JP2009156957A - Color image display device and monochromatic image display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image display device which improves gradation characteristics by using a display device provided with a display part for color display. <P>SOLUTION: In the color image display device 200, a display part 103 is provided with a display part for color display, which has a display pixel structure finer than the area of one pixel of information to be displayed, and conversion table information associating levels of input signals based on an input image signal with brightness values corresponding to display characteristics of three primary colors of color in the display part 103 is preliminarily stored in a storage circuit 102b per element of color signals. A conversion circuit 102c refers to the conversion table information stored in the storage circuit 102b to convert an input signal inputted by an input circuit 102a and then outputs the converted signal to the display part 103. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a color video display device and a monochrome video display method that use a display device having a display unit for color display, for example, to increase gradation display characteristics in monochrome display.

When a medical institution displays an X-ray picture or the like, a display device capable of multi-gradation display is required. This is because it is necessary to be able to express a subtle difference in luminance when identifying the lesion of a patient.
As a device intended for such an application, for example, there is a display device dedicated to monochrome display that employs a display unit for monochrome display as a display unit in a liquid crystal display device.

An example of the structure of a display unit used for a display unit of a display device dedicated to monochrome display is shown.
From the basic structure of the display unit for color display in which one pixel is formed and displayed by the three primary colors red (R), green (G), and blue (B) in the display unit for color display, R for color It is known that there is a method for expressing gradation characteristics in multiple gradations by using a driving method shown in FIG. 5 with a display unit dedicated to monochrome display that does not have a G / B coloring structure. ing.

FIG. 6 shows a pixel configuration according to this method.
FIG. 6A is a structural example corresponding to one pixel of information in the display unit 300 for color display using a color R / G / B color development structure. FIG. 6B is a structural example corresponding to one pixel of information in the display unit 310 for monochrome display that does not have the R, G, and B coloring structure.
The light emitting portions 301R, 301G, and 301B of the three primary colors in the display portion for color display in FIG. 6A emit light in red (R), green (G), and blue (B), respectively.
In the display unit for monochrome display in FIG. 6B, since it is not affected by the R, G, B coloring structure, the light emitting units 311S1, 311S2, and 311S3 provided in the display unit for monochrome display are each three in monochrome. (S1, S2, S3) can also be used as a light emitting unit, and one pixel is configured in combination. Here, a structure in which one pixel is composed of a plurality of light emitting portions is called a sub-pixel structure.
That is, instead of each color signal (R, G, B), luminance information for one pixel is represented by a monochrome signal (S1, S2, S3).

  In the method of FIG.

(S1, S2, S3) = (a, a, a),
(S1, S2, S3) = (a + 1, a + 1, a + 1)

As described above, the white gradation of one pixel is represented by the value of gradation information having the relationship of S1 = S2 = S3. Here, the case where the gradation is increased by one gradation with respect to the gradation of a is represented as (a + 1).

  The gradation level is interpolated by adding the following two gradations between a and (a + 1).

(S1, S2, S3) = (a + 1, a, a),
(S1, S2, S3) = (a + 1, a + 1, a)

  By such a method, the following gradation configuration can be taken.

(S1, S2, S3) = (a, a, a),
(S1, S2, S3) = (a + 1, a, a),
(S1, S2, S3) = (a + 1, a + 1, a),
(S1, S2, S3) = (a + 1, a + 1, a + 1)

Since there is no distinction of brightness for each signal in S1, S2, and S3, the order of increase may be performed in any order. For example, it can be expressed as
(1) When one of S1, S2, and S3 is a + 1 and the remaining two are a, the gradation is (a + 1/3).
(2) If any one of S1, S2, and S3 is a + 1 and the other one is a, the gradation is (a + 2/3).
(3) When all of S1, S2, and S3 are a + 1, white gradation is (a + 1).

  By using such a method, when a display unit for monochrome display is used, it is possible to express the gradation three times by combining light emission of the light emitting units.

  On the other hand, there is known a technique for improving gradation characteristics when a display unit for color display is used. This technique is a technique aiming to display a blue display color on the screen. (For example, see Patent Document 1 or Patent Document 2)

Furthermore, a system using a method of performing gradation processing by combining a plurality of devices in addition to a display device is known. (For example, see Patent Document 3)
In this system, the device that outputs the video signal to be displayed is converted into a signal unique to the system, so that the video signal input to the display device used in the system uses pseudo video information It is.
JP 2000-330530 A JP 2001-034322 A JP 2004-020942 A

  However, the techniques described in Patent Document 1 and Patent Document 2 are methods that use a display unit for general-purpose color display. However, the technique is limited to a specific color tone range. Therefore, there is a problem that it is impossible to display with monochrome gradations that do not depend on a specific color tone.

  Furthermore, since the technique described in Patent Document 3 requires an external device having an auxiliary conversion function, it is not a technique that presents a method for improving gradation characteristics using a single display device, and conversion processing is also performed. Therefore, there is a problem that causes a deterioration factor from the original signal to be originally displayed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a color image display device that uses a display device having a display unit for color display to make gradation display characteristics multi-gradation. To provide a monochrome video display method.

  In order to solve the above problems, the present invention provides a color display device having a display unit for color display having a display pixel structure smaller than the area of one pixel of information to be displayed, and an input signal based on an input video signal is obtained. An input circuit for input; and an accumulation circuit for storing in advance conversion table information in which the level of the input signal and the luminance value corresponding to the display characteristics of the three primary colors on the display unit are associated with each color signal element A color video display apparatus comprising: a conversion circuit that converts an input signal input by the input circuit with reference to conversion table information stored in the storage circuit and outputs the converted signal to the display unit.

  Further, the present invention relates to the above-described invention, a conversion control unit that generates the conversion table information based on the luminance characteristics of the color signals in the display unit and stores the conversion table information in the storage circuit, It is further provided with the feature.

  Further, according to the present invention, in the invention described above, the conversion control unit generates the conversion table information based on instruction information for instructing a change in display state and the luminance characteristic, and stores the conversion table information in the storage It is stored in a circuit.

  According to the present invention, the above-described invention is generated using the characteristics of red and green elements or red, green and blue elements among the display characteristics of the color signal elements in the display unit. And a storage circuit for storing the converted conversion table information.

  Further, according to the present invention, in the above-described invention, when the conversion table information is expressed as digital value information, the conversion circuit performs gradation information conversion processing using the least significant 1 bit. It is characterized by that.

  Further, according to the present invention, in the above-described invention, when the conversion table information is expressed as information having a digital value of 8 bits or more, the conversion circuit performs gradation information conversion processing using the least significant 1 bit. It is characterized by doing.

  The present invention is also a monochrome image display method in a color display device having a display unit for color display having a display pixel structure smaller than the area of one pixel of information to be displayed, and an input signal based on an input image signal is input. And storing in the storage circuit conversion table information in which the level of the input signal and the luminance value corresponding to the display characteristics of the three primary colors in the display unit are associated with each element of the color signal. And a process of converting the input signal with reference to conversion table information stored in the storage circuit and outputting the converted signal to the display unit.

According to the present invention, a color video display apparatus includes a display unit for color display having a display pixel structure smaller than the area of one pixel of information to be displayed, an input circuit for inputting an input signal based on an input video signal, And a storage circuit for storing in advance conversion table information in which the level of the input signal and the luminance value corresponding to the display characteristics of the three primary colors on the display unit are associated with each signal element. Furthermore, a configuration is provided that includes a conversion circuit that converts an input signal input by the input circuit with reference to conversion table information stored in the storage circuit and outputs the converted signal to the display unit.
As a result, there is an effect that the gradation information of the input image signal is displayed as a monochrome image with multiple gradations.

According to the present invention, the conversion control unit in the color video display device generates conversion table information based on the luminance characteristics of the color signals on the display unit, and stores the conversion table information in the storage circuit. .
Thereby, there is an effect that the conversion characteristic of the gradation characteristic can be switched.

According to the present invention, the conversion control unit in the color video display device generates conversion table information based on the instruction information for instructing the change of the display state and the luminance characteristic, and stores the conversion table information in the storage circuit. It was decided.
Thereby, in order to obtain a display state suitable for the display content of the screen, there is an effect that a plurality of characteristics can be switched or characteristics can be changed.

Further, according to the present invention, the color video display device uses the characteristics of the two elements of red and green or the characteristics of every three elements of red, green and blue among the display characteristics of the elements of the color signal in the display unit. The storage circuit for storing the generated conversion table information is provided.
Thereby, there is an effect of improving the luminance gradation characteristic without being influenced by the display characteristics of red, green and blue in the display unit.

Further, according to the present invention, when the conversion table information is expressed as digital value information, the conversion circuit performs a gradation information conversion process using the least significant 1 bit.
This has the effect of improving the gradation characteristics without increasing the circuit scale.

According to the present invention, when the conversion table information in the color video display device is expressed as information having a digital value of 8 bits or more, the conversion circuit uses the lowest 1 bit to convert the gradation information. I will do it.
This has the effect of suppressing changes in color information due to tone correction processing.

According to the present invention, there is also provided a monochrome video display method in a color display device having a display unit for color display having a display pixel structure smaller than the area of one pixel of information to be displayed, the input signal based on the input video signal For each color signal element, conversion table information that associates the level of the input signal with the luminance value corresponding to the display characteristics of the three primary colors on the display unit is stored in the storage circuit. And a process of converting the input signal with reference to conversion table information stored in the storage circuit and outputting the converted signal to the display unit.
Thereby, an effect of displaying the gradation information of the input image signal as a monochrome image with multiple gradations can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic block diagram showing a color video display device 200 according to the first embodiment.
The color video display device 200 includes a signal processing unit 100 that converts the level of an input video signal and a display unit 103 that displays the converted video signal. The signal processing unit 100 includes a conversion control unit 101 and a conversion processing unit 102. In the signal processing unit 100, the conversion control unit 101 generates conversion table information used by the conversion processing unit 102 and inputs the conversion table information to the conversion processing unit 102. The generated conversion table information is generated as information associated with the luminance values corresponding to the display characteristics of the three primary colors of color on the display unit for the three elements (R, G, B) of the color signal. And input. The display unit 103 receives a signal from the conversion processing unit 102, and performs video display on the display unit 103 for color display having a display pixel structure smaller than the area of one pixel of information to be displayed, that is, a sub-pixel structure. FIG. 6A shows a structural example of the display unit 103 having the same structure. FIG. 6A is a structural example corresponding to one pixel of information in the display unit 300 for color display using a color R / G / B color development structure. The light emitting portions 301R, 301G, and 301B of the three primary colors in the display portion for color display in FIG. 6A emit light in red (R), green (G), and blue (B), respectively.
The input video signal indicates a video signal input from an external device such as a personal computer.

The conversion processing unit 102 includes an input circuit 102a, a storage circuit 102b, and a conversion circuit 102c. In the conversion processing unit 102, the input circuit 102a separates the input video signal input to the color video display apparatus 200 into three elements (R, G, B) of the three primary colors and inputs the digital signal to the conversion circuit 102c. . The storage circuit 102 b stores conversion table information referred to when converting an input video signal into an output signal to the display unit 103, that is, conversion table information input to the conversion processing unit 102 by the conversion control unit 101. The stored conversion table information is configured as information for each of the three elements (R, G, B) of the color signal.
The conversion circuit 102 c refers to the conversion table information stored in the storage circuit 102 b based on the input signal input from the input circuit 102 a and converts it as an output signal to the display unit 103. The conversion circuit 102c is a circuit that performs γ characteristic conversion processing. Further, the conversion circuit 102c is configured by each circuit for the three elements (R, G, B) of the color signal in order to perform the γ characteristic conversion process as a color video signal. That is, the conversion circuit 102c includes a conversion circuit (red (R) element) 102c-R, a conversion circuit (green (G) element) 102c-G, and a conversion circuit (blue (B) element) 102c-B. Each of the conversion circuits (red (R) element) 102c-R performs conversion processing on the input red (R) element signal, and the conversion circuit (green (G) element) 102c-G is input. Conversion processing is performed on the green (G) element signal, and the conversion circuit (blue (B) element) 102c-B processes the input blue (B) element signal. Here, when each element is individually indicated, for example, “conversion circuit (red (R) element) 102c-R” is shown, and when the three elements are collectively described, “conversion circuit 102c” is representative. ".

The accumulation circuit 102b stores a conversion table as conversion table information. Here, the conversion table includes items of “input video level” and “output video level”.
The “input video level” corresponds to the level of the input signal of the conversion circuit 102 c, and the “output video level” corresponds to the level of the signal input to the display unit 103 by the conversion circuit 102 c.
FIG. 2 is a diagram showing conversion table information stored in the storage circuit 102b, that is, a data structure of the conversion table. The conversion table shown in FIG. 2 shows one element of a color signal, for example, a red (R) element. Similarly, the green (G) and blue (B) elements have similar conversion table information. FIG. 2A shows an example of conversion table information with 8-bit input and 8-bit output, and FIG. 2B shows an example of conversion table information with 8-bit input and 16-bit output.
The information handled by the conversion control unit 101, the storage circuit 102b, the conversion circuit 102c, and the conversion table information is generally handled by the number of output bits greater than the number of input bits, and is usually handled by 8 bits.
In the following operation, a signal expressed in 8 bits will be described as being processed in the 8th bit from the top.

Next, the operation in the first embodiment will be described.
Prior to the display operation, the conversion control unit 101 in the signal processing unit 100 is set to a predetermined level by an instruction to change the display state by an operation of the user or the like. Further, the conversion control unit 101 generates an output video level value corresponding to the set predetermined level, and records conversion table information in which the generated output video level is associated with the input video level in the storage circuit 102b. At this time, for example, the conversion table information shown in FIG. 2A is changed to the conversion table information shown in FIG.

Next, the input circuit 102a separates the digital input video signal input from the outside into three elements (R, G, B) of the three primary colors and inputs them to the conversion circuit 102c.
The conversion circuit 102c converts the input signal input from the input circuit 102a into an output signal (post-γLUT signal), which is input from the conversion processing unit 102 to the display unit 103, and an image is displayed on the display unit 103.

Next, conversion table information serving as basic data for defining display characteristics will be described.
The conversion table information is information configured from the conversion table shown in FIG. 2, and is information that defines the level value of the output signal with respect to the level value of the input signal. That is, the conversion table information is basic data for defining a γ characteristic that determines an appropriate output video level with respect to an input video level. When combined with signal conversion of three color elements, a total γ characteristic is obtained. Obtainable.
As for the configuration of the conversion table information, for example, in FIG. 2, the case where the conversion circuit (red (R) element) 102c-R is used as an example, and the γ characteristic for the red (R) element among the three elements of the color signal is taken as an example. An example of this is shown as a representative.

FIG. 2A shows an example of conversion table information with 8-bit input and 8-bit output.
If the input video level is 0, the output video level is 0,
If the input video level is 1, the output video level is 0,
If the input video level is 2, the output video level is 0,
If the input video level is 254, the output video level is 253,
When the input video level is 255, the output video level represents 255.

FIG. 2 (b) shows an example of conversion table information with 8-bit input and 16-bit output.
If the input video level is 0, the output video level is 0,
If the input video level is 1, the output video level is 0,
If the input video level is 2, the output video level is 1,
If the input video level is 254, the output video level is 64970,
When the input video level is 255, the output video level represents 65535.

The input video level and the output video level of the conversion table information are the same as the input signal input to the conversion circuit 102c-R and the output signal from the conversion circuit 102c-R, that is, the signal level of the input signal to the display unit 103. Equivalent to.
That is, this conversion table associates the output video level with the input video level to 1: 1.
In this way, by similarly defining green (G) and blue (B), the output characteristics of each color can be defined. By performing this regulation, it is possible to select the luminance signal output characteristics of the monochrome signal obtained by combining the output video level values. That is, by determining the output video level for each input video level for each of the three elements of the color signal, a characteristic (γ characteristic) that influences the gradation characteristic is set.

  Here, as the present embodiment, a gradation characteristic multi-gradation method by the above-described γ characteristic conversion process will be described. That is, the output video level value of the conversion table information is provided. In general, the luminance characteristic Y when the signal levels of the three elements of the color signal are represented by R, G, and B is expressed by the following equation (1).

Y = 0.229xR + 0.587xG + 0.114xB (1)

  From this, when the luminance conversion coefficients of the respective color elements are Kr, Kg, and Kb, and the values are approximated by approximate values, the following expression (2) is obtained.

Kr: Kg: Kb = 3: 6: 1 (2)

Strictly speaking, since it depends on the characteristics of the display device, the value may be different from the above.
However, any display device usually has the same tendency. That is, the tendency has a tendency (GREEN>RED> BLUE) that the degree of influence is reduced in the order of green (GREEN), red (RED), and blue (BLUE).

Further, when a liquid crystal display panel is used for the display unit 103 for color display, it depends on the characteristics of the R, G, B filters mounted on the liquid crystal display panel.
For example, there are cases where the characteristics of the B filter have a condition (GREEN> RED >> BLUE≈0) that has negligible influence compared to the characteristics of the G filter and the R filter.
FIG. 3 shows a case where the gradation characteristics are improved in this case.
The luminance conversion coefficients Kr, Kg, Kb of each color element under the above conditions are expressed by the following equation (3).

Kr: Kg: Kb = 3: 6: 0 = 1: 2: 0 (3)

  A method of interpolating the gradation level between two adjacent gradation levels before improvement in FIG. 3 will be described below. Two gradation levels are shown as follows.

(R, G, B) = (a, a, a),
(R, G, B) = (a + 1, a + 1, a + 1)

  Here, the values such as “a” and “a + 1” shown in the above expression represent the output level of each signal from the conversion circuit 102c to the color display unit 103, and the value of a when the output signal is 8 bits is And an integer value in the range of 0 to 254.

  A method of interpolating gradation levels by adding the following two gradations between a and (a + 1) will be described.

(R, G, B) = (a + 1, a, a),
(R, G, B) = (a, a + 1, a),

  By this interpolation, the following gradation characteristics can be obtained and the gradation can be increased.

(R, G, B) = (a, a, a),
(R, G, B) = (a + 1, a, a),
(R, G, B) = (a, a + 1, a),
(R, G, B) = (a + 1, a + 1, a + 1),

here,

(R, G, B) = (a, a, a)

When the white (W) gradation at the time is expressed as a, the luminance component at that time is expressed as k (a), and the luminance of the white (W) = a + 1 gradation is expressed as k (a + 1) Since the ratio of the component R: G: B is the same as the ratio of the luminance conversion coefficient in the equation (3), when the luminance component of the gradation level is obtained with R: G: B = 1: 2: 0, In order from

k (a),
k (a + 1/3),
k (a + 2/3),
k (a + 1)

Thus, the gradation can be increased by a factor of three by the gradation level that complements the characteristics before improvement.

  For example, in the case of a = 50,

(R, G, B) = (50, 50, 50),
(R, G, B) = (51, 50, 50),
(R, G, B) = (50, 51, 50),
(R, G, B) = (51, 51, 51),

It becomes. When the above value is converted into luminance, the following value can be defined from the gradation obtained as an intermediate gradation between 50 and 51.

k (50.0),
k (50.3),
k (50.7),
k (51.0)

Next, values set in the conversion table for determining the γ characteristic will be described.
The graph of FIG. 4 shows the output with respect to the input value x in the γ conversion processing when the above-described conditions are used in which the white tone characteristics are a, (a + 1/3), (a + 2/3), and (a + 1). The relationship with the brightness at the value y is shown. The curve of the graph is a γ conversion characteristic that is necessary for the display unit 103 to display with an appropriate gradation.
Here, the output values for the input values x and (x + 1) are points located on the γ characteristic curve, and the values yr1 and yr2 (for example, k (50.2) and k (50. 8)) is appropriate, but a value that can be taken as an output value is a value that can be taken as a signal after γ conversion processing.

Note that when the conversion is performed from the γ characteristic curve shown in FIG. 4 by the conventional method in which the output levels of the three primary colors are equal in the conversion table, the output value is selected from a limited gradation level. It is limited to k (a) or k (a + 1) corresponding to the points Q1 and Q2. In the above example, the values are k (50.0) and k (51.0).
In this embodiment, since the gradation level can be increased as described above, when the interpolated gradation level is closer to the ideal characteristic value than the gradation according to the conventional method, the error from the ideal characteristic is reduced. The gradation level to be selected is selected. By doing so, in FIG. 4, the P1 point and the P2 point close to the ideal value are selected, and the gradation levels thereof are (a + 1/3), (a + 2/3), 50.3, 50.7 can be obtained.
Therefore, k (a + 1/3) and k (a + 2/3) as luminance levels, k (50.3),
k (50.7) can be obtained.
Based on the optimum γ characteristic value, the conversion table information of the γ characteristic created using the value obtained from such a method is used.
Therefore, it can be understood that the gradation information can be multi-gradation by using the method according to the present embodiment.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
In the second embodiment, a description will be given of a case where the characteristic ratio of red and green is different from that of the first embodiment in the ratio of R: G: B in the display characteristics of the display unit 3 in the first embodiment.
For example, even when R: G: B = 1: 3: 0, the interpolated luminance obtained using the same method is
k (a),
k (a + 1/4),
k (a + 3/4),
k (a + 1)
Thus, although the linearity is slightly deteriorated, since it is a change of the lower 1 bit, it is possible to interpolate between k (a) and k (a + 1) without any visual influence on the display screen.
Therefore, it can be seen that even if there is a difference in the R: G: B characteristics of the color display unit, the gradation information can be multi-graded as in the first embodiment by using the method according to the present embodiment.

(Third embodiment)
Next, a third embodiment of the present invention will be described.
In the third embodiment, the B characteristic cannot be ignored in the ratio of R: G: B in the display characteristic of the display unit 3 in the first embodiment. That is, this is a condition for B ≠ 0.
In this case, it can be understood that interpolation between a and (a + 1) can be performed at seven levels by setting as follows.

(R, G, B) = (a, a, a),
(R, G, B) = (a + 1, a + 1, a + 1)

  A method of interpolating gradation levels by adding the following six gradations between a and (a + 1) will be described.

(R, G, B) = (a, a, a + 1),
(R, G, B) = (a + 1, a, a),
(R, G, B) = (a + 1, a, a + 1),
(R, G, B) = (a, a + 1, a),
(R, G, B) = (a, a + 1, a + 1),
(R, G, B) = (a + 1, a + 1, a)

  By this interpolation, the following gradation characteristics can be obtained.

(R, G, B) = (a, a, a),
(R, G, B) = (a, a, a + 1),
(R, G, B) = (a + 1, a, a),
(R, G, B) = (a + 1, a, a + 1),
(R, G, B) = (a, a + 1, a),
(R, G, B) = (a, a + 1, a + 1),
(R, G, B) = (a + 1, a + 1, a),
(R, G, B) = (a + 1, a + 1, a + 1)

  If the ratio of R: G: B is R: G: B = 3: 6: 1, the luminance component for each gradation is as follows.

k (a),
k (a + 1/10),
k (a + 3/10),
k (a + 4/10),
k (a + 6/10),
k (a + 7/10),
k (a + 9/10),
k (a + 1)
Thus, the gradation level that complements the characteristics before improvement can be further increased.

  For example, in the case of a = 50,

(R, G, B) = (50, 50, 50),
(R, G, B) = (50, 50, 51),
(R, G, B) = (51, 50, 50),
(R, G, B) = (51, 50, 51),
(R, G, B) = (50, 51, 50),
(R, G, B) = (50, 51, 51),
(R, G, B) = (51, 51, 50),
(R, G, B) = (51, 51, 51),

It becomes. When the above value is converted into luminance, the following value can be defined from the gradation obtained as an intermediate gradation between the levels of 50 and 51.

k (50),
k (50.1),
k (50.3),
k (50.4),
k (50.6),
k (50.7),
k (50.9),
k (51)

  Therefore, it can be seen that even if there is a difference in the R: G: B characteristics of the color display unit, the gradation information can be multi-graded as in the first embodiment by using the method according to the embodiment.

  In each embodiment, the video input signals from the outside are described as digital signals that are collectively input. However, in the method according to the present invention, the external video input signal may be a digital signal separated into RGB, or when the external video input signal is input as an analog signal, the video input signal In the input circuit 102a to which is input, an A / D conversion is performed from the input analog video input signal and the digital value is input to the conversion circuit 102c.

In each embodiment, the display on the display unit 103 has been described based on the case of displaying as monochrome video information having the same RGB balance. However, the method according to the present invention does not specify monochrome image information with the same RGB balance for display on the display unit 103, but can be applied to display gradations with a specific RGB balance. It is. In that case, it can be applied by performing interpolation between adjacent gradations while maintaining the RGB balance.
That is, the condition of R = G = B necessary for monochrome display with the same RGB balance is reviewed, and an interpolation procedure between adjacent gradations is performed while maintaining an appropriate RGB balance. Can be implemented.
That is, the specified value of the gradation level before interpolation,

(R, G, B) = (a, a, a),
(R, G, B) = (a + 1, a + 1, a + 1)

Will be reviewed as follows.
For example, an example will be described in which an image to be displayed is displayed in a color from black to reddish white instead of monochrome display.

(R, G, B) = (a, g1, b1),
(R, G, B) = (a + 1, g2, b2)

  Here, g1 and g2 represent adjacent gradations in the green component. B1 and b2 represent adjacent gradations based on the blue component. g1 and g2 represent adjacent gradations in the green component and take integer values from 0 to 255. b1 and b2 represent adjacent gradations in the blue component and take integer values from 0 to 255.

  In addition, information in the case of representing the brightest information is as follows.

(R, G, B) = (rmax, gmax, bmax)

Here, rmax, gmax, and bmax represent the maximum values of the red component, the green component, and the blue component when representing the brightest information, and take integer values from 0 to 255.
When a red screen is displayed as an example, rmax takes the maximum value among the above rmax, gmax, and bmax. That is, rmax is set to a value of 255, and the following equation is obtained.

(R, G, B) = (255, gmax, bmax)

  Further, with reference to the input signal level value “a” of the red component, the values of g1, g2, b1, and b2 are approximated by integers from the calculated values obtained from the following conversion expressions, respectively, and g1, g2 , B1 and b2.

g1 = gmax x a / 255,
g2 = gmax x (a + 1) / 255,
b1 = bmax x a / 255,
b2 = bmax x (a + 1) / 255

  At this time, the gradation to be interpolated similarly to the gradation obtained under the conditions of the first embodiment is

(R, G, B) = (a, g1, b1),
(R, G, B) = (a + 1, g1, b1),
(R, G, B) = (a, g2, b1),
(R, G, B) = (a + 1, g2, b2),

As can be obtained.
Note that there is a case where g1 and g2 or b1 and b2 are equal values by values set to gmax and bmax and by approximation of the calculation result by integers. In that case, the gradation level that can be interpolated will be reduced, but there will be no original gradation difference due to that component, so there will be no problem because there will be no visual impact. Recognize. Therefore, by using the value obtained by the above calculation as the gradation level of each color component that defines the γ characteristic, it is possible to obtain a multi-gradation display screen as in the other embodiments.
In the above description, the display from black to reddish white has been described as an example. However, even in the case of other colors, the display can be applied by changing the basic color component from red to another color.

  In the conventional technique, when the video display is performed using the result after the γ characteristic conversion process, the gradation becomes insufficient. Therefore, the lack of gradation is used as a correction means, and a γLUT having an 8-bit input and 10-bit output is used as 10 bits. In order to express in 8 bits, correction by dithering technique or correction by FRC (Frame Rate Control) is used as a method of time modulation technique. However, if the present invention is used, the necessary gradation can be increased in the process of performing the γ characteristic conversion process, so that the present invention can be used without using a dithering technique and a correction technique such as FRC that have been conventionally required. The invention makes it possible to obtain the required gradation characteristics using the increased gradation.

  Note that when the present technology is applied to information expressed with a small number of bits (for example, 6 bits), if processing is performed using the least significant 1 bit of the information expressed with the small number of bits, gradation interpolation is performed. Even if it can be done, it will be in a state where the change in color tone of the expressed image can be visually confirmed. However, if the processing is performed with the least significant bit of information expressed by 8 bits or more, the color tone change according to the present technology can be out of a visually recognizable range. Although the present embodiment has been described as processing with the least significant bit of 8-bit information, the present technology can also be applied to information expressed with 8 bits or more.

As described above, according to the present embodiment, a color video display device capable of performing monochrome video display with multi-gradation gradation display characteristics using a display device including a display unit for color display. It becomes possible to provide.
As a result, it is possible to display the gradation information of the input video signal as a multi-gradation monochrome image without using a monochrome-only display unit as the display unit.

It is a block diagram which shows the structure by 1st Embodiment by this invention. It is an example of R element of the conversion table 102 in the conversion table in the embodiment. This is a multi-tone monochrome display (output LUT) using sub-pixels in the display unit for color display in the embodiment. FIG. 6 is a relationship diagram between a γ characteristic and a gradation level of an output value. This is multi-tone monochrome display (output LUT) using subpixels in a display unit for monochrome display. It is a structural diagram of a display unit having a subpixel structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Signal processing part 101 Conversion control part 102 Conversion processing part 102a Input circuit 102b Accumulation circuit 102c Conversion circuit 102c-R Conversion circuit (red (R) element)
102c-G conversion circuit (green (G) element)
102c-B conversion circuit (blue (B) element)
103 display unit 200 color image display device

Claims (7)

A color display device including a display unit for color display having a display pixel structure smaller than the area of one pixel of information to be displayed,
An input circuit for inputting an input signal based on the input video signal;
A storage circuit for preliminarily storing conversion table information in which the level of the input signal and the luminance value corresponding to the display characteristics of the three primary colors in the display unit are associated with each element of the color signal;
A conversion circuit that converts an input signal input by the input circuit with reference to conversion table information stored in the storage circuit and outputs the converted signal to the display unit;
A color video display device comprising: A conversion control unit that generates the conversion table information based on the luminance characteristics of the color signals in the display unit, and stores the conversion table information in the storage circuit;
The color image display device according to claim 1, further comprising:   The conversion control unit generates the conversion table information based on instruction information for instructing a change in display state and the luminance characteristic, and stores the conversion table information in the storage circuit. Or the color image display apparatus of Claim 2.   The storage circuit stores conversion table information generated using characteristics of two elements of red and green or three elements of red, green, and blue among display characteristics of color signal elements in the display unit. The color image display device according to claim 1, wherein the color image display device is a color image display device.   5. The conversion circuit according to claim 1, wherein when the conversion table information is expressed as digital value information, the conversion circuit performs gradation information conversion processing using the least significant 1 bit. The color video display apparatus of any one of Claims.   2. The conversion circuit according to claim 1, wherein, when the conversion table information is expressed as information having a digital value of 8 bits or more, the conversion circuit performs gradation information conversion processing using the lowest 1 bit. 6. The color image display device according to any one of 5 above. A monochrome image display method in a color display device including a display unit for color display having a display pixel structure smaller than the area of one pixel of information to be displayed,
A process of inputting an input signal based on the input video signal;
Storing, in the storage circuit, conversion table information in which the level of the input signal and the luminance value corresponding to the display characteristics of the three primary colors in the display unit are associated with each element of the color signal;
Converting the input signal with reference to conversion table information stored in the storage circuit and outputting the converted signal to the display unit;
A monochrome video display method comprising:

Images