JP2003108110A - Computer device, display controller, display device, control method for display device, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for improving display quality. SOLUTION: A gradation upper-limit value (n) and a gradation lower-limit value (m) displayed on the display screen of an LCD module are detected at specific intervals and the setting of a γcurve is remapped according to the range to dynamically remap a luminance distribution. Further, when the gradation upper-limit value (n) or gradation lower-limit value (m) increases, the peak value of the γ curve is immediately varied. When the gradation upper-limit value (n) or gradation lower-limit value (m) decreases, on the other hand, the peak value of the γ curve is varied on condition that the decrease lasts for a specific number of frames or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display control device, a display device control method, and the like.

[0002]

2. Description of the Related Art A CRT (Cathode Ra) used as a display device of a personal computer (hereinafter referred to as a PC).
In a y tube) or an LCD (Liquid Crystal Display), RGB color tones are represented by 64 gradations, for example. At this time, the relationship between the gradation (gray scale) and the screen brightness is
It is not necessarily in a direct proportional relationship, but rather, in order to make it easier for humans to perceive visually (easy to see the difference in gradation),
(Gamma) correction is being performed. This γ correction is represented by a relational expression L = k · X ^γ (k is a coefficient) where X is the gradation and L is the brightness. Generally, in a PC display device, the γ value is γ = 2.2 or γ = 1.
Often 8 is used. In FIG. 5, for example, γ = 2.2
Represents a γ curve showing the relationship between the gradation and the brightness.

[0003]

By the way, when an image or the like is actually displayed on the display device, the range from the lowest gradation to the highest gradation in the image can be displayed on the display device.
It seems that it is rare for the case to cover the entire range of four gradations. In general, the image to be displayed is often only a part of the entire gradation (for example, the range (i) in FIG. 5). For example, when the gradation range displayed on the display screen is low (for example, the range (ii) in FIG. 5), the change in luminance with respect to the change in gradation is small (the slope of the curve is small). Therefore, the brightness distribution on the entire display screen
The difference (between the brightest part and the darkest part) is small, it is difficult to visually recognize the difference in gradation, and the display is low in contrast. As described above, the conventional display quality cannot always be said to be the best. The present invention has been made based on such technical problems,
It is an object of the present invention to provide a technique capable of improving display quality.

[0004]

Based on the above object, the computer apparatus according to the present invention outputs the data of the image to be displayed on the display means by the data output means in response to the external input received by the input reception means. The display control means performs the brightness distribution adjustment according to the range of the gradation of the image displayed on the display means. Thereby, even if the displayed image is only a part of the range of gradation, the brightness distribution adjustment can be performed according to the range. At this time, it is preferable to adjust the luminance distribution every predetermined time. More specifically, for each frame of the image output from the data output means,
Alternatively, the gradation range of the frame is detected for each predetermined frame, and the brightness distribution is adjusted accordingly. Such display control means may detect the range of gradation based on the image data output from the data output means including, for example, a graphics controller, or output from the data output means. It is also possible to detect the range of gradation after the image data is received by the display means. In addition to this, the display control means can detect the range of gradation on a transfer means such as a cable that transfers the image data output from the data output means to the display means, A board may be provided between the display means and the function of the display control means may be mounted on the board.

The display control device according to the present invention detects a video signal for displaying on the display device, and displays the distribution of the display brightness in the display device based on the parameters of the image detected based on the video signal. The information indicating the determined distribution of the display luminance is output to the display device. As a result, the display luminance distribution can be updated on the display device side. At this time, it is preferable to detect, as the parameter, the range of gradation for each frame displayed on the display device. Then, when the change of the parameter continues for a certain period or more, for example, for a predetermined number of frames or more or for a predetermined time or more, the information indicating the display luminance distribution can be output to the display device. Also,
Information indicating the distribution of display brightness may be output when the amount of change in the parameter is equal to or greater than a certain amount.

The display device according to the present invention is characterized in that the γ correction of the display panel in the γ correction circuit is dynamically performed based on the parameters of the image displayed on the display panel.
At this time, it is preferable to detect the upper limit value and the lower limit value of the gradation of the image displayed on the display panel as parameters, and correct the brightness corresponding to the upper limit value and the lower limit value by a predetermined function. As such a function, a function that represents the luminance L corresponding to the gradation X between the upper limit value and the lower limit value as L = k ′ · X ^γ + a can be used. However, here, k ′ = (b−a) / (S ^γ ), a = k · m ^γ , b = k · n ^γ , k = 100 / (S ^γ ), and S is displayed on the display panel. The number of gradations, m is the upper limit value of the gradation of the image displayed on the display panel, n is the lower limit value, and γ is a predetermined index. Then, the γ correction is executed when the upper limit value of the gradation of the image displayed on the display panel is increased, or the γ correction is executed when the lower limit value of the gradation is decreased for a certain period or more. Good. That is,
When the range of gradation expands or moves to the lower gradation side, the state is maintained for a certain amount or more, and then γ correction is performed according to the state.

A display device control method according to the present invention detects a video signal for displaying on a display device, and determines a distribution of display brightness on the display device based on an image parameter detected based on the detected video signal. , Adjust the display brightness of the display device. For this purpose, it is preferable to detect the parameter at predetermined intervals and adjust the display brightness when the parameter changes. This allows the display brightness of the display device to be dynamically controlled. At this time, it is possible to detect the upper limit value and the lower limit value of the gradation of the image as a parameter, and adjust the display brightness distribution when the variation continues for a certain amount or both of the upper limit value and the lower limit value. it can. At this time, with respect to one or both of the upper limit value and the lower limit value to be monitored for fluctuation, the display brightness when the fluctuation is falling is compared with the time until the display brightness is adjusted when the fluctuation is rising. The time until the adjustment may be set longer.

According to the present invention, a process of detecting a video signal for displaying on a display device, a process of detecting a parameter of an image based on the detected video signal, and a display brightness in the display device based on the detected parameter. A process of determining the distribution of, and a process of adjusting the display brightness of the display device based on the determined display brightness distribution,
It can also be regarded as a computer program characterized by having. Note that such a computer program can also be in the form of the following storage medium. That is, as the storage medium, the computer program as described above to be executed by the computer device may be stored in a storage medium such as a CD-ROM, a DVD, a memory, or a hard disk so that the computer device can read it.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. FIG. 1 is a diagram for explaining the configuration of a PC (computer device) in the present embodiment. As shown in FIG. 1, on the main body side of the PC, an input control unit (input receiving means: not shown) that receives an input of this operation as a result of the user operating the operating means such as a keyboard and a mouse. A graphics controller (data output means) 10 for outputting a video signal (image data) of an image to be displayed according to
The LCD module 20 as a display device performs display based on the video signal output from the graphics controller 10.

Here, the LCD module 20 is an LCD
Panel (cell: display means, display panel) 21 and this LC
The D panel 21 is provided with a backlight 22 that emits light from the back side thereof. The backlight 22 is configured such that a fluorescent tube (not shown) serving as a light emitting source is turned on by an inverter circuit 23.
The power supply is controlled by the embedded controller 11 provided on the main body side of the PC. The embedded controller 11 controls the inverter circuit 23 based on the table stored in the brightness control DB 12 to cause the backlight 22 to emit light according to the power mode of the PC or the like.
Here, the backlight 22 is basically always kept in a constant light emitting state unless the power mode is switched.

Further, when the LCD module 20 displays a screen based on the video signal sent from the graphics controller 10 on the LCD panel 21, gray level correction, that is, display brightness according to the gradation of the image to be displayed. A gamma correction circuit 24 for correcting the distribution is further provided. When performing the gray level correction by the γ correction circuit 24, a γ curve with γ = 2.2 is used in the default state.

This PC is equipped with an adjusting mechanism (display control means, display control device, correction control section) 30 for dynamically remapping (adjusting) the γ curve according to the display screen of the LCD module 20. Has been. The adjustment mechanism 30 is used when the γ correction circuit 24 performs gray level correction.
A remap processing unit (luminance distribution determination unit) 31 that remaps a curve and outputs it to the γ correction circuit 24, and a parameter detect that detects a predetermined parameter from a video signal output from the graphics controller 10 to the LCD module 20. A unit (signal detection unit) 32 and a parameter processing unit (parameter detection unit) 33 that performs a predetermined process based on the detected parameter.

In the adjusting mechanism 30 as described above, the lowest gradation of the frame obtained from the video signal of the frame output from the graphics controller 10 at a predetermined interval (hereinafter, referred to as a gradation lower limit value). And the highest gradation
Based on (hereinafter, referred to as a gradation upper limit value), the γ curve is remapped in the range from the gradation lower limit value to the gradation upper limit value. In FIG. 2, the γ curve (Z) is for displaying an image over the entire gradation range (gradation number S = 64) that can be displayed on the LCD panel 21, and the γ curve (Z) is
When the brightness is L and the gradation is X, it is expressed by the following equation: L = k · X ^γ (1), and the coefficient k is k = 100 / (S) ^γ depending on the number of gradations S. ………… It is decided by the formula (2).

In FIG. 2, the γ curve (Z ') has a gradation lower limit value m of the gradation distribution of the color tone in a certain frame (image),
The adjustment mechanism 30 remaps when the gradation upper limit value is n. Such a γ curve (Z ′) is a coordinate when the brightness of the mth gradation is a and the brightness of the nth gradation is b.
It is remapped so that (m, a) is the starting point and the coordinates (n, b) are the ending point. In equation (3), L '= k' · X ^γ + a expressed. Here, from the above equation (1), a = k · m ^γ (4) and b = k · n ^γ (5). Further, the coefficient k ′ is k ′ = (ba) / (64) ^γ (6).

In the remapping processor 31 of the adjusting mechanism 30,
The gradation upper limit value and the gradation lower limit value at the time when the γ curve is remapped as described above are held as peak values for γ curve correction, and further, as will be described later, The peak value for γ curve correction is held as the current peak because it is used as a reference for comparison. The peak value for γ curve correction remains unchanged unless the γ curve is remapped thereafter, while the current peak is appropriately updated during comparison, as described later.

FIG. 3 shows a specific processing flow in the adjusting mechanism 30. First, the parameter detect unit 32 determines, from the video signal output from the graphics controller 10, the lowest gradation lower limit value and the gradation upper limit value of a frame for each predetermined frame (for example, every one frame, every five frames, etc.). To detect (step S10
1).

Then, the gradation lower limit value and the gradation upper limit value of the frame are transferred to the parameter processing unit 33. The parameter processing unit 33 first compares each of the gradation lower limit value and the gradation upper limit value with the current peak held in the remapping processing unit 31 at that time (step S102).
Here, with respect to the processing of the following steps S103 to S107, the same processing is performed for both the gradation lower limit value and the gradation upper limit value. Therefore, in the following description, only the gradation lower limit value is given as an example, and the description of the gradation upper limit value is omitted.

In step S102, it is determined whether or not the detected gradation lower limit value is lower than the current peak (step S103). As a result, if “No”, that is, if it is not lower than the current peak (when it is bright), after updating the current peak to the detected gradation lower limit value (step S104), the step S107 described later is performed.
Proceed to. On the other hand, the determination result in step S103 is “Yes
s ", that is, when the detected gradation lower limit value is lower than the current peak (when it is dark), similarly, after updating the current peak to the detected gradation lower limit value (step S105), the current peak is updated. It is determined whether a predetermined number of predetermined frames (for example, 5 frames) are continuous (step S106), and if the predetermined number of frames has not been reached, the process returns to step S101 and the current peak is updated by the predetermined number of frames. At the time when the number of times reaches, that is, when the lower limit value of the gradation is lower than that of the immediately preceding frame by a predetermined number of frames, the process proceeds to step S107.

In step S107, the current peak updated to the detected gradation lower limit value is updated as a peak value for γ curve correction. In other words, if the detected gradation lower limit value is higher (brighter) than before, γ
If the peak value for curve correction is immediately updated and the lower limit gradation value is lower (darker) than before, the peak value for γ curve correction is updated when that state continues for a predetermined number of frames or longer. Of. Then, the updated peak value for γ curve correction is output to the remap processing unit 31 (step S108). The above-described processing of steps S102 to S108 is performed in the same manner for the gradation upper limit value. In steps S102 to S108,
The peak value for γ correction is not necessarily updated for both the upper limit gradation value and the lower gradation limit value. For example, when one of them is the same as the current peak, or when the continuation of a state lower than the current peak is less than the predetermined number of frames, the gradation upper limit value or the gradation lower limit value is the other. Only for this, the peak value for γ correction is updated.

In the remap processing section 31, step S10
Based on the peak value for γ curve correction output in 8,
A curve remapping process is performed (step S109). When both the gradation upper limit value and the gradation lower limit value are output from the parameter processing unit 33 as the peak values for γ curve correction,
By substituting these into m and n of the above equations (4) and (5), the γ curve of the above equation (3) is obtained. In addition, the parameter processing unit 3
If either the gradation upper limit value or the gradation lower limit value is output as the peak value for γ curve correction from 3, the value is substituted for m or n in the above equations (4) and (5). On the other hand, for the other, the γ curve of the above equation (3) is obtained by substituting the peak value for γ curve correction used in the previous remapping, which is held in the remapping processing unit 31. Then, the remapping processing unit 31 performs the remapping processing in this way.
The curve data (information indicating the distribution of the display) is output to the γ correction circuit 24. The γ correction circuit 24 performs brightness correction according to the remapped γ curve.

According to the above-mentioned structure, the upper limit value and the lower limit value of the gradation displayed on the display screen of the LCD module 20 are detected, and the setting of the γ curve is remapped according to the range to thereby obtain the luminance. The distribution was dynamically remapped. This makes it possible to constantly remap to an optimum luminance distribution according to the display screen, for example, when dark screens continue, when bright screens continue. Therefore, the user can always receive a so-called high-contrast display in which it is easy to visually recognize the difference in gradation regardless of the content of the display screen. As a result, L
The display quality of the PC equipped with the CD module 20 can be improved. By the way, in the present embodiment, when the gradation upper limit value or the gradation lower limit value rises, the peak value of the γ curve is immediately changed, while the gradation upper limit value or the gradation lower limit value decreases. In some cases, the peak value of the γ curve is changed when the decrease continues for a predetermined number of frames or more. As a result, as shown in FIG. 2, when the range of the γ curve expands to the high gradation side, as in the case where the gradation upper limit value of the image shifts from n to n ′, the γ curve is immediately remapped. On the contrary, when the range expands to the lower gradation side, the γ curve is remapped when the state continues for a certain amount or more. This is because the higher the gradation value is (the higher the brightness is), the steeper the change (slope) of the brightness with respect to the change of the gradation, and the user is more likely to feel a sense of incongruity. This is because it is preferable. On the other hand, the side with low gradation value (the side with low brightness)
Since the change (gradient) of the brightness with respect to the change of the gradation is gradual, it is difficult for the user to feel a sense of discomfort, and the remap of the γ curve can be minimized to reduce the load on the memory of the PC or the like. You can do it.

By the way, in the above-mentioned embodiment, the place where the adjusting mechanism 30 is provided is not mentioned in detail, but the following four examples can be considered. As shown in FIG.
The PC sends a signal from the graphics controller 10 in a predetermined format (for example, LVDS: Low Voltage Differentia).
It is provided with a transmitter 40 for converting the signal into a signal, and a receiver 41 for receiving and decoding this signal.
On the other hand, the adjusting mechanism 30 is roughly divided into FIG.
Alternatively, as shown in FIG. 4B, when it is provided in front of the transmitter 40, as shown in FIG. 4C, when it is provided between the transmitter 40 and the receiver 41, FIG.
In some cases, the receiver 41 may be provided on the subsequent stage side as shown in FIG. Of these, when the adjusting mechanism 30 is provided on the upstream side of the transmitter 40, the transmitter 40 is configured as shown in FIG.
As shown in FIG. 4A, it may be provided outside the graphics controller 10, and as shown in FIG. 4B, it may be provided inside the graphics controller 10. As shown in FIG. 4A, when the transmitter 40 is provided outside the graphics controller 10, the adjustment mechanism 30 is set to the graphics controller 10.
It can be provided outside the device and on the upstream side of the transmitter 40. On the other hand, as shown in FIG. 4B, when the transmitter 40 is provided in the graphics controller 10, the adjustment mechanism 30 is provided in the graphics controller 10 and in the front stage of the transmitter 40.
It can be provided on the (upstream) side. In the case shown in FIGS. 4 (a) and 4 (b), the adjusting mechanism 30 takes out the signal transmitted from the transmitter 40 and performs the above-described processing. In addition, in the case of FIGS. 4A and 4B, in practice, the function of realizing the adjustment mechanism 30 may be provided in the graphics controller 10 or the transmitter 40.

Further, as shown in FIG. 4 (c), the adjusting mechanism 3
When 0 is provided between the transmitter 40 and the receiver 41, it may be provided between the graphics controller 10 and the LCD module 20. In this case, the adjusting mechanism 30 takes out the signal in the state converted and transmitted by the transmitter 40 and performs the above-described processing. As shown in FIG. 4D, when the adjusting mechanism 30 is provided on the rear side of the receiver 41, it may be provided in the LCD module 20 and between the receiver 41 and the γ correction circuit 24. In this case, the adjustment mechanism 30 performs the above-described processing on the signal received and decoded by the receiver 41. In addition, in the case of FIGS. 4C and 4D, in practice, the receiver 41 may have a function of realizing the adjustment mechanism 30. By the way, FIG. 4 (c) and (d)
In FIG. 4, an example in which the transmitter 40 is built in the graphics controller 10 is shown, but as in the case of FIG. 4A, the transmitter 40 may be provided outside the graphics controller 10.

In the above embodiment, all frames (signals) sent from the graphics controller 10 are detected, and processing for determining whether or not to remap the γ curve is performed, but the present invention is not limited to this. Not something
For example, the signal of the frame may be detected every predetermined frame or predetermined time, and the above-described processing may be performed. Further, in the above-mentioned embodiment, the γ curve is immediately remapped when the detected gradation upper limit value or gradation lower limit value rises above the current peak, but like the case where it falls below the current peak, Remapping may be performed when the state continues for a certain amount or more. Furthermore, it is possible to perform remapping when the gradation upper limit value or gradation lower limit value changes (rises or falls) by a certain amount or more with respect to the current peak. By the way, in the above-described embodiment, the detected gradation upper limit value and gradation lower limit value are compared with the current peak, but the present invention is not limited to this, and the γ-curve correction held in the remapping processing unit 31 is performed. It is also possible to use the peak value for the comparison as a reference for comparison.

By the way, in the above-described embodiment, the above-described processing is performed on the entire display area of the LCD panel 21. On the other hand, it is also possible to display a window in a part of the display area and perform the above processing only within that window. In such a case, the OS notifies the video driver of information about the size of the window that defines the position of the window and the coordinates of the start point. Therefore, within the range of the window based on the information that the video driver has. It suffices to extract the gradation upper limit value and the gradation lower limit value and perform the above-mentioned processing with respect to these. Further, although the adjusting mechanism 30 is configured to detect the video signal output from the graphics controller 10 by the parameter detecting section 32, the present invention is not limited to this, and the parameter from a driver such as a DVD-ROM or a DVD-RAM is used. It is also possible that the processing unit 33 directly receives the video signal and performs the same processing as described above.

In the above embodiment, the LCD module 20 is taken as an example of the display device, but the present invention can be similarly applied to other types of display devices such as a CRT. In addition, it goes without saying that the same technique as that of the above-described embodiment can be applied not only to the PC but also to other display devices. Other than this, the configurations described in the above embodiments can be selected or changed to other configurations without departing from the gist of the present invention.

[0027]

As described above, according to the present invention,
The display quality can be improved by dynamically correcting the display device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a computer device in the present embodiment.

FIG. 2 is a diagram showing an example of adjusting a γ curve in an adjusting mechanism.

FIG. 3 shows a specific processing flow in the adjustment mechanism.

FIG. 4 is a diagram showing an arrangement example of an adjusting mechanism.

FIG. 5 is a diagram showing an example of a conventional γ curve.

[Explanation of symbols]

10 ... Graphics controller (data output means),
20 ... LCD module (display device), 21 ... LCD panel (display means, display panel), 22 ... Backlight, 24
Γ correction circuit, 30 adjustment mechanism (display control unit, display control device, correction control unit), 31 remap processing unit (luminance distribution determination unit), 32 parameter detection unit (signal detection unit), 33 parameter processing Part (parameter detection part),
40 ... Transmitter, 41 ... Receiver

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // G09G 3/20 641 G09G 3/20 641Q 3/36 3/36 (72) Inventor Rieko Kataoka Kanagawa 1623 Shimotsuruma, Yamato-shi 1423, Japan AIBM Co., Ltd. (72) Inventor Hiroaki Yasuda 1623-14 Shimotsuruma, Yamato, Kanagawa Japan (72) Yamato, Japan AB Inventor Masaki Kobayashi 1623 Shimotsuruma, Yamato-shi, Kanagawa 1423 Japan ABM Co., Ltd. Yamato Works (72) Inventor Yoshimasa Kiyonaya 1623 Shimotsuruma, Yamato-shi, Kanagawa 14 Japan AIBM Co., Ltd. Company's Yamato F-term (reference) 5C006 AA11 AF46 BB11 BC16 GA02 5C021 PA17 PA37 PA58 PA66 PA99 RB03 XA13 XA34 XA35 ZA01 5C058 AA06 BA05 BA08 BB25 5 C080 AA10 BB05 DD01 EE29 JJ02 JJ05 JJ07 5C082 AA01 BA34 BA35 CA11 CA81 CB01 DA51 DA87 MM10

Claims (18)

[Claims] 1. Input acceptance means for accepting an input from the outside, display means for displaying an image, and data output means for outputting data of an image to be displayed on the display means in response to an input accepted by the input acceptance means. A display control means for adjusting a luminance distribution according to a range of gradation of an image displayed on the display means. 2. The computer device according to claim 1, wherein the display control means adjusts the luminance distribution at predetermined time intervals. 3. The display control means detects the gradation range of the image displayed on the display means based on the image data output from the data output means. The computer device described. 4. The display control means detects a gradation range of an image displayed on the display means based on data of the image output from the data output means and received by the display means. The computer system according to claim 1, wherein the computer system is a computer system. 5. A device for controlling display in a display device, comprising a signal detect section for detecting a video signal for display on the display apparatus, and an image based on the video signal detected by the signal detect section. A parameter detection unit that detects a parameter, based on the parameter detected by the parameter detection unit, determines the distribution of display brightness in the display device,
A display control device, comprising: a brightness distribution determination unit that outputs information indicating the determined display brightness distribution to the display device. 6. The display according to claim 5, wherein the parameter detection unit detects, from the video signal for each frame displayed on the display device, a gradation range in the frame as the parameter. Control device. 7. The brightness distribution determination unit outputs information indicating the distribution of the display brightness to the display device when a change in the parameter detected by the parameter detection unit continues for a certain period or longer. The display control device according to claim 5. 8. The brightness distribution determination unit outputs information indicating the distribution of the display brightness to the display device when the amount of change in the parameter detected by the parameter detection unit is equal to or more than a certain amount. The display control device according to claim 5. 9. A display panel for displaying an image, a γ correction circuit for performing γ correction of the display panel, and a parameter of an image displayed on the display panel,
And a correction control unit that dynamically performs γ correction of the display panel in the γ correction circuit. 10. The correction control unit corrects the brightness corresponding to the upper limit value and the lower limit value by a predetermined function, based on the upper limit value and the lower limit value of the gradation of the image displayed on the display panel. The display device according to claim 9, wherein: 11. The function defines a luminance L corresponding to a gradation X between the upper limit value and the lower limit value as L = k ′ · X ^γ + a (where k ′ = (b−a) / (S ^γ ), A = k · m ^γ , b = k · n ^γ , k = 100 / (S ^γ ), S is the number of gradations displayed on the display panel, and m is the floor of the image displayed on the display panel. 11. The display device according to claim 10, wherein an upper limit value of the key, n is a lower limit value, and γ is a predetermined coefficient). 12. The display device according to claim 9, wherein the correction control unit executes γ correction when an upper limit value of gradation of an image displayed on the display panel rises. 13. The correction control unit executes the γ correction when the lower limit value of the gradation of the image displayed on the display panel continues for a certain amount or more. Display device. 14. A method for controlling a display device, comprising: detecting a video signal for display on the display device; detecting a parameter of an image based on the detected video signal; Based on the detected parameters, a determining step of determining a distribution of display luminance in the display device, and an adjusting step of adjusting the display luminance of the display device based on the determined distribution of display luminance, A method for controlling a display device having a feature. 15. The detecting step detects the parameter at predetermined intervals, and the adjusting step adjusts the display brightness when the detected parameter changes. A method for controlling the display device described. 16. The method of controlling a display device according to claim 15, wherein in the adjusting step, the display brightness is adjusted when a variation amount of the detected parameter is equal to or more than a certain amount. 17. The detecting step detects an upper limit value and a lower limit value of the gradation of the image as the parameter, and the determining step has a constant variation in one or both of the upper limit value and the lower limit value. When the above is continued, the distribution of the display luminance is adjusted, and when the variation is an increase, the time until the distribution of the display luminance is adjusted is changed. 16. The method for controlling a display device according to claim 15, wherein the time until the distribution is adjusted is set to be long. 18. A computer program executed by a control device for controlling a display device, comprising: a process of detecting a video signal for displaying on the display device; and a parameter of an image based on the detected video signal. Detecting process, based on the detected parameter, a process of determining a display brightness distribution in the display device, a process of adjusting the display brightness of the display device based on the determined display brightness distribution, A computer program having: