JP3515042B2 - Image display device and image signal correction device - Google Patents

Image display device and image signal correction device

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Publication number
JP3515042B2
JP3515042B2 JP2000112634A JP2000112634A JP3515042B2 JP 3515042 B2 JP3515042 B2 JP 3515042B2 JP 2000112634 A JP2000112634 A JP 2000112634A JP 2000112634 A JP2000112634 A JP 2000112634A JP 3515042 B2 JP3515042 B2 JP 3515042B2
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Prior art keywords
signal
image
input
luminance
output
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JP2001296855A (en
Inventor
成継 岡本
道幸 杉野
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シャープ株式会社
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Priority to JP2000112634A priority Critical patent/JP3515042B2/en
Priority claimed from US09/835,194 external-priority patent/US7170477B2/en
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Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a display unit (display device).
Image display device with a function to adjust the output brightness of
And a display image signal correction device. [0002] 2. Description of the Related Art Conventionally, an image display device has
Gamma correction or luminance correction corresponding to the image signal has not been performed.
You. Gamma correction refers to the difference between the input signal and the output luminance of the image display device.
Degree characteristics (change of output luminance with respect to change of input signal; gun)
(Referred to as the “ma-characteristic”). like this
Correction allows you to adjust the brightness, color (chromaticity), contra
By adjusting the strike ratio, an image almost equal to the input original image
Can be displayed. Also, for the input original image
Display the image with the contrast ratio adjusted.
The display quality can be freely adjusted. [0003] Gamma correction technology for liquid crystal display devices
Japanese Patent Application Laid-Open No. 10-126648 discloses an input analog.
Image signal with an AD (analog-digital) converter.
Gamma correction to convert to digital signal and then gamma correct
In the positive circuit, the input analog image signal is
The boost selected for the frontage (analog input voltage range)
After being amplified by width, converted to digital signal by AD converter
And then determine the parameters defined in connection with the amplification selection information.
Gamma correction circuit that performs gamma correction using the gamma correction characteristics
Is disclosed. In this configuration, the change in the number of bits is small.
Gamma correction can be performed over a wide band with high accuracy
Required to perform gamma correction over a wide band and with high accuracy.
It is possible to reduce the cost of necessary circuits. [0004] Japanese Patent Application Laid-Open No. 5-64037 discloses that
Input voltage-output based on transmittance characteristics measured with a luminance meter
In order to linearize the function representing the brightness characteristics,
Calculate the adapted gamma correction curve and obtain the obtained gamma correction song
For each signal of R (red), G (green), B (blue) using the line
Gamma correction circuit that performs appropriate gamma correction processing
Have been. Further, a CRT (cathode ray tube) display device is disclosed.
Japanese Patent Laid-Open No. 145942/1993
In the gazette, gamma characteristics of each color of RGB of a CRT display device are described.
The RGB signal is measured by using the measured gamma characteristic.
Color correction so that the luminance ratio of each level is constant
Both disclose performing gamma correction. Also, the brightness of a color light source for a liquid crystal display is high.
Japanese Patent Application Laid-Open No. 1-158416 (Japanese Patent Application
Japanese Patent Publication No. Hei 7-109456) discloses that RGB is
Color balance due to reduced relative luminous efficiency of each color
To prevent the appearance of collapse,
First brightness adjustment for commonly adjusting the brightness level of the optical element group
Means, and the brightness level adjusted by the first brightness adjusting means.
Depending on the bell, a green light emitting element group, a red light emitting element group,
Of luminance level between light emitting element groups for blue and blue
And a second brightness adjusting means for adjusting the brightness.
Have been. [0007] Conventionally, a CRT display device usually has an inverted
A gamma-corrected image signal is input.
You. Inverse gamma correction refers to the light intensity of the original image and the image display device.
In order to make the luminance of each pixel proportional to
Non-linear relationship representing input signal-output luminance characteristics (gamma characteristics)
The image signal is corrected using an inverse function of the number. C
A non-linear function representing the gamma characteristic of an RT display device is represented by an exponential function.
Exponents that can be approximated by numbers and are called gamma values
The value is usually on the order of about 2.2. Therefore, CRT
The display device usually has a gamma value of a CRT display device of 2.
2, the image signal subjected to the inverse gamma correction is input.
It is. [0008] Generally, different manufacturers
Average input luminance in two CRT displays D and E
Signal level (average luminance signal of the entire screen of the input image signal
Level) Gamma value γ (G) for G and maximum output brightness
Degree imax FIG. 10 shows the result of measuring the change in (G).
In addition, among the curves shown in FIG.
Curve representing the gamma value γ (G) of the CRT display device D of FIG.
The curve indicated by E is the gamma value γ of the other CRT display device E.
A curve representing (G), imaxThe curve indicated by D is the CRT display
Maximum output luminance i of device Dmax A curve representing (G), imax E
Is a maximum output luminance i of the CRT display device E.
maxIt is a curve showing (G). Also, the average input luminance signal
The level G is a relative value that represents the maximum value as 100%.
And the maximum output luminance is standardized so that the maximum value is 1.
Value. From the measured data shown in FIG.
Most of the power luminance signal level G is within a certain range.
In the input image, the maximum output luminance imax (G) and gamma
The value γ (G) is almost constant, but is outside the range.
In an input image having a high average input luminance signal level G, the maximum
Output luminance imax(G) is reduced
You. According to FIG. 10, the average input luminance signal level
When G is about 60%, the actually measured gamma
The value γ (G) is also about 2.2. So this
Occasionally, a CRT display device converts an input image signal into a line.
Shaped image, that is, original image before inverse gamma correction
The image (captured image) is reproduced faithfully. However, the average input luminance signal level G
Is lower than about 60% or higher than about 60%
The gamma value γ (G) of the image output of the CRT display device
Does not show 2.2, the linearization process is not complete and the original
A display faithful to an image (captured image) cannot be obtained. However, according to the study by the present inventors,
With such display characteristics, the average input luminance signal level
Is low, as shown in FIG.
Input signal-output luminance characteristics that are relatively raised
Therefore, the display advantage that the visibility of the dark area is improved is obtained.
I knew it could be done. According to the study by the inventors of the present invention,
With such display characteristics, the average input luminance signal level is high.
In this case, as shown in FIG.
In contrast, the input signal-output luminance characteristics
Since the output brightness of the entire screen relatively decreases,
In areas where there is no whitening, you can also feel the glare
It was found that the visibility was improved without being fogged. According to such display characteristics of the CRT display device,
It is said that the visibility of the image on the display is improved.
That is not generally recognized. Note that not all
CRT display devices do not exhibit such display characteristics.
However, in a general CRT display device, a CRT display device is used.
Eye to prevent CRT burnout due to specific drive current increase
To limit the increase in drive current due to the increase in display brightness
(Automatic brightness limiting circuit)
Such a display characteristic is usually exhibited. [0015] On the other hand, backlights and the like
And a light switching element such as a liquid crystal panel.
Display device such as a liquid crystal display device
When the image signal is reproduced on the display device, the maximum
The luminance is generally determined by the output of the light emitting element, and the input signal minus the output
Luminance characteristics are largely determined by the characteristics of the optical switching element.
You. The maximum brightness of the display image and the input signal-output brightness characteristics
Are independent of each other. And a table like this
FIG. 1 shows a measurement result in the case of a liquid crystal display device.
As is clear from FIG. 1, the maximum output luminance in the display image
imax (G) and non-linearity representing input signal-output luminance characteristics
Exponential value (gamma) when the function is approximated by an exponential function
Value) γ (G) is the average input luminance signal level of the input image
G (substantially equal to the input luminance signal level H of the background portion)
Not constant. Here, a table of the above-mentioned consumer CRT display device is shown.
Display characteristics (luminance characteristics) and the display of such a liquid crystal display device
Characteristics (luminance characteristics) were compared subjectively by the inventor of the present application.
At the same time, in terms of the naturalness of image quality, CRT display devices
It is somewhat desirable to have such display characteristics (luminance characteristics)
I found something new. FIG. 11 shows a liquid crystal display in a liquid crystal display device.
The signal processing circuit inside the display
Correction and correction of liquid crystal voltage-optical conversion characteristics (linear characteristics
Input signal obtained as a result of performing
This shows output luminance characteristics. It has an input signal-output luminance characteristic shown in FIG.
Transmitted from a TV broadcast station to a liquid crystal display device
If an image signal that has been inversely gamma-corrected
Output brightness of the reproduced image on the display surface of the liquid crystal display device
The characteristics are as shown in FIG. In this output luminance characteristic, the normalized luminance signal level
The normalized brightness is linear in the high brightness area where the bell is 0.4 or higher.
Considerably higher than the shape characteristics. This output luminance characteristic
Then, when you see the image, the impression that the whole is floating white
The image that gives the strong
Absent. Further, the reproduction image shown in FIG.
If the output luminance characteristic, display an image with high average luminance
In such a case, the luminance is increased as a whole. for that reason,
For the viewer, the entire screen is dazzling and bright
The small difference in brightness of the part cannot be recognized enough,
Above, I get the impression that white crush has occurred. Also reverse
In addition, when displaying a dark image with low average brightness,
Although reproduced with almost linear characteristics, it is dark overall
This gives the viewer an impression that the visibility of the dark part is not sufficient. On the other hand, in a CRT display device,
Since the maximum output luminance when the average luminance is low is relatively high,
The visibility of the dark part is relatively good. Also, average brightness
When displaying an overall bright image with high
Since the power brightness is relatively low, glare is suppressed,
There is some improvement in the overall visibility. Visibility and white floating due to such display characteristics
Color defects such as CRT display devices and liquid crystal displays
Flat display devices such as
This is remarkably observed in the display and projection display devices. Meanwhile, the conventional gamma correction technique is as follows.
The gamma characteristic of the display device does not change depending on the type of image
The same for any image.
Correction is performed using a set value (gamma value). So
Therefore, the visibility in the liquid crystal display device as described above
The shortage cannot be remedied. Further, the above-mentioned conventional luminance correction technique uses a color
This is related to the output adjustment of the light source.
No consideration is given to the level of the input image signal.
Not. Therefore, even with this technique,
It is not possible to improve the lack of visibility in liquid crystal display devices.
I can't. Originally, a display image is faithfully reproduced from an input signal.
In order to be done, at least on the image display surface of the display device
It is necessary to show a linear input signal-output luminance characteristic. Ma
In order to realize a natural image for the viewer,
Arbitrary input / output characteristics such as brightness and color tone characteristics for image reproduction
Can be adjusted to
The configuration of the signal processing circuit of the image display device.
Problems such as complexity and cost increase occur. The present invention has been made in view of the above-mentioned conventional problems.
The purpose is to display images with high display quality.
Image display device and image signal correction device
To provide. [0027] According to the present invention, there is provided a display device (table).
The maximum output brightness andEnteringForce signal-output luminance characteristics
Set according to the average signal level of the input image signal
By doing so, the above object is achieved. That is, the image display device of the present invention has
To solve the problem, multiple images to display
A pixel including a display unit having pixels and representing information for each pixel
An image to which an image signal including a signal is to be input
In the display device,Inverse gamma correctedPixel signal level
LeFull screenAverage that calculates the average as the average signal level
Average signal level calculation unit and pixel for pixel signal level
The input signal-output luminance characteristic representing the change in luminance of
Average signal levelchange ofIn response to theLeave it to change continuously
At willInput signal-output luminance characteristic setting section to be set
Input signal-output luminance characteristicsWith input / output characteristics equal toimage
Correct the signalFirstSignal correction unit and, Display input signal
-Image signal with input / output characteristics opposite to output luminance characteristics
And a second signal correction unit for correcting the average signal level
Maximum output brightness to adjust the maximum output brightness of the display unit pixels according to
Brightness adjuster andIt is characterized by having. [0029]Further, the image display device of the present invention includes the above-described section.
Multiple pixels to display the image to solve the problem
Pixel signal representing information for each pixel, comprising a display unit having
Image display in which an image signal containing
The device averages the pixel signal levels over the entire screen.
An average signal level calculator that calculates the average signal level;
An input representing the change in pixel brightness with respect to the pixel signal level
The signal-output luminance characteristics are set according to the average signal level.
Input signal-output luminance characteristic setting section
Image signal with input / output characteristics equal to output signal-output luminance characteristics
A first signal correction unit for correcting, and an input signal-output of the display unit
Corrects image signal with input / output characteristics opposite to luminance characteristics
And a second signal correction unit that performs
Maximum output brightness adjustment to adjust the maximum output brightness of the pixels on the display
And an input signal-output luminance characteristic setting unit,
When the input signal-output luminance characteristic is approximated by an exponential function
The exponent value of the signal with the change of the average signal level
It is characterized by things. The aboveeachAccording to the configuration, it
Input signal-output luminance characteristic can be changed
Therefore, for example, regardless of the average signal level, the input signal
Display unit with constant luminance characteristics (liquid crystal display
), The nonlinear function of the input signal-output luminance characteristic
Exponential value when C is approximated by an exponential function (CRT display
Gamma index).
Image display device with characteristics that increase
You. Therefore, the overall dark image (the image with low average brightness)
Image), the visibility of dark areas and the overall bright image (flat
Image with high brightness)
A display device can be provided. Therefore, aboveeach
According to the configuration, the input signal-output luminance characteristics of the display section are averaged.
High, regardless of whether it changes according to the signal level
An image display device capable of displaying images with display quality
Can be provided. Also,,UpRecordeachAccording to the configuration, the average signal level is
Adjust the maximum output brightness of the pixels in the display unit according to the
So that, for example, the maximum
Display unit with constant output luminance (liquid crystal display device, etc.)
The maximum output brightness as the average signal level increases.
Realizing an image display device with characteristics that reduce the degree of
Wear. Therefore, an image signal with a high average signal level is input.
Screen glare can be reduced when
Also, temporary blindness due to retinal bleaching phenomenon during direct vision
Visualization can be prevented, and bright images can be viewed overall
An image display device with excellent performance can be provided. sand
That is, aboveeachAccording to the configuration, the input signal-output luminance characteristic and
Both the maximum output luminance of the display unit and the average signal level of the image signal
By changing according to the bell, depending on the type of display
Image that can display images with high display quality
Display device can be provided. The average signal in the image display device of each of the above constructions is
Signal level and / or input signal
The signal-output luminance characteristics can be set arbitrarily.
Therefore, only this part of the image display device of each configuration described above is used.
If taken out, the display quality of various types of display devices
Evaluation and high-quality image reproduction parameters
It is also effective for evaluation when applying to. That is, the image signal correction apparatus of the present invention
In order to solve the above problem, an image representing information for each pixel
An image signal including an elementary signal is input, and the image signal is corrected.
Output to a display device with multiple pixels
Image signal correction device,Inverse gamma correctedPicture
Of the level of the raw signalFull screenLet the average be the average signal level
Signal level calculation unit that calculates the pixel signal level and the pixel signal level
Signal representing the change in the luminance of the pixel with respect to
The average signal level abovechange ofIn response to theContinuously changing
Arbitrarily asInput signal to output-output luminance characteristics setting
Section and set input signal-output luminance characteristicsIn and out equal to
With force characteristicsCorrect image signalFirstSignal correction unit and,display
Input / output characteristics that are inverse to the input signal-output luminance characteristics
A second signal correction unit for correcting the image signal with the
Adjusts the maximum output brightness of the pixels on the display according to the signal level
Maximum output brightness adjustment section andIs characterized by having
You. [0034]Further, the image signal correction device of the present invention
In order to solve the problem of
An image signal including a signal is input, and the image signal is corrected and
Output to a display device with a number of pixels
In the image signal correction device, the whole screen of the pixel signal level
Average signal level that calculates the average at
Pixel operation unit, and the change of pixel luminance with respect to the level of the pixel signal.
The input signal-output luminance characteristics representing the
Input signal-output luminance characteristic setting unit to be set according to the
Input signal-output set according to the average signal level
First to correct image signal with input / output characteristics equal to luminance characteristics
And the input signal-output luminance characteristics of the display unit.
To correct the image signal with the inverse input / output characteristics
Signal correction unit and the image of the display device according to the average signal level.
A maximum output luminance adjustment unit that adjusts the maximum output luminance
In addition, the input signal-output luminance characteristic setting unit outputs the input signal-
Exponent value when output luminance characteristics are approximated by exponential function
Is changed with the change of the average signal level.
It is characterized by that. The aboveeachAccording to the configuration, it
Input signal of the image signal correction device-output luminance characteristic of the display device.
Characteristics can be changed, for example, the average signal level
The input signal-output luminance characteristic is constant regardless of the bell
Even if a display device such as a liquid crystal display device is used,
Visibility of dark areas in dark images (images with low average brightness)
Or in an overall bright image (image with high average brightness)
It is possible to display an image with excellent visibility of bright portions.
Therefore, aboveeachAccording to the configuration, the input signal of the display device
-Whether the output luminance characteristic changes according to the average signal level
Regardless of whether the image is displayed with high display quality
It is possible to provide an image signal correction device capable of performing the following. Also,,UpRecordeachAccording to the configuration, the average signal level is
Adjust the maximum output luminance of the display device pixels according to the
For example, regardless of the average signal level,
A display device in which the large output luminance is constant (a liquid crystal display device)
Etc.), the maximum output increases as the average signal level increases.
It is possible to realize a display in which the power luminance is reduced. Souyu
When an image signal with a high average signal level is input
In addition to reducing screen glare,
Prevents temporary blindness due to retinal bleaching during direct vision
Can improve overall bright image visibility
Can be made. That is,eachAccording to the configuration
Both the output signal-output luminance characteristic and the maximum output luminance of the display unit
Is changed according to the average signal level of the image signal.
Image with high display quality regardless of the type of display device
To provide an image signal correction device capable of displaying
Can. The above average signal level calculation section is provided within the unit period.
SmellPictureOf the level of the raw signalFull screenAverage to average signal
It is preferable that the calculation is performed as a level. the above
The unit period constitutes one image such as one frame
It may be the entire period, one field or several fields.
Composing a single image, such as a field spanning fields
It may be part of a period. Also, the above average signal level
The arithmetic unit calculates the instants of all pixel signals at an appropriate sampling period.
Voltage level is sampled and the
The average of each voltage level is calculated as the average signal level.
It may be. [0038] The maximum output luminance adjusting section is adapted to output the average signal.
The maximum output brightness decreases as the level increases
It is desirable that it be adjusted well. With this,
When an image signal with a high average signal level is
Glare can be reduced, and when looking directly
To prevent temporary blindness due to retinal bleaching phenomenon
Can improve the visibility of bright images overall
Can be. The input signal-output luminance characteristic setting section
Is an approximation of the input signal-output luminance characteristic by an exponential function.
Exponent value (gamma exponent for CRT display)
Set to higher values as the average signal level increases
It is desirable that This allows overall
Visibility of dark areas in dark images (images with low average brightness)
Or in an overall bright image (image with high average brightness)
The visibility of the bright part can be improved. Further, the maximum output luminance adjusting section is
The maximum output brightness increases as the average signal level increases.
The input signal is adjusted to be smaller.
The output luminance characteristic setting unit calculates the input signal-output luminance characteristic as an index.
Exponential value approximated by a function (CRT display device
Gamma index) as the average signal level increases
It is even better to set it to a higher value.
Good. This allows the overall image to be bright (average brightness
(High image) to further improve the visibility of bright areas
Together with a dark image (image with low average brightness)
The visibility of the dark part can be improved. The image display device and the image signal of each of the above structures
In the correction device, the input image signal is
A black-and-white video signal comprising a luminance signal representing luminance information;
And a luminance signal representing luminance information for each pixel and a luminance signal for each pixel.
And a chrominance signal representing the chromaticity information of
Each of the three primary colors or more
It may be a color video signal including a color component signal. The input image signal is the luminance information of each pixel.
The average signal level calculation unit
Is, ShineDegree signal levelFull screenAverage to average signal level
It is desirable that the calculation be performed as a file. This
Therefore, the device configuration can be simplified. That is, in a standard image display device, an image
The image signal is composed of a luminance signal and a color difference signal.
Color video signal is input. In this case, the color video signal
Of the signals that constitute the
It is the luminance signal that affects the performance and the maximum output luminance.
You. Therefore, in the average signal level calculating section,
Average signal level using both degree and color difference signals
Rather than calculating the average signal level using only the luminance signal.
Computing the bell reduces the number of processed signals
The configuration can be simplified. Also, if the input image signal has three primary colors (for example, R
GB) or more primary color component signals
If it is a color video signal that includes
The arithmetic unit calculates the level of the value corresponding to the luminance value from the color component signal.
It is desirable to calculate the average. Brightness value
The method of calculating the average of the level of the corresponding value is conversion
From the color component signals of all colors,
After the calculation, a method of averaging the calculated values may be used.
After averaging the color component signals of all the colors,
How to convert the average value to an average value equivalent to luminance by using a conversion formula
It may be a law. It also performs the average of the luminance signal levels.
As a calculation method, without using the color component signals of all colors,
The average signal level is calculated using only the color component signals of some colors.
Alternatively, a calculation method may be employed. Also in this case,
As in the case of using the color component signal components of all colors,
The order of conversion to the value corresponding to the degree and the calculation of the average value are arbitrary.
It is. Further, a camera including such color component signals is used.
Error signal, the average signal level
The calculation unit calculates the average of the level of the value corresponding to the luminance value
And at least one of each color component signal
The average of the levels is calculated as the average signal level.
You may. That is, for example, if the three primary color signals of RGB are
Extracts only G signal when input as image signal
The average value of the G signal level as the average signal level
Or the average value of the level of each color component signal is averaged.
It may be calculated as a signal level. The input image signal is the luminance information of each pixel.
When the input signal includes the luminance signal representing the
The luminance setting unit changes the luminance of the pixel with respect to the level of the luminance signal.
The input luminance signal-output luminance characteristic representing the
Set according to the level.FirstSignal supplement
The positive part satisfies the set input luminance signal-output luminance characteristics.
It is preferable to correct the luminance signal as
No. Further, the input image signal is composed of three primary colors (eg,
For example, each color component of RGB) or more primary colors
Signal, the input signal-output luminance characteristic setting unit
Is the image for at least one level of each color component signal.
The input signal-output luminance characteristic representing the change in
Set according to the average signal level.First
ofThe signal correction unit calculates the set input signal-output luminance characteristic.
Correct at least one of each color component signal to satisfy
Preferably, it is Signal correction unit(The first signal correction unit and the second
Signal correction section)Image display device and image signal
The signal correction device averages the pixel signals of the input image signal.
Calculation of signal level and setting of input signal-output luminance characteristics
To the signal correction unit after delaying the time required for
Desirably, a delay unit is further provided. The input image signal is directly used as a signal correction unit.
The average signal level corresponding to that pixel signal.
Until the input signal-output luminance characteristic is set
The signal cannot be corrected. Therefore, the input image signal
Cannot be processed continuously, and as a result, the display (table
Display device) to display (play) the input image in real time
Output). On the other hand, the image input as described above
Signal average signal level calculation and input signal-output brightness
A delay unit is provided to delay the time required for setting the characteristics
In the configuration, the timing at which the image signal is output to the signal correction unit is
And an input signal-output luminance characteristic setting unit.
The input signal-output luminance characteristic is output to the signal correction unit.
It can synchronize with the imming. This allows the table
The input image is displayed on the display unit (display device) in real time.
(Playback output). The above-mentioned delay section is provided for the pixels of the input image signal.
It is necessary to save the signal temporarily. Therefore,
The extension unit is a storage unit capable of temporarily storing image data, for example,
For example, RAM (random access memory)
Is more desirable. The input signal-output luminance characteristic setting unit uses a calculation formula
The input signal-output luminance characteristic is calculated from the average signal level using
A configuration for calculating the parameters to be represented may be used. Also,
The input signal-output luminance characteristic setting unit determines the average signal level and the input signal.
Look-up table for associating force signals with output luminance characteristics
Cable in a storage device such as a memory.
Input signal-output luminance characteristics with reference to the backup table.
A configuration for setting may be used. Lookup table above
Bull measures various input signal-output luminance characteristics in advance,
What is necessary is just to create based on the obtained measurement result. [0053] The signal correction section determines whether the input signal-output luminance characteristic
If the arithmetic processing is performed using the sex parameter,
The signal correction unit includes an input signal-output luminance characteristic parameter.
Of the input signal-output luminance characteristics
First signal correction for converting pixel signals with corresponding input / output characteristics
Unit and the input signal-output luminance characteristics of the display unit (display device)
Signal correction unit for correcting deviation from linear characteristics in
It is desirable to be constituted by: According to the above arrangement, the second signal correction unit
Of the second signal correction unit and the display unit
However, the input signal-output luminance characteristic becomes a linear characteristic.
For this reason, the first signal correction unit calculates the input signal-output luminance characteristic.
Performing simple arithmetic processing using only sex parameters
Often, the structure of the operation unit is simplified. On the other hand, when there is no second signal correction unit,
The input signal-output luminance characteristic parameter and the input
Image using both force signal and output luminance characteristic parameter
It is necessary to correct the signal, which complicates the structure of the arithmetic unit.
You. In the second signal correction section,, tableIndicator (table
Function) representing the input signal-output luminance characteristic of
May be used to convert the pixel signal. However
Display on a plurality of different types of display units (display devices).
The type of display (display device) is not specified
The input signal-output luminance characteristics of the display unit (display device) vary.
It may change to various characteristics. Therefore, this place
Input signal of various display units (display devices)-output brightness
RAM by associating degree characteristics with the type of display unit (display device)
Etc. or a storage medium such as a hard disk.
Remember, the second signal correction unit refers to the stored contents.
Input signal of display unit (display device)-output luminance
Image signal is corrected with input / output characteristics opposite to the characteristics
Is preferred. The display section (display device) includes a light emitting element,
An optical switch for controlling the light from the light emitting element for each pixel
It suffices if it has a chining element. Therefore, the display
(Display device) is a light emitting type device having the function of a light emitting element.
Optical switching element (light emitting display element), for example, CR
T, light emitting diode, plasma display panel (P
DP), FED (Field Emission Display) etc.
And emits light without emitting light by itself.
A non-light-emitting optical switch that controls or modulates light from an optical element
Switching element (non-light emitting display element), for example, liquid crystal display element
A configuration including a child or the like may be employed. The display unit (display device) is, for example, a transmission type
A light emitting element and a non-light emitting type optical switch such as a liquid crystal display
Switching elements, which are controlled independently of each other.
If the configuration is such that the maximum output brightness adjustment unit
A configuration that calculates the output luminance and outputs the calculation result to the light emitting element
It is preferable that The calculation of the maximum output luminance is
After calculating the maximum output luminance in a standardized form,
Output based on the result and the externally provided brightness reference value.
It is performed by calculating the power brightness
It is desirable. On the other hand, the display unit (display device) is an optical switch.
A light emitting element having the function of a switching element,
If the configuration includes optical switching elements,
The maximum output luminance adjustment unit calculates the maximum output luminance
And the image signal corrected by the signal correction unit is
Conversion processing based on the calculation result of large output luminance, conversion processing
Output to the light-emitting optical switching element
It is desirable that a signal conversion unit be further provided. In each of the above-described configurations, the portion for performing the operation (average
Signal level calculation unit, input signal-output luminance characteristic setting unit, signal
Signal correction section and maximum output brightness adjustment section)
It is desirable to be realized by hardware,
It may be realized by software. Sand
That is, each unit that performs the operation in each of the above configurations is
Stores a computer program that describes arithmetic processing
A storage means such as a RAM and the like,
CPU (Central Processing Unit)
It may be shown. Next, the course in which the present inventors made the present invention
Will be described in detail with reference to FIGS. FIGS. 6 and 7 show various display devices.
What display characteristics are displayed for the input image signal
It is the figure which showed typically. FIG. 6 and FIG.
Display devices 30A to 30C having different display characteristics from each other
On the other hand, inputting the image signals S1 and S5 respectively
Shows a child. FIG. 6 shows a general TV broadcast.
Image signal S1 that has been subjected to inverse gamma correction
I have. Therefore, the input level of the image signal S1 (the original image
Output level (light level of the image signal)
The slope of the curve C1 representing the change in
Decreases in accordance with Such an image signal S1 is input
The reason is that the gamma characteristic as shown by the curve C2 is
The input level (the voltage level of the image signal)
Of the curve C2 representing the change in output level (luminance)
Have display characteristics that increase as the input level increases.
Before the image is reproduced on the CRT display device 30A.
Inverse gamma interpolation is performed to cancel this change in slope.
This is because they are doing positive. Therefore, the display device
6 having a gamma characteristic like the CRT display device 30A.
If there is, it is output (displayed) from the CRT display device 30A.
The output level (luminance) of the image S2 is as shown by the curve C5.
Becomes linear with respect to the input level (light intensity of the original image). Generally, a display device is provided with an image signal source (original image).
Various input / output characteristics for input (light intensity) from image)
(Display characteristics). For this reason, CRT display devices
The input image reproduced almost faithfully at 30A is
A display device, for example, an input / output characteristic represented by a curve C3.
Such as a display device 30B having a characteristic and a curve C4.
In the display device 30C having input / output characteristics, the curve C6
And C7, the input level from the original image
To output images S3 and S4 having non-linear output levels.
And the original image is not reproduced faithfully.
I am Further, the input as shown by the curve C8 in FIG.
Output level (image level) against force level (light intensity of original image)
The image signal S5 whose change in signal voltage level is linear is
When input, for example, it is created by a computer etc.
If image data is input directly, the input image
If the signal S5 is not corrected, the image signal S5
Are curves C9 to C1 in the display devices 30A to 30C.
The input / output characteristics of the display devices 30A to 30C as shown in FIG.
The image is converted into an image having the corresponding characteristics and output. That
Therefore, in the display devices 30A to 30C, the curves C12 to C14
As shown in the figure, the input level from the original image
S6 to S8 having the output levels shown in FIG. Accordingly
The original image is displayed on the display screens of the display devices 30A to 30C.
It can be seen that (input image) is not correctly reproduced. The input of such a display device (display device) is as follows.
The output characteristics will be described in more detail. In a display device such as a CRT display device
Generally, the input signal voltage-output luminance conversion characteristics
It is called a ma (γ) characteristic and is expressed as in the following equation (1). [0068] (Equation 1) Here, I is the output luminance, and V is the input signal power.
Pressure and exponent value γ are nonlinear parameters called gamma values
It is. A and b are offset constants. The input signal is the American Society of Motion Picture and Television Engineers.
(SMTPE) TV standard SMPTE standard 17
0M or 240M, or the traditional
Wave Law / CCIR (International Radio Communication Advisory Committee) Recommendation 624
/ Signal voltage conversion specified in RS170A
Is a normal TV image signal that has been inverse-gamma corrected by
Consider the case where This TV image signal has γ = 2.
Inverse gamma assuming input to the CRT display device 2
Since it has been corrected, it will not be displayed on the CRT display device.
Under certain conditions, the original image can be
The image is output after being approximately linearized. The input signal voltage is
The inverse gamma processing is roughly proportional to the
For the simplified input luminance signal level g, for simplicity
In equation (1), a = b = 0, and g is the maximum value.
Maximum luminance (maximum output luminance) imax Expression using
By rewriting (1), it can be expressed as the following equation (2)
You. [0071] (Equation 2) By doing so, the relationship between input and output
In the signal processing part by removing the restrictions of the display device
be able to. Here, to explain the concept,
Although the constant term in (1) is omitted, Equation (1) is
Describes CRT display device characteristics in more detail
May be. This further improves the accuracy of the equations described below.
To improve. Taking the CRT display device as an example, the average input brightness
Output luminance i in the system according to the degree signal level Gmax
Has been determined structurally. Therefore, in equation (2)
Maximum brightness imaxIs a function i of the average input luminance signal level Gmax
 Rewritten as (G), I is a function of g and G
And can be expressed as in the following equation (3). [0074] (Equation 3) Here, the average input luminance signal level G is expressed as
Luminance input corresponding to each pixel P (x, y) of the display device
Signal level gxyAnd can be expressed as
You. [0076] (Equation 4) The pixel P (x, y) is located in the i-th row (i ≧
2) A matrix arranged in a matrix of × j columns (j ≧ 2)
X-th row (1 ≦ x ≦ i) y-th column (1 ≦ y ≦
j) represents the pixel. However, a general CRT display device is
And the average input luminance signal as shown in FIGS.
Maximum output luminance i for signal level Gmax And gamma values
When the change in γ was examined, as shown in FIG.
Maximum output luminance imaxGamma value γ as well as average input
It changes with the change in the luminance signal level G. for that reason,
Maximum output luminance imax Similarly, the gamma value γ
It must be rewritten as a function of the luminance signal level G. That is, based on the characteristics shown in FIG.
(3) can be rewritten as the following equation (5)
You. [0080] (Equation 5) According to equation (5), the average input luminance signal level
The maximum output luminance i according to Gmax (G) and gamma value
If γ (G) is set, the CRT table
The same as the CRT display device using a display device other than the display device
Display with input / output characteristics and more reproducible entry / exit
It can be seen that the image can be reproduced with the force characteristics. Therefore, standardized input of an arbitrary display device is considered.
A function D representing a force signal-output luminance characteristic is represented by a standardized input
Power luminance signal level ginput And standardized output brightness
Level goutputDefined using goutput= D (ginput ) ・ ・ ・ ・ ・ (6) It becomes the relationship. Here, the logic of standardizing the signal levels and characteristics is described.
The reason is the input signal or output depending on the type of display device.
Signal accuracy is different or the type of display device
It is assumed that the scale of output brightness differs depending on
Because. That is, by adjusting the display device,
If the input signal is 8 bits and the output signal is 10 bits
In some cases, the input signal is 8 bits and the output signal is 6 bits.
The output brightness scale to a certain set value.
From 10 to 20 at another setting
This is because a case such as the following may occur. In actual signal processing, ginput , G
output, And imax And the value within the range of 0 to 1 in advance
Standardization so that changes to the final signal form can be achieved.
In other words, the operation result is represented by the maximum number of representations of the signal (n-bit digit
If the signal is a total signal, the maximum number of expressions is 2nMultiply -1)
Therefore, the calculation can be easily performed. From the above, it is possible to obtain an optimum display output.
For this purpose, various image signals must be corrected for the input image signal.
It turned out to be necessary. [0086] DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 shows an embodiment of the image display device of the present invention.
The description is based on the following. The image display device of this embodiment is shown in FIG.
As shown, a plurality of pixels for displaying an image (not shown)
(Display unit) 8 having an image signal correction device
And an image including a pixel signal representing information of each pixel.
Signal g0 (Luminance signal level g0 ) Is the image signal correction device 7
Is input to the display device 8 via the. The image signal correction device 7, PaintingRaw signal level
ofFull screenPerform the average as the average input luminance signal level G.
Average signal level calculation circuit (average signal level calculation
Part) 1 and the change of the luminance of the pixel with respect to the level of the pixel signal
The input signal-output luminance characteristic representing
Input signal-output luminance characteristic setting time set according to bell G
Path (input signal-output luminance characteristic setting unit) 2 and average input luminance
The maximum output brightness of the pixel of the display device 8 according to the degree signal level G
Maximum output brightness adjustment circuit (maximum output brightness adjustment
Part) 3 and satisfy the set input signal-output luminance characteristic
So that the image signal g0 Signal correction unit 4 for correcting
I have. The signal correction unit 4 is configured to output the set input signal-output
Image signal g with input / output characteristics equal to0 Correct
Γ (G) correction circuit (first signal correction unit) 5 and a display device
Input / output characteristics (input signal-output luminance characteristics)
Inverted input / output characteristics further increase image signal g1Correct the reverse
A characteristic correction circuit (second signal correction unit) 6. Next, image reproduction using the above image display device
The method will be described. First, the average signal level calculation circuit 1
Gamma corrected input image signal g0 Luminance signal level g
0 , An average input luminance signal level G is calculated. Next, an input signal-output luminance characteristic setting circuit
In 2, the input signal-output luminance characteristic of the image display device is indexed
Exponential value (gamma value) γ (G) when approximated by a function
Is calculated from the average input luminance signal level G. Specifically
Is an exponential function of the input signal-output luminance characteristic of the image display device.
The exponent value (gamma value) γ (G) when approximated by
For example, as shown by the curve γD in FIG.
Set to increase as signal level G increases
I do. [0093] Further, the signal correction unit 4 controls the image display device.
Of the input signal-output luminance characteristics of
Index value (gamma value) matches the set value γ (G)
Input image signal g0 Is corrected, and the corrected image signal
g0 Is output to the display device 8. Specifically, first, γ
(G) In the correction circuit 5, the set value γ (G) is used as an exponent value.
Using the exponential function, the image signal g0Luminance signal level g0
From the image signal g1 Luminance signal level g1 And calculate the brightness
Signal level g1Image signal g having1 Generate Next
In the inverse characteristic correction circuit 6, the input signal of the display device 8
The image signal g is obtained by using the inverse function of the function representing the power luminance characteristic.1
Luminance signal level g1 From the image signal gout Brightness signal level
Bell gout Is calculated, and the luminance signal level goutImages with
Signal gout Is output to the display device 8. In the maximum output luminance adjustment circuit 3, the average
The maximum number of pixels of the display device 8 according to the input luminance signal level G
Adjust the output brightness. Specifically, the average input luminance signal level
From the bell G to the maximum output luminance i of the display device 8max Perform (G)
And the result of this operation is calculated as the maximum output luminance i.outDisplay as
Output to the device 8. Maximum output luminance imax The operation of (G) is
For example, the curve i in FIG.max Average input like D
The maximum output luminance i increases as the luminance signal level G increases.
max(G) is calculated to be small. In this case, the input to the display element of the display device 8 is
Image signal gout Luminance signal level gout And display
Maximum output luminance i of device 8out Is the following equation (7) and equation
It can be expressed by (8). [0096] (Equation 6) The final output luminance I of the display device 8
Can be expressed as in the following equation (9). [0098] (Equation 7) Note that goutIs g in the above formula (6)input
Represents a standardized input luminance signal level corresponding to
-1() Indicates a standardized output luminance level g of the display device 8.
d(G of the above formula (6)outputCorresponding to)
D (gout ). As described above, in the image display device according to the present invention,
Is the inverse gamma corrected image signal g0 Average input at
Using the luminance signal level G as a reference value and the gamma value γ (G)
Large output luminance imax By setting (G) and
High-quality images with good reproducibility are displayed regardless of the type of the display device 8.
Can be shown. It should be noted that in the above equations (2) to (9)
Shows the processing on the luminance signal of the input image signal
However, in an actual image display device, a luminance signal is represented by a display element.
Drive voltage v for child drive1 To convert to
Intensity iout Is the driving voltage v of the light emitting element of the display device 8.TwoTo
Conversion processing is generally included. Therefore, equation (9) is obtained by the following equation (10).
Can also be expressed. [0103] (Equation 8)Here, V in the equation is the average of the luminance signal voltage.
Indicates the input voltage value. Further, the luminance signal level gout From display device
8 drive voltage v1 Conversion to, and maximum output
Brightness iout From the driving voltage v of the light emitting element of the display device 8TwoWhat
Is a linear function V1And VTwo Using the following equation
It can be expressed as (11A) and (11B). V1 = V1(Gout ) ... (11A) vTwo = VTwo(Iout ) ... (11B) Expressions (10), (11A), and (11B) are displayed.
A mode in which the operation mode of the device 8 is driven by a change in the voltage value
In this case, the operation mode of the display device 8 is
Other signals such as heat, light, pressure, vibration, sound waves, etc.
Shape driven bystateEven if
Equations similar to Equations (11A) and (11B) hold. FIG. 1 shows that the display devices 8 are independent of each other.
When a display element and a light emitting element that can be controlled
2 shows a configuration of an image display device. In this case, equation (7)
Signal g obtained byout (Luminance signal level g
out ) And the maximum output luminance i obtained by equation (8)
outAre input to the display element and the light-emitting element, respectively.Ba
Good. The display device 8 also functions as a light emitting element.
Switching element, that is, so-called light emitting type
Display element (self-luminous switching element)ToWhen to prepare
, The maximum output luminance iout Adjustment of the image signal
Signal processing. Therefore, the display device is controlled by the inverse characteristic correction circuit 6.
Before correcting the inverse characteristic of the input signal-output luminance characteristic of the device 8
Image signal g of1 Output luminance iout Multiply
You can do it. That is, in this case, the image signal correction device
Image signal g output from device 7outLuminance signal level g
out Is represented by the following equation (12). [0110] (Equation 9) The final output luminance I is given by the following equation (1).
It can be expressed in 3). The expression form of the signal
Is the same as described above. [0112] (Equation 10) Here, a reverse gun for television broadcast images and the like is used.
The corrected image signal g0 Image signal when is input
The outline of the process has been described. So in this case
Did not require any special pre-processing.
Linearization directly from a computer or other device capable of generating image signals
Reverse gamma correction when the
Then, the above processing may be performed. Further, regarding the above-described processing of the image signal,
Is performed similarly for analog and digital signal systems.
It is possible to calculate numerical values by using a digital signal system.
Can be easily changed, and parameters can be changed easily.
Easy. In a digital signal system, an analog signal is
Conversion, convert analog signals to digital signals.
The above processing may be performed. Digital in this process
At least 8 bits for data gradation expression bit number
If it is above, processing can be performed with high accuracy, but accuracy is low.
If not required or if you want to simplify the configuration.
Even if processing is performed with the current bit number smaller than 8 bits,
Good. In the above processing, the display device 8 performs, for example, transmission
Elements and light-emitting elements such as liquid crystal display devices
And FED (Field Emi
light-emitting elements such as ssion display) and PDPs
Even if it is integrated with the
The display quality can be easily set. In the above processing, the brightness of the image display device
Gamma value γ (G) which is a parameter and maximum output luminance i
max (G) can be freely set. for that reason,
Gamma value γ (G) and maximum output luminance imax(G) seed
Each setting pattern is stored in the storage device,
If you can read the memory contents as needed,
Even if the display device 8 is used, it is possible to unify the image display quality.
It will be easier. The signal from the image signal correction device 7 is used.
Signal processing, the input image signal is a luminance signal g0 And color difference
Output luminance signal goutSignal level
Le gout Is the input luminance signal g0 Signal level g0 Α (0
α≤1) times, the same applies to color difference signals.
, And output the obtained color difference signal. The signal generated by the image signal correcting device 7 is used.
In the signal processing, the input image signal is
Brightness is expressed by the combination of each color component signal.
Output luminance signal obtained by the above calculation
No. gout Signal level gout Is the input luminance signal g0Signal
Level g0 Β (0 ≦ β ≦ 1) times
If the result of multiplying the color component signal by β is output as an output signal
Good. In the above processing, the input
Processing based on the linearized luminance signal of the image signal
, Three primary colors of RGB, or more primary colors
Set to process each color component signal independently.
You can also. In that case, change the luminance signal level in the expression
Change to each color component signal level and process each
Good. When this method is used, only the luminance signal
It is possible to perform correction with higher accuracy than when performing
The number of independent parameters increases and memorizes the parameters
Costs of storage devices and arithmetic processing circuits
You. Therefore, priority is given to improving accuracy over equipment costs
In this case, this method may be applied. [Embodiment 2] Next, a preferred form of the embodiment described in the first embodiment
The state will be described with reference to FIGS. Note that the description
For convenience, the same machine as each member shown in the first embodiment is used.
The same reference numerals are given to members having functions,
Omitted. The image display device of this embodiment is shown in FIG.
As described above, the image signal correction device 7 ', the light emitting element and the display element
(Switching element) and display device that can be controlled independently
8 is provided. The display device 8 has a plurality of pixels (not shown).
A non-light-emitting display element 16 such as a liquid crystal panel
Signal g output from the signal correction device 7out Display drive
Signal (drive signal) Sout LCD drive circuit to convert to
Display element drive form conversion circuit 15 and a backlight
The light emitting element 18 and the light output from the image signal
Large output luminance ioutIn the form corresponding to the input of the light emitting element 18
Signal Iout A light-emitting element drive mode conversion circuit 17 for converting
For example, the maximum output luminance ioutTo generate a voltage corresponding to
And a variable voltage source. The image signal correction device 7 'is different from the first embodiment in that
Similar average signal level operation circuit 1, input signal-output luminance
Characteristic setting circuit 2, maximum output brightness adjustment circuit 3, and signal
In addition to the correction unit 4, a switch 9, an inverse gamma correction circuit 1
0 and a delay circuit 11. The switch 9 is supplied from the inverse gamma correction circuit 10
Image signal g of0 And inverse gamma correction
Image signal g0 And delay circuit 11 and
And average signal level calculation circuit 1
is there. Also, the inverse gamma correction circuit 10OutsideInput from the department
Linearly corrected image signal g0’By inverse gamma correction,
Image signal g after correction0 Is output to the switch 9.
You. Further, the delay circuit 11 outputs the image signal g0 Enters
Timing output to force signal-output luminance characteristic setting circuit 2
And the setting parameters of the input signal-output luminance characteristics of the image display device.
The gamma value γ (G), which is a parameter, is output to the signal correction unit 4.
Average signal level so that the timing
Calculation of the average input luminance signal level G in the arithmetic circuit 1
And gamma in input signal-output luminance characteristic setting circuit 2
The image signal g for the time required to calculate the value γ (G)0The delay
It is to let. The maximum output luminance adjustment circuit 3 of the present embodiment comprises:
Based on the average input luminance signal level G,
Large output luminance setting value Imax Output brightness setting to calculate
The circuit 12 and the set value I of the standardized maximum output luminancemax
And the brightness reference value α given from the outside.
Intensity imax Is calculated, and the calculation result is used as the light emitting element of the display device 8.
Luminance output control circuit 1 for outputting to child drive form conversion circuit 17
3 is provided. FIG. 2 shows an image subjected to inverse gamma correction.
Signal g0 And the linearly corrected input image signal g0 ’
But these are not always entered at the same time.
Not something. In addition, here, for convenience of explanation,
The image signal that has been corrected for linearity and the input image signal that has been linearly corrected
No. g0′ Is further inverted gamma corrected
Sign g0 Indicates that these are the same signal.
It is not something. In this embodiment, the inverse gamma correction is performed.
Image signal g0 And the linearly corrected image signal (the original image
Signal) g0 ’, Whichever input is entered,
But only supports input of one of the image signals
It is also possible to adopt a configuration in which For example, switch 9
And the inverse gamma correction circuit 10 is omitted.
Image signal g0May be configured to support only the input of
No. Next, image reproduction using the above image display device
The method will be described with reference to FIGS. In addition, here
Then, the luminance signal level g0 , G1 , Gout , Average input brightness
Degree signal level G, maximum output luminance (lighting luminance adjustment level)
Imax(G), iout , And the brightness reference value (external brightness control)
Α) are normalized so that they are all 0 to 1.
It is assumed that The input terminal (signal input port) of the display device 8
Input image signal g0 Is the linearly processed image signal g
0 'And reverse gamma correction for CRT displays
Image signal g0It may be. That
First, the linearly processed image signal g0 ’Was entered
In this case, the inverse gamma correction circuit 10
Do. On the other hand, an image signal g that has been inversely gamma-corrected in advance0Enters
When it is input, no inverse gamma correction is performed. Next, the average signal level calculation circuit 1
Gamma corrected image signal g0 For a certain amount of signal
Average AVE (g) of pixel signal levels in an image signal
0 xy) (= F1(G0 )) Is the average input luminance signal level G
Is calculated as Image signal for a fixed amount of signal to be averaged
g0 Is the image signal g for the image of one field0But good
And the voltage value of the pixel signal sampled at appropriate intervals
There may be. Further, the input image signal g0 Shines
Degree-color difference signal (YPbPr or YCbCr)
In this case, the average signal level of the luminance signal Y may be calculated.
No. Further, the input image signal g0Are three primary color signals (RG
B), the average signal of the three primary color signals (RGB)
The level may be calculated, and the three primary color signals (RGB) may be
After converting to the signal Y, the average signal level of the luminance signal Y is performed.
May be calculated. Next, the input signal-output luminance characteristic setting circuit 2
In accordance with the average input luminance signal level G, the input signal −
Gamma value γ (G) (= f) which is an output luminance characteristic parameter
Two (G)) is set. Also, the maximum output luminance adjustment circuit 3
The maximum output luminance corresponding to the average input luminance signal level G at
imax(G) (= iout ) Is set. Specifically,
In the maximum output luminance setting circuit 12, the average input luminance signal
Setting of standardized maximum output luminance based on level G
Value Imax(G) is calculated. Next, the luminance output control circuit
At 13, the standardized maximum output luminance setting value Imax When
Multiplied by a luminance reference value α given from the outside,
Value α · ImaxIs the maximum output luminance imax Luminescent element as (G)
It outputs to the child drive form conversion circuit 17. Thereafter, the γ (G) correction circuit 5
It is expressed by the following equation (14) using the comma value γ (G) as an index value.
Using the exponential function given below, the image signal g0 Luminance signal level
g0 From the image signal g1Luminance signal level g1 Calculate
You. [0134] (Equation 11) At this time, the input image signal g0 Is γ (G)
Before being supplied to the correction circuit 5, an average signal level calculation circuit
Calculation and input of average input luminance signal level G at 1
Gamma value γ in signal-output luminance characteristic setting circuit 2
(G) is delayed by the time required for the calculation, and the average input luminance
When the signal level G is equal to the input image signal g at the same time.0Will be reflected in
It is planned as follows. Next, the inverse characteristic correction circuit 6 uses the display device.
Inverse function g of the function representing the input signal-output luminance characteristic of 8out
= D-1(G1 ) Using the image signal g1Luminance signal level
Le g1 From the image signal gout Luminance signal level gout Is calculated
Output, luminance signal level goutImage signal g havingout The table
Output to the display element drive form conversion circuit 15. Thereafter, the image signal gout Is the display element drive
The signal S of the input form of the display element 16 in the form conversion circuit 15
out Is converted to Specifically, for example, as shown in FIG.
So the function v1= V1(Gout ) Using the display element 16
Drive voltage level v corresponding to1 (= SoutIs converted to
You. At this time, the maximum luminance value gout Is a display element as data
Assuming that the signal is input to the drive form conversion circuit 15, the display element
In the drive form conversion circuit 15, the maximum luminance value goutdata from
Is an n-bit digital signal (0 to 2n -1)
After that, the n-bit digital signal is supplied to the drive voltage level v1
(= Sout). On the other hand, the maximum luminance value iout Is a light emitting element drive
The form conversion circuit 17 corresponds to the driving form of the light emitting element 18.
Signal Iout Is converted to Specifically, for example, FIG.
The function vTwo= VTwo (Iout )
Drive voltage level v corresponding to element 16Two (= Iout)
Is converted. At this time, the maximum luminance value iout Is as data
If it is input to the light emitting element drive form conversion circuit 17,
In the light emitting element drive mode conversion circuit 17, the maximum luminance value iout
Is converted to an n-bit digital signal (0 to 2).n -1)
After the conversion, the n-bit digital signal is
Bell vTwo (= Iout). In this embodiment, such image signal processing is performed.
Is performed, the display element 16 and the light emitting element 18 are independently
What kind of luminance characteristics can be provided for the controllable display device 8
(Average input luminance signal level-gamma value characteristics and average input
Display device with power luminance signal level-maximum output luminance characteristic)
8 can realize an image display device having an optimum luminance characteristic.
And display with high quality.
it can. [Embodiment 3] Referring to FIGS. 4 and 5, another embodiment of the present invention will be described.
This will be described below. For convenience of explanation
Above, the same as each member shown in the first or second embodiment.
The same reference numerals are given to members having the function of
Description is omitted. The image display device of this embodiment is shown in FIG.
As described above, the image signal correction device 27 and the display element (switch
Device 28 which itself functions as a light emitting element
And The display device 28 includes a plurality of pixels (not shown).
Display device 23 such as a CRT and image signal correction
The image signal g output from the device 27out ’For display drive
Signal (drive signal) Sout Luminescent display device
And a drive form conversion circuit 22. The image signal correcting device 27 according to the second embodiment
The inverse of the γ (G) correction circuit 5 in the image signal correction device 7
The signal conversion circuit 21 is inserted between the signal conversion circuit 6 and the
The output of the luminance output control circuit 13 is supplied to the signal conversion circuit 21
Except that the image signal of the second embodiment is
This is the same as the signal correction device 7. The signal conversion circuit 21 includes a γ (G) correction circuit 5
Image signal g output from1 Signal level g1 And up
Intensity i1 (= Imax (G)) and the resulting image
Image signal gTwoIs output to the inverse characteristic correction circuit 6. Next, image reproduction using the above image display device
The method will be described with reference to FIGS. In addition, here
Then, the luminance signal level g0 , G1 , GTwo , Gout',flat
Average input luminance signal level G, maximum output luminance (lighting luminance adjustment
Level) Imax (G), i1 , And luminance reference values (external
Brightness adjustment level) α is set so that all values are 0 to 1.
Shall be classified. First, the input image signal g0 From the proper maximum
Intensity i1 (= Imax (G)) and gamma value γ (G)
Γ (G) correction circuit 5 calculates the input image signal g0To
Image signal g1 The steps until the correction is made in the second embodiment
Is the same as However, in the maximum output luminance adjustment circuit 3,
In the display device 28, which is set in advance in the image display device
Set the maximum output luminance level that can be output as 100% and average
The maximum output luminance i according to the input luminance signal level Gmax
Change (G). Here, the maximum output that can be output by the display device 28 is described.
Force luminance level is Y100 And the average input luminance signal level G
Output luminance i for the input image ofmax (G) and Y100
The following equation is satisfied when the ratio of α to α is set to α. Α = Imax (G) / Y100... (15) Here, the following equation may be set. Y100 = Imax(G100 ) ・ ・ ・ (16) In the present embodiment, after each of these steps, a signal conversion circuit
At 21, the image signal output from the γ (G) correction circuit 5
g1 Signal level g1 And the maximum output luminance i1(= Imax
(G)). That is, the image signal g1 Up to
Output luminance i1 And the image signal g is calculated by the following equation.TwoAsk for
You. GTwo = I1・ G1 ... (17) Thus, the image signal (luminance signal) g1 To maximum output brightness
i1 The signal conversion for multiplying by
8 is the input signal level of the light emitting display element 23.
Because it depends on the file. Thereafter, the obtained image signal gTwo The reverse characteristics
Output to the correction circuit 6 and the inverse characteristic correction circuit 6
Inverse function g of a function representing an input signal-output luminance characteristic of 28
out’= D-1(GTwo ) Using the image signal gTwo Luminance signal
Issue level gTwo From the image signal gout’Luminance signal level g
out’. Further, the luminance signal level gout ’
Image signal gout ′ Is a light emitting display element driving form conversion circuit 2
2 to the light-emitting display element driving form conversion circuit 22.
Input signal S corresponding to the display device 28out
Is converted. Specifically, for example, as shown in FIG.
Function vThree = VThree (Gout ′) To form a light-emitting display element 2
Drive voltage level v corresponding to 3Three(= Sout ')Conversion to
Is done. At this time, the maximum luminance value gout ’As data
It is assumed that the input is input to the optical display element drive mode conversion circuit 22
In the light emitting type display element driving mode conversion circuit 22, the maximum brightness
Degree value gout′ Data to an n-bit digital signal (0
~ 2n -1), for example, an 8-bit digital signal (0
~ 255), and then convert the n-bit digital signal
Drive voltage level vThree(= Sout ’). In this embodiment, such image signal processing is performed.
What luminance characteristics (average input luminance signal
Level-Gamma value characteristics and average input luminance signal level-
Display with light-emitting display element with maximum output luminance characteristics)
Even if the device 28 is used, an image display
Display with high quality.
be able to. In each of the above embodiments, the average input
According to the luminance signal level, the input signal of the image display device
Adjust both the luminance characteristics and the maximum output luminance of the pixels on the display.
The display was of high quality,
According to the luminance signal level, the input signal of the image display device
Only one of the power luminance characteristic and the maximum output luminance of the pixel of the display unit
Can provide a somewhat high-quality display
Noh. [0156] [Example] [Example 1] First, a commercially available HDTV that is a high-quality CRT display device
(High-definition television), average input luminance signal level
(The average value of the input luminance signal over the entire screen) and the input luminance signal
The relationship between the data and the maximum output luminance was measured. For the measurement, 1920 × 1035 pixels
150 x 150 pixels in the center of the frame image
Using the image with the box of the
Degree signal level B (relative to the maximum value as 100%)
Value) and the input luminance signal of the background part (part other than the box)
Level H (relative value with the maximum value as 100%)
Change and measure the output luminance of the box with a color luminance meter
did. In addition, linearized data is used for the input luminance signal.
Using. As a result of the measurement, the input luminance signal level of the background portion
H is fixed and the input luminance signal level B of the box is changed.
The output luminance of each box is shown in FIG.
there were. Further, the input luminance signal level H of the background portion is fixed.
Of the box for the average input luminance signal level G of the screen
The output luminance was plotted as shown in FIG. In this case, the area of the box is
1.13% of the product, which is small enough. Therefore, the background
Is the average input luminance of the entire image.
Even if it is assumed that it is equal to the signal level G, there is no problem. Therefore, in the present embodiment, the above-described embodiment will be described.
Table 1 of the CRT display device D (or E)
To display (play back) the same as the display characteristics,
Data, that is, the maximum output luminance imax (G) and gamma
The set value of the value γ (G) corresponds to the average input luminance signal level G.
The curve i shown in FIG.maxD (or imax E) Oh
And curve γD (or γE). this
Display devices other than CRT display devices, such as liquid crystal
Using a display device, the same as the CRT display device D (or E)
Average input luminance signal level-maximum output luminance characteristic (flat
Maximum output luminance i for average input luminance signal level G
max(G) change) and average input luminance signal level-
Gamma value characteristics (gamma for average input luminance signal level G
Image display device having a value γ (G) change).
You. In this image display device, FIGS.
From the result of No. 10, when the average input luminance signal level G is low
In addition, the gamma value γ (G) is increased and the output
Increase the visibility of dark areas.
Is expected. Also, the average input luminance signal level G is high.
The gamma value γ (G) is reduced, and
By reducing the degree relatively, the visibility of bright areas
It is expected to improve. Furthermore, the average input luminance signal
When the level G is high, the maximum output luminance imax (G)
Reduced screen glare reduces visual perception
It is also expected that recognition will increase. Next, the input signal of a general liquid crystal display device is
Output luminance characteristics were measured using the same method as for CRT display devices.
Was. However, here, NTSC is used as the liquid crystal display device.
(National Television System Committee) LCD display for system display
The difference in the number of display pixels from HDTV
The box area should be approximately 1% of the total screen area
It was set so that. Based on the measurement results obtained, based on the maximum value
This is shown in FIG. The input signal shown in FIG.
The signal-output luminance characteristic is determined by the liquid crystal display
The inverse gamma of the input image signal is determined by the signal processing circuit in the device.
Correction and correction of liquid crystal voltage-optical conversion characteristics (linear characteristics
Input signal-output obtained as a result of
The figure shows the force-luminance characteristics. Input signal of this liquid crystal display
The output luminance characteristic is represented by an average input luminance signal level G (= background
Is almost constant irrespective of the input luminance signal level H) of the section.
Was. The characteristics shown in FIG. 11 are different from those of the CRT display device.
Approximate expression with nonlinear exponential function as used
Since the error increased in the high-degree part, the sixth-order polynomial
Therefore, approximation was performed and processing was performed. These input signal-output luminance characteristics are simulated.
Liquid crystal display through the signal processing shown in FIG.
Applied to the device. Average input luminance signal level G is almost 0%
The input signal-output luminance characteristic of the liquid crystal display device when
FIG. 12 shows that the average input luminance signal level G is about 75%.
FIG. 1 shows an input signal-output luminance characteristic of a liquid crystal display device when
3 is shown. In this processing mode, the liquid crystal shown in FIG.
The input signal-output luminance characteristic of the display device is expressed by Expression (9).
Processed to be converted to linear characteristics through signal processing
Is done. Therefore, the input signal shown in FIG.
The signal-output luminance characteristic is realized in the liquid crystal display device. As a result of evaluation on actual images,
The effect was obtained. Also, the data corresponding to FIG.
Measure with different display devices and obtain the measured data
If it is stored in a storage device or the like, as shown in FIG.
Reproducing images on any display device after processing
Becomes possible. [Comparative Example 1] According to the present invention, the liquid crystal display device used in the first embodiment is
Without inputting image signal correction device, input image signal as it is
FIG. 14 shows the display characteristics when input to the liquid crystal display device.
Was. It is assumed that an image signal subjected to inverse gamma correction is input
And the display result (output luminance) on the liquid crystal display
If the linear characteristic is shown for the original image (light intensity of the original image), the original image
This means that an image (a captured image or the like) has been faithfully reproduced.
In the display characteristics of FIG. 14, the luminance of 40% or more is high.
Because the level is relatively increasing in the part,
Likely to be perceived as a whitish image
No. In addition, as a result of evaluation on an actual image,
Signal-output luminance characteristics as compared to an image with a linear
It was visually recognized as a whitish display. Also, for that,
The color tone of the image seems slightly faded,
It felt as if the freshness had been impaired. [0169] The image display device of the present invention has the following features.
ToInverse gamma correctedPixel signal levelFull picture In terms of
Average signal level operation that calculates the average as the average signal level
Calculation unit and the change in pixel luminance with respect to the pixel signal level.
The input signal-output luminance characteristics are represented by the average signal level.of
changeIn response to theArbitrarily to change continuouslySet on
Force signal-output luminance characteristic setting unit, set input signal-
Output luminance characteristicsWith input / output characteristics equal toCorrect image signal
FirstSignal correction unit and, Display input signal-output luminance characteristics
To correct the image signal with the input / output characteristics of the opposite characteristics
Of the display unit according to the average signal level.
A maximum output luminance adjustment unit for adjusting the maximum output luminance of the pixel;To
It is a configuration provided. [0170]Further, the image display device of the present invention
The average of the pixel signal level over the entire screen is
Average signal level calculation unit that calculates as a bell, and pixel signal
Signal representing the change in pixel brightness with respect to the level of
Input to set the power luminance characteristics according to the average signal level.
Force signal-output luminance characteristic setting unit, set input signal-
Corrects image signal with input / output characteristics equal to output luminance characteristics
First signal correction unit and input signal-output luminance characteristics of display unit
To correct the image signal with the input / output characteristics of the opposite characteristics
Of the display unit according to the average signal level.
A maximum output luminance adjustment unit that adjusts the maximum output luminance of the pixel
The input signal-output luminance characteristic setting unit includes:
-Exponent value when output luminance characteristic is approximated by exponential function
Is changed with the change of the average signal level.
Configuration. The aboveeachAccording to the configuration, it
Input signal-output luminance characteristic can be changed
Therefore, for example, regardless of the average signal level, the input signal
Display unit with constant luminance characteristics (liquid crystal display
Etc.), but it is visually recognized when it is dark or bright overall
An image display device with excellent performance can be provided. did
AboveeachThe configuration is based on the input signal of the display
Whether or not the gender varies with the average signal level
Image table that can display images with high display quality
There is an effect that an indicating device can be provided. Also,,UpRecordeachAccording to the configuration, the average signal level is
Adjust the maximum output brightness of the pixels in the display unit according to the
So that, for example, the maximum
Display unit with constant output luminance (liquid crystal display device, etc.)
Screen when displaying a bright image overall
Glare can be reduced and at the time of direct viewing
To prevent temporary blindness due to retinal bleaching
Image display device with excellent visibility of bright images
Can be provided. Therefore, aboveeachConstitution
Displays images with high display quality regardless of the type of display unit
Image display device capable of performing
Has the effect of. The image signal correction apparatus of the present invention
ToInverse gamma correctedPixel signal levelFull screen
Average signal level operation that calculates the average as the average signal level
Calculation unit and the change in pixel luminance with respect to the pixel signal level.
The input signal-output luminance characteristics are represented by the average signal level.of
changeIn response to theArbitrarily to change continuouslySet on
Force signal-output luminance characteristic setting unit, set input signal-
Output luminance characteristicsWith input / output characteristics equal toCorrect image signal
FirstSignal correction unit and, Display input signal-output luminance characteristics
To correct the image signal with the input / output characteristics of the opposite characteristics
Of the average signal level.
The maximum output for continuously adjusting the maximum output brightness of the pixel of the display device
Power brightness adjustment unit andIt is a structure provided with. [0174]Further, the image signal correction device of the present invention
The average of the pixel signal level over the entire screen is
Average signal level calculator that calculates the signal level
An input signal representing the change in pixel brightness relative to the signal level
-Set the output luminance characteristics according to the average signal level.
Input signal-output luminance characteristic setting section and the set input signal
Corrects image signal with input / output characteristics equal to signal-output luminance characteristics
A first signal correction unit for performing the operation, and an input signal-output luminance of the display unit
Corrects image signals with input / output characteristics that are inverse to the characteristics
A second signal correction unit and display according to the average signal level
Maximum output brightness adjustment to adjust the maximum output brightness of the device pixels
And the above input The signal-output luminance characteristic setting section
When the force signal-output luminance characteristic is approximated by an exponential function
The exponent value changes as the average signal level changes.
The configuration is as follows. The aboveeachAccording to the configuration, it
Input signal of the image signal correction device-output luminance characteristic of the display device.
Characteristics can be changed, for example, the average signal level
The input signal-output luminance characteristic is constant regardless of the bell
Even if a display device such as a liquid crystal display device is used,
Visibility of dark areas in dark images (images with low average brightness)
Or in an overall bright image (image with high average brightness)
It is possible to display an image with excellent visibility of bright portions.
Therefore, aboveeachThe configuration is based on the input signal of the display device
Whether the luminance characteristic changes according to the average signal level
Regardless, it is possible to display images with high display quality
Of providing a simple image signal correction device
To play. Also,,UpRecordeachAccording to the configuration, the average signal level is
Adjust the maximum output luminance of the display device pixels according to the
For example, regardless of the average signal level,
A display device in which the large output luminance is constant (a liquid crystal display device)
Etc.) when displaying a bright image overall
Reduces glare on the screen and allows direct viewing
To prevent temporary blindness due to retinal bleaching during bleeding
Can improve overall bright image visibility
be able to. Therefore, aboveeachThe configuration of the display device
Images can be displayed with high display quality regardless of the type
That an effective image signal correction device can be provided.
Play a fruit. [0177] The maximum output luminance adjustment section is adapted to output the average signal.
The maximum output brightness decreases as the level increases
It is desirable that it be adjusted well. With this,
When an image signal with a high average signal level is
Glare can be reduced, and when looking directly
To prevent temporary blindness due to retinal bleaching phenomenon
Can improve the visibility of bright images overall
Is obtained. Also, the input signal-output luminance characteristic setting section
Is an approximation of the input signal-output luminance characteristic by an exponential function.
Exponent value (gamma exponent for CRT display)
Set to higher values as the average signal level increases
It is desirable that This allows overall
Visibility of dark areas in dark images (images with low average brightness)
Or in an overall bright image (image with high average brightness)
The effect that the visibility of the bright part can be improved
can get. Further, the maximum output luminance adjustment section is provided with
The maximum output brightness increases as the average signal level increases.
The input signal is adjusted to be smaller.
The output luminance characteristic setting unit calculates the input signal-output luminance characteristic as an index.
Exponential value approximated by a function (CRT display device
Gamma index) as the average signal level increases
It is even better to set it to a higher value.
Good. This allows the overall image to be bright (average brightness
(High image) to further improve the visibility of bright areas
Together with a dark image (image with low average brightness)
That the visibility of dark areas can be improved
Is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a schematic configuration of an image display device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of an image display device according to a more preferred embodiment of the embodiment shown in FIG. 1, in which a display element and a light-emitting element which are independently controlled are provided in a display unit. is there. FIG. 3 is a block diagram schematically showing a flow of signal processing in the image display device shown in FIG. 2; FIG. 4 is a block diagram showing a schematic configuration of an image display device according to another embodiment of the present invention, in which a light-emitting display element is provided in a display unit. 5 is a block diagram schematically showing a flow of signal processing in the image display device shown in FIG. FIG. 6 is an explanatory diagram schematically showing a change in an input signal-output luminance characteristic together with an input / output characteristic of a display device when an image signal subjected to inverse gamma correction is output through various display devices. FIG. 7 is an explanatory diagram schematically illustrating a change in an input signal-output luminance characteristic together with an input / output characteristic of a display device when a linearly processed image signal is output through various display devices. FIG. 8 is a graph showing a change in the output luminance of the box with respect to the input luminance signal level of the box when the input luminance signal level of the background portion of the CRT display device is constant. FIG. 9 is a graph showing a change in box output luminance with respect to an average input luminance signal level of a CRT display device. FIG. 10 is a graph showing a change in a standardized maximum output luminance and a gamma value with respect to an average input luminance signal level in a CRT display device. FIG. 11 is a graph showing a change in the output luminance of the box with respect to the input luminance signal level of the box when the input luminance signal level of the background portion of the liquid crystal display device is constant. FIG. 12 is a graph showing an input signal-output luminance characteristic of the liquid crystal display device when the average input luminance signal level is 0%. FIG. 13 is a graph showing an input signal-output luminance characteristic of the liquid crystal display device when the average input luminance signal level is 75%. FIG. 14 is a graph showing an input signal-output luminance characteristic of the liquid crystal display device when the present invention is not applied. [Description of Signs] 1 Average signal level operation circuit (average signal level operation section) 2 Input signal-output luminance characteristic setting circuit (input signal-output luminance characteristic setting section) 3 Maximum output luminance adjustment circuit (maximum output luminance adjustment section) Reference Signs List 4 signal correction unit 5 γ (G) correction circuit 6 inverse characteristic correction circuit 7 image signal correction device 7 ′ image signal correction device 8 display device (display unit) 9 switch 10 reverse gamma correction circuit 11 delay circuit 12 maximum output luminance setting circuit 13 brightness output control circuit 15 display element driving form conversion circuit 16 display element 17 light emitting element driving form conversion circuit 18 light emitting element 21 signal conversion circuit 22 light emitting display element driving form conversion circuit 23 light emitting display element 27 image signal correction device 28 display apparatus

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. 7 Identification code FI H04N 5/202 H04N 5/66 A 5/66 G09G 5/36 520A JP-A-2000-20013 (JP, A) JP-A-11-305734 (JP, A) JP-A 8-194450 (JP, A) JP-A 8-190363 (JP, A) JP-A 8-190362 ( JP, A) JP-A-2000-98995 (JP, A) JP-A-9-154042 (JP, A) JP-A-8-205049 (JP, A) JP-A-8-223507 (JP, A) (58) Field surveyed (Int.Cl. 7 , DB name) G09G 3/00-5/42 G02F 1/33 H04N 5/202

Claims (1)

  1. (57) Claims 1. A display unit having a plurality of pixels for displaying an image is provided, and an image signal including a pixel signal representing information for each pixel is input. An average signal level calculation unit that calculates the average of the levels of pixel signals subjected to inverse gamma correction over the entire screen as an average signal level, and an input signal representing a change in pixel luminance with respect to the pixel signal level. -An input signal for arbitrarily setting an output luminance characteristic so as to continuously change in accordance with a change in the average signal level-
    Output luminance characteristic setting section, input / output characteristics equal to the set input signal-output luminance characteristics
    A first signal correction unit for correcting an image signal by inputting and outputting a characteristic reverse to an input signal-output luminance characteristic of a display unit
    A second signal correction unit for correcting an image signal with a force characteristic, and a maximum output luminance of a pixel of the display unit according to the average signal level.
    An image display device comprising: a maximum output luminance adjustment unit that adjusts a degree . 2. An image display device comprising a plurality of pixels for displaying an image.
    An image including a pixel signal representing information for each pixel is provided.
    An image display device to which an image signal is input
    The average of the pixel signal levels over the entire screen is referred to as the average signal level.
    Signal level calculating section for calculating the luminance of a pixel with respect to the level of a pixel signal
    The signal-output luminance characteristics are set according to the average signal level.
    Input signal-output luminance characteristic setting section to set, and input / output characteristics equal to the set input signal-output luminance characteristic
    A first signal correction unit for correcting an image signal by inputting and outputting a characteristic reverse to an input signal-output luminance characteristic of a display unit
    A second signal correction unit for correcting an image signal with a force characteristic, and a maximum output luminance of a pixel of the display unit according to the average signal level.
    A maximum output luminance adjustment unit for adjusting the degree, wherein the input signal-output luminance characteristic setting unit includes an input signal-output luminance
    The exponent value when the brightness characteristic is approximated by an exponential function is
    Images display you characterized in that to vary with a change in average signal level. 3. An input signal-output luminance characteristic setting unit, comprising:
    When the force signal-output luminance characteristic is approximated by an exponential function
    Exponential value increases with increasing average signal level
    3. The method according to claim 1, wherein
    3. The image display device according to 2. 4. The maximum output luminance adjustment section includes:
    The maximum output brightness decreases as the level increases
    3. The image display device according to claim 1, wherein the image display device is adjusted . 5. An input signal-output luminance characteristic setting unit, comprising:
    When the force signal-output luminance characteristic is approximated by an exponential function
    Exponential value increases with increasing average signal level
    3. The image display device according to claim 1 , wherein the maximum output luminance adjustment unit adjusts the maximum output luminance to be smaller as the average signal level increases. 4. apparatus. 6. The display section includes a light emitting element and a non-light emitting optical switch.
    And a maximum output luminance adjusting unit that adjusts the maximum output luminance to the light emitting element.
    Output to the optical switching element
    The image display device according to any one of claims 1 to 5, wherein the light emitting element is controlled independently of the control . 7. An image signal correction device which receives an image signal including a pixel signal representing information for each pixel, corrects the image signal, and outputs the corrected image signal to a display device having a plurality of pixels. An average signal level calculation unit that calculates an average of the levels of the pixel signals subjected to inverse gamma correction over the entire screen as an average signal level; and an input signal-output luminance characteristic indicating a change in pixel luminance with respect to the pixel signal level. An input signal arbitrarily set so as to continuously change in accordance with a change in the average signal level.
    Output luminance characteristic setting section, input / output characteristics equal to the set input signal-output luminance characteristics
    A first signal correction unit for correcting an image signal by inputting and outputting a characteristic reverse to an input signal-output luminance characteristic of a display unit
    A second signal correction unit for correcting an image signal with a force characteristic, and a maximum pixel of a display unit according to the change in the average signal level.
    An image signal correction device comprising: a maximum output luminance adjustment unit that continuously adjusts output luminance . 8. An image including a pixel signal representing information for each pixel.
    A signal is input and the image signal is corrected to have a plurality of pixels.
    Image signal correction adapted to be output to a display device
    In the device, the average of the pixel signal levels over the entire screen is defined as the average signal level.
    Signal level calculating section for calculating the luminance of a pixel with respect to the level of a pixel signal
    The signal-output luminance characteristics are set according to the average signal level.
    An input signal-output luminance characteristic setting unit to be set; and an input signal-output set according to the average signal level.
    First to correct image signal with input / output characteristics equal to luminance characteristics
    Signal input / output luminance characteristics of the display unit
    A second signal correction unit for correcting an image signal with a force characteristic, and a maximum output of a pixel of the display device according to the average signal level
    A maximum output brightness adjustment unit for adjusting brightness, wherein the input signal-output brightness characteristic setting unit includes an input signal-output
    The exponent value when the brightness characteristic is approximated by an exponential function is
    Images display you characterized in that to vary with a change in average signal level. 9. The display device according to claim 1, wherein the display device includes a light emitting element and a non-light emitting type light.
    A switching element, wherein the maximum output luminance adjustment section sets the maximum output luminance to the light emitting element.
    Output to the optical switching element
    The image display device according to claim 7, wherein the light emitting element is controlled independently of the control .
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