WO2018131357A1

WO2018131357A1 - Display device and display method

Info

Publication number: WO2018131357A1
Application number: PCT/JP2017/044314
Authority: WO
Inventors: 浩平稲村
Original assignee: キヤノン株式会社
Priority date: 2017-01-16
Filing date: 2017-12-11
Publication date: 2018-07-19

Abstract

A display device according to the present invention comprises a setting means for establishing gradation conversion characteristics for input image data, a correction means for correcting the input image data in accordance with the established gradation conversion characteristics to thereby generate corrected image data, and a display means for causing a light-emitting part to emit light at an emission luminance based on the generated corrected image data to thereby display an image based on the corrected image data. The setting means acquires a power association value associated with the power consumption of the display device on the basis of the input image data and the established first gradation conversion characteristics. When the acquired power association value is greater than a power threshold, the setting means changes the established characteristics to second gradation conversion characteristics that reduce a gradation value greater than a gradation threshold for the input image data compared to the other cases.

Description

Display device and display method

The present invention relates to a display device and a display method.

In recent years, display devices with a wide dynamic range of display brightness (screen brightness) have been developed. The wide dynamic range is called “HDR (High Dynamic Range)”. Hereinafter, a display device having a wide dynamic range of display luminance is referred to as an “HDR display device”. The HDR display device can perform display with very high display luminance. However, in the case where display with very high display luminance is performed on the entire screen, very high power consumption is required as the power consumption of the HDR display device.

An ABL (Auto Brightness Limiter) function is known as a function for reducing power consumption of a display device. In the ABL function, when the APL (Average Picture Level) of the image data is high, the display brightness is reduced over the entire screen. Patent Document 1 discloses an ABL function that limits power consumption within a predetermined range.

JP 2002-32052 A

However, as a standard for image data having HDR, there is a standard in which display luminance is defined, and there is a case where display that faithfully reproduces the specified display luminance is desired. When the ABL function is used, the display brightness is reduced over the entire screen, and display with a suitable display brightness such as the specified display brightness cannot be maintained.

It is an object of the present invention to provide a technique that makes it possible to reduce power consumption of a display device while maintaining display at a suitable display luminance.

The first aspect of the present invention is:
Setting means for setting gradation conversion characteristics for input image data;
Correction means for performing correction processing on the input image data in accordance with the set gradation conversion characteristics and generating corrected image data;
Display means for causing a light emitting unit to emit light at a light emission luminance based on the generated corrected image data and displaying an image based on the corrected image data;
With
The setting means acquires a power related value that is a value related to power consumption of the display device based on the input image data and the set first gradation conversion characteristic, and the acquired power related value is The display is characterized in that the setting is changed to the second gradation conversion characteristic that reduces the gradation value larger than the gradation threshold value of the input image data when it is larger than the power threshold value compared with the case where it is not. Device.

The second aspect of the present invention is:
A setting step for setting gradation conversion characteristics for the input image data;
A correction step for performing correction processing on the input image data according to the set gradation conversion characteristics and generating corrected image data;
Displaying the image based on the corrected image data by causing the light emitting unit to emit light at a light emission luminance based on the generated corrected image data;
Have
In the setting step, a power related value that is a value related to power consumption of the display device is acquired based on the input image data and the set first gradation conversion characteristic, and the acquired power related value is The display is characterized in that the setting is changed to the second gradation conversion characteristic that reduces the gradation value larger than the gradation threshold value of the input image data when it is larger than the power threshold value compared with the case where it is not. Is the method.

A third aspect of the present invention is a program for causing a computer to execute each step of the display method described above.

According to the present invention, it is possible to reduce the power consumption of the display device while maintaining display at a suitable display luminance.

1 is a block diagram illustrating a configuration example of a display device according to a first embodiment. 6 is a flowchart illustrating an operation example of the display device according to the first embodiment. FIG. 6 is a diagram illustrating an example of a luminance relationship according to the first embodiment. FIG. 9 is a block diagram illustrating a configuration example of a display device according to the second embodiment. 10 is a flowchart illustrating an operation example of the display device according to the second embodiment. FIG. 10 is a diagram illustrating an example of a luminance histogram according to the second embodiment. The figure which shows an example of the various parameters which concern on Example 2. FIG. 9 is a block diagram illustrating a configuration example of a display device according to a third embodiment. FIG. 9 is a block diagram illustrating a configuration example of a display device according to a fourth embodiment. The figure which shows an example of the luminance relationship which concerns on Example 4. FIG. The figure which shows an example of the graphic image which concerns on Example 4. FIG.

<Example 1>
Embodiment 1 of the present invention will be described below. In this embodiment, an example of a transmissive liquid crystal display device will be described. The display device according to the present embodiment is not limited to a transmissive liquid crystal display device. For example, another display device having a light emitting unit and a display panel (modulation panel) that displays an image on a screen by modulating (transmitting) light emitted from the light emitting unit may be used. Specifically, a MEMS shutter-type display device having a MEMS (Micro Electro Mechanical System) shutter, a projector, or the like may be used as the display element. A self-luminous display device such as an organic EL (Electro Luminescence) display device or a plasma display device may be used.

In this embodiment, an example in which the light emitting unit (backlight unit) has a plurality of light source units will be described. In this embodiment, the light emission luminance of each light source unit is individually controlled. Such control is called “local deming control”. By performing local dimming control, the contrast of the display image (image displayed on the screen) can be improved.

FIG. 1 is a block diagram illustrating a configuration example of a display device according to the present embodiment.

The luminance relationship setting unit (conversion characteristic setting unit) 1 sets a luminance relationship (gradation conversion characteristic) that is a correspondence relationship between the data luminance of the input image data and the display luminance of the display device for the first correction unit 2. To do. The data brightness of the input image data is, for example, “display brightness defined by the standard of the input image data”, “brightness assumed in the input image data”, “brightness represented by the input image data”, “input image data” It can also be said that “the gradation value”. The display brightness is the screen brightness. It can also be said that the luminance relationship setting unit 1 sets a gradation conversion characteristic representing a correspondence relationship between the input gradation value and the output gradation value of the correction processing by the first correction unit 2.

In the present embodiment, the luminance relationship setting unit 1 is based on input image data and a candidate relationship (gradation conversion characteristic candidate) that is a candidate for a luminance relationship (gradation conversion characteristic) used in the first correction unit 2. Then, a power related value that is a value related to the power consumption of the display device when the candidate relationship is used as the luminance relationship is acquired. In the present embodiment, the backlight unit 5 emits light with the light emission luminance based on the input image data and the luminance relationship. In this case, a value based on the light emission luminance of the backlight unit 5 can be used as the power-related value. Specifically, each of the plurality of light source units included in the backlight unit 5 emits light with individual light emission luminance based on the input image data and the luminance relationship. In this case, values based on a plurality of light emission luminances respectively corresponding to the plurality of light source units can be used as the power-related values. In the present embodiment, the luminance relationship setting unit 1 acquires a value based on the total luminance of a plurality of light emission luminances as a power related value.

Note that values based on other light emission luminances such as the average luminance of a plurality of light emission luminances respectively corresponding to a plurality of light source units may be acquired as power-related values. The number of light source units, the arrangement of the light source units, and the like are not particularly limited. For example, the plurality of light source units may be arranged in a matrix or in a staggered pattern. The backlight unit 5 may have one light source unit. In that case, a value based on the light emission luminance of the light source unit can be used as the power-related value.

When the power consumption corresponding to the first candidate relationship (first gradation conversion characteristic candidate) is larger than the power threshold, the luminance relationship setting unit 1 sets the second power relationship based on the acquired power related value. A candidate relationship (second gradation conversion characteristic candidate) is determined. In the second candidate relationship, the correspondence relationship in the range of the data luminance (data luminance of the input image data) whose power consumption is equal to or less than the power threshold and equal to or less than the luminance threshold (gradation threshold) is substantially the same as the first candidate relationship. This is a candidate relationship. “Power consumption corresponding to candidate relationship (gradation conversion characteristic candidate)” is “candidate relationship (gradation conversion characteristic candidate) is used as a luminance relationship (gradation conversion characteristic) of correction processing by the first correction unit 2. It can be said that the power consumption of the display device in the case. “Substantially identical” includes “completely identical”.

In the present embodiment, when the power consumption corresponding to the first candidate relationship is equal to or less than the power threshold, the luminance relationship setting unit 1 sets the first candidate relationship as the luminance relationship used by the first correction unit 2. . When the power consumption corresponding to the first candidate relationship is larger than the power threshold, the luminance relationship setting unit 1 sets the second candidate relationship as the luminance relationship used by the first correction unit 2. Specifically, when the power consumption corresponding to the first candidate relationship is equal to or less than the power threshold, the luminance relationship setting unit 1 outputs a correction value that does not correct the first candidate relationship to the first correction unit 2. To do. When the power consumption corresponding to the first candidate relationship is larger than the power threshold, the luminance relationship setting unit 1 sets a correction value for correcting the first candidate relationship to the second candidate relationship as the first correction unit. Output to 2. Note that other information (table, function, etc.) indicating the candidate relationship used as the luminance relationship may be output to the first correction unit 2.

Note that the luminance relationship (gradation conversion characteristics) and the correction value used in the luminance relationship setting unit 1 may be for the luminance signal of the image data, or the R (red) signal / G (green) of the image data. For each of the signal and B (blue) signal. The luminance relationship setting unit 1 may be configured to store a plurality of LUTs (Look Up Tables) corresponding to a plurality of candidate relationships (gradation conversion characteristic candidates) in advance and select a LUT to be used. Further, the luminance relationship setting unit 1 may be configured to store a function corresponding to the luminance relationship (gradation conversion characteristics) in advance and appropriately change a coefficient used in the function.

The first correction unit 2, the feature amount acquisition unit 3, the BL control value determination unit 4, the backlight unit 5, the second correction unit 6, and the liquid crystal panel 7 allow an image to be displayed on the screen based on the input image data and the luminance relationship. Is displayed.

The first correction unit 2 generates corrected image data by correcting the input image data in accordance with the luminance relationship set by the luminance relationship setting unit 1. Specifically, the first correction unit 2 corrects the input image data so that display according to the luminance relationship is performed. In the present embodiment, the first correction unit 2 corrects the input image data based on the correction value output from the luminance relationship setting unit 1 and the first candidate relationship. The correction performed by the first correction unit 2 is, for example, gamma correction. It can be said that the first correction unit 2 converts the gradation value of the pixel according to the set luminance relationship (gradation conversion characteristic) for each of the plurality of pixels (all pixels) included in the input image data. .

The feature amount acquisition unit 3 acquires the feature amount of the corrected image data generated by the first correction unit 2 for each of the plurality of light source units included in the backlight unit 5. In the present embodiment, each of the plurality of light source units is associated with at least a partial area (corresponding area) of the screen. Specifically, the plurality of light source units are respectively associated with a plurality of divided areas constituting the entire screen area. And the feature-value acquisition part 3 acquires the feature-value of the correction | amendment image data in the division area (corresponding area | region) corresponding to the light source part about each of several light source parts. In this embodiment, the maximum value of a plurality of pixel values (gradation values) in the divided area is acquired as the feature amount.

Note that the arrangement of the corresponding areas, the number of corresponding areas, the shape of the corresponding areas, etc. are not particularly limited. For example, the plurality of corresponding regions may be arranged in a matrix or in a staggered pattern. The arrangement of the corresponding area may be the same as or different from the arrangement of the light source units. The corresponding area may not be a divided area. The corresponding area may be separated from other corresponding areas, or at least a part of the corresponding area may overlap with at least a part of the other corresponding area. The correspondence relationship between the corresponding region and the light source unit may not be a one-to-one correspondence relationship. For example, two or more light source units may be associated with one partial region. The area of the entire screen may be associated with one light source unit. The shape of the corresponding region may be a quadrangle, a triangle, a pentagon, a circle, or the like.

Note that the feature amount is not limited to the maximum pixel value. For example, other representative values (average value, minimum value, intermediate value, mode value, etc.) of pixel values, pixel value histograms, representative values of luminance values, histograms of luminance values, etc. are acquired as feature quantities. Also good.

The BL control value determination unit 4 determines the BL control value for each of the plurality of light source units according to the feature amount acquired by the feature amount acquisition unit 3. The BL control value is a control value corresponding to the light emission luminance of the light source unit. For example, the BL control value determination unit 4 sets the light emission luminance of the light source unit corresponding to the divided region where the bright image is displayed to be higher than the light emission luminance of the light source unit corresponding to the divided region where the dark image is displayed. The BL control value of each light source unit is determined so as to be controlled. The correspondence relationship between the BL control value and the light emission luminance is not particularly limited, but in this embodiment, the higher the light emission luminance, the larger the BL control value.

The backlight unit 5 has a plurality of light source units. Each of the plurality of light source units has one or more light emitting elements. For example, a light emitting diode, an organic EL element, a plasma element, a laser light source, or the like is used as the light emitting element. Each of the plurality of light source units emits light according to the BL control value determined by the BL control value determination unit 4. Specifically, each of the plurality of light source units emits light with light emission luminance corresponding to the BL control value.

The second correction unit 6 generates display image data by correcting the corrected image data based on each BL control value determined by the BL control value determination unit 4. In the present embodiment, the second correction unit 6 corrects the corrected image data so that a change in display luminance due to a change in the emission luminance of each light source unit from a predetermined reference luminance is suppressed. For example, the second correction unit 6 reduces the pixel value of the corrected image data (compression processing) for a region where the light emission luminance of the light source unit is increased from a predetermined reference luminance, and the light emission luminance of the light source unit is changed from the predetermined reference luminance. For the area to be reduced, the pixel value of the corrected image data is increased (decompression process). By correcting the pixel value of the corrected image data in this way according to the change in the light emission luminance of the light source unit, the gradation to be displayed can be correctly displayed.

The liquid crystal panel 7 displays an image on the screen by transmitting the light emitted from the backlight unit 5 according to the display image data generated by the second correction unit 6. In the present embodiment, the liquid crystal panel 7 includes a liquid crystal driver, a control substrate, and a plurality of liquid crystal elements. The control board controls the processing of the liquid crystal driver according to the display image data. The liquid crystal driver drives each liquid crystal element in accordance with an instruction from the control board. Thereby, the transmittance (aperture ratio; modulation factor) of each liquid crystal element is controlled to a value corresponding to the display image data. The light emitted from the backlight unit 5 passes through each liquid crystal element, whereby an image is displayed on the screen.

Next, an operation example of the display device according to the present embodiment will be described with reference to the flowchart of FIG.

First, in S201, the luminance relationship setting unit 1 sets the first candidate relationship as the luminance relationship. Specifically, the luminance relationship setting unit 1 sets the correction value CG = 0.

Next, in S202, the first correction unit 2 corrects the input image data according to the luminance relationship set by the luminance relationship setting unit 1, thereby generating corrected image data. Specifically, the first correction unit 2 corrects each pixel value of the input image data using the following equations 1-1 and 1-2. In the expressions 1-1 and 1-2, “Lin” is the data luminance of the input image data. “Lout” is the data luminance of the corrected image data, and is the display luminance corresponding to the luminance relationship. “Lmax” is the upper limit of the data luminance of the input image data.

When Lin ≦ Lmax−CG:
Lout = Lin (Formula 1-1)
For Lin> Lmax-CG:
Lout = Lmax−CG (Formula 1-2)

According to Equations 1-1 and 1-2, the data luminance Lin below Lmax-CG is not converted. In other words, the data luminance Lin below Lmax−CG is converted into a data luminance Lout equal to the data luminance Lin. Then, the data luminance Lin higher than Lmax-CG is converted into a data luminance Lout equal to Lmax-CG.

When the correction value CG = 0, the data luminance (input value) Lin is converted into the data luminance (output value) Lout according to the conversion characteristic (first candidate relationship) of FIG. In the conversion characteristic of FIG. 3A, the data luminance Lout is substantially equal to the data luminance Lin corresponding to the data luminance Lout. “Substantially equal” includes “perfectly equal”. In the conversion characteristic of FIG. 3A, the data luminance Lout is completely equal to the data luminance Lin corresponding to the data luminance Lout. Therefore, “correction value CG = 0” can also be said to be “correction value CG without correcting the first candidate relationship”.

When the correction value CG> 0, the data luminance Lin is converted into the data luminance Lout according to the conversion characteristic of FIG. In the conversion characteristic of FIG. 3B, the conversion characteristic in the range of the data luminance Lin below Lmax-CG is completely the same (substantially the same) as the conversion characteristic of FIG. Therefore, it can be said that “Lmax-CG” is the above-described “luminance threshold (tone threshold)”. Also, a conversion process (clip process) for clipping the output value Lout to a constant value Lmax-CG is performed on the range of the data luminance Lin that is greater than Lmax-CG. In the conversion characteristic of FIG. 3B, the output value Lout in the range (gradation range) of the data luminance Lin larger than Lmax-CG is reduced to a value (gradation value) lower than the conversion characteristic of FIG. ing.

Note that the first candidate relationship is not limited to the conversion characteristics shown in FIG. For example, in the first candidate relationship, the display brightness (data brightness Lout) may be different from the data brightness Lin corresponding to the display brightness. As the first candidate relation, other candidate relations for realizing display at a suitable display brightness regardless of the data brightness Lin may be used. Further, when the correction value CG> 0, the correspondence relationship (conversion characteristics) in the range of the data luminance Lin below Lmax−CG is not completely the same as the first candidate relationship (conversion characteristics in FIG. 3A). May be.

In S203, the luminance relationship setting unit 1 acquires the feature amount of the corrected image data generated in S202 for each of the plurality of light source units. In the present embodiment, the luminance relationship setting unit 1 has a feature amount acquisition function for executing processing similar to the processing of the feature amount acquisition unit 3. The process of S203 is realized by the feature amount acquisition function of the luminance relationship setting unit 1. Note that the process executed by the feature amount acquisition function of the luminance relationship setting unit 1 may or may not be completely the same as the process of the feature amount acquisition unit 3. For example, a process that simplifies the process of the feature quantity acquisition unit 3 may be executed by the feature quantity acquisition function of the luminance relationship setting unit 1. In this embodiment, when the correction value CG = 0, the corrected image data is equal to the input image data. Therefore, when the correction value CG = 0, the luminance relationship setting unit 1 may acquire the feature amount from the input image data.

Next, in S204, the luminance relationship setting unit 1 determines a BL control value for each of the plurality of light source units according to the feature amount acquired in S203. In the present embodiment, the luminance relationship setting unit 1 has a control value determination function for executing the same processing as that of the BL control value determination unit 4. The process of S204 is realized by the control value determination function of the luminance relationship setting unit 1. Note that the process executed by the control value determination function of the luminance relationship setting unit 1 may or may not be completely equal to the process of the BL control value determination unit 4. For example, a process that simplifies the process of the BL control value determination unit 4 may be executed by the control value determination function of the luminance relationship setting unit 1.

In S205, the luminance relationship setting unit 1 acquires a power-related value based on the plurality of BL control values determined in S204. Specifically, the luminance relationship setting unit 1 calculates the sum of a plurality of BL control values as a power related value.

Next, in S206, the luminance relationship setting unit 1 determines whether or not the power consumption of the display device is greater than the power threshold based on the power-related value calculated in S205. In the present embodiment, when the power-related value calculated in S205 is larger than the threshold value Wth, the luminance relationship setting unit 1 determines that the power consumption of the display device is larger than the power threshold value. When the power related value calculated in S205 is equal to or less than the threshold value Wth, the luminance relationship setting unit 1 determines that the power consumption of the display device does not become larger than the power threshold value.

If it is determined that the power consumption of the display device is not greater than the power threshold value, this flowchart is terminated. If it is determined that the power consumption of the display device is greater than the power threshold, the process proceeds to S207.

In S207, the luminance relationship setting unit 1 sets the luminance relationship to the second candidate relationship in which the correspondence relationship in the range of the data luminance Lin that is equal to or lower than the luminance threshold (less than the gradation threshold) is substantially the same as the first candidate relationship. Update. Specifically, the luminance relationship setting unit 1 updates the correction value CG by adding the offset value ΔCG to the correction value CG. Then, the process returns to S202. As a result, the conversion characteristic as shown in FIG. 3B is used in S202, and the power-related value corresponding to the second candidate relationship is acquired in S205. Then, the processes of S202 to S207 are repeated until it is determined that the power consumption of the display device does not exceed the power threshold. The “power-related value corresponding to the candidate relationship (gradation conversion characteristic candidate)” is the “candidate relationship (gradation conversion characteristic candidate) used as the luminance relationship (gradation conversion characteristic) of correction processing by the first correction unit 2. It can also be said to be a value relating to power consumption of the display device in the case of “The process of adding the offset value ΔCG to the correction value CG” can be said to be “a process of reducing the luminance threshold (tone threshold)”.

According to the flowchart of FIG. 2, when the power consumption corresponding to the first candidate relationship is equal to or less than the power threshold, the process proceeds to S207 and the display is performed using the first candidate relationship as the luminance relationship. Done. If the power consumption corresponding to the first candidate relationship is larger than the power threshold, the process proceeds to S207, the second candidate relationship is determined, and the display is performed using the second candidate relationship as the luminance relationship. Is called.

Specifically, when a power-related value equal to or lower than the threshold value Wth is acquired as the power-related value corresponding to the second candidate relationship determined first, the second candidate relationship is determined as the first correction unit 2. It is determined as the luminance relationship used in. The “power-related value below the threshold Wth” can be said to be “the power-related value related to power consumption below the power threshold”. When a power-related value larger than the threshold value Wth is acquired as a power-related value corresponding to the second candidate relationship determined first, the luminance threshold value is set so that a power-related value equal to or lower than the threshold value Wth is acquired. Further, the updated second candidate relationship is updated. Specifically, the process of updating the second candidate relationship is repeated so that the luminance threshold is reduced until a power-related value equal to or lower than the threshold Wth is acquired. It can be said that “a power-related value larger than the threshold value Wth” is “a power-related value related to power consumption larger than the power threshold value”.

In this embodiment, until the second candidate relationship in which the power-related value less than or equal to the threshold value Wth is acquired is determined, the subsequent stage of the first correction unit 2 (the feature amount acquisition unit 3 and the second correction unit 6). ) Is not output. Thereby, it is possible to perform display with power consumption equal to or lower than the power threshold. However, if display with power consumption equal to or greater than the power threshold is temporarily allowed, output to the subsequent stage may be performed when the second candidate relationship is updated. In this case, the flowchart of FIG. 2 is not applied to a single input image, but is applied to a plurality of temporally continuous input images. When the process proceeds from S207 to S202, the generation of the corrected image in S202 is applied to an input image that is later in time. In this case, without acquiring the feature amount and determining the BL control value in the luminance relationship setting unit 1, the feature amount is acquired from the subsequent feature amount acquisition unit 3, and the BL control value is determined from the BL control value determination unit 4. May be obtained. That is, the luminance relationship setting unit 1 may be configured not to have a feature amount acquisition function and a control value determination function.

As described above, according to this embodiment, the second candidate relationship is determined when the power consumption corresponding to the first candidate relationship is larger than the power threshold. As a result, it is possible to reduce the power consumption of the display device below the power threshold while maintaining display at a suitable display luminance. Specifically, in the second candidate relationship, the correspondence relationship in the range of the data luminance Lin that is equal to or lower than the luminance threshold is substantially the same as the first candidate relationship. Therefore, not only can the power consumption be reduced by using the second candidate relationship, but also the display luminance that is substantially the same as when the first candidate relationship is used in an area where the data luminance Lin is less than or equal to the luminance threshold. Display with can be realized. For example, in a region where the data luminance Lin is less than or equal to the luminance threshold, it is possible to realize a display that faithfully reproduces the display luminance defined by the input image data standard.

Note that the offset value ΔCG may or may not be a fixed value. For example, the offset value ΔCG may be changed according to the difference between the power-related value and the threshold value Wth. Specifically, the larger the difference between the power-related value and the threshold value Wth, the larger the offset value ΔCG is set, so that the power consumption of the display device is less than or equal to the power threshold value by performing the processing of S202 to S207 only once. You may make it reduce to. Further, the offset value ΔCG may be changed according to a user operation on the display device. The offset value ΔCG may be determined so that the second correction relationship is determined only by performing the process of S207 once. In such a case, the luminance relationship setting unit 1 may acquire the feature amount from the input image data instead of from the corrected image data generated by the first correction unit 2.

Note that, according to the present embodiment, the second candidate relationship is determined by determining the smaller luminance threshold as the power consumption corresponding to the first candidate relationship is larger. However, the method for determining the second candidate relationship is not limited to the above method. For example, the second candidate is determined by determining the smaller inclination as the power consumption corresponding to the first candidate relationship is larger as the inclination of the display luminance change with respect to the change in the data luminance Lin that is greater than or equal to the luminance threshold (more than the gradation threshold). A relationship may be determined. The second candidate relationship may be determined by determining both the brightness threshold value and the slope, or the second candidate relationship may be determined by determining only one of the brightness threshold value and the slope.

When the inclination is determined, for example, the data luminance Lin is converted into the data luminance Lout according to the conversion characteristics of FIG. 3C (gradation compression processing). Specifically, the first correction unit 2 corrects each pixel value of the input image data using the following equations 2-1 and 2-2. In expressions 2-1 and 2-2, “Lth” is a luminance threshold value. The correction value CG is the above inclination. The luminance relationship setting unit 1 determines a value between 0 and 1 as the correction value CG. For example, when the power consumption corresponding to the first candidate relationship is larger than the power threshold, the luminance relationship setting unit 1 determines a smaller value as the power consumption corresponding to the first candidate relationship as the correction value CG. To do. It can be said that the slope is a slope of a change in an output value (output gradation value) with respect to a change in an input value (input gradation value) that is equal to or greater than a luminance threshold (tone threshold).

When Lin ≦ Lth:
Lout = Lin (Formula 2-1)
If Lin> Lth:
Lout = CG × (Lin−Lth) + Lth (Formula 2-2)

According to the conversion characteristic of FIG. 3C, in the range of the data luminance Lin that is higher than the luminance threshold Lth, the data luminance Lout increases as the data luminance Lin increases. Therefore, for a region where the data luminance Lin is higher than the luminance threshold value, a luminance distribution expressing a difference (change) in the data luminance Lin can be obtained as a luminance distribution in the region, instead of a uniform luminance distribution.

Note that the first candidate relationship is not limited to the candidate relationship (conversion characteristics) in FIG. For example, the display brightness (data brightness Lout) may increase linearly with an increase in data brightness Lin, or the display brightness (data brightness Lout) may increase non-linearly with an increase in data brightness Lin. . Both a linear portion where the display luminance increases linearly with respect to the increase in the data luminance Lin and a non-linear portion where the display luminance increases nonlinearly with respect to the increase in the data luminance Lin may be included.

Note that the second candidate relationship is not limited to the candidate relationship (conversion characteristics) shown in FIGS. 3 (B) and 3 (C). The second candidate relationship may be a candidate relationship in which the power consumption of the display device is equal to or lower than the power threshold value and the correspondence relationship in the range of the data luminance Lin equal to or lower than the luminance threshold value is substantially the same as the first candidate relationship. When the power consumption corresponding to the first candidate relationship is large, a value larger than that when the power consumption corresponding to the first candidate relationship is small may be used as the luminance threshold. When the power consumption corresponding to the first candidate relationship is large, a larger gradient may be used as the gradient than when the power consumption corresponding to the first candidate relationship is small. As the upper limit of the display brightness, the same display brightness as that of the first candidate relationship may be used. In the range of the data luminance Lin below the luminance threshold, the display luminance may increase linearly with respect to the increase in the data luminance Lin, or the display luminance may increase nonlinearly with respect to the increase in the data luminance Lin. In the range of the data luminance Lin that is higher than the luminance threshold, the display luminance may increase linearly with respect to the increase of the data luminance Lin, or the display luminance may increase nonlinearly with respect to the increase of the data luminance Lin. . The range of the data luminance Lin below the luminance threshold may include both a linear portion and a non-linear portion. The range of the data luminance Lin that is higher than the luminance threshold may include both a linear portion and a non-linear portion.

<Example 2>
Embodiment 2 of the present invention will be described below. In this embodiment, an example of an organic EL display device will be described. In the following, differences (configuration, processing, etc.) from the first embodiment will be described in detail, and description of the same points as in the first embodiment will be omitted. FIG. 4 is a block diagram illustrating a configuration example of the display device according to the present embodiment. 4, the same reference numerals as those in the first embodiment are assigned to the same functional units as those in the first embodiment (FIG. 1). In the example of FIG. 4, the corrected image data generated by the first correction unit 2 is used as display image data. Specifically, the first correction unit 2 outputs display image data (corrected image data) to the organic EL panel 8. The organic EL panel 8 is a self-luminous display panel that displays an image on a screen according to display image data.

In the present embodiment, the processing of the luminance relationship setting unit (conversion characteristic setting unit) 1 is different from that of the first embodiment. The power consumption of the display device is approximately proportional to the display brightness. When a self-luminous display panel is used, a plurality of data luminances Lin corresponding to a plurality of pixels (all pixels) of the input image data are converted according to a candidate relationship (gradation conversion characteristic candidate). A value based on a plurality of display luminances (data luminance Lout) obtained in this manner can be used as the power related value. In the present embodiment, the luminance relationship setting unit 1 sets a value based on the total luminance of a plurality of data luminances Lout (a plurality of data luminances Lout corresponding to a plurality of pixels (all pixels)) according to the candidate relationship as a power related value. Get as.

Specifically, for each of a plurality of pixels included in the input image data, the first correction unit 2 converts the data luminance Lin included in the pixel into display luminance according to the set luminance relationship (gradation conversion characteristics). Conversion into (data luminance Lout). It can be said that the first correction unit 2 converts the gradation value of the pixel according to the set luminance relationship (gradation conversion characteristic) for each of the plurality of pixels (all pixels) included in the input image data. . Then, the luminance relationship setting unit 1 acquires the data luminance Lout of each pixel, and acquires (generates) a luminance histogram based on the data luminance Lout of each pixel. In the present embodiment, a plurality of luminance category values respectively corresponding to a plurality of ranges constituting a predetermined range of the data luminance Lout are predetermined. In this embodiment, n integers from 1 to n are determined in advance as the plurality of luminance category values, and the luminance category value increases as the data luminance Lout increases. The process of acquiring the brightness histogram is a process of counting the number of pixels (frequency) having the data brightness Lout of the brightness category value for each of the plurality of brightness category values.

Thereafter, the luminance relationship setting unit 1 calculates the power-related value TW using the following Expression 3. In Equation 3, Ct (x) is the frequency Ct of the luminance category value x (x is an integer greater than or equal to 1 and less than or equal to n). According to Equation 3, the sum of a plurality of frequencies Ct (x) respectively corresponding to the plurality of luminance category values x is calculated as the power-related value TW.

TW = 1 × Ct (1) + 2 × Ct (2).
+ (N−1) × Ct (n−1) + n × Ct (n)
... (Formula 3)

Note that the number of luminance category values is not particularly limited. The correspondence relationship between the luminance category value and the data luminance Lout is not particularly limited. For example, the luminance category value may be smaller as the data luminance Lout is higher. A plurality of data luminances Lout may or may not belong to the range corresponding to the luminance category value. One data luminance Lout may belong to the range corresponding to the luminance category value. The data luminance Lout may be used as the luminance category value. The predetermined range is not particularly limited. For example, the range of the data luminance Lout obtained by the first candidate relationship is used as the predetermined range.

Note that a value based on another display luminance such as an average luminance of a plurality of display luminances according to the candidate relationship may be acquired as the power-related value. An average luminance level (APL: Average Pixel Level) of image data may be acquired as a power-related value. Further, in a display device having a light emitting unit and a modulation panel, even when the light emitting unit emits light with higher light emission luminance as the data luminance Lin is higher, a value based on a plurality of display luminances corresponding to the candidate relationship is set as a power-related value. Can be used as

An example of a method for determining the luminance relationship (correction value CG) according to the present embodiment will be described with reference to the flowchart of FIG. In the present embodiment, an example will be described in which a value that determines a luminance threshold (tone threshold) is determined as the correction value CG. Specifically, the correction value CG used in the expressions 1-1 and 1-2 is determined, and the conversion characteristics as shown in FIGS. 3A and 3B are determined as the luminance relationship. Will be explained.

First, in S501, the luminance relationship setting unit 1 sets a first candidate relationship as the luminance relationship, and acquires a luminance histogram (feature amount) corresponding to the first candidate relationship. Specifically, the luminance relationship setting unit 1 sets the correction value CG = 0, and acquires the data luminance Lout corresponding to the conversion characteristics of FIG. 3A as the data luminance Lout of each pixel. The luminance relationship setting unit 1 then counts the number of pixels having the data luminance Lout of the luminance category value x (frequency Ct (x)) for each of the plurality of luminance category values x.

Next, in S502, the luminance relationship setting unit 1 determines, for each of the plurality of luminance category values x, a power-related value tW (x) related to the power consumption required for displaying the pixel corresponding to the luminance category value x. To do. Specifically, the luminance relationship setting unit 1 calculates the power-related value tW (x) by multiplying the luminance category value x by the frequency Ct (x). The power related value tW (x) is a value tW corresponding to the luminance category value x. The power-related value tW (x) is also a value when the first candidate relationship is used as the luminance relationship.

In S <b> 503, the luminance relationship setting unit 1 calculates, for each of the plurality of luminance category values x, the total sum WUsum (x) of the power related values tW of the luminance category values smaller than the luminance category value x. Specifically, the luminance relationship setting unit 1 calculates a power-related value (total) WUsum (x) using the following equations 4-1 and 4-2. The power related value WUsum (x) is a value WUsum corresponding to the luminance category value x. “Power-related value WUsum (x)” can also be said to be “power consumption required for display of pixels corresponding to a luminance category value smaller than luminance category value x”. The power related value WUsum (x) is also a value when the first candidate relationship is used as the luminance relationship.

Next, in S504, the luminance relationship setting unit 1 assumes that the luminance category value larger than the luminance category value x is equal to the luminance category value x for each of the plurality of luminance category values x. x) is determined. The power related value Wasum (x) is a value Wasum related to the power consumption required for displaying the pixel corresponding to the luminance category value x.

In S505, the luminance relationship setting unit 1 calculates the sum tTW (x) of the power related value WUsum (x) and the power related value Wasum (x) for each of the plurality of luminance category values x. The power related value (sum) tTW (x) is a value tTW corresponding to the luminance category value x. Ask. By the process of S505, the plurality of power related values TW respectively corresponding to the plurality of candidate relationships are obtained as the plurality of power related values tTW (x). Here, in each of the plurality of candidate relationships, the correspondence relationship in the range of the data luminance Lin that is equal to or less than the luminance threshold is substantially the same as the first candidate relationship. In the present embodiment, in the candidate relationship corresponding to the power related value tTW (x), the luminance threshold corresponds to the luminance category value x. Specifically, in the candidate relationship corresponding to the power related value tTW (x), the luminance threshold is equal to the data luminance Lout of the luminance category value x.

Next, in S506, the luminance relationship setting unit 1 determines, based on the plurality of power related values tTW (x), one of the plurality of candidate relationships respectively corresponding to the plurality of power related values tTW (x) as the luminance. Determine as a relationship. Specifically, the luminance relationship setting unit 1 determines the correction value CG so that the luminance threshold value corresponding to the luminance category value x of the power related value tTW (x) equal to or less than the threshold value Wth is set. When two or more power related values tTW (x) less than or equal to the threshold Wth are obtained, the brightness relationship setting unit 1 determines the brightness category of the maximum value of the two or more power related values tTW (x). The correction value CG is determined so that a luminance threshold value corresponding to the value x is set.

In the present embodiment, the power consumption value of the display device can be reduced below the power threshold value by using the candidate relationship whose power related value tTW (x) is equal to or less than the threshold value Wth as the luminance relationship. Therefore, according to the above processing in S506, a candidate relationship in which the power consumption related to the power related value tTW (x) is equal to or less than the power threshold is determined as the luminance relationship. The power related value tTW (x) related to the power consumption below the power threshold may be acquired for two or more candidate relationships among a plurality of candidate relationships. In that case, the candidate relationship having the largest power consumption related to the power related value tTW (x) among the two or more candidate relationships is determined as the luminance relationship.

When the power related value tTW (n) is equal to or less than the threshold value Wth, the first candidate relationship as shown in FIG. 3A is determined as the luminance relationship. When the power related value tTW (n) is larger than the threshold value Wth, the second candidate relationship as shown in FIG. 3B is determined as the luminance relationship.

Next, a specific example of a method for determining the correction value CG will be described with reference to FIGS. Here, for the sake of simplicity, an example will be described in which the luminance category value x is a five-level value from 1 to 5, and the input image data has a total of 50 pixels of 10 pixels in the horizontal direction and 5 pixels in the vertical direction. When all the pixels correspond to the luminance category value x = 5, the power consumption of the display device is maximized. According to Expression 3, the power-related value TW (power consumption of the display device) is 250 at the maximum. Here, an example in which 125, which is half of the maximum value 250, is used as the threshold value Wth will be described.

First, in S501, the luminance histogram of FIG. 6 is acquired. Specifically, the frequency Ct (x) in FIG. 7 is acquired. Next, in S502, the power related value tW (x) in FIG. 7 is calculated. For example, since the frequency Ct (3) of the luminance category value x = 3 is 14, 3 × 14 = 42 is calculated as the power-related value tW (3). The power related values tW (1), tW (2), tW (4), and tW (5) are calculated in the same manner.

In S503, the power-related value WUsum (x) in FIG. 7 is calculated. For example, there is no luminance category value smaller than the luminance category value x = 1. Therefore, 0 is calculated as the power related value WUsum (1). Further, there are three luminance category values x = 1, 2, 3 as luminance category values smaller than the luminance category value x = 4. The power related value tW (1) of the luminance category value x = 1 is 4, the power related value tW (2) of the luminance category value x = 2 is 34, and the power related value of the luminance category value x = 3. tW (3) is 42. Therefore, 4 + 34 + 42 = 80 is calculated as the power-related value WUsum (4). The power related values WUsum (2), WUsum (3), and WUsum (5) are calculated in the same manner.

Next, in S504, the power related value Wasum (x) in FIG. 7 is calculated. In FIG. 7, “UpCt (x)” is the number (frequency) of pixels corresponding to a luminance category value equal to or higher than the luminance category value x. For example, the frequency Ct (1) with the luminance category value x = 1 is 4, and the frequency Ct (2) with the luminance category value x = 2 is 17. Therefore, the frequency UpCt (3) of the luminance category value x = 3 is 50-4-17 = 29. As a result, 3 × 29 = 87 is calculated as the power related value Wasum (3) of the luminance category value x = 3. The power related values Wasum (1), Wasum (2), Wasum (4), and Wasum (5) are calculated in the same manner.

Then, in S505, the power related value tTW (x) in FIG. 7 is calculated. For example, the power related value WUsum (5) of the luminance category value x = 5 is 120, and the power related value Wasum (5) of the luminance category value x = 5 is 25. Therefore, 120 + 25 = 145 is calculated as the power related value tTW (5). The power related values tTW (1), tTW (2), tTW (3), and tTW (4) are similarly calculated.

Next, in S506, the maximum value of the luminance category value x corresponding to the power related value tTW (x) equal to or less than the threshold value Wth is detected. In the example of FIG. 7, the power-related values tTW (1), tTW (2), and tTW (3) are equal to or less than the threshold value Wth = 125, and thus the luminance category value x = 3 is detected. As a result, the correction value CG is determined so that a luminance threshold value corresponding to the luminance category value x = 3 is set. Thereby, the second candidate relationship corresponding to the power related value tTW (3) is used as the luminance relationship. As a result, the power consumption of the display device can be reduced below the power threshold, and the first candidate relationship is used in a region where the data luminance Lin is equal to or lower than the data luminance Lout of the luminance category value x = 3. Display with substantially the same display luminance can be realized. In the present embodiment, output to the subsequent stage (organic EL panel 8) of the first correction unit 2 is not performed until the correction value CG is determined in S506. Thereby, it is possible to perform display with power consumption equal to or lower than the power threshold.

As described above, also in the method of the present embodiment, the second candidate relationship is determined when the power consumption corresponding to the first candidate relationship is larger than the power threshold. As a result, it is possible to reduce the power consumption of the display device below the power threshold while maintaining display at a suitable display luminance.

Note that the method for determining the luminance relationship is not limited to the above method. For example, the luminance relationship setting unit 1 sets a luminance threshold value corresponding to the luminance category value x of the power-related value tTW (x) that is not the maximum value among two or more power-related values tTW (x) that are equal to or less than the threshold value Wth. May be. The luminance relationship setting unit 1 may acquire a plurality of luminance histograms respectively corresponding to the plurality of candidate relationships by setting each of the plurality of candidate relationships as a luminance relationship. Then, the luminance relationship setting unit 1 may acquire a plurality of power related values tTW (x) using a plurality of luminance histograms. The luminance relationship setting unit 1 may acquire the power related value tTW (x) for each of the plurality of candidate relationships by the method of the first embodiment. Further, the luminance relationship setting unit 1 may acquire the feature amount from the input image data instead of from the data luminance Lout obtained by the first correction unit 2.

<Example 3>
Embodiment 3 of the present invention will be described below. In the following, differences (configuration, processing, etc.) from the first embodiment will be described in detail, and description of the same points as in the first embodiment will be omitted. FIG. 8 is a block diagram illustrating a configuration example of the display device according to the present embodiment. In FIG. 8, the same reference numerals as those in the first embodiment are assigned to the same functional units as those in the first embodiment (FIG. 1).

The threshold setting unit 9 sets a threshold Wth according to a user operation on the display device. Specifically, the threshold setting unit 9 outputs a threshold Wth corresponding to the user operation to the luminance relationship setting unit (conversion characteristic setting unit) 1. The luminance relationship setting unit 1 stores and uses the threshold value Wth output from the threshold value setting unit 9. As described above, in this embodiment, the threshold value Wth is appropriately changed according to the user operation.

As described above, according to this embodiment, the threshold value Wth (power threshold value) is appropriately changed according to the user operation. Thereby, the power consumption of the display device can be reliably reduced to the power consumption desired by the user. The configuration of this embodiment is preferable, for example, when it is desired to extend the usable time of a battery-powered display device. A user operation for reducing the threshold value Wth (power threshold value) can extend the usable time of the battery-powered display device.

<Example 4>
Embodiment 4 of the present invention will be described below. In the following, differences (configuration, processing, etc.) from the first embodiment will be described in detail, and description of the same points as in the first embodiment will be omitted. FIG. 9 is a block diagram illustrating a configuration example of the display device according to the present embodiment. 9, the same reference numerals as those in the first embodiment are assigned to the same functional units as those in the first embodiment (FIG. 1).

In the present embodiment, the first correction unit 2 uses a candidate relationship (gradation conversion characteristic candidate) according to a user operation on the display device as a luminance relationship (gradation conversion characteristic) of correction processing by the first correction unit 2. To do. When the power consumption corresponding to the current luminance relationship used in the first correction unit 2 (power consumption of the display device) is larger than the power threshold, the power limiting unit 11 is configured so that the power consumption is equal to or lower than the power threshold. Processing for display in which display luminance is reduced at substantially the same ratio over the entire screen is performed. Hereinafter, “a display in which the display luminance is reduced at substantially the same ratio over the entire screen so that the power consumption is equal to or less than the power threshold value” is referred to as “restricted display”.

In the present embodiment, the power limiting unit 11 determines the power consumption corresponding to the current luminance relationship used in the first correction unit 2 based on the plurality of BL control values output from the BL control value determination unit 4. To do. When the determined power consumption is larger than the power threshold, the power limiting unit 11 reduces the plurality of BL control values at the same ratio so that the power consumption is equal to or less than the threshold. Then, the power limiting unit 11 outputs the reduced BL control value to the backlight unit 5. As a result, the light source unit of the backlight unit 5 emits light with the light emission luminance corresponding to the BL control value after reduction, and the limited display is performed. In the present embodiment, the higher the emission luminance, the larger the BL control value. Therefore, it can be said that “BL control value reduction” is “reduction of emission luminance”. When a self-luminous display device is used, for example, the limited display can be realized by reducing each pixel value of the display image data at the same ratio. If the determined power consumption is less than or equal to the power threshold, the power limiting unit 11 outputs the plurality of BL control values output from the BL control value determining unit 4 to the backlight unit 5. As a result, the light source unit emits light with a light emission luminance corresponding to the BL control value output from the BL control value determination unit 4.

For example, when the sum of a plurality of BL control values output from the BL control value determining unit 4 is larger than the threshold value Wth, the power limiting unit 11 corresponds to the current luminance relationship used in the first correction unit 2. It is determined that the power consumption is greater than the power threshold. The power limiting unit 11 corresponds to the current luminance relationship used in the first correction unit 2 when the sum of the plurality of BL control values output from the BL control value determination unit 4 is equal to or less than the threshold value Wth. It is determined that the power consumption is below the power threshold.

An example of actual luminance relationship will be described with reference to FIG. The actual luminance relationship is a correspondence relationship between the data luminance Lin and the actual display luminance confirmed by the user.

Reference numeral 101 indicates a candidate relationship corresponding to a user operation, that is, a luminance relationship used in the first correction unit 2. When the power consumption corresponding to the luminance relationship 101 is less than or equal to the power threshold, the limited display is not performed and the luminance relationship 101 becomes the actual luminance relationship. As a result, pixels having a data luminance Lin that is equal to or lower than the luminance threshold (tone threshold) of the luminance relationship 101 can be displayed with substantially the same display luminance as when the first candidate relationship is used.

When the power consumption corresponding to the luminance relationship 101 is larger than the power threshold, limited display is performed, and the luminance relationship 102 obtained by reducing each display luminance in the luminance relationship 101 becomes the actual luminance relationship. As a result, a pixel having a data luminance Lin equal to or lower than the luminance threshold value of the luminance relationship 101 cannot be displayed with substantially the same display luminance as when the first candidate relationship is used. However, the difference in the data luminance Lin can be displayed for the range of the data luminance Lin that is equal to or lower than the luminance threshold value of the luminance relationship 101.

The parameter display / setting unit 10 determines a candidate relationship according to a user operation on the display device, and outputs information on the determined candidate relationship to the luminance relationship setting unit (conversion characteristic setting unit) 1. The luminance relationship setting unit 1 determines a candidate relationship according to the user operation from the information output from the parameter display / setting unit 10. Then, the luminance relationship setting unit 1 sets the determined candidate relationship as the luminance relationship for the first correction unit 2.

In this embodiment, the parameter display / setting unit 10 determines a luminance threshold according to a user operation, and outputs the determined luminance threshold to the luminance relationship setting unit 1. Then, the luminance relationship setting unit 1 sets the luminance threshold output from the parameter display / setting unit 10 for the first correction unit 2. As a result, the data luminance Lin that is equal to the data luminance Lin is associated with the data luminance Lin that is equal to or lower than the luminance threshold, and the data luminance Lin that is equal to the luminance threshold is associated with the data luminance Lin that is higher than the luminance threshold. The relationship is used in the first correction unit 2.

Note that the method for determining the candidate relationship according to the user operation is not particularly limited. For example, other parameters such as a slope of a change in display luminance with respect to a change in data luminance Lin that is equal to or higher than the luminance threshold may be determined according to a user operation.

The parameter display / setting unit 10 notifies the user of information regarding candidate relationships in which the power consumption of the display device is equal to or less than the power threshold. Thereby, the user can easily grasp a candidate relationship in which power consumption is equal to or less than the power threshold, and can easily perform an operation for setting a candidate relationship in which power consumption is equal to or less than the power threshold.

A candidate relationship in which the power consumption of the display device is less than or equal to the power threshold can be determined from, for example, a power-related value, a correction value CG, and the like. In this embodiment, it is assumed that the upper limit Lmax of the data luminance Lin is 2000 cd / m ² . When the correction value CG = 0 is determined by the method of Example 1, a 0 cd / m ² or more and 2000 cd / m ² or less of the range, a range of brightness threshold power consumption is less than the power threshold value of the display device Judgment can be made. In that case, parameter display / setting unit 10, for example, information indicating a 0 cd / ^{m 2} or more and 2000 cd / ^{m 2} or less of the range, and notifies the user. Thereby, the user can easily grasp the range of the luminance threshold value where the power consumption is equal to or less than the power threshold value, and can easily perform an operation for setting the luminance threshold value where the power consumption is equal to or less than the power threshold value. it can.

The parameter display / setting unit 10 further notifies the user of information regarding the current luminance relationship used in the first correction unit 2. Thereby, the user can easily grasp the current luminance relationship used in the first correction unit 2, and can easily perform an operation for updating the actual luminance relationship to a desired candidate relationship. it can.

The notification of information to the user is realized by, for example, image display, audio output, lamp lighting, and the like. In the present embodiment, information is notified to the user by displaying graphic images as shown in FIGS. 11 (A) to 11 (C). 11A to 11B, a line 111 indicates a luminance threshold corresponding to a user operation, that is, a luminance-related luminance threshold used in the first correction unit 2. The bar 112 indicates the range of the brightness threshold where the power consumption is equal to or less than the power threshold.

In FIG. 11 (A), the line 111 represents the 1500 cd / ^{m 2,} bar 112 represents the 2000 cd / ^{m 2} or less. In this case, since 1500 cd / ^{m 2} is less than 2000 cd / ^{m 2,} limit the display is not performed, the candidate relation corresponding to the user operation is the actual luminance relationship. Specifically, the luminance relationship 101 in FIG. 10A is an actual luminance relationship. Note that the bar 112 does not mean that there is a pixel having a data luminance Lin of 2000 cd / m ² or less. Therefore, the user may be further notified of the maximum brightness of the data brightness Lin that the input image data has.

In FIG. 11 (B), line 111 represents the 1500 cd / ^{m 2,} bar 112 represents the 1000 cd / ^{m 2} or less. In this case, 1500 cd / m ² is higher than 1000 cd / m ^2, limited display is performed, the luminance relationship with reduced each display luminance of the candidate relations in accordance with the user operation is the actual luminance relationship. Specifically, the luminance relationship 102 in FIG. 10A is an actual luminance relationship.

By checking the bar 112 in FIG. 11B, the user can easily grasp that the restriction display is not performed if a luminance threshold value of 1000 cd / m ² or less is set. When the user performs an operation for updating the brightness threshold to 1000 cd / m ² , the brightness-related brightness threshold used in the first correction unit ² is updated to 1000 cd / m ² . As a result, the restriction display is not performed, and the candidate relationship according to the user operation becomes the actual luminance relationship. Specifically, the luminance relationship 103 in FIG. 10B is an actual luminance relationship.

By updating the brightness threshold from 1500 cd / ^{m 2} to 1000 cd / ^{m 2,} the range of data luminance Lin to show the differences in data luminance Lin is from 1500 cd / ^{m 2} or less in the range, in the range of 1000 cd / ^{m 2} or less It narrows. However, a pixel having a data luminance Lin of 1000 cd / m ² or less can be displayed with substantially the same display luminance as when the first candidate relationship is used.

In this way, the user performs an operation to update the brightness threshold value, so that the display with a wide range of data brightness Lin that can display the difference in the data brightness Lin and the display that is substantially the same as when the first candidate relationship is used. Display with brightness can be selected.

Further, by updating the luminance threshold value from 1500 cd / m ² to 1000 cd / m ² , the graphic image is updated from the graphic image in FIG. 11B to the graphic image in FIG. Thereby, the user can easily grasp that the restriction display is not performed.

As described above, according to the present embodiment, the user is notified of information on candidate relationships in which the power consumption of the display device is equal to or less than the power threshold. Thereby, the convenience of the display device can be improved. For example, the user can easily perform an operation for obtaining various desired luminance relationships as actual luminance relationships. As various luminance relationships, for example, a luminance relationship with a wide range of data luminance Lin that can display a difference in data luminance Lin, a luminance relationship that can realize display with substantially the same display luminance as when the first candidate relationship is used, Etc.

Note that the graphic image for notification is not limited to the graphic images of FIGS. 11 (A) to 11 (C). For example, instead of at least one of the line 111 and the bar 112, an icon, a text image, or the like may be used. More specifically, the "current brightness threshold is 1000cd / m ^2", "1500cd / when m ² high brightness threshold than has been set brightness of the entire screen will decrease", text image etc. is displayed May be.

Note that each functional unit in the first to fourth embodiments may or may not be a separate hardware. The functions of two or more functional units may be realized by common hardware. Each of a plurality of functions of one functional unit may be realized by individual hardware. Two or more functions of one functional unit may be realized by common hardware. Each functional unit may be realized by hardware or not. For example, the apparatus may include a processor and a memory in which a control program is stored. The functions of at least some of the functional units included in the apparatus may be realized by the processor reading and executing the control program from the memory.

The first to fourth embodiments are merely examples, and the present invention includes configurations obtained by appropriately modifying or changing the configurations of the first to fourth embodiments within the scope of the present invention. Configurations obtained by appropriately combining the configurations of Examples 1 to 4 are also included in the present invention.

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

1: luminance relation setting unit (conversion characteristic setting unit) 2: first correction unit 3: feature amount acquisition unit 4: BL control value determination unit 5: backlight unit 6: second correction unit 7: liquid crystal panel 8: organic EL panel

Claims

Setting means for setting gradation conversion characteristics for input image data;
Correction means for performing correction processing on the input image data in accordance with the set gradation conversion characteristics and generating corrected image data;
Display means for causing a light emitting unit to emit light at a light emission luminance based on the generated corrected image data and displaying an image based on the corrected image data;
With
The setting means acquires a power related value that is a value related to power consumption of the display device based on the input image data and the set first gradation conversion characteristic, and the acquired power related value is The display is characterized in that the setting is changed to the second gradation conversion characteristic that reduces the gradation value larger than the gradation threshold value of the input image data when it is larger than the power threshold value compared with the case where it is not. apparatus.
The display device according to claim 1, wherein the second gradation conversion characteristic is a gradation conversion characteristic that does not correct a gradation value equal to or less than the gradation threshold.
The display device according to claim 1, wherein the second gradation conversion characteristic is a gradation conversion characteristic that clips a gradation value larger than the gradation threshold value to a constant value.
The display device according to claim 3, wherein the gradation threshold is smaller as the power-related value is larger than the power threshold.
3. The setting means determines the second gradation conversion characteristic by determining a slope of an output value change with respect to an input value change equal to or greater than the gradation threshold. The display device described.
The display device according to claim 5, wherein the inclination is smaller as the power-related value is larger than the power threshold.
The setting means acquires a power-related value that is a value related to power consumption of the display device based on the input image data and the set second gradation conversion characteristic, and acquires the acquired power-related value 7. The second gradation conversion characteristic is updated so that the power consumption of the display device is further reduced when is larger than the power threshold value. The display device described.
The setting means acquires a plurality of power-related values respectively corresponding to a plurality of gradation conversion characteristic candidates, and determines any one of the plurality of gradation conversion characteristic candidates as the second gradation conversion characteristic. The display device according to any one of claims 1 to 7, characterized in that:
9. The display device according to claim 1, wherein the setting unit sets the power threshold according to a user operation.
The display device according to claim 1, wherein the power-related value is a value based on light emission luminance of the light emitting unit.
The display means includes the light emitting unit, and a display panel that displays the image by modulating light emitted from the light emitting unit,
The light emitting unit has a plurality of light source units,
Each of the plurality of light source units emits light with individual light emission brightness based on the corrected image data,
The display device according to claim 10, wherein the setting unit acquires values based on a plurality of light emission luminances respectively corresponding to the plurality of light source units as the power-related values.
The display device according to claim 11, wherein the setting unit acquires a value based on a total luminance or an average luminance of the plurality of light emission luminances as the power-related value.
The display device according to any one of claims 1 to 9, wherein the display means is a self-luminous display panel.
The display device according to any one of claims 1 to 9, wherein the power-related value is a value based on a luminance value of each of a plurality of pixels of the input image data.
A setting step for setting gradation conversion characteristics for the input image data;
A correction step for performing correction processing on the input image data according to the set gradation conversion characteristics and generating corrected image data;
Displaying the image based on the corrected image data by causing the light emitting unit to emit light at a light emission luminance based on the generated corrected image data;
Have
In the setting step, a power related value that is a value related to power consumption of the display device is acquired based on the input image data and the set first gradation conversion characteristic, and the acquired power related value is The display is characterized in that the setting is changed to the second gradation conversion characteristic that reduces the gradation value larger than the gradation threshold value of the input image data when it is larger than the power threshold value compared with the case where it is not. Method.
A program for causing a computer to execute each step of the display method according to claim 15.