Image display device, image display method, and image display program

Abstract

The present invention provides an image display device, an image display method, and an image display program capable of displaying an image with gradation characteristics conforming to desired gradation characteristics. The image display device includes a luminance acquisition unit, a gradation characteristic acquisition unit, and a display unit. The luminance acquisition unit predicts an output luminance value at the maximum output gradation value of the image display device at the first timing and thereby acquires a first luminance value as the output luminance value. The gradation characteristic acquisition unit acquires a first gradation characteristic indicating a correspondence relationship between an input gradation value of the image displayed by the display unit and an output luminance value to be outputted by the display unit according to the input gradation value on the basis of the first luminance value, as gradation characteristics conforming to the gradation characteristic defined by the absolute value of luminance. The display unit displays the image using the first gradation characteristic. At a second timing after the first timing, the luminance acquisition unit predicts an output luminance value which is an output luminance value at the maximum output gradation value of the image display device and which has changed over time from the first timing and thereby acquires a second luminance value as the output luminance value. The gradation characteristic acquisition unit acquires a second gradation characteristic indicating a correspondence relationship between an input gradation value of the image displayed by the display unit and an output luminance value to be outputted by the display unit according to the input gradation value on the basis of the second luminance value, as gradation characteristics conforming to the gradation characteristic defined by the absolute value of luminance. The display unit displays the image using the second gradation characteristic.

Description

Image display device, image display method, and image display program

[0001] The present invention relates to an image display device, an image display method, and an image display program.

[0002] Display devices capable of displaying images with a wider dynamic range than conventional dynamic ranges (the range of brightness that the human eye can perceive) have appeared. The dynamic range that can be represented by conventional display devices is called SDR (Standard Dynamic Range), and a dynamic range that can be represented wider than conventional display devices is called HDR (High Dynamic Range). For example, Patent Document 1 discloses a technique for comparatively displaying an HDR image with a wide dynamic range and an SDR image with a narrow dynamic range.

[0003] To properly display HDR images, it is important not only to increase brightness but also to express color and gradation in accordance with human visual characteristics. The color and gradation are influenced by the input / output characteristics of each input / output device, known as gamma (EOTF: Electro Optical Transfer Function). The international HDR standard, ITU-R BT.2100, defines two gamma curves (PQ and HLG) to suit different applications.

[0004] The PQ (Perceptual Quantization) method uses gamma that matches the characteristics of human vision and is suitable for the production of movies and web-based content, where reproducibility is important, while the HLG (Hybrid Log Gamma) method is suitable for television broadcasting and live coverage, as it emphasizes that the image can be displayed naturally on conventional SDR televisions.

[0005] In the case of the PQ system, the peak luminance (maximum brightness) is 10,000 cd / m ２This standard specifies that the same gamma curve (PQ curve) is always drawn up to the luminance that the display device can reproduce, so that in the gradation range up to the peak luminance of the display device, HDR images that accurately reproduce the PQ curve can be displayed. On the other hand, in the case of the HLG system, the peak luminance coincides with the maximum luminance of the display device. In other words, because the gamma curve changes depending on the maximum luminance of the display device, HDR images can be displayed without significant image distortion even when displayed on a conventional SDR television.

[0006] In recent years, technological developments in the display field have progressed, and display devices with high display quality that use self-luminous elements such as organic light-emitting diodes (OLEDs) as light sources have been proposed. However, self-luminous elements have a short lifespan. In display devices that use self-luminous elements as light sources, for example, the peak luminance decreases as the light-emitting time of the self-luminous elements (specifically, the current (load current) flowing through the self-luminous elements and the cumulative amount of time the current flows) increases, resulting in a relative decrease in the output luminance value of the display device corresponding to each input luminance value of the displayed image. For this reason, it has been difficult to display HDR images with gradation characteristics compliant with the PQ method, i.e., gradation characteristics that require the display device to always depict the same gamma curve in the gradation range up to the peak luminance.

[0007] JP 2017-181762 A

[0008] An object of the present invention is to provide an image display device, an image display method, and an image display program that are capable of displaying an image with gradation characteristics that conform to desired gradation characteristics.

[0009] According to the present invention, there is provided an image display device having the following configuration: [1] An image display device including a luminance acquisition unit, a gradation characteristic acquisition unit, and a display unit, wherein the luminance acquisition unit acquires a first luminance value as the output luminance value by predicting an output luminance value at a maximum output gradation value of the image display device at a first timing, the gradation characteristic acquisition unit acquires a first luminance value as the output luminance value, as a gradation characteristic conforming to a gradation characteristic defined by an absolute value of luminance, the first gradation characteristic indicating a correspondence relationship between an input gradation value of an image to be displayed by the display unit and an output luminance value to be output by the display unit in accordance with the input gradation value, based on the first luminance value, and the display unit displays an image using the first gradation characteristic, the unit acquires a second luminance value as the output luminance value at a second timing after the first timing, the second luminance value being an output luminance value at a maximum output luminance value of the image display device by predicting an output luminance value that has changed over time since the first timing; the gradation characteristic acquisition unit acquires a second luminance characteristic that indicates a correspondence between an input gradation value of an image to be displayed by the display unit and, based on the second luminance value, a gradation characteristic that conforms to a gradation characteristic defined by an absolute value of luminance; and the display unit displays an image using the second gradation characteristic.

[0010] According to the present invention, at the second timing, a second luminance value that has changed over time since the first timing is acquired, and instead of the first gradation characteristic, an image is displayed using the second gradation characteristic that indicates the correspondence between the input gradation value of the image displayed by the display unit and the output luminance value that the display unit should output in accordance with the input gradation value based on the second luminance value, as a gradation characteristic that conforms to the gradation characteristic defined by the absolute value of luminance.Therefore, even at the second timing that is later than the first timing, an image can be displayed with gradation characteristics that conform to the desired gradation characteristic.

[0011] Various embodiments of the present invention are exemplified below. The embodiments shown below can be combined with each other. [2] The image display device according to [1], wherein the gradation characteristics defined by the absolute value of luminance are gradation characteristics that satisfy the PQ curve standard. [3] The image display device according to [1], wherein the gradation characteristics defined by the absolute value of luminance are gradation characteristics that satisfy the Grayscale Standard Display Function (GSDF) of the DICOM standard. [4] The image display device according to any one of [1] to [3], wherein the luminance acquisition unit acquires a third luminance value as the output luminance value by actually measuring an output luminance value at a maximum output luminance value of the image display device at a third timing different from the first and second timings, the luminance acquisition unit acquires a third luminance value as the output luminance value, the luminance characteristic acquisition unit acquires a third luminance characteristic as a luminance characteristic conforming to a luminance absolute value, the third luminance characteristic indicating a correspondence relationship between an input luminance value of an image to be displayed by the display unit and an output luminance value to be output by the display unit in accordance with the input luminance value, based on the third luminance value, and the display unit displays the image using the third luminance characteristic. [5] The image display device according to any one of [1] to [4], wherein the luminance acquisition unit acquires the output luminance value at a frequency equal to or greater than a frequency when an image is displayed using a luminance characteristic conforming to a luminance absolute value as compared to a frequency when an image is displayed using a luminance characteristic conforming to a luminance relative value. [6] The image display device according to any one of [1] to [5], wherein the luminance acquisition unit decreases the frequency of acquisition of the output luminance value as the display time of the image by the display unit becomes longer. [7] The image display device according to any one of [1] to [6], wherein the display unit is a self-luminous type.[8] An image display method having a luminance acquisition step, a gradation characteristic acquisition step, and a display step, wherein in the luminance acquisition step, a first luminance value is acquired as the output luminance value by predicting an output luminance value at a maximum output gradation value of the image display device at a first timing, and in the gradation characteristic ...gradation characteristic is acquired as a gradation characteristic conforming to a gradation characteristic defined by an absolute value of luminance, the first gradation characteristic indicating a correspondence relationship between an input gradation value of an image to be displayed in the display step and an output luminance value to be output in the display step according to the input gradation value, based on the first luminance value, and in the display step, an image is displayed using the first gradation characteristic, an image display method, wherein the brightness acquisition step acquires a second brightness value as the output brightness value by predicting an output brightness value that is an output brightness value at a maximum output grayscale value of the image display device at a second timing that is later than the first timing and that has changed over time since the first timing, and the grayscale characteristic acquisition step acquires a second grayscale characteristic that indicates a correspondence between an input grayscale value of the image to be displayed at the display step and an output brightness value to be output at the display step in accordance with the input grayscale value, based on the second brightness value, as a grayscale characteristic that conforms to a grayscale characteristic defined by an absolute value of brightness, and the image is displayed at the display step using the second grayscale characteristic.[9] An image display method, wherein the brightness acquisition step acquires a second brightness value as the output brightness value at a second timing that is later than the first timing and that has changed over time since the first timing, and the second grayscale characteristic that indicates a correspondence between an input grayscale value of the image to be displayed at the display step and an output brightness value to be output at the display step in accordance with the input grayscale value, based on the second brightness value, as a grayscale characteristic that conforms to a grayscale characteristic defined by an absolute value of brightness, and the image is displayed using the second grayscale characteristic.

[0012] According to the present invention, an image can be displayed using desired gradation characteristics.

[0013] 3A is a block diagram showing a functional configuration of an image display device 10 according to an embodiment of the present invention. FIG. 3B is a diagram showing an example of a PQ curve. FIG. 3A is a diagram showing an example of a gradation characteristic curve of the display unit 3 when the output luminance value (peak luminance value) of the display unit 3 is 300. FIG. 3B is a diagram showing an example of a gradation characteristic curve of the display unit 3 when the output luminance value of the display unit 3 is 1000. FIG. 3C is a diagram showing an example of a gradation characteristic curve of the display unit 3 when the output luminance value of the display unit 3 is 4000. FIG. 3C is a diagram showing an example of a deterioration characteristic curve of a self-luminous element. FIG. 5A is a diagram showing an example of a gradation characteristic curve 25 showing a first gradation characteristic when the first luminance value is 300. FIG. 5B is a diagram showing an example of a gradation characteristic curve 26 showing a first gradation characteristic when the first luminance value is 1000. FIG. 6A is a diagram showing an example of a gradation characteristic curve 27 showing a first gradation characteristic when the first luminance value is 4000. FIG. 6B is a diagram showing an example of a gradation characteristic curve 28 showing a first gradation characteristic when the first luminance value is 10000. 8A is a flowchart showing an example of an image display process performed by the image display device 10. Fig. 8A is a diagram showing an example of a gradation characteristic curve 33 showing a first gradation characteristic when the first luminance value is 1000. Fig. 8B is a diagram showing an example of a gradation characteristic curve 34 showing a second gradation characteristic when the second luminance value is 800. Fig. 9 is a diagram showing an example of a gradation characteristic curve 36 of the display unit 3 when the first luminance value of the display unit 3 is 1000, and an example of a gradation characteristic curve 37 of the display unit 3 when the second luminance value of the display unit 3 is 800. Fig. 9 is a diagram showing an example of a prediction timing and an actual measurement timing of an output luminance value by the luminance acquisition unit 5.

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0015] 1 is a block diagram showing the functional configuration of an image display device 10 according to an embodiment of the present invention. As shown in Fig. 1, the image display device 10 is a color image display device using, for example, three colors of RGB, and includes an image acquisition unit 1, a display control unit 2, a display unit 3, a luminance acquisition unit 5, a gradation characteristic acquisition unit 8, a storage unit 9, and an operation reception unit 11.

[0016] Each component of the image display device 10 may be implemented by software or hardware. When implemented by software, various functions can be realized by a CPU executing a computer program. The program may be stored in an internal storage unit or a computer-readable non-transitory recording medium. Alternatively, the program may be read from an external storage unit and implemented using so-called cloud computing. When implemented by hardware, the functions can be realized by various circuits such as an ASIC, an FPGA, or a DRP (Dynamically Reconfigurable Processor). This embodiment deals with various pieces of information and concepts that encompass them. These are represented by high or low signal values ​​as a binary bit group consisting of 0 or 1, and communication and calculations can be performed using the above software or hardware aspects.

[0017] The image display device 10 is a display device capable of displaying images in a wider dynamic range than a conventional dynamic range (the range of brightness that the human eye can perceive). The dynamic range that can be expressed by a conventional display device is called SDR (Standard Dynamic Range), and a dynamic range that can be expressed wider than a conventional display device is called HDR (High Dynamic Range).

[0018] To properly display HDR images (hereafter referred to as "HDR images"), it is important not only to increase brightness but also to express "color" and "gradation" that are suited to human visual characteristics. The color and gradation are influenced by the input / output characteristic "gamma (EOTF: Electro Optical Transfer Function)" of each input / output device. The international HDR standard "ITU-R BT.2100" defines two gamma curves (PQ method and HLG method) to suit different applications.

[0019] The PQ (Perceptual Quantization) method uses gamma that matches the characteristics of human vision and is suitable for the production of movies and web-based content, where reproducibility is important, while the HLG (Hybrid Log Gamma) method is suitable for television broadcasting and live coverage, as it emphasizes that the image can be displayed naturally on conventional SDR televisions.

[0020] In the case of the PQ system, the peak luminance (maximum brightness) is 10,000 cd / m ２ and the luminance values ​​of the HDR image are treated as absolute values ​​(constant regardless of the display device), and the same gamma curve (PQ curve) is always drawn up to the luminance that can be reproduced by the display unit 3, so that in the gradation range up to the peak luminance of the display unit 3, an HDR image that accurately reproduces the PQ curve can be displayed.

[0021] 2 is a diagram showing an example of a PQ curve 20. As shown in FIG. 2, the PQ curve 20 has a maximum luminance of 10,000 cd / m in a predetermined gradation range (gradation value: 0 to 1,023). ２ It is a fixed curve in which the brightness up to is specified as an absolute value.

[0022] 3A is a diagram showing an example of a gradation characteristic curve 22 of the display unit 3 when the peak luminance value of the display unit 3 is 300. FIG. 3B is a diagram showing an example of a gradation characteristic curve 23 of the display unit 3 when the peak luminance value of the display unit 3 is 1000. FIG. 3C is a diagram showing an example of a gradation characteristic curve 24 of the display unit 3 when the peak luminance value of the display unit 3 is 4000. In FIGS. 3A, 3B, and 3C, the curve indicated by reference numeral 21 represents a maximum gradation of 10000 cd / m in a predetermined gradation range (gradation value: 0 to 1023). ２ It is a PQ curve in which the luminance up to 1 / 3 is specified as an absolute value. The peak luminance value of the display unit 3 is the output luminance value at the maximum output gradation value of the image display device 10. For example, the peak luminance value is the output luminance value that the image display device 10 can output when a specific area (e.g., a rectangular area) on an image is displayed at the maximum output gradation value.

[0023] As shown by gradation characteristic curve 22 in FIG. 3A , in the case of the PQ system, the same gamma curve (PQ curve) is always drawn up to the luminance that can be reproduced by display unit 3, and therefore, in the gradation range up to the peak luminance value (300) of display unit 3, an HDR image that accurately reproduces PQ curve 21 can be displayed on display unit 3. Similarly, as shown by gradation characteristic curve 23 in FIG. 3B , in the gradation range up to the peak luminance value (1000) of display unit 3, an HDR image that accurately reproduces PQ curve 21 can be displayed on display unit 3. Furthermore, as shown by gradation characteristic curve 24 in FIG. 3C , in the gradation range up to the peak luminance value (4000) of display unit 3, an HDR image that accurately reproduces PQ curve 21 can be displayed on display unit 3.

[0024] On the other hand, in the case of the HLG method, the brightness value of an HDR image is treated as a relative value (which varies depending on the display device), and the peak brightness value coincides with the maximum brightness value of the display device. In other words, because the gamma curve changes depending on the maximum brightness value on the display device side, HDR images can be displayed without significant image distortion even when displayed on a conventional SDR image display device (for example, a television).

[0025] The functional configuration of the image display device 10 will be described below.

[0026] The image acquisition unit 1 acquires HDR image data (input image data) from an input device (not shown), performs predetermined image processing on the acquired HDR image data to generate display image data, and outputs the generated display image data to the display control unit 2. The input device is, for example, an information processing device such as a personal computer, and is configured to be able to output various types of data such as image data including HDR image data.

[0027] The display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to cause the display unit 3 to display an image corresponding to the display image data.

[0028] The display unit 3 includes a display panel including a plurality of pixels arranged on a substrate, and an optical sensor 4, and, under the control of the display control unit 2, displays an image corresponding to the display image data output from the display control unit 2. The images displayed by the display unit 3 include still images and moving images. In this embodiment, each of the plurality of pixels includes a self-luminous element such as an organic light-emitting diode (OLED). In other words, the display unit 3 is a self-luminous display device (e.g., an OLED display, a MicroLED display) that does not require a backlight.

[0029] The optical sensor 4 measures (actually measures) the output luminance value (peak luminance value) that the display unit 3 can output when the display unit 3 displays an image at the maximum output gradation value (maximum output gradation value of the image display device 10), and outputs the measurement result to the luminance measurement unit 7 (luminance acquisition unit 5). The optical sensor 4 is provided in a frame-like portion that surrounds the display panel of the housing of the display unit 3. For example, the optical sensor 4 can be configured to move in and out from within the housing onto the display surface of the display panel in response to the operation of an actuator, a motor, or the like, and the luminance measurement unit 7 can move the optical sensor 4 onto the display surface to measure the output luminance value.

[0030] Furthermore, the optical sensor 4 may be configured to be detachably connected to the display unit 3 via a signal line or the like, and when measuring the output luminance value, the user may attach the optical sensor 4 to the display surface of the display panel and connect the signal line or the like to the display unit 3. Note that in this embodiment, the optical sensor 4 is configured to measure the output luminance value as a display characteristic value of the display unit 3, but this is not limiting, and the optical sensor 4 may be configured to measure other display characteristic values ​​such as chromaticity, for example.

[0031] Although it is ideal to provide the optical sensor 4 on the display surface of the display panel, the optical sensor 4 may be provided near the display panel other than the display surface, and the output luminance value on the display surface of the display panel may be estimated from the luminance measured by the optical sensor 4. The output luminance value on the display surface of the display panel may also be estimated from the drive amount of the display panel.

[0032] The luminance acquisition unit 5 includes a luminance prediction unit 6 and a luminance measurement unit 7, and acquires an output luminance value that the display unit 3 can output when the display unit 3 displays an image (HDR image) at the maximum output gradation value. Note that the output luminance value that the display unit 3 can output is a value that can change due to various factors (e.g., the passage of time), and the luminance acquisition unit 5 acquires the output luminance in accordance with changes in the output luminance value.

[0033] The luminance prediction unit 6 predicts an output luminance value that the display unit 3 can output when the display unit 3 displays an image (HDR image) at the maximum output gradation value at the first timing, thereby acquiring a first luminance value as the output luminance value. This allows the luminance prediction unit 6 to easily acquire the first luminance value without using the optical sensor 4. The luminance prediction unit 6 then outputs the acquired first luminance value to the gradation characteristic acquisition unit 8. Note that the luminance prediction unit 6 may also predict a luminance range centered on the output luminance value at the first timing. In this case, the luminance prediction unit 6 acquires, as the first luminance value, an average luminance value obtained by, for example, averaging the luminance values ​​included in the predicted luminance range.

[0034] Furthermore, at a second timing after the first timing, the luminance prediction unit 6 predicts an output luminance value that the display unit 3 can output when the display unit 3 displays an image (HDR image) at the maximum output gradation value and that has changed over time since the first timing, thereby acquiring a second luminance value as the output luminance value. The second timing is, for example, a timing when a predetermined time has elapsed since the first timing. This allows the luminance prediction unit 6 to easily acquire the second luminance value without using the optical sensor 4. The luminance prediction unit 6 then outputs the acquired second luminance value to the gradation characteristic acquisition unit 8. Note that the output luminance value that has changed over time since the first timing includes an output luminance value that has increased, decreased, or been maintained since the first timing. Furthermore, the luminance prediction unit 6 may predict a luminance range centered on the output luminance value at the second timing. In this case, the luminance prediction unit 6 acquires, as the second luminance value, an average luminance value obtained by, for example, averaging the luminance values ​​included in the predicted luminance range.

[0035] In this embodiment, the brightness prediction unit 6 predicts the output brightness value that the display unit 3 can output when displaying an image at the maximum output grayscale value, based on the degradation characteristic that the output brightness value (peak brightness value) at the maximum output grayscale value of the image display device 10 decreases as the light-emitting time of the self-luminous elements used as pixels of the display panel (specifically, the current (load current) flowing through the self-luminous elements and the cumulative amount of time the current flows) increases.

[0036] FIG. 4 is a diagram showing an example of a deterioration characteristic curve 30 of a self-luminous element. As shown in FIG. 4, the deterioration characteristic curve 30 is a curve that correlates the light-emitting time of the self-luminous element (the horizontal axis in FIG. 4) with the output luminance value (the vertical axis in FIG. 4) that the display unit 3 can output when displaying an image at the maximum output gradation value. The curve shows that as the light-emitting time of the self-luminous element increases, the output luminance value at the maximum output gradation value of the image display device 10 deteriorates (decreases). Here, the output luminance value is normalized, with the maximum output luminance value being 1 and the minimum output luminance value being 0. It can be seen that when the light-emitting time of the self-luminous element is short (e.g., as shown by range 31), the deterioration rate of the output luminance value is faster than when the light-emitting time of the self-luminous element is long (e.g., as shown by range 32).

[0037] The light-emitting time of the light-emitting elements, specifically the current (load current) flowing through the light-emitting elements and the cumulative time during which the current flows, differ for each light-emitting element, and the output luminance value is calculated for each light-emitting element. For example, in an OLED display (a self-luminous display device), although the degradation (decrease) of the output luminance value differs for each display area, burn-in correction is generally performed so that the degradation of the output luminance value does not differ for each display area. Therefore, by calculating the light-emitting time of the light-emitting elements for a portion of the display area of ​​the display screen, the output luminance value corresponding to the calculated light-emitting time can be determined as the output luminance value for the entire display screen.

[0038] The luminance measurement unit 7 acquires a third luminance value as the output luminance value by measuring an output luminance value that the display unit 3 can output when the display unit 3 displays an image (HDR image) at the maximum output gradation value at a third timing different from the first and second timings (prediction timings). In this embodiment, the luminance measurement unit 7 acquires the third luminance value by inputting the measurement result output from the optical sensor 4 at the third timing. This allows the luminance measurement unit 7 to acquire the third luminance value more easily and accurately without performing prediction calculation processing itself, compared to when predicting the output luminance value at the maximum output gradation value of the image display device 10. The luminance measurement unit 7 then outputs the acquired third luminance value to the gradation characteristic acquisition unit 8. In addition, the brightness measurement unit 7 may obtain the third brightness value as the output brightness value by measuring the output brightness value that the display unit 3 is capable of outputting at a third timing that is later than the first and second timings (predicted timings) when the display unit 3 displays an image (HDR image) at the maximum output gradation value, and by measuring the output brightness value that has changed over time since the predicted timing.

[0039] Furthermore, the luminance measurement unit 7 acquires a fourth luminance value as the output luminance value by measuring the output luminance value that the display unit 3 is capable of outputting when displaying an image (HDR image) at the maximum output gradation value at a fourth timing that is different from the first and second timings (prediction timings) and that is later than the third timing. The fourth timing is, for example, a timing a predetermined time has elapsed since the third timing. In this embodiment, the luminance measurement unit 7 acquires the fourth luminance value by inputting the measurement result output from the optical sensor 4 at the fourth timing. This allows the luminance measurement unit 7 to acquire the fourth luminance value more easily and accurately than when predicting an output luminance value, without having to perform a prediction calculation process on its own. The luminance measurement unit 7 then outputs the acquired third luminance value to the gradation characteristic acquisition unit 8.

[0040] The gradation characteristic acquisition unit 8 acquires first gradation characteristics that conform to gradation characteristics defined by absolute values ​​of luminance, based on the first luminance value output from the luminance prediction unit 6. For example, the gradation characteristic acquisition unit 8 references the storage unit 9 and acquires the first gradation characteristics based on gradation characteristic information (LUT: Look Up Table) that is the basis for the first gradation characteristics. The gradation characteristic acquisition unit 8 then outputs first gradation characteristic information indicating the acquired first gradation characteristics to the display control unit 2. In this embodiment, the gradation characteristics defined by absolute values ​​of luminance are gradation characteristics that satisfy the PQ curve standard. Note that the gradation characteristic acquisition unit 8 may acquire the first gradation characteristics by calculating the first gradation characteristics that conform to gradation characteristics defined by absolute values ​​of luminance, based on the first luminance value output from the luminance prediction unit 6.

[0041] The first gradation characteristic indicates the correspondence between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value based on the first luminance value output from the luminance prediction unit 6, and is a gradation characteristic for reproducing the PQ curve in the gradation range up to the first luminance value.

[0042] 5A is a diagram showing an example of gradation characteristic information (LUT) that is the basis of the first gradation characteristic (the same applies to the second, third, and fourth gradation characteristics below) when the first luminance value (the same applies to the second, third, and fourth luminance values ​​below) is 300. Here, the output gradation value (shown by curve 25) that the display unit 3 should output is normalized, with the maximum value of the output gradation value (maximum output gradation value) being 1 and the minimum value of the output gradation value being 0. If the output gradation is, for example, 8 bits, the maximum output gradation value is 255.

[0043] 5B is a diagram showing an example of gradation characteristic information (LUT) that is the basis of the first gradation characteristic (the same applies to the second, third, and fourth gradation characteristics below) when the first luminance value (the same applies to the second, third, and fourth luminance values ​​below) is 1000. Here, the output gradation value (shown by curve 26) that the display unit 3 should output is normalized, with the maximum value of the output gradation value (maximum output gradation value) being 1 and the minimum value of the output gradation value being 0. If the output gradation is, for example, 8 bits, the maximum output gradation value is 255.

[0044] 6A is a diagram showing an example of gradation characteristic information (LUT) that is the basis of the first gradation characteristic (the same applies to the second, third, and fourth gradation characteristics below) when the first luminance value (the same applies to the second, third, and fourth luminance values ​​below) is 4000. Here, the output gradation value (shown by curve 27) that the display unit 3 should output is normalized, with the maximum value of the output gradation value (maximum output gradation value) being 1 and the minimum value of the output gradation value being 0. If the output gradation is, for example, 8 bits, the maximum output gradation value is 255.

[0045] 6B is a diagram showing an example of gradation characteristic information (LUT) that is the basis of the first gradation characteristic (the same applies to the second, third, and fourth gradation characteristics below) when the first luminance value (the same applies to the second, third, and fourth luminance values ​​below) is 10000. Here, the output gradation value (shown by curve 28) that the display unit 3 should output is normalized, with the maximum value of the output gradation value (maximum output gradation value) being 1 and the minimum value of the output gradation value being 0. If the output gradation is, for example, 8 bits, the maximum output gradation value is 255.

[0046] The gradation characteristics defined by the absolute value of luminance may be gradation characteristics that satisfy the Grayscale Standard Display Function (GSDF) of the DICOM standard, instead of gradation characteristics that satisfy the PQ curve standard. In this case, the input gradation value of the image displayed on the display unit 3 is JND (Just-Noticeable Difference).

[0047] When first gradation characteristic information is output from the gradation characteristic acquisition unit 8, the display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data on the display unit 3 using the first gradation characteristic indicated by the first gradation characteristic information.

[0048] Furthermore, the gradation characteristic acquisition unit 8 acquires second gradation characteristics that conform to gradation characteristics defined by an absolute value of luminance, based on the second luminance value output from the luminance prediction unit 6. For example, the gradation characteristic acquisition unit 8 references the storage unit 9 and acquires the second gradation characteristics based on gradation characteristic information (LUT) that is the basis of the second gradation characteristics. The gradation characteristic acquisition unit 8 then outputs second gradation characteristic information indicating the acquired second gradation characteristics to the display control unit 2. Note that the gradation characteristic acquisition unit 8 may also acquire the second gradation characteristics by calculating the second gradation characteristics that conform to gradation characteristics defined by an absolute value of luminance, based on the second luminance value output from the luminance prediction unit 6.

[0049] The second gradation characteristic indicates the correspondence between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value based on the second luminance value output from the luminance prediction unit 6, and is a gradation characteristic for reproducing the PQ curve in the gradation range up to the second luminance value.

[0050] When second gradation characteristic information is output from the gradation characteristic acquisition unit 8, the display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data on the display unit 3 using the second gradation characteristic indicated by the second gradation characteristic information.

[0051] Furthermore, the gradation characteristic acquisition unit 8 acquires third gradation characteristics that conform to gradation characteristics defined by an absolute value of luminance, based on the third luminance value output from the luminance actual measurement unit 7. For example, the gradation characteristic acquisition unit 8 references the storage unit 9 and acquires the third gradation characteristics based on gradation characteristic information (LUT) that is the basis of the third gradation characteristic. The gradation characteristic acquisition unit 8 then outputs third gradation characteristic information indicating the acquired third gradation characteristic to the display control unit 2. Note that the gradation characteristic acquisition unit 8 may also acquire the third gradation characteristic by calculating the third gradation characteristic that conforms to gradation characteristics defined by an absolute value of luminance, based on the third luminance value output from the luminance prediction unit 6.

[0052] The third gradation characteristic indicates the correspondence between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value based on the third luminance value output from the luminance measurement unit 7, and is a gradation characteristic for reproducing the PQ curve in the gradation range up to the third luminance value.

[0053] When the third gradation characteristic information is output from the gradation characteristic acquisition unit 8, the display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data on the display unit 3 using the third gradation characteristic indicated by the third gradation characteristic information.

[0054] Furthermore, the gradation characteristic acquisition unit 8 acquires fourth gradation characteristics that conform to gradation characteristics defined by an absolute value of luminance, based on the fourth luminance value output from the luminance actual measurement unit 7. For example, the gradation characteristic acquisition unit 8 references the storage unit 9 and acquires the fourth gradation characteristics based on gradation characteristic information (LUT) that is the basis of the fourth gradation characteristic. The gradation characteristic acquisition unit 8 then outputs fourth gradation characteristic information indicating the acquired fourth gradation characteristic to the display control unit 2. Note that the gradation characteristic acquisition unit 8 may also acquire the fourth gradation characteristic by calculating the fourth gradation characteristic that conforms to gradation characteristics defined by an absolute value of luminance, based on the fourth luminance value output from the luminance prediction unit 6.

[0055] The fourth gradation characteristic indicates the correspondence between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value based on the fourth luminance value output from the luminance measurement unit 7, and is a gradation characteristic for reproducing the PQ curve in the gradation range up to the fourth luminance value.

[0056] When the fourth gradation characteristic information is output from the gradation characteristic acquisition unit 8, the display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data on the display unit 3 using the fourth gradation characteristic indicated by the fourth gradation characteristic information.

[0057] The storage unit 9 stores degradation characteristic information indicating the degradation characteristics of each pixel (self-luminous element) of a plurality of pixels included in the display panel of the display unit 3. The storage unit 9 also stores gradation characteristic information indicating the correspondence between the input gradation value of the image displayed by the display unit 3 and the output gradation value that should be output by the display unit 3 in accordance with the input gradation value, for each of a plurality of luminance values ​​(the above-mentioned first luminance value, second luminance value, third luminance value, and fourth luminance value) that can be output from the luminance prediction unit 6 and the luminance actual measurement unit 7.

[0058] A portion of the storage unit 9 is configured with, for example, a RAM (Random Access Memory) or a DRAM (Dynamic Random Access Memory), and is used as a work area when executing processes based on various programs. Another portion of the storage unit 9 is, for example, a non-volatile memory such as a ROM (Read Only Memory) or an HDD (Hard Disk Drive), and stores various data and programs used for various processes. The storage unit 9 can hold a database including one or more tables for recording various information, processing results, and the like.

[0059] The operation acceptance unit 11 is configured with, for example, a keyboard, a mouse, etc., and accepts input of various operations by the user. In this embodiment, the operation acceptance unit 11 accepts a setting operation for displaying an image corresponding to display image data on the display unit 3 in the PQ format or the HLG format. The operation acceptance unit 11 then outputs setting operation information indicating the content of the accepted setting operation (PQ format or HLG format) to the display control unit 2.

[0060] When the setting operation information output from the operation accepting unit 11 indicates that the PQ method is the content of the setting operation, the display control unit 2 outputs the display image data output from the image acquiring unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data in the PQ method on the display unit 3. Furthermore, when the setting operation information output from the operation accepting unit 11 indicates that the HLG method is the content of the setting operation, the display control unit 2 outputs the display image data output from the image acquiring unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data in the HLG method on the display unit 3.

[0061] FIG. 7 is a flowchart showing an example of image display processing (corresponding to the "image display method" of the present invention) performed by the image display device 10 in this embodiment.

[0062] First, the brightness acquisition unit 5 determines whether it is the predicted timing (the first timing or the second timing described above) at which the display unit 3 predicts the output brightness value that can be output when the display unit 3 displays an image (HDR image) at the maximum output gradation value (step S100).

[0063] If the result of the determination is that it is the prediction timing (step S100, YES), the luminance prediction unit 6 predicts the output luminance value that the display unit 3 can output when the display unit 3 displays an image with the maximum output gradation value, and thereby obtains the output luminance value (the above-mentioned first luminance value or second luminance value) (step S110).The luminance prediction unit 6 then outputs the obtained output luminance value to the gradation characteristic acquisition unit 8.

[0064] Next, the gradation characteristic acquisition unit 8 acquires gradation characteristics (the above-mentioned first gradation characteristics or second gradation characteristics) that conform to gradation characteristics defined by the absolute value of luminance based on the output luminance value output from the luminance prediction unit 6 (step S120).The gradation characteristic acquisition unit 8 then outputs gradation characteristic information (the above-mentioned first gradation characteristic information or second gradation characteristic information) that indicates the acquired gradation characteristics to the display control unit 2.

[0065] Finally, the display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data on the display unit 3 using the gradation characteristics indicated by the gradation characteristic information output from the gradation characteristic acquisition unit 8 (step S130). When the processing of step S130 is completed, the image display device 10 ends the image display processing shown in FIG.

[0066] Returning to the determination process of step S100, if it is not the predicted timing (step S100, NO), the luminance acquisition unit 5 determines whether it is the actual measurement timing (the third timing or the fourth timing described above) at which the display unit 3 actually measures the output luminance value that can be output when the display unit 3 displays an image at the maximum output gradation value (step S140). If the determination result is that it is not the actual measurement timing (step S140, NO), the image display device 10 ends the image display process shown in FIG.

[0067] On the other hand, if it is the measurement timing (step S140, YES), the luminance measurement unit 7 acquires the output luminance value (the above-mentioned third luminance value or fourth luminance value) by measuring the output luminance value that the display unit 3 can output when the display unit 3 displays an image at the maximum output gradation value (step S150).The luminance measurement unit 7 then outputs the acquired output luminance value to the gradation characteristic acquisition unit 8.

[0068] Next, the gradation characteristic acquisition unit 8 acquires gradation characteristics (the above-mentioned third gradation characteristic or fourth gradation characteristic) that conform to gradation characteristics defined by the absolute value of luminance based on the output luminance value output from the luminance actual measurement unit 7 (step S160). Then, the gradation characteristic acquisition unit 8 outputs gradation characteristic information (the above-mentioned third gradation characteristic information or fourth gradation characteristic information) that indicates the acquired gradation characteristics to the display control unit 2.

[0069] Finally, the display control unit 2 outputs the display image data output from the image acquisition unit 1 to the display unit 3 and controls the display unit 3 to display an image corresponding to the display image data on the display unit 3 using the gradation characteristics indicated by the gradation characteristic information output from the gradation characteristic acquisition unit 8 (step S170). When the processing of step S170 is completed, the image display device 10 ends the image display processing shown in FIG.

[0070] As described in detail above, in this embodiment, the image display device 10 includes the luminance acquisition unit 5, the gradation characteristic acquisition unit 8, and the display unit 3. The luminance acquisition unit 5 predicts an output luminance value at the maximum output gradation value of the image display device 10 at a first timing, thereby acquiring a first luminance value as the output luminance value. The gradation characteristic acquisition unit 8 acquires, as a gradation characteristic conforming to a gradation characteristic (PQ curve standard) defined by an absolute value of luminance, a first gradation characteristic indicating a correspondence relationship between an input gradation value of an image to be displayed by the display unit 3 and an output luminance value that the display unit 3 should output in accordance with the input gradation value, based on the first luminance value. The display unit 3 displays an image using the first gradation characteristic.

[0071] Furthermore, the luminance acquisition unit 5 acquires a second luminance value as the output luminance value by predicting, at a second timing after the first timing, an output luminance value at the maximum output luminance value of the image display device 10, which has changed over time since the first timing. The gradation characteristic acquisition unit 8 acquires a second luminance characteristic that indicates a correspondence between an input luminance value of an image to be displayed by the display unit 3 and, based on the second luminance value, an output luminance value that the display unit 3 should output in accordance with the input luminance value, as a gradation characteristic that conforms to a gradation characteristic (PQ curve standard) defined by an absolute value of luminance. The display unit 3 displays an image using the second gradation characteristic.

[0072] According to the present embodiment configured as described above, at the second timing, the second luminance value that has changed over time since the first timing is acquired, and instead of the first gradation characteristic, an image is displayed using the second gradation characteristic that indicates a correspondence relationship between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value, based on the second luminance value, as the gradation characteristic that complies with the gradation characteristic defined by the absolute value of luminance. Therefore, even at the second timing that is after the first timing, an HDR image can be displayed with the gradation characteristic that complies with the PQ method, that is, the gradation characteristic that is required to always depict the same gamma curve in the gradation range up to the output luminance value (peak luminance value) at the maximum output gradation value of the image display device 10, and ultimately an image can be displayed with the gradation characteristic that complies with the desired gradation characteristic.

[0073] For example, if a first luminance value (e.g., 1000) is acquired at a first timing, and a second luminance value (e.g., 800) that has changed over time since the first timing is acquired at a second timing, instead of the first luminance value based on the first luminance value, an image is displayed using second gradation characteristics that indicate a correspondence relationship between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value based on the second luminance value, as gradation characteristics that comply with gradation characteristics defined by the absolute value of luminance. Therefore, even at a second timing that is later than the first timing, an HDR image can be displayed using gradation characteristics that comply with the PQ method, i.e., gradation characteristics that are required to always depict the same gamma curve in a gradation range up to the output luminance value at the maximum output gradation value of the image display device 10 (peak luminance value, e.g., 800).

[0074] 8A is a diagram showing an example of gradation characteristic information (LUT) on which the first gradation characteristic is based when the first luminance value is 1000. Here, the output gradation value (shown by curve 33) to be output by the display unit 3 is normalized, with the maximum value of the output gradation value (maximum output gradation value) being 1 and the minimum value of the output gradation value being 0. FIG. 8B is a diagram showing an example of gradation characteristic information (LUT) on which the second gradation characteristic is based when the second luminance value is 800. Here, the output gradation value (shown by curve 34) to be output by the display unit 3 is normalized, with the maximum value of the output gradation value (maximum output gradation value) being 1 and the minimum value of the output gradation value being 0.

[0075] 9 is a diagram showing an example of a gradation characteristic curve 36 of the display unit 3 when the first luminance value at the maximum output gradation value of the image display device 10 is 1000, and an example of a gradation characteristic curve 37 of the display unit 3 when the second luminance value at the maximum output gradation value of the image display device 10 is 800. In FIG. 9, the curve indicated by reference numeral 35 shows a maximum gradation of 10000 cd / m in a predetermined gradation range (gradation value: 0 to 1023). ２ 9 , when the second luminance value at the maximum output gradation value of image display device 10 is 800, the gradation range in which an HDR image that accurately reproduces PQ curve 35 can be displayed on display unit 3 is smaller than when the first luminance value at the maximum output gradation value of image display device 10 is 1000.

[0076] Furthermore, in this embodiment, the luminance acquisition unit 5 acquires a third luminance value as the output luminance value by actually measuring the output luminance value at the maximum output luminance value of the image display device 10 at a third timing different from the first and second timings. The gradation characteristic acquisition unit 8 acquires a third luminance characteristic that indicates a correspondence between an input luminance value of an image to be displayed by the display unit 3 and an output luminance value that should be output by the display unit 3 in accordance with the input luminance value, based on the third luminance value, as a gradation characteristic that conforms to a gradation characteristic (PQ curve standard) defined by an absolute value of luminance. The display unit 3 displays an image using the third luminance characteristic.

[0077] Furthermore, the luminance acquisition unit 5 acquires a fourth luminance value as the output luminance value by actually measuring the output luminance value at the maximum output luminance value of the image display device 10 at a fourth timing that is different from the first and second timings and that comes after the third timing, the output luminance value having changed over time since the third timing. The gradation characteristic acquisition unit 8 acquires a fourth luminance characteristic that indicates a correspondence between an input luminance value of the image displayed by the display unit 3 and an output luminance value that the display unit 3 should output in accordance with the input luminance value, based on the fourth luminance value, as a gradation characteristic that conforms to a gradation characteristic (PQ curve standard) defined by an absolute value of luminance. The display unit 3 displays an image using the fourth luminance characteristic.

[0078] According to the present embodiment configured as described above, at the fourth timing, a fourth luminance value that has changed over time since the third timing is acquired, and instead of the third gradation characteristic, an image is displayed using the fourth gradation characteristic that indicates a correspondence relationship between the input gradation value of the image displayed by the display unit 3 and the output luminance value that the display unit 3 should output in accordance with the input gradation value based on the fourth luminance value, as a gradation characteristic that complies with the gradation characteristic defined by the absolute value of luminance. Therefore, even at the fourth timing that is after the third timing, an HDR image can be displayed with gradation characteristics that comply with the PQ method, i.e., gradation characteristics that are required to always depict the same gamma curve in the gradation range up to the output luminance value (peak luminance value) at the maximum output gradation value of the image display device 10, and ultimately an image can be displayed with gradation characteristics that comply with the desired gradation characteristics.

[0079] In the above embodiment, the luminance acquisition unit 5 both predicts and measures the output luminance value at the maximum output gradation value of the image display device 10. However, the timing of the prediction and measurement may be set arbitrarily. For example, the luminance acquisition unit 5 may predict the output luminance value at the maximum output gradation value of the image display device 10 more closely than the actual measurement. FIG. 10 is a diagram showing an example of the timing of prediction and measurement of the output luminance value by the luminance acquisition unit 5. As shown in FIG. 10, the luminance acquisition unit 5 predicts the output luminance value at times T1, T2, T4, T5, and T7, and actually measures the output luminance value at times T3 and T6. That is, in the example shown in FIG. 10, the luminance acquisition unit 5 predicts the output luminance value twice, and then actually measures the output luminance value once.

[0080] Furthermore, in the above embodiment, the brightness acquisition unit 5 may perform only either prediction or actual measurement of the output brightness value that the display unit 3 can output, rather than performing both prediction and actual measurement of the output brightness value at the maximum output gradation value of the image display device 10.

[0081] Furthermore, in the above embodiment, when an image is displayed on the display unit 3 using gradation characteristics that comply with gradation characteristics defined by an absolute value of luminance, the luminance acquisition unit 5 may acquire the output luminance value at a frequency equal to or greater than that when an image is displayed on the display unit 3 using gradation characteristics that comply with gradation characteristics defined by a relative value of luminance (for example, the HLG curve standard). This is because when an image is displayed using gradation characteristics that comply with gradation characteristics defined by an absolute value of luminance, there is a greater need to switch the gradation characteristics that the display unit 3 uses to display an image due to a decrease in the output luminance value at the maximum output gradation value of the image display device 10, compared to when an image is displayed using gradation characteristics that comply with gradation characteristics defined by a relative value of luminance.

[0082] Furthermore, in the above embodiment, the luminance acquisition unit 5 may decrease the frequency of acquiring the output luminance value at the maximum output gradation value of the image display device 10 as the display time of the image by the display unit 3 becomes longer (i.e., as the deterioration rate of the self-luminous elements becomes slower), because as the deterioration rate of the self-luminous elements becomes slower, there is less need to switch the gradation characteristics used by the display unit 3 when displaying an image due to a decrease in the output luminance value at the maximum output gradation value of the image display device 10.

[0083] In the above embodiment, the display unit 3 is a self-luminous display device that does not require a backlight, but the present invention is not limited to this. For example, the display unit 3 may be a display device that requires a backlight (e.g., a liquid crystal display device).

[0084] Various embodiments of the present invention have been described above, but these are presented as examples and are not intended to limit the scope of the invention. The novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. Such embodiments and modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0085] 1: image acquisition unit, 2: display control unit, 3: display unit, 4: optical sensor, 5: luminance acquisition unit, 6: luminance prediction unit, 7: luminance actual measurement unit, 8: gradation characteristic acquisition unit, 9: memory unit, 10: image display device, 11: operation reception unit, 20, 21, 35: PQ curve, 22, 23, 24, 36, 37: gradation characteristic curve, 25, 26, 27, 28, 33, 34: curve, 30: deterioration characteristic curve, 31, 32: range

Claims

1. An image display device including a luminance acquisition unit, a gradation characteristic acquisition unit, and a display unit, wherein: The luminance acquisition unit acquires, at a first timing, a first luminance value as the output luminance value by predicting the output luminance value at the maximum output gradation value of the image display device; The gradation characteristic acquisition unit acquires, as a gradation characteristic conforming to the gradation characteristic defined by the absolute value of luminance, a first gradation characteristic indicating a correspondence relationship between the input gradation value of the image displayed by the display unit and the output luminance value that the display unit should output according to the input gradation value, based on the input gradation value and the first luminance value; The display unit displays an image using the first gradation characteristic; The luminance acquisition unit acquires, at a second timing after the first timing, a second luminance value as the output luminance value by predicting the output luminance value at the maximum output gradation value of the image display device, which is the output luminance value that has changed over time since the first timing; The gradation characteristic acquisition unit acquires, as a gradation characteristic conforming to the gradation characteristic defined by the absolute value of luminance, a second gradation characteristic indicating a correspondence relationship between the input gradation value of the image displayed by the display unit and the output luminance value that the display unit should output according to the input gradation value, based on the input gradation value and the second luminance value; The display unit displays an image using the second gradation characteristic. An image display device.

2. The image display device according to claim 1, wherein The gradation characteristic defined by the absolute value of luminance is a gradation characteristic that satisfies the PQ curve standard. An image display device.

3. The image display device according to claim 1, wherein The gradation characteristic defined by the absolute value of luminance is a gradation characteristic that satisfies the grayscale standard display function (GSDF) of the DICOM standard. An image display device.

4. An image display device according to any one of claims 1 to 3, wherein the luminance acquisition unit acquires a third luminance value as the output luminance value by actually measuring the output luminance value at the maximum output gradation value of the image display device at a third timing different from the first and second timings; the gradation characteristic acquisition unit acquires a third gradation characteristic indicating a correspondence relationship between an input gradation value of an image displayed by the display unit and an output luminance value that the display unit should output according to the input gradation value, based on the input gradation value and the third luminance value, as a gradation characteristic conforming to a gradation characteristic defined by an absolute value of luminance; and the display unit displays an image using the third gradation characteristic. Image display device.

5. An image display device according to any one of claims 1 to 3, wherein the luminance acquisition unit acquires the output luminance value with a frequency equal to or higher than that when an image is displayed using a gradation characteristic conforming to a gradation characteristic defined by a relative value of luminance when the image is displayed using a gradation characteristic conforming to a gradation characteristic defined by an absolute value of luminance. Image display device.

6. An image display device according to any one of claims 1 to 3, wherein the luminance acquisition unit decreases the acquisition frequency of the output luminance value as the display time of an image by the display unit becomes longer. Image display device.

7. An image display device according to any one of claims 1 to 3, wherein the display unit is a self-emitting display device. Image display device.

8. An image display method having a luminance acquisition step, a gradation characteristic acquisition step, and a display step, wherein in the luminance acquisition step, at a first timing, a first luminance value as the output luminance value is acquired by predicting the output luminance value at the maximum output gradation value of the image display device, in the gradation characteristic acquisition step, as a gradation characteristic conforming to the gradation characteristic defined by the absolute value of luminance, a first gradation characteristic indicating the correspondence between the input gradation value of the image to be displayed in the display step and the output luminance value to be output in the display step according to the input gradation value based on the first luminance value is acquired, in the display step, an image is displayed using the first gradation characteristic, in the luminance acquisition step, at a second timing after the first timing, a second luminance value as the output luminance value is acquired by predicting the output luminance value at the maximum output gradation value of the image display device, which is the output luminance value that has changed over time since the first timing, in the gradation characteristic acquisition step, as a gradation characteristic conforming to the gradation characteristic defined by the absolute value of luminance, a second gradation characteristic indicating the correspondence between the input gradation value of the image to be displayed in the display step and the output luminance value to be output in the display step according to the input gradation value based on the second luminance value is acquired, in the display step, an image is displayed using the second gradation characteristic, Image display method.

9. An image display program for causing a processor to execute the image display method according to claim 8.

Images