region, the brightness of the overlapping region when adjacent images are displayed appears to be equivalent to the brightness of the non-overlapping region. As a result, the multi-projection system can display multiple images as a single virtual image content without compromising the visibility of the overlapping region. For example, Patent Document 1 discloses a projection control device that can smoothly connect overlapping regions.

[0003] Japanese Patent Application Laid-Open No. 2020-134882

[0004] Depending on the gamma characteristics of the input images, the luminance of the overlap region in the displayed image after edge blending may decrease nonlinearly rather than linearly with position within the overlap region.

[0005] An object of the present disclosure is to provide an image processing device, a display device, and a control method that can prevent the luminance of an overlapping area in a projected image from decreasing nonlinearly depending on the position within the overlapping area due to edge blending processing.

[0006] An image processing device according to one aspect of the present disclosure is an image processing device that includes an arithmetic circuit and a memory device and transmits an output video signal to a display device, wherein the display device generates a single image content by displaying an image that at least partially overlaps with another display device, and the arithmetic circuit performs gamma correction on the received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal, and performs edge blending processing on the corrected signal using the second gamma characteristic to adjust the brightness of a previously acquired predetermined area of ​​an image displayed based on the input video signal according to the position within the predetermined area to generate an output video signal, wherein the second gamma characteristic is an inverse function of a third gamma characteristic of the display device, and the third gamma characteristic has a gamma curve expressed by an exponential function, and the predetermined area is an area where the image displayed by the display device overlaps with another image displayed by the other display device.

[0007] According to the present disclosure, it is possible to provide an image processing device, a display device, and a control method that can prevent the luminance of the overlapping area in the projected image from decreasing nonlinearly depending on the position within the overlapping area through edge blending processing.

[0008] 1 is a schematic diagram of a display system according to an embodiment of the present disclosure. 2 is a schematic diagram of a control device according to an embodiment of the present disclosure. 3 is a schematic diagram of a display device according to an embodiment of the present disclosure. 4 is a flowchart showing an example of processing by a display device according to an embodiment of the present disclosure. 5 is a gamma curve of an example of pre-correction gamma characteristics. 6 is a gamma curve of an example of first gamma characteristics. 7 is a gamma curve of an example of second gamma characteristics. 8 is a graph showing an example of a correction curve used in edge blending processing. 9 is a gamma curve of an example of display gamma characteristics. 10 is a graph showing an example of a luminance adjustment rate according to a position in a projected image. 11 is a graph showing luminance adjustment rates of a plurality of images projected onto a screen by a plurality of display devices. 12 is a schematic diagram of a display system according to a modified example. 13 is a schematic diagram of an image processing device according to a modified example. 14 is a flowchart showing an example of processing by an image processing device according to a modified example. 15 is a flowchart showing an example of processing by a display device according to a modified example. 16 is a schematic diagram of a modified example of a display device.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the configurations described below are merely examples of the present disclosure, and the present disclosure is not limited to the following embodiments. The technology in the present disclosure is not limited to these embodiments, and various modifications, substitutions, additions, omissions, etc. are possible depending on the design, etc., as long as they do not deviate from the technical concept of the present disclosure.

[0010] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art, and such changes and modifications are to be understood as included within the scope of the present disclosure as defined by the appended claims unless they depart therefrom.

[0011] In this disclosure, when describing modified examples, differences from the embodiment will be mainly described. In this case, components in the modified examples that are the same as or equivalent to those in the embodiment will be described using the same reference numerals. Furthermore, descriptions of the modified examples that overlap with those in the embodiment may be omitted.

[0012] Conventionally, a multi-projection system that projects multiple images as a single virtual image content reduces the brightness of overlapping areas of adjacent images using edge blending processing to prevent the brightness of the overlapping areas from being greater than the brightness of non-overlapping areas. As a result, when adjacent images overlap, the multi-projection system can display the overlapping areas and non-overlapping areas with the same brightness.

[0013] Such a multi-projection system linearly reduces the brightness of the overlapping region according to the position within the overlapping region in the direction of overlap with the adjacent images. Because the brightness of the overlapping region in each of the two adjacent images decreases linearly according to the position within the overlapping region, the multi-projection system can display the overlapping region and non-overlapping region with equal brightness when two images are overlapped.

[0014] When a conventional system performs edge blending on gamma characteristics of a gamma curve that are expressed as an exponential function, it can linearly reduce the luminance of overlapping areas of projected images depending on the position. However, when a conventional system performs edge blending on gamma characteristics of a gamma curve that cannot be expressed as an exponential function, it cannot linearly reduce the luminance of overlapping areas depending on the position, except when the luminance ratio of the original images is 100%. Therefore, when a conventional multi-projection system displays multiple images using gamma characteristics of gamma curves that cannot be expressed as an exponential function, the luminance of overlapping areas may increase or decrease relative to the luminance of non-overlapping areas of adjacent images.

[0015] A display device according to the present disclosure includes an arithmetic circuit and a storage device. The display device generates a single image content by displaying an image that at least partially overlaps with another display device. The arithmetic circuit performs gamma correction on a received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal. The arithmetic circuit performs edge blending on the corrected signal, using the second gamma characteristic to adjust the luminance of a predetermined region of an image displayed based on the input video signal according to the position within the predetermined region, to generate an output video signal. The second gamma characteristic is an inverse function of a third gamma characteristic of the display device. The third gamma characteristic has a gamma curve expressed by an exponential function. The predetermined region is a region where an image displayed by the display device overlaps with another image displayed by the other display device.

[0016] With this configuration, the arithmetic circuit can linearly reduce the luminance in the overlapping area of ​​the image displayed by the optical mechanism according to the position in the overlapping area through edge blending processing, even if the gamma characteristics of the input image have a gamma curve that is not expressed as an exponential function. Furthermore, the processing by the arithmetic circuit can be performed not only by the display device but also by an image processing device that transmits an output video signal to the display device. The display device outputs a display image based on the output video signal via the optical mechanism. In this way, the display device and image processing device according to the present disclosure can suppress a nonlinear decrease in the luminance in the overlapping area of ​​the projected image according to the position in the overlapping area through edge blending processing.

[0017] (Embodiment) 1. Configuration [Display System] A display system 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic diagram of the display system 1 according to an embodiment of the present disclosure. The display system 1 includes a control device 2, a first display device 3a, and a second display device 3b. Hereinafter, in this specification, when there is no need to distinguish between the multiple display devices 3a, 3b, they will be collectively referred to as the display device 3. The control device 2 is, for example, an information processing device such as a computer or a media server device. The display device 3 is, for example, a projector. The control device 2 and the display device 3 can be connected via a cable 4. The display device 3 displays a projection image by projecting a video signal received from the control device 2 onto a screen 5.

[0018] The control device 2 can transmit a control signal to the display device 3 via the cable 4. The control signal includes a signal for controlling the display device 3. The control device 2 may also be able to transmit an audio signal to the display device 3 via the cable 4. The display device 3 can also transmit a control signal to the control device 2 via the cable 4. The control signal may include a resolution and a frame rate that the display device 3 can display. The control signal may also include a gamma characteristic of an image for a video signal transmitted by the control device 2. For example, the cable 4 complies with standards such as HDMI (High-Definition Multimedia Interface) (registered trademark) and SDI (Serial Digital Interface).

[0019] 2 is a schematic diagram of a control device 2 according to an embodiment of the present disclosure. The control device 2 includes an arithmetic circuit 21, a storage device 22, a communication circuit 23, an input device 24, and an output device 25.

[0020] The arithmetic circuit 21 controls the overall operation of the control device 2. The arithmetic circuit 21 may be configured to realize a predetermined function through cooperation between hardware resources and software, or may be configured to realize a predetermined function using a dedicated hardware circuit.

[0021] As an example of the former, the arithmetic circuit 21 includes a general-purpose processor such as a CPU or MPU that executes a program to achieve predetermined processing or functions. The arithmetic circuit 21 is configured to be able to communicate with the storage device 22. The arithmetic circuit 21 reads and executes arithmetic programs stored in the storage device 22, thereby achieving various functions in the control device 2. As an example of the latter, the arithmetic circuit 21 includes an FPGA or an ASIC. As can be understood from the above, the arithmetic circuit 21 can be achieved using a semiconductor integrated circuit such as a CPU, MPU, GPU, FPGA, DSP, or ASIC.

[0022] The storage device 22 is a storage medium capable of storing various information. The information includes programs and data. For example, the storage device 22 stores an arithmetic program for implementing various functions according to the present embodiment. The storage device 22 is realized, for example, by a volatile or non-volatile semiconductor memory such as a DRAM, an SRAM, or a flash memory, an SSD, an HDD, or other storage device, or an appropriate combination thereof. The data includes content such as images.

[0023] The communication circuit 23 is an interface device for connecting to other devices or systems via a communication line or a communication cable, either wired or wirelessly. The interface device is capable of performing communication in accordance with wired communication standards such as USB (registered trademark), HDMI (registered trademark), or Ethernet (registered trademark). The interface device is also capable of performing communication in accordance with wireless communication standards such as Wi-Fi (registered trademark), Bluetooth (registered trademark), or a mobile phone line.

[0024] The arithmetic circuit 21 can communicate video signals, audio signals, and control signals with external devices through the communication circuit 23. As described above, data communication with external devices such as the display device 3 complies with standards such as HDMI (registered trademark) and SDI. The arithmetic circuit 21 can transmit video signals, audio signals, and control signals to the display device 3 via the communication circuit 23.

[0025] The input device 24 has a function of allowing a user to input information to the control device 2. The input device 24 includes one or more human-machine interface devices. The human-machine interface devices include, for example, a keyboard, a pointing device (such as a mouse or a trackball), a touchpad, and the like.

[0026] The output device 25 has a function of outputting information from the control device 2 to the user. The output device 25 includes one or more human-machine interface devices. The human-machine interface devices include output devices such as a display and a speaker. The human-machine interface devices may also include input / output devices such as a display (e.g., a liquid crystal panel or an organic EL panel) equipped with an in-cell touch panel.

[0027] 3 is a schematic diagram of a display device 3 according to an embodiment of the present disclosure. The display device 3 includes an arithmetic circuit 31, a storage device 32, a communication circuit 33, an input device 34, an output device 35, and an optical mechanism 36. The arithmetic circuit 31, the storage device 32, the communication circuit 33, the input device 34, and the output device 35 can be realized by the same specific means as the arithmetic circuit 21, the storage device 22, the communication circuit 23, the input device 24, and the output device 25 described above with reference to FIG. 2. The display device 3 can generate a single image content by displaying, on a screen 5, an image that at least partially overlaps with another display device 3.

[0028] The storage device 32 stores a lookup table indicating gamma characteristics for performing gamma correction, which adjusts the luminance ratio of each pixel of an image to an output value corresponding to an input value. The storage device 32 also stores coordinates on the image indicating an overlapping area between an image displayed by the display device 3 and another image displayed by another display device 3. In this specification, the other display device 3 refers to a display device 3 that displays an image that overlaps with the image displayed by the target display device 3. The overlapping area can be set in advance by the user via the input device 34. The arithmetic circuit 31 may capture the image displayed by the display device 3 and the image displayed by the other display device 3 using an imaging device, and set the overlapping area between the images as the overlapping area.

[0029] The optical mechanism 36 is a mechanism for displaying an image. The optical mechanism 36 includes a light source such as a laser diode, an LED, or a lamp, and an optical unit. The optical unit may include a plurality of optical elements. The optical unit includes, for example, a light modulation element such as a liquid crystal element or a DMD (Digital Mirror Device) that modulates light emitted from the light source, and a projection lens system that guides the image light modulated by the light modulation element to a projection surface.

[0030] 2. Operation An overview of the processing performed by the display device 3 of the display system 1 according to this embodiment will now be described. Fig. 4 is a flowchart showing an example of the processing performed by the display device 3 according to the present disclosure.

[0031] In this specification, the luminance percentages described in the processing of the display device 3 below refer to percentages relative to the maximum luminance value. For example, when the luminance percentage of a given pixel is 100%, this indicates that the pixel is displayed at the highest luminance. When the luminance percentage of a given pixel is 0%, this indicates that the pixel is displayed at the lowest luminance.

[0032] First, the arithmetic circuit 31 of the display device 3 receives an input video signal from the control device 2 (S10). When the arithmetic circuit 21 of the control device 2 transmits an input video signal for an image to be displayed on the display device 3 to the display device 3 via the communication circuit 23, the arithmetic circuit 31 receives the input video signal and stores it in the storage device 32. The input video signal has a predetermined gamma characteristic (so-called camera gamma). Hereinafter, in this specification, the gamma characteristic of the input video signal is also referred to as the input gamma characteristic. In this embodiment, the input gamma characteristic has a gamma characteristic used for high dynamic range (HDR) images.

[0033] The arithmetic circuit 31 performs gamma correction on the input video signal using predetermined gamma characteristics (S11). Hereinafter, in this specification, the gamma characteristics used in the gamma correction performed on the input video signal will also be referred to as pre-correction gamma characteristics, where appropriate. The arithmetic circuit 31 performs gamma correction on the input video signal using the pre-correction gamma characteristics to generate a corrected signal.

[0034] The pre-correction gamma characteristics are gamma characteristics that are stored in advance in the storage device 32. The pre-correction gamma characteristics may be stored in the storage device 32, for example, as a lookup table having a combination of input and output values ​​for the luminance ratio. The pre-correction gamma characteristics are generated by combining a gamma characteristic expressed as an inverse function of the input gamma characteristic (so-called inverse gamma) with a gamma characteristic expressed as an inverse function of the display gamma characteristic (described below). The display gamma characteristic is a gamma characteristic that is applied when an image is displayed by the optical mechanism 36. Hereinafter, in this specification, the gamma characteristic expressed as an inverse function of the input gamma characteristic is also referred to as a first gamma characteristic. Hereinafter, in this specification, the gamma characteristic expressed as an inverse function of the display gamma characteristic is also referred to as a second gamma characteristic. Hereinafter, in this specification, the display gamma characteristic is also referred to as a third gamma characteristic.

[0035] The input gamma characteristics are any gamma characteristics, including those expressed by an exponential gamma curve and those expressed by a non-exponential gamma curve. Gamma characteristics expressed by an exponential gamma curve include, for example, gamma characteristics such as gamma 2.2 or gamma 1.8. Gamma characteristics expressed by a non-exponential gamma curve include gamma characteristics used in HDR images or gamma characteristics used in the Grayscale Standard Display Function (GSDF) of Digital Imaging and Communications in Medicine (DICOM), a standard for imaging and communication in medical imaging equipment.

[0036] Fig. 5 is a gamma curve of an example of a pre-correction gamma characteristic. Fig. 6 is a gamma curve of an example of a first gamma characteristic expressed as an inverse function of an input gamma characteristic. Fig. 7 is a gamma curve of an example of a second gamma characteristic expressed as an inverse function of a display gamma characteristic, which will be described later. In the gamma curves shown in Figs. 5 to 7, the horizontal axis represents the percentage [%] of luminance of the input signal. The vertical axis represents the percentage [%] of luminance of the output signal. Alternatively, the horizontal axis may represent the signal level [%] of the input signal, and the vertical axis may represent the signal level [%] of the output signal.

[0037] The first gamma characteristic is any gamma characteristic, including a gamma characteristic expressed as an exponential gamma curve and a gamma characteristic expressed as a non-exponential gamma curve. As shown in Figure 6, in this embodiment, the first gamma characteristic has a gamma curve that is not expressed as an exponential function. The first gamma characteristic determines the ratio of the luminance of the output signal to the luminance of the input signal using a combination of input and output values ​​expressed by the gamma curve. In this embodiment, the input gamma characteristic is a gamma characteristic used in HDR images, and therefore has a gamma curve that is an inverse function of the gamma characteristic.

[0038] As shown in Fig. 7, the second gamma characteristic has a gamma curve expressed by an exponential function. The second gamma characteristic determines the ratio of the luminance of the output signal to the luminance of the input signal by a combination of input and output values ​​expressed by the gamma curve. In this embodiment, the display gamma characteristic is gamma 2.2, so the second gamma characteristic is expressed by y = x １／２．２ The gamma curve is expressed as an exponential function of x, where x is the ratio of luminance of the input signal, and y is the ratio of luminance of the output signal. Also, x may be the signal level of the input signal, and y may be the signal level of the output signal.

[0039] The gamma correction using the pre-correction gamma characteristic cancels out the input gamma characteristic, so that the corrected signal produced has a second gamma characteristic.

[0040] The storage device 32 stores a plurality of pre-correction gamma characteristics. The arithmetic circuit 31 determines an input gamma characteristic for an input video signal based on an input by a user via the input device 34, and acquires a corresponding pre-correction gamma characteristic from among the plurality of pre-correction gamma characteristics stored in the storage device 32. The user can input the input gamma characteristic via the input device 34, for example. The arithmetic circuit 31 may acquire a corresponding pre-correction gamma characteristic from among the plurality of pre-correction gamma characteristics stored in the storage device 32 based on information about the input gamma characteristic of the input video signal. The corresponding pre-correction gamma characteristic refers to a pre-correction gamma characteristic generated using a first gamma characteristic expressed as an inverse function of the input gamma characteristic.

[0041] Next, the arithmetic circuit 31 performs edge blending processing on the corrected signal (S12). The arithmetic circuit 31 determines an overlapping area of ​​an image displayed by the display device 3 including the arithmetic circuit 31, which overlaps with an image displayed by another display device 3. The arithmetic circuit 31 also determines an overlapping direction of an image displayed by the display device 3 and an image displayed by another display device 3. The arithmetic circuit 31 adjusts the luminance ratio of the image displayed in the overlapping area according to the position within the overlapping area in the overlapping direction. In this embodiment, the two display devices 3 are arranged side by side in the horizontal direction. Therefore, in this embodiment, the overlapping direction is the horizontal direction.

[0042] FIG. 8 is a graph showing an example of a correction curve used in edge blending processing. The arithmetic circuit 31 generates an output video signal by multiplying the corrected signal by the correction curve. In FIG. 8, the vertical axis represents the luminance correction rate [%]. In FIG. 8, the horizontal axis represents the position within the image in the overlap direction. Therefore, the correction curve in FIG. 8 shows the relationship between the image position and the luminance correction rate.

[0043] As shown in Figure 8, the projected image displayed by the display device 3 according to this embodiment has an image width from position x1 to position x3. In the image, the overlapping region is the range from position x1 to position x2. In the non-overlapping region, which is the range from position x2 to position x3, the correction rate is 100%. In other words, in the non-overlapping region, the luminance ratio of the image information contained in the signal does not change before and after edge blending processing.

[0044] In the overlapping region, between position x1 and position x2, the correction rate varies depending on the position between 0% and 100%. At position x1, which indicates the edge of the image displayed by the display device 3, the correction rate is 0%. That is, the arithmetic circuit 31 corrects the luminance rate of the image information at position x1 contained in the corrected signal to 0%. At position x2, which indicates the edge of the image displayed by the other display device 3, the correction rate is 100%. That is, the arithmetic circuit 31 does not change the luminance rate of the image information at position x2 contained in the corrected signal.

[0045] In the correction curve shown in Fig. 8, the correction rate in the overlapping region corresponds to the second gamma characteristic. １／２．２ The correction factor according to the position is determined by a combination of input and output values ​​expressed by a gamma curve expressed as an exponential function of . Position x1 corresponds to a luminance ratio of 0% of the input signal in the second gamma characteristic. Position x2 corresponds to a luminance ratio of 100% of the input signal in the second gamma characteristic. In this way, the arithmetic circuit 31 determines the correction factor according to the position in the overlapping area by edge blending processing, with position x1 being 0% and position x2 being 100%. １／２．２ The brightness ratio is changed by a correction factor expressed as follows: where x is a value in the range of 0 to 100 determined according to the position of the overlapping region, and y is a correction factor according to the position.

[0046] The arithmetic circuit 31 projects an image through the optical mechanism 36 based on the generated output video signal (S13). As a result, the display device 3 displays a projection image based on the input video signal output by the control device 2 on the screen 5. The optical mechanism 36 has a predetermined gamma characteristic (so-called panel gamma). In this specification, the gamma characteristic of the optical mechanism 36 is also referred to as the display gamma characteristic. The display gamma characteristic has a gamma curve expressed by an exponential function.

[0047] 9 is a gamma curve showing an example of a display gamma characteristic. In the gamma curve shown in FIG. 9, the horizontal axis represents the percentage [%] of luminance of the input signal. The vertical axis represents the percentage [%] of luminance of the output signal. The horizontal axis may represent the signal level [%] of the input signal, and the vertical axis may represent the signal level [%] of the output signal.

[0048] In this embodiment, the optical mechanism 36 has a display gamma characteristic of gamma 2.2. That is, the display gamma characteristic is expressed as y=x ２．２ The display gamma characteristic determines the ratio of the luminance of the output signal to the luminance of the input signal by a combination of input and output values ​​represented by the gamma curve. Here, x is the luminance ratio of the input signal, and y is the luminance ratio of the output signal. Also, x may be the signal level of the input signal, and y may be the signal level of the output signal.

[0049] The arithmetic circuit 31 drives, for example, a light modulation element to project an image based on the signal adjusted by the display gamma characteristic onto the screen 5. The output video signal has image information adjusted by the second gamma characteristic, and the projected image is displayed by applying the display gamma characteristic to the image information. Because the second gamma characteristic is offset by the display gamma characteristic, the arithmetic circuit 31 can display, via the optical mechanism 36, a projected image having the luminance ratio of the original image that the control device 2 intends to display via the display device 3. In this specification, the image that the control device 2 intends to display is referred to as the original image.

[0050] Fig. 10 is a graph showing an example of the brightness adjustment rate according to position in the projected image. In Fig. 10, the vertical axis represents the brightness adjustment rate [%] of the projected image. In Fig. 10, the horizontal axis represents the position in the projected image in the overlapping direction. Therefore, the graph in Fig. 10 shows the brightness adjustment rate according to the position of the image after brightness adjustment by edge blending processing. Positions x1, x2, and x3 shown in Fig. 10 correspond to the respective positions of the correction curve in Fig. 8. In Fig. 10, the brightness adjustment rate is expressed as a minimum of 0% and a maximum of 100%.

[0051] The brightness adjustment rates shown in Figure 10 and the graphs shown in Figure 11 (described later) indicate the ratio of brightness of the image displayed by the display device 3 to the brightness of the original image. For example, if the brightness ratio of a specific pixel in the original image is 100% and the display device 3 according to the present disclosure displays a projected image in which the brightness ratio of that pixel has been reduced by an adjustment rate of 70%, the brightness ratio of the projected image will be 70%. If the brightness ratio of a specific pixel in the original image is 50% and the display device 3 according to the present disclosure displays a projected image in which the brightness of that pixel has been reduced by an adjustment rate of 70%, the brightness ratio of the projected image will be 35%.

[0052] 10, the brightness adjustment rate is 100% in the non-overlapping region from position x2 to position x3. Therefore, the arithmetic circuit 31 displays the brightness ratio for the non-overlapping region of the image at the same brightness ratio as when edge blending processing is not performed.

[0053] 10, in the overlapping region between positions x1 and x2, the brightness adjustment rate is linearly inclined between 0% and 100% depending on the position within the overlapping region. Therefore, the arithmetic circuit 31 displays the brightness rate for the overlapping region of the image at a brightness rate that is reduced by a predetermined rate depending on the position within the overlapping region compared to the brightness rate when edge blending processing is not performed.

[0054] Fig. 11 is a graph showing the adjustment rate of brightness of multiple images projected onto the screen 5 by multiple display devices 3. In Fig. 11, the vertical axis represents the adjustment rate [%] of brightness of the projected images, and the horizontal axis represents the position of each projected image on the screen in the overlapping direction.

[0055] The dashed-dotted line a indicates the brightness adjustment rate for each position of the image projected from the first display device 3a. The dashed-two-dotted line b indicates the brightness adjustment rate for each position of the image projected from the second display device 3b. The solid line c indicates the total value of the brightness adjustment rate when the image projected from the first display device 3a and the image projected from the second display device 3b are displayed simultaneously. In other words, the solid line c indicates the brightness adjustment rate for each position of an image projected from multiple images as a single virtual image content. Hereinafter, in this specification, the image projected from the first display device 3a will also be referred to as a left-projected image. In this specification, the image projected from the second display device 3b will also be referred to as a right-projected image.

[0056] In this embodiment, the first display device 3a projects an image onto the left side of the screen 5. The second display device 3b projects an image onto the right side of the screen. The left projected image has an overlapping area on the right side of the image. The right projected image has an overlapping area on the left side of the image. As shown in FIG. 11 , the left projected image has an image width from position y1 to position y3. The right projected image has an image width from position z1 to position z3. Position y1 in the left projected image corresponds to position z2 in the right projected image. Position y2 in the left projected image corresponds to position z1 in the right projected image.

[0057] As shown in FIG. 11 , the left projection image has a brightness adjustment rate of 0% at position y1, a brightness adjustment rate of 100% at position y2, and a brightness adjustment rate of 100% at position y3. The right projection image has a brightness adjustment rate of 0% at position z1, a brightness adjustment rate of 100% at position z2, and a brightness adjustment rate of 100% at position z3. In the left projection image, the brightness adjustment rate in the overlapping region from position y1 to position y2 increases linearly from position y1 to position y2. Similarly, in the right projection image, the brightness adjustment rate in the overlapping region from position z1 to position z2 increases linearly from position z1 to position z2. Therefore, the sum of the brightness adjustment rates in the overlapping region is the same as the brightness adjustment rate in the non-overlapping region regardless of position. If the brightness ratio of the original image to be displayed by the control device 2 is the same value throughout the entire region, the projection images displayed by the two display devices 3 will have the same brightness regardless of position.

[0058] The display device 3 according to this embodiment can linearly reduce the luminance ratio of overlapping regions in projected images according to the position in the overlap direction, even if the gamma characteristics of the input video signal have a gamma curve that is not expressed by an exponential function. Therefore, a single virtual image content displayed by multiple projected images displayed by a display system 1 including multiple display devices 3 has the same luminance ratio as the original image regardless of position. Therefore, the display system 1 according to this embodiment can display a single virtual image content without increasing or decreasing the luminance ratio of overlapping regions in adjacent projected images, even if the input video signal has gamma characteristics that are not expressed by an exponential function.

[0059] In conventional technology, even when edge blending is performed, the luminance of the overlapping area of ​​adjacent images may increase or decrease relative to the original image depending on the gamma characteristics of the input video signal, depending on the overlapping area where the luminance of the original image is not 100%. The arithmetic circuit 31 of the display device 3 according to the present disclosure performs a predetermined gamma correction corresponding to the gamma characteristics of the input video signal. Therefore, even in overlapping areas where the luminance of the original image is not 100%, the arithmetic circuit 31 can adjust the luminance of the projected image so that the luminance of the overlapping area of ​​the adjacent images is equivalent to that of the original image, regardless of the gamma characteristics of the input video signal. Furthermore, this processing can be performed using a lookup table or the like stored in the storage device 32 that can be used for gamma correction. In this way, the display system 1 can achieve edge blending processing that supports any gamma characteristics that was previously not possible, at low cost.

[0060] (Modification) In the above embodiment, the arithmetic circuit 31 of the display device 3 executes the correction process using the pre-correction gamma characteristics and the edge blending process, but these processes may be executed by an arithmetic circuit of a device different from the display device 3.

[0061] FIG. 12 is a schematic diagram of a display system 1 according to a modified example. The display system 1 according to the modified example includes a control device 2, a first display device 3a, and a second display device 3b, as well as a first image processing device 6a and a second image processing device 6b. Hereinafter, in this specification, when there is no need to distinguish between the multiple image processing devices 6a and 6b, they will be collectively referred to as the image processing device 6. The image processing device 6 is an information processing device such as a computer or a media server device. The control device 2 and the image processing device 6 are connected via a cable 4. The image processing device 6 and the display device 3 are also connected via a cable 4. The control device 2 causes the display device 3 to project a projection image via the image processing device 6.

[0062] 13 is a schematic diagram of an image processing device 6 according to a modified example. The image processing device 6 includes an arithmetic circuit 61, a storage device 62, a communication circuit 63, an input device 64, and an output device 65. The arithmetic circuit 61, the storage device 62, the communication circuit 63, the input device 64, and the output device 65 can be realized by the same specific means as the arithmetic circuit 21, the storage device 22, the communication circuit 23, the input device 24, and the output device 25 described above with reference to FIG. 2.

[0063] The storage device 62 stores a lookup table indicating gamma characteristics for gamma correcting the luminance ratio, and also stores coordinates on the image indicating an overlapping area between an image displayed by a display device 3 corresponding to the image processing device 6 and another image displayed by another display device 3.

[0064] The arithmetic circuit 61 can execute part of the processing performed by the arithmetic circuit 31 in the above-described embodiment. Fig. 14 is a flowchart showing an example of processing performed by the image processing device 6 according to the modified example. S20 to S22 shown in Fig. 14 correspond to S10 to S12 in Fig. 4, respectively.

[0065] When the arithmetic circuit 61 of the image processing device 6 receives an input video signal from the control device 2 (20), it performs gamma correction using the pre-correction gamma characteristics (S21). As a result, the arithmetic circuit 61 generates a corrected signal. The arithmetic circuit 61 then performs edge blending on the corrected signal (S22) to generate an output video signal in which the luminance ratio of the overlapping range is reduced by a predetermined ratio depending on the position. The arithmetic circuit 61 then transmits the generated output video signal to the display device 3 via the communication circuit 63 (S23).

[0066] 15 is a flowchart showing an example of processing by the display device 3 according to the modified example. S31 shown in FIG. 15 corresponds to S13 in FIG.

[0067] When the arithmetic circuit 31 of the display device 3 receives the output video signal from the image processing device 6 (S30), it displays an image based on the output video signal through the optical mechanism 36 (S31). As a result, the display device 3 displays an image based on the input video signal output by the control device 2.

[0068] In this way, the display system 1 can execute part of the processing executed by the arithmetic circuit 31 using a device other than the display device 3 .

[0069] In the above-described embodiment, the display device 3 is configured as shown in Fig. 3, but the display device 3 is not limited to this configuration. For example, the display device 3 may be configured as shown in Fig. 16. Fig. 16 shows a schematic diagram of a modified example of the display device 3.

[0070] 16 includes an image processing device 6 and an optical mechanism 36. In this manner, the display device 3 may be configured with a plurality of devices. In this case, the arithmetic circuit 61 and the like, which are components of the image processing device 6, function as components of the display device 3. For example, the processing executed by the arithmetic circuit 31 in the above-described embodiment is executed by the arithmetic circuit 61.

[0071] In the above embodiment, the arithmetic circuit 31 performs gamma correction on the input video signal using the pre-correction gamma characteristics, but the gamma correction is not limited to processing using the pre-correction gamma characteristics. For example, the arithmetic circuit 31 may perform gamma correction in multiple steps.

[0072] As described above, the pre-correction gamma characteristic is generated by combining the first gamma characteristic and the second gamma characteristic. For example, the arithmetic circuit 31 may first perform gamma correction on the input video signal using the first gamma characteristic to generate an intermediate signal. Alternatively, the arithmetic circuit 31 may then perform further gamma correction on the intermediate signal using the second gamma characteristic to generate a corrected signal.

[0073] In the above embodiment, the overlapping direction is the horizontal direction, but the overlapping direction is not limited to the horizontal direction. For example, when two display devices 3 are arranged side by side in the vertical direction, the overlapping direction is the vertical direction.

[0074] In the above embodiment, the display system 1 includes two display devices 3, but the display system 1 may include three or more display devices 3. In the above embodiment, only one side of the image overlaps, but when there are three or more display devices 3, two or more sides of the image may overlap.

[0075] In the above embodiment, the arithmetic circuit 31 adjusts the luminance ratio in the image, but the processing by the arithmetic circuit 31 is not limited to adjusting the luminance ratio. For example, the arithmetic circuit 31 may perform the above processing by adjusting the luminance in the image.

[0076] 3. Effects According to the image processing device 6 or the display device 3 according to the embodiment of the present disclosure, the following effects can be achieved.

[0077] The image processing device 6 includes an arithmetic circuit 61 and a storage device 62, and transmits an output video signal to the display device 3. The display device 3 generates a single image content by displaying an image that at least partially overlaps with another display device 3. The arithmetic circuit 61 performs gamma correction on the received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal. The arithmetic circuit 61 performs edge blending on the corrected signal, using the second gamma characteristic to adjust the luminance of a predetermined region of an image displayed based on the input video signal according to the position within the predetermined region, to generate an output video signal. The second gamma characteristic is an inverse function of the third gamma characteristic of the display device 3. The third gamma characteristic has a gamma curve expressed by an exponential function. The predetermined region is an overlapping region between an image displayed by the display device 3 and another image displayed by another display device 3.

[0078] With this configuration, the image processing device 6 can linearly reduce the luminance in the overlapping area performed by edge blending processing according to the position in the overlapping area, even if the input gamma characteristics have a gamma curve that is not expressed as an exponential function. Therefore, the image processing device 6 can perform edge blending processing corresponding to any input gamma characteristics. Furthermore, this processing can be performed by storing gamma characteristics corresponding to any input gamma characteristics in the storage device 62 and performing gamma correction using those gamma characteristics. For example, if a lookup table for performing gamma correction using those gamma characteristics is stored in the storage device 62, the arithmetic circuit 61 can perform that gamma correction, allowing the image processing device 6 to be implemented at low cost.

[0079] In the image processing device 6, the first gamma characteristic is an inverse function of the gamma characteristic of the input video signal.

[0080] With this configuration, the arithmetic circuit 61 can offset the gamma characteristics of the input video signal, and therefore the image processing device 6 can perform edge blending processing that corresponds to any gamma characteristics.

[0081] In the image processing device 6, the first gamma characteristic has a gamma curve expressed by a non-exponential function.

[0082] With this configuration, the arithmetic circuit 61 can offset gamma characteristics having a gamma curve that is not expressed by an exponential function with the first gamma characteristic. Therefore, even if the gamma characteristic of the input video signal has a gamma curve that is not expressed by an exponential function, the image processing device 6 can perform edge blending processing corresponding to the gamma characteristic.

[0083] In the image processing device 6, the first gamma characteristic has a gamma curve expressed by an exponential function.

[0084] With this configuration, the arithmetic circuit 61 can offset the gamma characteristic having a gamma curve expressed by an exponential function with the first gamma characteristic. Therefore, even if the gamma characteristic of the input video signal has a gamma curve expressed by an exponential function, the image processing device 6 can perform edge blending processing corresponding to the gamma characteristic.

[0085] In the image processing device 6, generating the first signal includes the arithmetic circuit 61 performing gamma correction on the input video signal using the first gamma characteristic to generate an intermediate signal, and also the arithmetic circuit 61 performing gamma correction on the intermediate signal using the second gamma characteristic to generate a corrected signal.

[0086] With this configuration, the arithmetic circuit 61 can perform gamma correction using the first gamma characteristic and the second gamma characteristic instead of using the pre-correction gamma characteristic. In this way, the image processing device 6 according to the present disclosure can be realized in a variety of configurations.

[0087] The display device 3 includes an image processing device 6 and an optical mechanism 36 that outputs a display image based on an output video signal received from the image processing device 6. The arithmetic circuits 31 and 61 output a display image to which the third gamma characteristic has been applied to the output video signal via the optical mechanism 36.

[0088] With this configuration, the display device 3 can perform functions equivalent to those of the image processing device 6. The arithmetic circuit 31 corresponds to the arithmetic circuit 61. Therefore, even if the input gamma characteristics have a gamma curve that is not expressed as an exponential function, the display device 3 can linearly reduce the luminance in the overlapping area performed by edge blending processing according to the position in the overlapping area. Therefore, the display device 3 can perform edge blending processing corresponding to any input gamma characteristics. Furthermore, this processing can be performed by storing gamma characteristics corresponding to any input gamma characteristics in the storage device 32 and performing gamma correction using the gamma characteristics. For example, if a lookup table for performing gamma correction using the gamma characteristics is stored in the storage device 32, the arithmetic circuit 31 can perform the gamma correction, thereby reducing the cost of the display device 3. Furthermore, the display device 3 can project an image in which the luminance in the overlapping area is linearly reduced. Therefore, by combining multiple display devices 3, the multiple display devices 3 can perform edge blending processing corresponding to any input gamma characteristics and display the overlapping area with brightness equivalent to that of the original image.

[0089] In a control method for transmitting an output video signal to a display device (3), the display device (3) generates a single image content by displaying an image that at least partially overlaps with another display device (3). The control method includes performing gamma correction on a received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal. The control method also includes performing edge blending on the corrected signal, using the second gamma characteristic to adjust the luminance of a predetermined region of an image displayed based on the input video signal according to the position within the predetermined region, to generate an output video signal. The second gamma characteristic is an inverse function of a third gamma characteristic of the display device. The third gamma characteristic has a gamma curve expressed by an exponential function. The predetermined region is a region where an image displayed by the display device (3) overlaps with another image displayed by the other display device (3).

[0090] According to this method, even if the input gamma characteristics have a gamma curve that is not expressed as an exponential function, the image processing device 6 can linearly reduce the luminance in the overlapping area, which is performed by edge blending, depending on the position in the overlapping area. Therefore, the image processing device 6 can perform edge blending corresponding to any input gamma characteristics. Furthermore, this processing can be performed by storing gamma characteristics corresponding to any input gamma characteristics in the storage device 62 and performing gamma correction using these gamma characteristics. For example, if a lookup table for performing gamma correction using these gamma characteristics is stored in the storage device 62, the arithmetic circuit 61 can perform the gamma correction. Therefore, the image processing device 6 capable of performing this method can be realized at low cost.

[0091] (Summary of Aspects) As is clear from the above description, the present disclosure includes the following aspects. In the following, reference numerals are given in parentheses only to clarify the correspondence with the embodiments.

[0092] (Aspect 1) An image processing device (6) according to the present disclosure is an image processing device that includes an arithmetic circuit (61) and a memory device (62) and transmits an output video signal to a display device (3), wherein the display device generates one image content by displaying an image that overlaps at least a portion of the image with another display device, and the arithmetic circuit performs gamma correction on the received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal, and performs edge blending processing on the corrected signal using the second gamma characteristic to adjust the luminance of a predetermined area of ​​an image displayed based on the input video signal according to the position within the predetermined area to generate the output video signal, wherein the second gamma characteristic is an inverse function of a third gamma characteristic of the display device, and the third gamma characteristic has a gamma curve expressed by an exponential function, and the predetermined area is an area where the image displayed by the display device and another image displayed by the other display device overlap.

[0093] (Aspect 2) In the image processing device (6) of aspect 1, the first gamma characteristic may be an inverse function of the gamma characteristic of the input video signal.

[0094] (Aspect 3) In the image processing device (6) of Aspect 1 or Aspect 2, the first gamma characteristic may have a gamma curve expressed by a non-exponential function.

[0095] (Aspect 4) In the image processing device (6) of Aspect 1 or Aspect 2, the first gamma characteristic may have a gamma curve expressed by an exponential function.

[0096] (Aspect 5) In the image processing device (6) of any one of Aspects 1 to 3, generating a first signal may include the arithmetic circuit (61) performing gamma correction on the input video signal using the first gamma characteristic to generate an intermediate signal, and performing gamma correction on the intermediate signal using the second gamma characteristic to generate the corrected signal.

[0097] (Aspect 6) A display device (3) according to the present disclosure is a display device comprising: an image processing device (6) according to any one of aspects 1 to 5; and an optical mechanism (36) that outputs a display image based on the output video signal received from the image processing device, wherein the arithmetic circuit (61, 31) outputs the display image to which the third gamma characteristic has been applied to the output video signal via the optical mechanism.

[0098] (Aspect 7) A control method according to the present disclosure is a control method for transmitting an output video signal to a display device (3), wherein the display device generates a single image content by displaying an image that at least partially overlaps with another display device, the control method comprising: performing gamma correction on a received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal; and performing edge blending processing on the corrected signal, using the second gamma characteristic to adjust the luminance of a previously acquired predetermined area of ​​an image to be displayed based on the input video signal according to a position within the predetermined area, to generate the output video signal, wherein the second gamma characteristic is an inverse function of a third gamma characteristic of the display device, the third gamma characteristic has a gamma curve expressed by an exponential function, and the predetermined area is an area where the image displayed by the display device and another image displayed by the other display device overlap.

[0099] As used herein, terms such as "first," "second," etc. are used for descriptive purposes only and should not be understood as expressing or implying relative importance or ranking of technical features. Features qualified as "first" and "second" expressly or imply the inclusion of one or more of that feature.

[0100] The display device 3 and the image processing device 6 described in the present disclosure are realized by the cooperation of hardware resources, such as a processor and a memory, and software (computer program).

[0101] According to the present disclosure, it is possible to provide an image processing device, a display device, and a control method that can suppress a nonlinear decrease in luminance in an overlapping area of ​​a projected image due to edge blending processing depending on the position within the overlapping area, and thus can be suitably used in this type of industrial field.

Claims

1. An image processing device comprising an arithmetic circuit and a storage device, for transmitting an output video signal to a display device, wherein the display device generates one image content by displaying an image that at least partially overlaps with another display device, and the arithmetic circuit performs gamma correction on the received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal, and performs edge blending on the corrected signal, using the second gamma characteristic to adjust the luminance of a pre-acquired predetermined area of ​​an image to be displayed based on the input video signal according to the position within the predetermined area, to generate the output video signal, wherein the second gamma characteristic is an inverse function of a third gamma characteristic of the display device, and the third gamma characteristic has a gamma curve expressed by an exponential function, and the predetermined area is an area where the image displayed by the display device and another image displayed by the other display device overlap.

2. The image processing device according to claim 1, wherein the first gamma characteristic is an inverse function of the gamma characteristic of the input video signal.

3. The image processing device according to claim 1, wherein the first gamma characteristic has a gamma curve expressed by a non-exponential function.

4. The image processing device according to claim 1, wherein the first gamma characteristic has a gamma curve expressed by an exponential function.

5. The image processing device according to claim 1, wherein generating the first signal includes the calculation circuit performing gamma correction on the input video signal using the first gamma characteristic to generate an intermediate signal, and performing gamma correction on the intermediate signal using the second gamma characteristic to generate the corrected signal.

6. A display device comprising: the image processing device according to any one of claims 1 to 5; and an optical mechanism that outputs a display image based on the output video signal received from the image processing device, wherein the arithmetic circuit outputs the display image to which the third gamma characteristic has been applied to the output video signal via the optical mechanism.

7. A control method for transmitting an output video signal to a display device, wherein the display device generates one image content by displaying an image that at least partially overlaps with another display device, the control method comprising: performing gamma correction on a received input video signal using a first gamma characteristic and a second gamma characteristic different from the first gamma characteristic to generate a corrected signal; and performing edge blending processing on the corrected signal, using the second gamma characteristic to adjust the luminance of a pre-acquired predetermined area of ​​an image to be displayed based on the input video signal according to the position within the predetermined area, to generate the output video signal, wherein the second gamma characteristic is an inverse function of a third gamma characteristic of the display device, and the third gamma characteristic has a gamma curve expressed by an exponential function, and the predetermined area is an area where the image displayed by the display device and another image displayed by the other display device overlap.

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