JP5322322B2 - Aperture control circuit, projector apparatus, aperture control program, and aperture control method - Google Patents

Description

    The present invention relates to an aperture control circuit, a projector device, an aperture control program, and an aperture control method that control the amount of light output in accordance with an input video signal.

    In the projector device, the light amount from the light source is modulated using a light modulation element in accordance with the input video signal, and the output light amount is changed to display an image based on the video signal. It is difficult to ensure the required contrast ratio only by the light modulation rate of the light modulation element. There is a technique for controlling the amount of light input to the light modulation element or the amount of light output from the light modulation element in order to compensate for the insufficient light modulation rate and increase the contrast ratio. The control of the amount of light is realized by an optical system that combines a lens and a diaphragm and a control unit that adjusts the aperture ratio of the diaphragm (see, for example, Patent Document 1).

JP 2005-099299 A

However, in the technique according to Patent Document 1, the amount of light to be output is adjusted according to the input video signal, but it is shown that the input video signal is determined using a peak level, an average level, or the like. . Suppose a case where an image including a white image in the center with a black background is output. When the peak level is used as a determination condition, if there is even a white region, the light is output without limiting the amount of light regardless of the area of the white region, and the luminance of the black region increases. As described above, when the peak level is set as a determination condition, when the area of the white region is small, the image has a reduced contrast.
Further, when the average level is used as a determination condition, the amount of light changes according to the area of the white region. In other words, when the area of the white area decreases, the amount of light decreases according to the area of the white area, and the brightness of the black area can be reduced, but the brightness of the white area also decreases extremely and the contrast decreases. Become an image. As described above, when the average level is set as the determination condition, the brightness of the background and the image changes due to the change of the area in an image having a large difference in luminance. In the determination using the peak level and the average level as the determination conditions, there is a problem that the video signal cannot be properly determined, the light amount cannot be secured at an appropriate value, and the image quality is deteriorated.

    The present invention has been made to solve the above problems, and its object is to provide an aperture control circuit, a projector device, an aperture control program, and an aperture control circuit that ensure an appropriate value of the amount of light output corresponding to an input video signal. It is to provide an aperture control method.

In order to solve the above-described problem, the present invention displays an image based on the video signal when the amount of light output according to the information indicating the brightness of the input video signal is limited using a diaphragm. in the image, the wider breadth of bright regions than the brightness determined in advance is determined in advance, if it is determined based on the number of pixels included in the brightness distribution and the light areas of the image signal, opens the throttle portion When the degree is open and it is determined that the area is not wider than a predetermined area, the opening degree of the diaphragm unit corresponding to the peak value of the histogram indicating the brightness distribution of the video signal is adjusted. An aperture control circuit including a control unit for performing the control.

According to the present invention, the aperture control circuit limits the amount of light output by the control unit according to the information indicating the brightness of the input video signal using the aperture unit. At that time, the control unit determines that in the image displayed based on the video signal, the area that is brighter than the predetermined brightness is wider than the predetermined area. When it determines based on the number of, it adjusts which raises the opening degree of a throttle part.
Thus, the aperture control circuit allows the control unit to open the aperture of the aperture unit to the open side when an area brighter than the predetermined brightness is wider than the predetermined size in the image displayed based on the video signal. Since the adjustment is performed, it is possible to ensure an appropriate value of the amount of light output corresponding to the input video signal.

It is a schematic block diagram of the projector apparatus by this embodiment. FIG. 3 is a block diagram of a control system that controls the amount of light output in the projector device according to the embodiment. It is a figure which graphs and shows the histogram analysis result in the same embodiment. It is a figure which shows the result of having performed the histogram analysis about the image different from FIG. 3 in the embodiment. It is a figure which shows the aperture position table which shows the aperture position according to the luminance peak in the embodiment. It is a figure which shows the example of an image with a big luminance change in the same embodiment. It is a figure which shows the histogram of the result of having performed the histogram process with respect to the figure shown in FIG. 6 in the embodiment.

Hereinafter, a projector device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram of the projector apparatus according to the present embodiment.
The projector device 100 receives a video signal from the video output device 200 connected thereto, and modulates and outputs the intensity of light to be output based on the input video signal.
The projector device 100 shown in this figure includes a light source 110, an aperture unit 120, a spatial light modulator 130, a projection lens 140, an image processing unit 150, and an aperture drive unit 160.

    The light source 110 is a light source that outputs light projected from the projector device 100, and is, for example, a lamp or an LED (Light Emitting Diode). The aperture unit 120 adjusts the amount of light from the light source by blocking a part of the optical path of the light output from the light source 110. The aperture unit 120 can set the range of shielding the optical path in stages, and in this embodiment, 100 stages can be set, and the amount of light output can be adjusted according to the setting. Is possible. The spatial light modulator 130 adjusts the amount of light and polarization of the light output from the light source 110, and modulates the intensity of the output light with the input video signal. Examples of optical elements constituting the spatial light modulator 130 include a liquid crystal display element and a digital mirror device (DMD). The projection lens 140 is a member that includes a lens for forming an image projected on the screen by an output light.

The video processing unit 150 controls the range of shielding the optical path in the aperture unit 120 based on the video signal input from the video output device 200 to cause the aperture unit 120 to adjust the light shielding amount and The intensity modulation of the light in the light modulator 130 is controlled to cause the spatial light modulator 130 to adjust the intensity modulation of the light forming the image.
The aperture driving unit 160 outputs a drive signal for driving the motor 122 of the aperture unit 120 in accordance with the motor control signal output from the video processing unit 150.

FIG. 2 is a block diagram of a control system that controls the amount of light output from the projector apparatus.
The projector apparatus 100 shown in this figure includes an aperture unit 120, a spatial light modulator 130, an image processing unit 150, and an aperture drive unit 160 as a control system that controls the amount of light to be output. The same components as those in FIG.

The aperture unit 120 includes an aperture 121 and a motor 122.
The diaphragm 121 is a main part of an “aperture” that adjusts the light output from the light source 110 (FIG. 1). The diaphragm 121 is composed of a plurality of movable wings mechanically interlocked with the shaft of the motor 122, and the movable wing operates according to the rotation of the motor 122, and the aperture (opening ratio) of the diaphragm corresponding to the diaphragm position is determined. .
The motor 122 controls the opening degree of the diaphragm 121. The motor 122 is driven according to the control amount input from the aperture driving unit 160, and the rotation of the rotation shaft is transmitted to operate the movable wings of the aperture 121 to adjust the opening degree of the aperture 121. Further, it is assumed that the motor 122 stores a motor rotation position corresponding to the aperture position indicating the opening degree of the aperture 121.

The video processing unit 150 in the projector device 100 includes a scaling processing unit 151, a spatial light modulator drive processing unit 152, a histogram acquisition unit 153, a memory unit 154, and an aperture control unit 155.
In the video processing unit 150, the scaling processing unit 151 performs a process of converting into a signal having a resolution necessary for internal processing according to the resolution of the input video signal. The scaling processing unit 151 generates a synchronization signal synchronized with the timing of the input video signal, and performs sampling processing of the input video signal according to the synchronization signal according to the synchronization signal. The scaling processing unit 151 performs scaling conversion for converting to a predetermined resolution based on the sampled information.
The spatial light modulator drive processing unit 152 outputs a signal for driving the liquid crystal display element (or DMD) constituting the spatial light modulator 130 based on the signal converted by the scaling processing unit 151.

The histogram acquisition unit 153 acquires a histogram generated according to the brightness of the video signal input from the video output device 200. The brightness of the video signal is represented by a luminance level, and is represented as a gradation value in a digital signal converted into a discrete value.
The histogram analysis in the histogram acquisition unit 153 acquires the luminance level distribution in units of one field of the image. In the example shown in the present embodiment, the histogram acquisition unit 153 performs analysis by dividing the luminance level into 16 values, and values from H ₀ to H ₁₅ as histogram information from the histogram classified according to the luminance level (FIG. 3). To get. The histogram acquisition unit 153 outputs the obtained histogram information to the aperture control unit 155.
The memory unit 154 stores predetermined data such as table information referred to in the conversion process and threshold information used as a reference in the determination process, and a storage area for temporarily storing variables referred to in the arithmetic process or the like. It is the memory | storage part arrange | positioned. The memory unit 154 stores a program for operating the computer included in the aperture control unit 155.
The aperture control unit 155 acquires histogram information from the histogram acquisition unit 153, refers to data stored in the memory unit 154, outputs a motor control signal to the aperture drive unit 160, and controls each unit of the projector device 100. To do. Further, the aperture control unit 155 acquires the aperture position of the aperture 121 in that state from the information on the motor rotation position input from the aperture drive unit 160.

    The aperture driver 160 receives the motor control signal output from the aperture controller 155 and controls the rotation direction and rotation speed of the motor 122. In addition, the aperture driving unit 160 refers to the motor rotation position stored in the motor 122 for referring to the aperture position of the aperture 121 and inputs the motor rotation position to the aperture control unit 155.

A method for controlling the diaphragm 121 according to the present embodiment will be described with reference to the drawings.
First, the histogram analysis performed by the histogram acquisition unit 153 in the present embodiment will be described.
FIG. 3 is an example in which the histogram analysis results are graphed.
The horizontal axis of this figure indicates the luminance level of the video signal, and the brighter the level is on the right side. The vertical axis indicates the frequency included in the luminance level range, that is, the number of pixels. For example, when the luminance level of the video signal is 8-bit processing, H ₀ is an integrated value of luminance levels 0 to 15, and after H ₁ is an integrated value of a luminance level having a large value by 16 each. Here, specifically, in the case of an 8-bit video signal, H ₀ to H ₁₅ indicate integrated values in the following range.

H ₀ = integrated value of luminance levels 0 to 15 in one field,
H ₁ = 1 integrated value of luminance levels 16 to 31 in one field,
Integrated value of luminance levels 32 to 47 in H ₂ = 1 field,
H ₃ = integrated value of luminance levels 48 to 63 in one field,
H ₄ = integrated value of luminance levels 64 to 79 in one field,
H ₅ = integrated value of luminance levels 80 to 95 in one field,
H ₆ = 1 integrated value of luminance levels 96 to 111 in one field,
H ₇ = integrated value of luminance levels 112 to 127 in one field,
H ₈ = integrated value of luminance levels 128 to 143 in one field,
H ₉ = integrated value of luminance levels 144 to 159 in one field,
Integrated value of luminance levels 160 to 175 in H ₁₀ = 1 field,
Integrated value of luminance levels 176 to 191 in H ₁₁ = 1 field,
Integrated value of luminance levels 192 to 207 in H ₁₂ = 1 field,
H ₁₃ = 1 integrated value of luminance levels 208 to 223 in one field,
H ₁₄ = integrated value of luminance levels 224 to 239 in one field,
H ₁₅ = 1 integrated value of luminance levels 240 to 255 in one field

When the threshold value for determining the brightness is set to “160”, the region lower than the value (from H ₀ to H ₉ ) is determined as the dark determination level 301 and the region higher than the value (H ₁₀ to H _15). Is determined to be the bright determination level 302.
Histogram acquisition unit 153 in the H ₀ of the histogram of H _15, most, selected more range of luminance levels of the luminance distribution. The range of the luminance level having a large luminance distribution is a range of the luminance level showing the highest value in the bar graph in the histogram analysis result. In the case of FIG. 3, it is the range of the luminance level of H ₅ indicated as the luminance peak 303. Hereinafter, the range of the luminance level having a large luminance distribution is referred to as “luminance peak”.
FIG. 4 is a diagram illustrating a result of histogram analysis performed on an image different from that in FIG.
In this figure, histogram analysis is performed under the same conditions as in FIG. 3, and the same coordinate axes are defined. The luminance peak in the case of FIG. 4 is a range of the luminance level of H ₁₃ shown as the luminance peak 401.

Subsequently, control of the diaphragm 121 based on the histogram analysis result will be shown.
The histogram acquisition unit 153 generates a histogram based on the brightness information of the input video signal. The aperture control unit 155 outputs a control signal to the aperture drive unit 160 based on the histogram information detected by the histogram acquisition unit 153, drives the motor 122, and drives the aperture 121. The aperture control unit 155 basically throttles the aperture 121 when it is determined that the darkness determination level 301 is in a region (from H ₀ to H ₉ ) where the luminance peak is lower than the threshold value in the histogram of the input video signal. The diaphragm 121 is opened when it is determined that the brightness determination level 302 in the region (from H ₁₀ to H ₁₅ ) where the luminance peak is higher than the threshold value in the histogram.

Here, the aperture control unit 155 defines an aperture position table that determines the aperture of the aperture 121, that is, the aperture position to be controlled, according to the histogram information.
FIG. 5 is a diagram showing an aperture position table showing aperture positions according to luminance peaks.
In the aperture position table shown in this figure, the aperture position can be referred to using the luminance peak as a key. The luminance peak is as shown in FIG. The aperture position indicates a state where the aperture 121 is fully opened when the aperture position is 100, and a state where the light amount of the light source 110 is output to the 100% spatial light modulator 130. Further, when the aperture position is 10, the state where the aperture 121 is stopped is shown so that the amount of light transmitted to the spatial light modulator 130 becomes 10% of the state where the aperture 121 is fully opened.

In the example shown in the present embodiment, aperture control is performed using aperture positions set in 100 stages according to the luminance peak. That is, the aperture controller 155, the luminance peak be any of _{H 15} from _{H 10,} the diaphragm position is "100". If the luminance peaks at H _9, the diaphragm position is "90". Similarly, the aperture control unit 155 selects a smaller aperture position value as the luminance decreases, and sets the aperture position to “1” if the luminance peak with the lowest luminance is H ₀ .
Here, the aperture position “100” indicates an open state, the aperture position “10” indicates a state in which the aperture 121 is stopped and 10% of light is transmitted, and the aperture opening degree is 10%.

In the control of the aperture 121 performed by the aperture controller 155, it is first determined whether the aperture is to be reduced or not with reference to the table of FIG. Basically, it is determined whether the luminance peak is in a bright direction or a dark direction. In the example shown in the present embodiment, as shown in FIG. 3, when the luminance peak is at the light determination level 302, the aperture is opened, and when the luminance peak is at the dark determination level 301, the aperture is reduced.
In FIG. 3, since the luminance peak 303 exists at the dark judgment level 301, the diaphragm is in a narrowed state. For example, in the case of the histogram characteristics of Figure 3, the brightness peak 303 is at H _5, throttle opening degree and referring to FIG. 5 will be 50%.
On the other hand, in the case of the histogram characteristics shown in FIG. 4, the luminance peak 401 is H _13, stop because of the bright determination level is opened.

FIG. 6 is a diagram illustrating an example of an image having a large luminance change. As shown in this figure, a part of the screen with a black background shows an image having a high luminance area such as a circle indicated by reference numeral 602. For example, a model of an image when a night sky moon is photographed.
FIG. 7 is a diagram illustrating a histogram obtained as a result of performing histogram processing on the diagram illustrated in FIG. 6. The coordinate axes in this figure are the same as those in FIGS. A graph 701 corresponds to a black region in the background, and a graph 702 corresponds to a region 602 indicated by a high-luminance circle.

Assuming that the aperture control unit 155 selects the aperture opening with reference to the table shown in FIG. 5, the luminance peak is H ₀ , so “1%” is selected as the aperture opening. For this reason, even in the portion 602 where the luminance is high, the amount of light is uniformly reduced to 1% with respect to the fully open state. Therefore, the luminance of the white region is shown with 1% of light amount with respect to the fully open state. It will fall to the brightness. In an image displayed in this state, the visual contrast is significantly reduced.

In the case of an image in which a high-brightness portion having a certain area or more exists on a black background like the image illustrated in FIG. 6, it is desirable to open the diaphragm in order to ensure a visual contrast.
Therefore, a control procedure for obtaining a good image even when an image as shown in FIG. 6 is displayed will be described. A process based on the determination of the brightness of the image shown below is added to the procedure described above.
In the process to be added, the aperture control unit 155 takes a value in which the ratio of the pixels whose brightness is equal to or higher than a predetermined threshold to all the pixels corresponding to the input video signal is larger than a predetermined value. In the case shown, the opening degree of the diaphragm 121 is adjusted to be increased.

Below, the concrete method is demonstrated.
First, a peak detection area for extracting a region with relatively high luminance is defined, and an area occupied by a region determined to be a bright region is detected. The aperture control unit 155 uses the peak detection area for determination, specifies a range indicated by a luminance higher than a predetermined threshold value, and refers to a histogram value included in the determination range corresponding to the threshold value. Thus, the range of the peak detection area is determined in advance.
In the present embodiment, the aperture control unit 155 predetermines the threshold used for determination as “208”, and sets the peak detection area in the range from H ₁₃ to H ₁₅ . The aperture control unit 155 calculates the integrated value of the peak detection area as a peak detection value using the formula (1).

    The aperture control unit 155 calculates a peak ratio indicating a ratio of pixels detected as a peak detection area in all the pixels based on the peak detection value obtained in Expression (1) using Expression (2).

    Here, the aperture control unit 155 calculates the total number of pixels using Expression (3).

    In addition, the diaphragm control unit 155 opens the diaphragm 121 when the condition shown in Expression (4) is satisfied according to the calculated peak ratio. In addition, the threshold value of the peak ratio used for the determination to switch the aperture 121 to the full opening is determined in advance.

    As illustrated in FIG. 7, the aperture control unit 155 determines that a signal included in a range defined as the peak detection area 703, that is, a signal having a luminance higher than a predetermined threshold is a signal having a high luminance. In addition, the diaphragm control unit 155 can determine according to the peak ratio how much area the image indicates by the area indicated by the signal having a higher luminance than the predetermined threshold. If the result of the determination indicates that the area indicated by the signal having a higher luminance than the predetermined threshold is large, the aperture control unit 155 switches the aperture to the open position.

    When the ratio of the area in which the brightness is equal to or higher than the predetermined threshold is greater than the predetermined value by the determination processing according to the expressions (1) to (4) described above, the aperture control unit The projector device 100 can perform display using a sufficient amount of light by performing control to increase the opening degree of the diaphragm 121 and opening the diaphragm 121.

The aperture control unit 155 in the embodiment of the present invention is displayed based on the video signal when the amount of light to be output is limited using the aperture 121 according to information indicating the brightness of the input video signal. When it is determined based on the brightness distribution of the video signal and the number of pixels included in the bright area that the area brighter than the predetermined brightness is wider than the predetermined area in the image, the opening of the aperture 121 Make adjustments to increase.
As a result, in the image displayed on the basis of the video signal, the video processing unit 150 allows the aperture control unit 155 to increase the aperture of the aperture when the region brighter than the predetermined brightness is wider than the predetermined size. Since the adjustment is made to the open side, an appropriate value of the output light amount can be ensured in correspondence with the input video signal.

In addition, the aperture control unit 155 according to the embodiment of the present invention has a value in which the ratio of the area where the brightness is equal to or higher than a predetermined threshold to the area indicated by the input video signal is larger than a predetermined value. Is adjusted to increase the opening of the aperture 121.
Thereby, the video processing unit 150, when the ratio of the area in which the brightness is equal to or higher than a predetermined threshold with respect to the area indicated by the input video signal is larger than a predetermined value, Since the aperture control unit 155 performs adjustment to increase the opening degree of the aperture 121, it is possible to ensure an appropriate value of the amount of light output corresponding to the input video signal.
In the video processing unit 150, the aperture control unit 155 performs processing for detecting a target area as an area.

In addition, the aperture control unit 155 according to the embodiment of the present invention has a value in which the ratio of the area where the brightness is equal to or higher than a predetermined threshold to the area indicated by the input video signal is larger than a predetermined value. Is adjusted so that the aperture 121 is opened.
As a result, the diaphragm control unit 155 performs adjustment to open the diaphragm 121, so that an appropriate value of the output light amount can be ensured in correspondence with the input video signal. Even if the input image has a large luminance difference, the necessary amount of light can be secured.

Further, the aperture control unit 155 in the embodiment of the present invention shows the distribution of brightness of the video signal with respect to the aperture 121 in a histogram and adjusts the aperture of the aperture 121 associated with the peak value of the histogram.
Thereby, the aperture control unit 155 adjusts the opening degree of the aperture 121 associated with the peak value of the histogram, so that an appropriate value of the output light amount is ensured in correspondence with the input video signal. can do. Since the input image can be determined by histogram processing, the processing load can be reduced.

In addition, the diaphragm control unit 155 according to the embodiment of the present invention sets a correspondence table that associates the histogram with the opening degree of the diaphragm 121 for the diaphragm 121, and adjusts the opening degree of the diaphragm 121 corresponding to the peak value of the histogram.
Thereby, the aperture control unit 155 refers to the correspondence table and adjusts the opening degree of the aperture 121 corresponding to the peak value of the histogram, so that the appropriate amount of light to be output is associated with the input video signal. The value can be secured. The processing load can be reduced according to the determination result by the histogram processing according to the input image.

In the aperture control unit 155 according to the embodiment of the present invention, the ratio of the pixels whose brightness is equal to or higher than a predetermined threshold to all the pixels corresponding to the input video signal is larger than a predetermined value. When the value is indicated, adjustment to increase the opening degree of the diaphragm 121 is performed.
As a result, when the aperture control unit 155 shows that the ratio of the pixels whose brightness is equal to or higher than a predetermined threshold to all the pixels corresponding to the input video signal is larger than a predetermined value. Since the adjustment for increasing the opening degree of the diaphragm 121 is performed, it is possible to ensure an appropriate value for the amount of light output in correspondence with the input video signal.

Further, the aperture control unit 155 according to the embodiment of the present invention has a value in which the number of pixels whose brightness is equal to or greater than a predetermined threshold for all the pixels corresponding to the input video signal is larger than a predetermined value. Is adjusted to increase the opening of the aperture 121.
Thereby, the aperture control unit 155 reduces the aperture when the number of pixels whose brightness is equal to or greater than a predetermined threshold value for all the pixels corresponding to the input video signal is greater than a predetermined value. Since the adjustment for increasing the opening degree of 121 is performed, it is possible to ensure an appropriate value of the amount of light output corresponding to the input video signal.

    The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention. In the video processing unit 150 of the present invention, the level detection cycle can be set to a frame cycle or a time longer than the frame cycle in addition to being performed in synchronization with the field cycle. .

    The projector apparatus 100 described above has a computer system inside. The above-described aperture position control process is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

100 Projector device 121 Aperture (aperture part)
150 Video processor (aperture control circuit)
155 Aperture control unit (control unit)

Claims (8)

When the amount of light output according to the information indicating the brightness of the input video signal is limited using the diaphragm, an area brighter than a predetermined brightness is previously displayed in the image displayed based on the video signal. If broader than breadth defined, if it is determined based on the number of pixels included in the brightness distribution and the light areas of the image signal, to open the opening of said throttle portion, the wide the area is predetermined A diaphragm control unit that adjusts the aperture of the diaphragm associated with the peak value of the histogram indicating the brightness distribution of the video signal when it is determined that the brightness is not wider than circuit. Before Symbol control section is,
When the ratio of the area where the brightness is equal to or higher than a predetermined threshold to the area indicated by the input video signal is larger than a predetermined value, the opening of the aperture is opened. aperture control circuit according to claim 1, characterized in that. The controller is
With respect to the throttle portion, sets a correspondence table that associates the opening of the narrowed portion and the histogram, and wherein the throttling the opening degree of the throttle portion to the opening of the throttle portion corresponding to the peak value of the histogram The aperture control circuit according to claim 1 or 2 . Before Symbol control section is,
When the ratio of the pixels whose brightness is equal to or higher than a predetermined threshold to all the pixels corresponding to the input video signal is larger than a predetermined value, the opening degree of the diaphragm unit is set. The aperture control circuit according to claim 1, wherein the aperture control circuit is opened . Before Symbol control section is,
When the number of pixels whose brightness is equal to or greater than a predetermined threshold for all the pixels corresponding to the input video signal is greater than a predetermined value, the aperture of the aperture is opened. The aperture control circuit according to claim 1, wherein: When limiting the amount of light to be output according to information indicating the brightness of the input video signal using the aperture unit, in the image displayed based on the video signal, an area brighter than a predetermined brightness is If broader than the predetermined is wide, if it is determined based on the number of pixels included in the brightness distribution and the light areas of the image signal, to open the opening of said throttle portion, said regions are defined in advance A projector that adjusts the aperture of the diaphragm associated with the peak value of the histogram indicating the brightness distribution of the video signal when it is determined that the brightness is not wider than apparatus. When limiting the amount of light to be output according to information indicating the brightness of the input video signal using the aperture unit, in the image displayed based on the video signal, an area brighter than a predetermined brightness is If broader than the predetermined is wide, if it is determined based on the number of pixels included in the brightness distribution and the light areas of the image signal, to open the opening of said throttle portion, said regions are defined in advance A diaphragm control for causing the computer to execute a procedure for adjusting the opening of the diaphragm unit associated with the peak value of the histogram indicating the brightness distribution of the video signal when it is determined that the brightness is not wider than program. When limiting the amount of light to be output according to information indicating the brightness of the input video signal using the aperture unit, in the image displayed based on the video signal, an area brighter than a predetermined brightness is If broader than the predetermined is wide, if it is determined based on the number of pixels included in the brightness distribution and the light areas of the image signal, to open the opening of said throttle portion, said regions are defined in advance Adjusting the aperture of the aperture associated with the peak value of the histogram indicating the brightness distribution of the video signal when it is determined that the aperture is not wider than the width. Method.

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