JP2011013422A - Image quality adjusting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the mode transition processing so that the user can return to the original dark energy-saving mode screen again as much as possible without discomfort after shifting from the energy-saving mode screen to the bright screen on the display screen of the television device. An adjustment device is provided.
[Solution]
Based on the image content displayed on the image display, it is necessary to execute an operation of transition from the energy saving mode, which is the first luminance display mode, to the bright display mode, which is the second luminance display mode higher than the first luminance. Energy saving mode shift / return determiner that determines whether or not the return operation from the bright display mode to the energy saving mode is necessary, and the transition operation or the return operation by the energy saving mode shift / return determiner And a backlight luminance change time series controller for controlling a temporal change in the backlight luminance of the image display.
[Selection] Figure 1

Description

  The present invention relates to an image quality adjustment device that adjusts the image quality of an image displayed by a television device.

  The development of energy-saving technologies that take the global environment into consideration is becoming important, and various types of home appliances used in ordinary households are also making efforts for industry-government-government in order to spread “energy-saving home appliances”. Against this background, energy-saving modes are gradually being introduced on screens displayed on television devices in the home. Currently, technological development related to the energy saving mode implementation method has been accelerated, and in the near future, users who view television devices will normally view the screen displayed in the energy saving mode. Conceivable.

  2. Description of the Related Art Conventionally, a video display device described in Patent Document 1 has been disclosed as a technique for saving energy by controlling the image quality of a screen displayed on a television device in a home. As shown in FIG. 2, the video display device includes an ambient illuminance sensor 20 that measures the brightness (illuminance) around the device, a luminance signal average value calculator 21 that calculates the average luminance of the video signal, The condition determining unit 22 is configured to control the backlight luminance switching unit 23 and the gamma curve switching unit 24 to optimally adjust according to the brightness and the average luminance of the video signal. Since the conventional technology is configured as described above, the image defined by the broadcast program producer can be displayed at an appropriate brightness suitable for the ambient brightness in the home. It is.

JP 2007-171258 A

  Since the screen displayed in the energy saving mode is generally a dark image, a problem that ordinary users do not like this dark image has been found from our previous research. For this reason, it is considered that there is a demand for the user to see a scene that the user wants to see or an important scene on the original bright screen (bright display screen). That is, only in these scenes, a function for automatically shifting to the original screen that is not in the energy saving mode is required.

  Such an automatic transition function is used to automatically detect scenes that the user wants to see and important scenes automatically, and based on the detection, the screen is actually changed from the energy-saving mode screen to the bright bright display mode screen. This can be realized by the mode transition process for shifting to. In this transition process in the mode transition process, a technique for controlling the mode transition process so that each image quality factor such as a gamma curve, black level, and contrast, which are parameters that influence the image quality, transitions while maintaining an appropriate relationship. Is required. Furthermore, after shifting from the energy saving mode to the bright screen, there is also a need for a technique for controlling the mode shifting process so that the user can return to the original dark energy saving mode screen as much as possible.

  However, in the conventional technique described in Patent Document 1, the following two points become problems when shifting between the screen in the energy saving mode and the bright screen in both directions.

  The first challenge is to achieve bright, appropriate "only when necessary" from a screen that asks the user to make a compromise, that is, from an inappropriate screen that is darkly displayed in the energy saving mode, in order to achieve the purpose such as energy saving. There is no mechanism to detect “when necessary” when trying to move to a new screen. In other words, there is no scene detection process for automatically detecting a scene that a user wants to see or an important scene.

  The second problem is that if you move to a bright and appropriate screen, you can move all at once. However, if you want to return to the normal energy saving mode screen again, make the user feel as unnatural as possible. In spite of having to return gradually, the conventional technology only shows the final state of the transition, and means to realize a transition process that does not feel unnatural. There is no point.

  In order to solve the above-described problem, the image quality adjustment device according to the present invention is higher than the first luminance from the energy saving mode, which is the display mode of the first luminance, based on the image content displayed on the image display. An energy saving mode shift / return determiner that determines whether or not to perform the transition operation to the bright display mode, which is the second luminance display mode, and whether or not to perform the return operation from the bright display mode to the energy saving mode; Backlight luminance change time series control for controlling temporal change in backlight luminance of the image display when the transition operation or the return operation is determined to be necessary by the energy saving mode transition / return determiner A container.

  According to the present invention, in a mode transition process in which a bright screen is shifted to a dark screen in an energy saving mode, control is performed so that each image quality factor, which is a parameter that affects image quality, is shifted while maintaining an appropriate relationship. There is a remarkable effect that it is possible to realize a mode transition process that does not feel unnatural.

It is a block diagram which shows an example of the image quality adjustment apparatus in Embodiment 1 of this invention. It is a block diagram which shows the video display apparatus of a prior art. 6 is a diagram illustrating a flowchart of image quality adjustment processing in the image quality adjustment apparatus according to Embodiment 1. FIG. It is a figure which shows an example of the luminance distribution of the image output from the image display. It is a figure which shows the process of the change of a backlight luminance value in the transfer from an energy saving mode screen to a bright screen / return from a bright screen to an energy saving mode screen. It is a figure which shows an example of the parameter space trajectory from which the evaluation value of an image quality factor parameter (black level) becomes an optimal value.

1 image quality adjustment device, 2 ambient illuminance sensor, 3 luminance signal pattern determiner, 4 program genre determiner, 5 event detector, 6 scene change detector, 7 highlight scene detector, 8 user operation detector, 9 commercial start End detector, 10 Energy saving mode transition / return determination unit, 11 Backlight luminance time series change controller, 12 Gamma curve time series change controller, 13 Black level time series change controller, 14 Contrast time series change controller, 15 sharpness time series change controller, 16 color temperature time series change controller, 17 color density time series change controller, 18 hue time series change controller, 19 image display, 20 image quality time series change controller.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating an example of an image quality adjustment apparatus according to Embodiment 1 of the present invention.
In FIG. 1, the image quality adjustment apparatus 1 is connected to an image display 19 and adjusts the image quality of an image to be displayed based on various image information output from the image display 19. The ambient illuminance sensor 2 measures the illuminance around the image display 19. The luminance signal pattern determination unit 3 constitutes a luminance signal distribution from the luminance signal of the image output from the image display 19 and determines the luminance signal pattern. The program genre determination unit 4 determines the program genre when the content displayed on the image display 19 is a television program.

  The event detector 5 includes a scene change detector 6, a highlight scene detector 7, a user operation detector 8, and a commercial start / end detector 9, and is output from the image display 19 by controlling them. Content information is analyzed to detect events such as scene changes, highlight scenes, user operations, and commercials.

  The energy saving mode transition / return determiner 10 inputs the output of the ambient illuminance sensor 2 and the outputs of the luminance signal pattern determiner 3, the program genre determiner 4, and the event detector 5, and switches from the energy saving mode screen to a bright screen. It is determined and output whether or not the transition operation can be executed and whether or not the return operation to the subsequent energy saving mode screen can be executed.

  The backlight luminance time-series change controller 11 receives the output of the energy saving mode transition / return determiner 10 and backlight in transition from the energy saving mode screen to the bright screen or in returning from the bright screen to the energy saving mode screen. Controls the process of changing the brightness value. Here, the backlight luminance used in the liquid crystal television will be described as an example to indicate the luminance of the image. However, the luminance of the image controlled by the backlight luminance time-series change controller 11 is the backlight luminance. The brightness of the image of a plasma television, an organic EL television, a laser television, or the like may be used.

  Reference numeral 20 denotes an image quality time-series change controller that controls time-series changes in parameters that determine image quality, and includes 12 to 18 controllers corresponding to the respective parameters. The time series of the backlight brightness output from the backlight brightness time series change controller 11 is input to each of these controllers. The gamma curve time series change controller 12 controls the process of changing the gamma curve while adapting to the input backlight luminance and the change. The black level time series change controller 13 controls the process of changing the black level while adapting to the input backlight luminance and the change. The contrast time series change controller 14 controls the process of contrast change while adapting to the input backlight brightness and the change. The sharpness time series change controller 15 controls the change process of sharpness while adapting to the input backlight luminance and the change. The color temperature time series change controller 16 controls the process of changing the color temperature while adapting to the input backlight luminance and the change. The color density time-series change controller 17 controls the process of changing the color density while adapting to the input backlight luminance and the change. The hue time series change controller 18 controls the process of changing the hue while adapting to the input backlight luminance and the change.

Next, the operation of the image quality adjustment apparatus according to the first embodiment will be described with reference to FIGS.
FIG. 3 is a flowchart of image quality adjustment processing in the image quality adjustment apparatus according to the first embodiment.
FIG. 4 is a diagram illustrating an example of a luminance distribution of an image output from the image display 19.
FIG. 5 is a diagram illustrating a process of a change in backlight luminance value in transition from the energy saving mode screen to the bright screen / return from the bright screen to the energy saving mode screen.
FIG. 6 is a diagram illustrating an example of a parameter space trajectory in which the evaluation value of the image quality factor parameter (black level) is an optimum value.

  First, in step S <b> 101 of FIG. 3, the ambient illuminance sensor 2 measures the illuminance around the image display 19, and outputs the measurement result to the energy saving mode transition / recovery determiner 10. The ambient illuminance sensor 2 may be anything as long as it is generally used. The ambient illuminance sensor 2 may always perform measurement processing and continuously output the measurement result to the energy saving mode shift / return determiner 10.

  Next, in step S102, the luminance signal pattern determination unit 3 constructs a luminance signal level distribution (luminance distribution) from the luminance signal of the image output from the image display 19, and the luminance signal level distribution pattern ( (Luminance distribution pattern) is determined. An example of the luminance distribution of the image output from the image display 19 is shown in FIG. In FIG. 4, the horizontal axis represents the luminance signal level, and the vertical axis represents the cumulative number of pixels in which the pixels corresponding to the luminance signal level exist on the image display 19.

  By paying attention to such shape characteristics of the luminance distribution, whether the image given from the program producer side is (1) a bright image, (2) a dark image, or (3) a bright place is also dark. However, it can be divided into types such as whether the image is uniform. Therefore, for example, as the simplest example, the case of (1) is the luminance distribution pattern A, the case of (2) is the luminance distribution pattern B, and the case of (3) is the luminance distribution pattern C. By determining the determination conditions in advance and applying the determination conditions to the luminance signal of the image output from the image display 19, these luminance distribution patterns can be determined. It should be noted that the determination conditions for determining these luminance distribution patterns may be detailed to further classify into various types of luminance distribution patterns. In the example of FIG. 4, the luminance signal pattern determination unit 3 determines that the image on the image display 19 has many low luminance region components, that is, a picture in which many dark parts exist in the image. The luminance distribution pattern B is output as the determination result.

Next, in step S103, the program genre determination unit 4 determines the program genre when the content displayed on the image display 19 is a television program. For example, the program genre is determined by referring to the electronic program guide sent along with the broadcast.
In the first embodiment, the program genre determination unit 4 determines that the program on the image display 19 is a sport, and that it is a soccer, and outputs it.

  Next, in step S104, the event detector 5 controls the scene change detector 6, the highlight scene detector 7, the user operation detector 8, and the commercial start / end detector 9 to output from the image display 19. The content information to be analyzed is analyzed to detect events such as scene changes, highlight scenes, user operations, and commercials. Here, for example, the event detector 5 is composed of a highlight scene detector 8 and detects and outputs a highlight scene of content on the image display 19. For example, in the case of soccer, the operation of the highlight scene detector 7 is to increase the volume of the audio signal and increase the frequency, to recognize a specific word included in the voice, or to detect a specific character string or symbol included in the image. A highlight scene can be detected from recognition or the like. In the first embodiment, the event detector 5 detects and outputs a soccer highlight scene.

  Next, in step S105, the energy saving mode transition / return determiner 10 inputs the output of the ambient illuminance sensor 2 and the outputs of the luminance signal pattern determiner 3, the program genre determiner 4, and the event detector 5 to save energy. Determine and output the transition timing from the mode screen to the bright screen and the subsequent return timing to the energy saving mode screen.

  In the first embodiment, for example, the energy saving mode transition / return determiner 10 has a bright scene from the energy saving mode with respect to the outputs of the luminance signal pattern determiner 3, the program genre determiner 4, and the event detector 5. It is assumed that a determination condition (transition determination condition) for shifting to is defined in advance, and whether to shift is determined based on the transition determination condition.

  The transition determination condition is, for example, “(the luminance distribution pattern is B)” as the logical product of the outputs of the luminance signal pattern determiner 3, the program genre determiner 4, and the event detector 5. If the program genre is soccer) and (the event is a highlight scene), the transition from the energy saving mode to a bright scene is determined. This means that when the soccer program becomes a highlight scene and there are many dark parts in the image at that time, the energy saving mode is stopped and the program is viewed on a bright screen.

  In this way, the energy saving mode transition / return determination unit 10 is measured by the ambient illuminance sensor 2 for the transition to a bright scene, the subsequent return to the energy saving mode, and the transition process and the recovery process. Judgment is made according to the brightness around the image display 19. As a result of the determination, if the screen shifts to a bright screen or returns to the energy saving mode, the process proceeds to step S106. Otherwise, the process returns to step S101.

  Next, in step S106, the backlight luminance time series change controller 11 inputs the output of the energy saving mode transition / return determiner 10, and shifts from the energy saving mode screen to a bright screen, or from the bright screen to the energy saving mode screen. Controls the process of changing the backlight brightness value when returning to.

  FIG. 5 shows a specific process of changing the backlight luminance value during the transition and restoration. FIG. 5 shows a state in which an event is detected by the event detector 5 when, for example, a soccer program becomes a highlight scene at time T1. At this time, if the luminance signal pattern determination unit 3 determines that the image at that time has many dark parts (luminance distribution pattern B), the energy saving mode shift / return determination unit 10 shifts from the energy saving mode to a bright scene. , And at once, shift from energy saving mode to bright screen. That is, the backlight brightness is increased at once. Then, after maintaining a bright image for a certain time, the backlight luminance value is gradually lowered, and finally the screen is returned to the original screen in the energy saving mode. The fixed time can be set as a fixed time, or can be set as the time during which the event is continuously detected.

  In such a transition process from the energy saving mode screen to the bright screen, or in the process of returning from the bright screen to the energy saving mode screen, the image quality is set so that the viewing user is not unnatural with respect to the change in the image quality. Controls the parameters (image quality factor parameters) that affect the image quality. Such image quality control is performed based on the backlight luminance time series output from the backlight luminance time-series change controller 11 based on each of the controllers (image quality time-series change controllers 12 to 18 related to the image quality factor parameter). 20) and operates as follows.

  The gamma curve time series change controller 12 controls the process of changing the gamma curve while adapting to the input backlight luminance and the change. The black level time series change controller 13 controls the process of changing the black level while adapting to the input backlight luminance and the change. The contrast time series change controller 14 controls the process of contrast change while adapting to the input backlight brightness and the change. The sharpness time series change controller 15 controls the change process of sharpness while adapting to the input backlight luminance and the change. The color temperature time series change controller 16 controls the process of changing the color temperature while adapting to the input backlight luminance and the change. The color density time-series change controller 17 controls the process of changing the color density while adapting to the input backlight luminance and the change. The hue time series change controller 18 controls the process of changing the hue while adapting to the input backlight luminance and the change.

  In the first embodiment, each image quality factor is controlled as follows in accordance with a change in backlight luminance. When the backlight luminance is bright, the gamma curve is natural, the black level is sunk, and the contrast, sharpness, color temperature, color density, and hue are also natural. On the other hand, as the backlight brightness becomes darker due to the energy saving mode, the gamma curve becomes an es-curve with a steep rise in the intermediate brightness range, the black level becomes shallower, the contrast and sharpness become stronger, that is, sharper. The color temperature is lowered, that is, it approaches the reddish side, the color intensity is increased to compensate for the fading due to the black level increase, and the hue is not changed Will be performed.

  As described above, the image quality adjustment apparatus according to the present invention changes each image quality factor parameter in a coordinated manner in accordance with a change in backlight luminance, and the cooperation is always maintained even in the course of the change. It is something that changes. In the control operation for each image quality factor parameter, the distribution of evaluation values of each image quality factor parameter in the process of changing the backlight luminance, for example, the change process as shown in FIG. It is realized by. That is, for each backlight luminance value, evaluation value distribution data indicating how much each value of the image quality factor parameter is desirable for the viewer (user) is provided as an image quality factor parameter evaluation criterion. Based on the data, at the time of execution, the backlight brightness change is set as an independent variable, and the evaluation value of each image quality factor parameter is determined to be given as a dependent variable so that the evaluation value of each image quality factor always maintains an optimum value. .

  As a specific example of such a control operation, an evaluation value of each value of the black level is taken as an example and will be described with reference to FIG. FIG. 6 shows an example of a parameter space trajectory in which the evaluation value of the image quality factor parameter (black level) is the optimum value. In FIG. 6, the backlight luminance value is taken on the horizontal axis and the black level value is taken on the vertical axis, and the preference for the viewer in the direct product space is represented by contour lines as evaluation values. This contour line can be obtained by an experiment using a subject in an experimental environment in which optical and other conditions are controlled. Then, for example, as shown in FIG. 5, when the backlight luminance value changes, the backlight luminance value of FIG. 6 changes accordingly. In the process, the maximum value of the contour line is always taken. , Change the black level value. The locus drawn at this time is the optimum black level value curve. In the cooperative image quality factor parameter control described above, an optimum value curve corresponding to the optimum black level value curve in FIG. 6 is obtained as an image quality factor parameter evaluation standard corresponding to each image quality factor parameter. Based on the curve, the change of each image quality factor parameter can be cooperatively controlled.

  In the above description, the evaluation value is described as a higher value as the desired degree of image quality is higher. Conversely, when the evaluation value is higher as the degree of dissatisfaction with the image quality is higher, The optimum curve is drawn so as to always take a minimum value in accordance with a change in backlight luminance.

  In the above description, the image quality factor parameter value has been described as being determined only by the backlight luminance value. However, in addition to the backlight luminance, a plurality of image quality factor parameters may be changed in cooperation. In this case, a further effective effect can be obtained by designing each image quality factor parameter value to be determined by the other image quality factor parameter values and the backlight luminance value.

  In the above description, the image quality adjustment apparatus according to the present invention has been described as an application to the transition and restoration of the image quality in the energy saving mode and the image quality in other modes. However, the present invention is not necessarily limited to this application. It can be applied to transition and return between other image quality modes, and more generally to transition and return between two or more different image quality.

  Finally, in step S107, the energy saving mode transition / return determiner 10 determines whether or not to end the image quality adjustment process, and if not, returns to step S101. When the process ends, a series of image quality adjustment processing ends.

  As described above, according to the first embodiment, in the mode transition process in which the screen shifts from the bright screen to the dark screen in the energy saving mode, each image quality factor, which is a parameter that affects the image quality, is shifted while maintaining an appropriate relationship. By controlling, there is a remarkable effect that it becomes possible to realize a mode transition process that does not make the user feel unnatural.

Claims (17)

Based on the image content displayed on the image display, it is necessary to execute an operation of transition from the energy saving mode, which is the first luminance display mode, to the bright display mode, which is the second luminance display mode higher than the first luminance. And an energy-saving mode transition / return determiner that determines whether or not it is necessary to execute a return operation from the bright display mode to the energy-saving mode;
A backlight luminance change time series controller that controls temporal changes in the backlight luminance of the image display when the transition operation or the return operation is determined to be necessary by the energy saving mode transition / return determiner. And an image quality adjustment device. Based on the image quality factor parameter evaluation criteria for evaluating the correspondence between the image quality factor parameter for determining the image quality of the image and the backlight luminance, according to the backlight luminance controlled by the backlight luminance change time series controller The image quality adjusting apparatus according to claim 1, further comprising an image quality time-series change controller that controls temporal changes in image quality. The image quality time series change controller is configured to control a time change of a gamma curve for determining a physical brightness of an image according to the backlight brightness controlled by the backlight brightness change time series controller. The image quality adjusting apparatus according to claim 2, further comprising a sequence change controller. The image quality time-series change controller is a black circuit that controls a temporal change in a black level that determines characteristics of a low-brightness area of an image according to the backlight brightness controlled by the backlight brightness change time-series controller. The image quality adjusting apparatus according to claim 2, further comprising a level time-series change controller. The image quality time-series change controller is a temporal change in contrast that determines a relationship between a bright display portion and a dark display portion of an image according to the backlight luminance controlled by the backlight luminance change time-series controller. The image quality adjusting apparatus according to claim 2, further comprising a contrast time series change controller for controlling the image quality. The image quality time series change controller is a sharpness time series for controlling a temporal change in sharpness that determines the contour or roughness of an image in accordance with the backlight brightness controlled by the backlight brightness change time series controller. The image quality adjusting apparatus according to claim 2, further comprising a change controller. The image quality time series change controller includes a color temperature time series change controller that controls a temporal change in color temperature according to the backlight brightness controlled by the backlight brightness change time series controller. Item 3. The image quality adjusting apparatus according to Item 2. The image quality time-series change controller is configured to control a color change that controls a temporal change in color intensity that determines color saturation according to the backlight brightness controlled by the backlight brightness change time-series controller. The image quality adjusting apparatus according to claim 2, further comprising a darkness time series change controller. The image quality time series change controller includes a hue time series change controller that controls a temporal change in hue that determines a hue in accordance with the backlight brightness controlled by the backlight brightness change time series controller. The image quality adjusting apparatus according to claim 2. An ambient illuminance sensor that measures the illuminance around the image display and outputs the illuminance to the energy saving mode transition / recovery determiner is provided, and the energy saving mode transition / return determiner is output from the ambient illuminance sensor. 10. The determination according to claim 1, wherein whether or not a transition operation from the energy saving mode to the bright display mode is necessary and whether or not a return operation from the bright display mode to the energy saving mode is necessary is determined according to illuminance. Image quality adjustment device. A luminance signal pattern determination unit for determining the luminance distribution pattern to which the distribution of the luminance signal level of the image output from the image display belongs, based on a luminance distribution pattern typifying the distribution of the luminance signal level of the image;
The energy-saving mode transition / return determiner is configured to determine whether or not to perform a transition operation from the energy-saving mode to the bright display mode according to the luminance distribution pattern determined by the luminance signal pattern determiner, and the bright display mode. The image quality adjustment apparatus according to claim 1, wherein it is determined whether or not the operation for returning to the energy saving mode is necessary. A program genre determining unit that determines a program genre of an image displayed on the image display based on an electronic program guide included in the image content displayed on the image display;
The energy saving mode transition / return determiner determines whether or not to perform the transition operation from the energy saving mode to the bright display mode according to the program genre determined by the program genre determiner, and from the bright display mode to the The image quality adjustment apparatus according to claim 1, wherein it is determined whether or not a return operation to the energy saving mode is necessary. An event detector for detecting an event indicating a temporal change in image content displayed on the image display;
The energy saving mode transition / return determiner is configured to determine whether or not to perform a transition operation from the energy saving mode to the bright display mode according to the event determined by the event detector, and from the bright display mode to the energy saving mode. The image quality adjustment apparatus according to claim 1, wherein it is determined whether or not a return operation is required. The event detector recognizes, from the image content displayed on the image display, a first scene in which a display scene having a certain property is maintained, and a property different from the first scene is maintained. A scene change detector for detecting that the display scene is changed to the second scene,
The energy saving mode transition / return determiner is configured to perform an operation of transition from the energy saving mode to the bright display mode in response to a change from the first scene to the second scene detected by the scene change detector. The image quality adjustment apparatus according to claim 13, wherein it is determined whether or not execution is necessary and whether or not a return operation from the bright display mode to the energy saving mode is necessary. The event detector includes a highlight scene detector that detects a highlight scene of a program based on image content displayed on the image display and audio information associated with the image content.
The energy-saving mode transition / return determiner is configured to determine whether or not to perform a transition operation from the energy-saving mode to the bright display mode according to the highlight scene detected by the highlight scene detector, and the bright display mode. The image quality adjustment device according to claim 13, wherein it is determined whether or not the operation for returning to the energy saving mode is necessary. The event detector includes a user operation detector that detects a user operation on the image content displayed on the image display,
The energy-saving mode transition / return determiner determines whether or not to perform a transition operation from the energy-saving mode to the bright display mode according to the user operation detected by the user operation detector, and from the bright display mode to the The image quality adjustment apparatus according to claim 13, wherein it is determined whether or not a return operation to the energy saving mode is necessary. The event detector includes a commercial start / end detector that detects a transition from a program to a commercial, or a transition from a commercial to a program, from the image content displayed on the image display.
The energy-saving mode transition / return determiner is switched from the energy-saving mode to the bright display mode in response to the transition from the program to the commercial or the transition from the commercial to the program detected by the commercial start / end detector. The image quality adjustment apparatus according to claim 13, wherein it is determined whether or not it is necessary to execute the transition operation and whether or not the return operation from the bright display mode to the energy saving mode is necessary.

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