JP3531015B2 - Video display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video display device for digitally processing a video signal and displaying it on a display surface.

[0002]

2. Description of the Related Art FIG. 7 is a circuit diagram showing an example of a white peak control circuit in a conventional image display device. In the figure, reference numerals 1, 2 and 3 denote buffer circuits for outputting a red primary color signal (R), a green primary color signal (G), and a blue primary color signal (B), respectively, with low impedance. Each buffer circuit 1,
The emitters of the transistors in 2 and 3 are connected to the bases of the transistors in the white peak amplifying circuit 8 via resistors 4, 5 and 6, respectively. The base of the transistor in the white peak amplifying circuit 8 is grounded via the resistor 7. These resistors 4, 5, 6, 7 are resistors for setting an addition ratio when adding the R, G, B primary color signals output from the buffer circuits 1, 2, 3.

The collector of the transistor in the white peak amplifying circuit 8 is connected to the base of the transistor 901 in the white peak detecting circuit 9. The white peak amplifier circuit 8 has a resistor 4
The signals added in ~ 7 are inverted and amplified, and the white peak detection circuit 9 extracts a voltage of a predetermined level or less from the output of the white peak amplification circuit 8. The emitter of the transistor 901 is connected to the base of the transistor 1001 in the gamma drive circuit 10. The gamma drive circuit 10 transmits the voltage detected by the white peak detection circuit 9 to the correction circuits 11, 12, 13 at the next stage.

The emitter of the transistor 1001 has an R gamma correction circuit 11, a G gamma correction circuit 12, and a B gamma correction circuit 13.
It is connected to each emitter of the transistors 1101, 1201, 1301 inside. The emitters of the transistors 1101, 1201, 1301 are grounded via the resistors 1102, 1202, 1302, respectively. Furthermore, the emitter of the transistor in the buffer circuit 1 and the transistor 11 in the R gamma correction circuit 11 are
The collector of 01 is connected, the emitter of the transistor in the buffer circuit 2 and the collector of the transistor 1201 in the G gamma correction circuit 12 are connected, and the emitter of the transistor in the buffer circuit 3 and the transistor in the B gamma correction circuit 13 are connected. The collector of 1301 is connected. The emitters of the transistors in the buffer circuits 1, 2 and 3 are connected to the transistors 1101 and 12 via resistors 4, 5 and 6, respectively.
It is connected to the 01, 1301 base. R gamma correction circuit
Reference numeral 11 is an output of the gamma drive circuit 10 and corrects the R primary color signal. G gamma correction circuit 12 is a gamma drive circuit.
The G primary color signal is corrected by receiving the output of 10 and the B gamma correction circuit 13 corrects the B primary color signal by receiving the output of the gamma drive circuit 10.

Next, the operation will be described. The R, G, and B video signals output from the buffer circuits 1, 2, and 3 are added together at a ratio determined by the resistors 4, 5, 6 and 7, and the white peak amplifying circuit 8 inverts and amplifies the white signal. In the peak detection circuit 9, the base voltage of the transistor 901 is the voltage -V _BE (transistor base-
Transistor 901 turns on when the voltage becomes less than the (emitter voltage), and the emitter voltage of the transistor 901 is the base voltage + V
Set to _BE .

When the emitter voltage of the transistor 901 decreases as the transistor 901 turns on, the base voltage of the transistor 1001 of the gamma drive circuit 10 also decreases. As a result, the emitter voltage of the transistor 1001 also decreases, and the emitter voltage of each of the transistors 1101, 1201, 1301 of the R gamma correction circuit 11, G gamma correction circuit 12, and B gamma correction circuit 13 decreases, and the difference from the base voltage is reduced. When the voltage difference exceeds V _BE , the transistors 1101, 1201, 1301 are turned on, respectively, whereby the amplitudes of the R, G, B primary color signals are suppressed.

When the resistors 1102, 1202, 1302 have the same value, the R, G, B video signals are equally compressed, so that the color temperature of white does not change, but the resistors 1102, 120
By appropriately changing the ratio of the values of 2, 1302, the color temperature of white can be changed arbitrarily.

[0008]

Since the white peak control circuit in the conventional video display device is constructed as described above, when the level sum of the video signals of the three primary colors exceeds a predetermined level, the white peak is not necessarily a white peak. However, there is a problem in that the compression control works and the hue changes.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an image display device in which the control works only on the white peak signal and does not affect the display of other colors. To do.

[0010]

According to a first aspect of the present invention, there is provided a video display device in which a level difference in digital video signal data of primary color signals of three colors is equal to or less than a predetermined value.
When at least one of the color data is at or above a predetermined threshold level, the amplitude ratio of the three-color digital video signal data is changed.

The video display device according to the second invention of the present application is 3
Is equal to or less than a predetermined value level difference is in the digital video signal data of the color primary color signals, moreover, when at least one of the three colors of the data but is above a predetermined threshold level, the three-color level of the digital video signal data Each is configured to be compressed.

In the video display device according to the third invention of the present application, in the digital video signal data of the luminance signal and the two color difference signals, the two color difference signals are each less than or equal to a predetermined value, and the brightness signal is predetermined. When the threshold level is exceeded, the amplitude ratio of the three-color digital video signal data generated from the luminance signal and the two color difference signals is changed.

In the video display device according to the fourth invention of the present application, in the digital video signal data of the luminance signal and the two color difference signals, the two color difference signals are each less than or equal to a predetermined value, and the brightness signal is predetermined. If it is the threshold level or higher, which is constituted to compress the level of the digital video signal data of the luminance signal and the three color digital video signal data, or luminance signals generated from the two color difference signals.

[0014]

In the image display device according to the first aspect of the invention, the level difference between the three signals is detected for the digital image signal data of the three primary color signals, and the level difference is less than or equal to the predetermined value, and the three primary color signals are detected. If at least one of them is above a predetermined threshold level, the amplitude level ratio of the digital video signal data of the three primary color signals is changed. Therefore, the color temperature of the white peak portion of the displayed image can be changed.

In the video display device of the second invention, the level difference between the three signals is detected in the digital video signal data of the three primary color signals, and the level difference is not more than the predetermined value, and the three primary color signals are detected. If at least one of them is above a predetermined threshold level, the levels of the digital video signal data of the three primary color signals are respectively compressed. Therefore, the level of the white peak portion of the displayed image can be suppressed, and the focus performance can be improved.

In the image display device of the third invention, the level of the digital image signal data of the luminance signal is equal to or higher than a predetermined threshold level, and RY and B are set.
When the levels of the digital video signal data of the two Y-color difference signals are equal to or less than the predetermined values, the amplitude level ratio of the digital video signal data of the primary color signals of the three colors generated from the luminance signal and the color difference signal is changed. Therefore, the color temperature of the white peak portion of the displayed image can be changed.

In the video display device of the fourth invention, the level of the digital video signal data of the luminance signal is equal to or higher than a predetermined threshold level, and RY and B
-When the levels of the digital video signal data of the two color difference signals of Y are each less than or equal to a predetermined value, the level of the digital video signal data of the luminance signal or the three primary color signals generated from the luminance signal and the color difference signal The level of the digital video signal data of is compressed. Therefore, the focus performance of the white peak portion of the displayed video can be improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

Embodiment 1 FIG. 1 is a block diagram showing the configuration of a video display device according to Embodiment 1 of the present invention. In the figure, 14 is a subtracter for calculating the difference between the R (red) primary color signal data and G (green) primary color signal data, and 15 is the difference between the G (green) primary color signal data and the B (blue) primary color signal data. And each of the subtracters 14,
15 outputs the subtraction result to the comparators 16 and 17, respectively. The comparator 16 compares the output of the subtractor 14 with a predetermined threshold level (hereinafter referred to as TH level) and outputs the comparison result to the AND circuit 19. Further, the comparator 17 is a subtractor
The output of 15 is compared with a predetermined TH level, and the comparison result is A
Output to the ND circuit 19. The AND circuit 19 includes both comparators 16,
The output of 17 is logically ANDed and the result is output to the AND circuit 20. On the other hand, the comparator 18 compares the G (green) primary color signal data with a predetermined TH level and outputs the comparison result to the AND circuit 20.
Output to.

The AND circuit 20 includes a comparator 18 and an AND circuit 19
The outputs of and are ANDed and the result is output to the selection circuits 21 and 22. Each of the selection circuits 21 and 22 selects either the control data at the normal time or the control data at the white peak signal according to the output from the AND circuit 20, and sends the selected control data to the multipliers 23 and 24. Output each. The multiplier 23 multiplies the R primary color signal data by the control data from the selection circuit 21 and outputs the result. In addition, the multiplier 24 is a circuit for selecting the B primary color signal data.
The control data from 22 is multiplied and output.

Next, the operation will be described. R (red),
Video signal data of the three primary colors of G (green) and B (blue) are subtracted
Input to 14 and 15, the level difference between the R and G and G and B primary color signals is detected. Each detected difference data is a comparator
It is output to 16 and 17, and the predetermined T set here is set.
Compared to H level. When the difference data is equal to or lower than the TH level, the comparators 16 and 17 output High level signals to the AND circuit 19, respectively. On the other hand, in the comparator 18, the video signal data of the G (green) primary color signal is compared with a predetermined TH level. If the G primary color signal data is equal to or higher than the TH level, the comparator 18 outputs a high level signal. It is output to the AND circuit 20.

The output signals from the comparators 16 and 17 are logically ANDed by the AND circuit 19, and the output signal of the AND circuit 19 and the output signal from the comparator 18 are logically ANDed by the AND circuit 20. Then, the output signal of the AND circuit 20 becomes a selection switching signal in the selection circuits 21 and 22. The normal amplitude level control data and the amplitude / amplitude level control data at the time of the white peak are input to the selection circuits 21 and 22, respectively.
In response to the selection switching signal from 20, both control data are switched and output to the multipliers 23 and 24. Each of the multipliers 23 and 24 adjusts the amplitude level by multiplying the R primary color signal data and the B primary color signal data by the input control data, thereby changing the amplitude level ratio of the three primary color signals.

As described above, the color temperature of the displayed image can be changed between the white peak portion and the other portion of the displayed image.

In the above example, when comparing the amplitude level of the three primary color signals with a predetermined TH level, only the G primary color signal data is extracted, but this is the difference between the G primary color signal and the other two primary color signals. This is effective when the TH level to be compared with the data has a relatively small value. When the TH level has a large value, the configuration shown in FIG. 2 improves the accuracy.

In FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. 25 is a comparator for comparing the R (red) primary color signal data with a predetermined TH level, and 26 is a comparator for comparing the B (blue) primary color signal data with a predetermined TH level.
Each of the comparators 25 and 26 outputs the comparison result to the OR circuit 27. The comparator 18 also outputs the comparison result to the OR circuit 27.
Here, the respective comparators 25, 18, 26 compare the respective amplitude levels of the R, G, B primary color signals with a predetermined TH level, and when the amplitude level of the primary color signal is equal to or higher than the TH level, A high level signal is output to the OR circuit 27. In the OR circuit 27, the output of any one of the three comparators 25, 18, 26 is High.
At the time of the level, it outputs a high level signal to the AND circuit 20. The configuration and operation of the other parts are the same as in the example shown in FIG.

Second Embodiment FIG. 3 is a block diagram showing the configuration of a video display device according to a second embodiment of the present invention. 3, the same parts as those in FIG. 1 are designated by the same reference numerals. Reference numeral 28 is an AND circuit that takes the logical product of the outputs of the comparators 16 and 17, and 29 is a subtractor that calculates the difference between the G (green) primary color signal data and a predetermined TH level. The subtractor 29 outputs the obtained difference data to the inverter 30. The inverter 30 inverts the output data of the subtractor 29 and outputs it to the multiplier 31. The multiplier 31 is an inverter
The output data of 30 is multiplied by predetermined amplitude control data (hereinafter referred to as first amplitude control data) and output to the selection circuit 32. The selection circuit 32 switches between the first amplitude control data that is the input data to the multiplier 31 and the output data of the multiplier 31 (hereinafter referred to as the second amplitude control data) according to the output of the AND circuit 28. Output to the multipliers 33, 34, 35. The multiplier 33 multiplies the R (red) primary color signal data by the output data of the selection circuit 32 and outputs the multiplied data. Further, the multiplier 34 multiplies the G (green) primary color signal data by the output data of the selection circuit 32 and outputs the multiplied data. Further, the multiplier 35 multiplies the B (blue) primary color signal data by the output data of the selection circuit 32 and outputs the multiplied data.

Next, the operation will be described. Similar to the first embodiment, the video signal data of the three primary colors of R (red), G (green), and B (blue) are input to the subtractors 14 and 15, and R and G, G and B are input.
The level difference between the respective primary color signals is detected. Each detected difference data is output to the comparators 16 and 17, and is compared with a predetermined TH level set in advance here. When the difference data is below the TH level, each comparator 1
High-level signals from 6 and 17 are output to the AND circuit 28, respectively. The output from each comparator 16, 17 is an AND circuit 28.
Is ANDed and the output signal of the AND circuit 28 becomes the selection switching signal in the selection circuit 32.

On the other hand, in the subtractor 29, the difference between the video signal data of the G (green) primary color signal and the predetermined TH level is calculated, the one's complement is taken by the inverter 30, and then the first by the multiplier 31. Is multiplied by the amplitude control data of
Is inputted to the selection circuit 32 as amplitude control data. In the selection circuit 32, the first amplitude control data and the second amplitude control data are switched according to the output of the AND circuit 28 and sent to the multipliers 33, 34, 35, and the R, G, B primary color signals are output. The video signal data of is compressed.

As described above, the focus level can be improved by lowering the amplitude level of the white peak portion.

Embodiment 3 FIG. 4 is a block diagram showing the configuration of an image display device according to Embodiment 3 of the present invention. In FIG. 4, 36 is the brightness (Y)
A comparator for comparing the signal data with a predetermined TH level, 37
Is a comparator for comparing the color difference (RY) signal data with a predetermined TH level, 38 is a comparator for comparing the color difference (BY) signal data with a predetermined TH level, and each comparator 36, 3
7, 38 output the comparison result to the AND circuit 39. The AND circuit 39 takes the logical product of the outputs of the comparators 36, 37, 38 and outputs the result to the selection circuits 41, 42. In addition, 40 is from Y signal data, RY signal data and BY signal data,
It is a matrix circuit that generates R, G, B primary color signal data. Each of the selection circuits 41 and 42 selects either the control data at the normal time or the control data at the white peak signal according to the output data from the AND circuit 39, and the selected control data is multiplied by the multipliers 43 and 44. Output to each. The multiplier 43 is
The R primary color signal data is multiplied by the control data from the selection circuit 41 and output. Further, the multiplier 44 multiplies the B primary color signal data by the control data from the selection circuit 42 and outputs the result.

Next, the operation will be described. In the comparator 36, the amplitude level of the Y signal data is compared with a predetermined TH level, and when the amplitude level of the Y signal data is higher than the TH level, a high level signal is output to the AND circuit 39. Further, in the comparators 37 and 38, the amplitude levels of the two RY signal data and the BY signal data and the predetermined TH
And the amplitude level of the color difference signal data is T
If it is lower than H level, the High level signal is A
It is output to each ND circuit 39. And AND circuit
If all three inputs to 39 are high, A
A high level signal is output from the ND circuit 39 to the selection circuits 41 and 42.

On the other hand, the Y signal data, the RY signal data and the BY signal data are input to the matrix circuit 40, and the primary color signal data of three colors of R (red), G (green) and B (blue). And the R and B primary color signal data are converted into the multiplier 43,
Sent to 44 each. The multipliers 43, 44 have a selection circuit 41,
The amplitude control data is input from 42, and the AND circuit 39
By switching the two amplitude control data in the selection circuits 41 and 42 by using the output signal of, the amplitude level ratio of the primary color signals of the three colors can be changed.

As described above, when the amplitude level of the luminance signal is large and the amplitude level of the color difference signal is small, that is, the color density at the white peak portion of the displayed image can be changed.

Embodiment 4 FIG. 5 is a block diagram showing the configuration of a video display device according to Embodiment 4 of the present invention. 5, the same parts as those in FIG. 4 are designated by the same reference numerals. Reference numeral 45 is an AND circuit that takes the logical product of the outputs of the comparators 37 and 38, and the AND circuit 45 outputs the result of the logical product to the selection circuit 47. Further, 46 is a subtractor for calculating the difference between the luminance (Y) signal data and a predetermined TH level, and the subtractor 46 outputs the calculated difference data to the selection circuit 47. The selection circuit 47 switches between the output data of the subtractor 46 and “zero” data according to the output of the AND circuit 45, and outputs it to the inverter 48. Inverter 48
Outputs the inverted data of the selection circuit 47 to the multiplier 49. The multiplier 49 multiplies the Y signal data by the output data of the inverter 48 and outputs the multiplication result.

Next, the operation will be described. The subtracter 46 calculates the difference between the Y signal data and a predetermined TH level. Here, when the amplitude level of the Y signal data is equal to or higher than the TH level, the difference data is valid as it is, but when the amplitude level of the Y signal data is smaller than the TH level, the difference data becomes zero. In the comparators 37 and 38, the amplitude levels of the two color difference (RY, BY) signal data are compared with a predetermined TH level, respectively, and when the amplitude level of the color difference signal is higher than the TH level, Hi
The gh level signal is output to each AND circuit 45.
When the output signals of both the comparators 37 and 38 are both at the high level, the AND circuit 45 outputs the high level signal to the selection circuit 47.
It is output to the control terminal of.

The selection circuit 47 has two input terminals, one of which receives the output data from the subtractor 46 and the other of which receives the data of level "zero". A
When the control data sent from the ND circuit 45 is at the high level, the output data from the subtractor 46 is selected and output to the inverter 48. The output data of the selection circuit 47 is complemented by an inverter 48 and then sent to a multiplier 49 to compress the Y signal data.

As described above, when the amplitude level of the luminance signal is large and the amplitude level of the color difference signal is small, that is, the brightness of the image at the white peak portion of the displayed image is suppressed to improve the focusing performance. You can

Embodiment 5 FIG. 6 is a block diagram showing the structure of a video display device according to Embodiment 5 of the present invention. 6, the same parts as those in FIGS. 4 and 5 are designated by the same reference numerals. Reference numeral 50 denotes a multiplier that multiplies the output data of the inverter 48 by predetermined amplitude control data, and the multiplier 50 outputs the multiplication result to the multipliers 51, 52, 53, respectively. The multiplier 51 multiplies the R primary color signal data from the matrix circuit 40 by the output data of the multiplier 50 and outputs it. Further, the multiplier 52 multiplies the G primary color signal data from the matrix circuit 40 by the output data of the multiplier 50 and outputs the result. Further, the multiplier 53 multiplies the B primary color signal data from the matrix circuit 40 by the output data of the multiplier 50 and outputs the result.

Next, the operation will be described. Inverter
The operation up to 48 is the same as that of the above-described fourth embodiment, and thus the description thereof is omitted. The output of the inverter 48 is multiplied by predetermined amplitude control data in the multiplier 50, and the multiplication result is multiplied by the multiplier 5
Sent to 1, 52, 53. The data of each primary color signal of the three colors converted by the matrix circuit 40 from the luminance signal and the two color difference signals are multiplied by the multiplication result in the multipliers 51, 52 and 53 to obtain the three primary color signals. Amplitude data is compressed. As a result, similar to the fourth embodiment, it is possible to suppress the brightness of the image in the white peak portion of the displayed image and improve the focus performance.

[0040]

As described above, in the first invention, the level difference between the three primary color signals is detected in the digital video signal data of the three primary color signals, and the level difference is a predetermined T.
Since the amplitude level ratio of the digital video signal data of the three primary color signals is changed when it is at the H level or lower and at least one of the three primary color signals is at the predetermined TH level or higher, The color temperature of only the white peak portion can be changed, and white characters and the like can be made to look beautiful without adversely affecting other display colors.

In the second invention, the level difference between the three signals is detected for the digital video signal data of the three primary color signals,
This level difference is less than or equal to a predetermined TH level, and 3
When at least one of the primary color signals is equal to or higher than the predetermined TH level, the levels of the digital video signal data of the three primary color signals are respectively compressed, so that the brightness of the white peak portion of the display video is suppressed, It is possible to improve the deterioration of the focus performance that tends to occur in the high-brightness portion.

According to the third aspect of the invention, regarding the luminance signal and the two color difference signals, the amplitude level of the digital video signal data of the luminance signal is equal to or higher than a predetermined TH level, and the amplitude of the digital video signal data of the two color difference signals. Since the amplitude level ratio of the digital video signal data of the primary color signals of the three colors generated from the luminance signal and the color difference signal is changed when the levels are lower than the predetermined TH level, the white peak portion of the display video is displayed. It is possible to change the color temperature of only the white color, and to make white characters and the like look beautiful without adversely affecting other display colors.

In the fourth invention, regarding the luminance signal and the two color difference signals, the amplitude level of the digital image signal data of the luminance signal is equal to or higher than a predetermined TH level, and the amplitude of the digital image signal data of the two color difference signals. If the level is below the respective predetermined TH level, the level of the digital video signal data of the luminance signal, or so as to compress the level of the digital video signal data of the three-color primary color signals generated from the luminance signal and color difference signal Since it is configured as described above, it is possible to suppress the luminance of the white peak portion of the display image and improve the deterioration of the focus performance that tends to occur in the high luminance portion.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a modified example of the video display device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an image display device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an image display device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an image display device according to Example 4 of the present invention.

FIG. 6 is a block diagram showing a configuration of an image display device according to Example 5 of the present invention.

FIG. 7 is a circuit configuration diagram of a white peak control circuit in a conventional image display device.

[Explanation of symbols]

14,15 Subtractor, 16,17,18 Comparator, 19,20 AND
Circuit, 21, 22 selection circuit, 23, 24 multiplier, 25, 26 comparator, 27 OR circuit, 28 AND circuit, 29 subtractor, 30
Inverter, 31 multiplier, 32 selection circuit, 33, 34, 35
Multiplier, 37, 38 comparator, 39 AND circuit, 40 matrix circuit, 41, 42 selection circuit, 43, 44 multiplier, 45
AND circuit, 46 subtractor, 47 selection circuit, 48 inverter, 49 multiplier, 50 inverter, 51, 52, 53 multiplier.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 63-160492 (JP, A) JP 60-180394 (JP, A) JP 5-292534 (JP, A) 69986 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 9/44-9/78

Claims (4)

(57) [Claims] 1. A video display device for displaying three primary color signals on a display surface, and means for obtaining a level difference between the three primary color signals for digital video signal data of the three primary color signals.
A means for changing the amplitude level ratio of the digital video signal data of the three primary color signals when the calculated level difference is less than or equal to a predetermined value and at least one of the three primary color signals is at least a predetermined threshold level. An image display device comprising: 2. A video display device for displaying three primary color signals on a display surface, and means for obtaining a level difference between the three primary color signals for digital video signal data of the three primary color signals.
A means for compressing the level of the digital video signal data of the three primary color signals when the obtained level difference is less than or equal to a predetermined value and at least one of the three primary color signals is at least a predetermined threshold level. A video display device characterized by the above. 3. A video display device for generating primary color signals of three colors from a luminance signal and two color difference signals and displaying the generated primary color signals of the three colors on a display surface. Digital video signal data of the luminance signal. Of the first and second level detecting means for detecting the amplitude levels of the digital video signal data of the two color difference signals, respectively. A means for changing the amplitude level ratio of the digital video signal data of the three primary color signals when the output is above a predetermined threshold level and the outputs of the second and third level detecting means are below a predetermined value. An image display device comprising: 4. A video display device for generating primary color signals of three colors from a luminance signal and two color difference signals and displaying the generated primary color signals of the three colors on a display surface. Digital video signal data of the luminance signal. Of the first and second level detecting means for detecting the amplitude levels of the digital video signal data of the two color difference signals, respectively. When the output is above a predetermined threshold level and the outputs of the second and third level detecting means are below a predetermined value, respectively , the level of the digital video signal data of the luminance signal or the three primary color signals is changed. An image display device comprising: a means for compressing.