JPH0638234A - Crt display device and white balance adjustment method - Google Patents

Abstract

PURPOSE:To allow the operator to select freely white color chromaticity by implementing interpolation arithmetic operation to red, green, blue gain, the ratio and offset for the white chromaticity when the desired white chromaticity is inputted so as to eliminate the need for re-adjustment of a white balance. CONSTITUTION:A video signal 9 inputted to a gain control circuit 100 is amplified by a video amplifier 600 and displayed on a CRT 1 as a video image. The gain, the ratio and the offset data of the video signal in the white balance adjustment executed to a reference white chromaticity in the white balance adjustment are stored in a memory 300. Furthermore, the device is provided with a white balance adjustment section 4 to allow the operator to input white chromaticity and a white chromaticity input switch 500. When the desired white chromaticity is inputted, the interpolation arithmetic operation to red, green, blue gain, the ratio and offset for the inputted white chromaticity is implemented based on the data in the memory 300.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT having a function of calculating and interpolating whites of a plurality of chromaticities from information of chromaticity of one white.
The present invention relates to a display device and a white balance adjusting method.

[0002]

2. Description of the Related Art A conventional CRT display device is disclosed in Japanese Laid-Open Patent Publication No. 3-231290.
Two memories are provided, and after correcting the input signal by the information of the two memories, R (red), G (green), B
It is known to convert to a (blue) signal. In addition, some kinds of chromaticity (color temperature) information including hue and saturation are prepared in a required number of memories, and the information in the memories is converted into R, G, B signals. Are known.

[0003]

However, in the above-mentioned prior art, in which two memories are provided, when displaying a plurality of white chromaticities, it is necessary to perform arithmetic processing every time a signal changes. However, there is a drawback that it takes time to adjust the white balance.

In the case of preparing the chromaticity on the memory, it is necessary to adjust the number of white chromaticities to be prepared.
It takes a lot of time for the adjustment. Moreover, as memory, three channels of red (r), green (g), and blue (b) are required for four elements of picture level, black level, contrast tracking, and brightness tracking, and one white At least 12 memories must be prepared for chromaticity.

It is an object of the present invention to provide a CRT display device capable of performing white balance adjustment in a short time and without requiring a large amount of memory, and a white balance adjusting method for the device.

[0006]

In order to achieve the above object, the present invention inputs a red, green and blue video signals, amplifies them, performs scanning according to horizontal and vertical synchronizing signals, and displays them on a CRT screen. In a CRT display device that displays an image on top, a storage unit that stores the gain, ratio, and offset data of the video signal in the white balance adjustment performed for white having a reference chromaticity, and white chromaticity A chromaticity input means for inputting, and when a desired white chromaticity is input from the chromaticity input means, the input white chromaticity red,
And a calculation means for performing interpolation calculation of gains, ratios, and offsets of green and blue based on the data in the storage means.

Further, according to the present invention, white balance adjustment is performed in advance for white having a reference chromaticity, and gain, ratio, and offset data of red, green, and blue video signals in the white balance adjustment at that time are obtained. When the operator inputs the desired white chromaticity stored in the storage means, the interpolation calculation of the gains, ratios and offsets of the input white chromaticities of red, green and blue is stored in the storage means. The white balance adjustment is performed by executing the operation based on the data.

[0008]

According to the present invention, the interpolation calculation can be executed for any white by adjusting the white balance once, so that the readjustment of the white balance becomes unnecessary and the operator can freely adjust the chromaticity of white. You can choose.

Further, since only one piece of white balance adjustment data needs to be prepared on the memory, there is an advantage that the adjustment only needs to be performed once and the memory is saved.

[0010]

EXAMPLES Before describing the examples of the present invention, color characteristics will be described. To express a color qualitatively, the following three properties called three attributes of color should be considered. Hue (hue) The color changes as shown in Fig. 2 depending on the wavelength of light, and red → orange →
It shows a shade of yellow → green → cyan → blue → purple. Saturation (color intensity, saturation) It is the vividness of the color, and conversely, it indicates the ratio of the color being diluted with white, that is, the color intensity. White has the lowest color intensity. Brightness This is the degree of light quantity, and quantitatively indicates brightness.

FIG. 3 conceptually shows the relationship among hue, saturation, and brightness. A disk is placed at a white position, and red to purple are arranged in order of wavelength on the circumference of the disk. There is. According to this, the hue is represented by concentric circles centered on white, and the saturation is represented by the distance from white. That is, the farther from white, the deeper the color becomes and the brighter it becomes. For example, the colors on the line connecting yellow and white are white to yellowish yellow and bright yellow, which have different degrees of saturation.

As can be inferred from this cone, even if the brightness of the color changes, if the hue and saturation are the same, the image of the color does not change except that it becomes brighter or darker. (If it is white, it is imaged as white, gray, and black). Therefore, the hue excluding the luminance and the saturation are collectively called chromaticity.

This chromaticity is represented by the plane on the disk in FIG. That is, the direction with respect to a certain color with the center point (white) of the disk as an origin represents the hue, and the saturation degree can be represented with the distance from the center point to the certain color. However, generally, the chromaticity is expressed by the x and y coordinates using the chromaticity diagram of the International Commission on Illumination (CIE) shown in FIG. This is called the CIE chromaticity diagram, and generally, this is called the chromaticity diagram.

Next, color mixing and white balance adjustment will be described. Red, green, and blue are called the three primary colors of light, and various colors can be created by additively mixing these three primary colors. That is, it is possible to create colors of all chromaticities (hue and saturation) and luminance.

An example of color addition will be described with reference to the chromaticity diagram of FIG. Make R (red) and G (green) glow with appropriate brightness,
By adding the two colors, YR (orange) or (yellow) is created. Further, if Y (yellow) and B (blue) are added with appropriate brightness, the white gradually becomes yellow and finally becomes white, and then the white becomes more whitish. Pink is created by adding YR (orange) and B (blue) with appropriate brightness. In this way, any color can be created.

The method of expressing chromaticity is based on the coordinates on the chromaticity diagram.
There are a method using (x, y) and a method using color temperature. Here, the color temperature will be described. First, consider the radiation of a full radiator, that is, a black boby. Spectral radiant of a black body
FIG. 5 shows the relative value of the exitarce) in the visible range for various values of the temperature T. When the temperature is low, it has spectral energy mainly on the long wavelength side (red), but as the temperature rises, the energy on the short wavelength side (blue) increases, and it becomes a flat distribution for almost wavelength at about 5000K. . At higher temperatures, on the contrary, the energy on the short wavelength side (blue) becomes larger. Therefore, if you observe the color against changes in temperature, it should change from red to yellow to white to blue. Since color and temperature are related in this way, color temperature is a representation of color.

Strictly speaking, the colors that can be represented by the color temperature are only those on the black body radiation locus, and FIG. 6 shows these colors superposed on the CIE chromaticity diagram. However, this limits the range that can be represented by color temperature. Therefore, as shown in FIG. 7, a method of extending the concept of color temperature to both sides of the black body radiation locus is adopted. Even if the color deviates slightly from the blackbody radiation locus, the temperature on the locus is read along the isochromatic temperature line and used as the color temperature. Such color temperature is called correlated color temperature. The MPCD (Minimum Perceptible Chromatici) is a display of the chromaticity of the light source by measuring the distance from the black body radiation locus on the above-mentioned constant color temperature line in an appropriate unit of chromaticity difference.
ty Difference). Using this, for example, 650
The expression 0K + 27MPCD is used to define white. The brightness is expressed as 100 cd / m ² .

Next, a method of white balance adjustment in the CRT display device will be described. The factors that determine the white balance are four levels: picture level, black level, contrast tracking, and brightness tracking.
Is one. The above four elements will be described below.

The picture level is the maximum value of the voltage for controlling the brightness when the input signal is maximum. The black level is the minimum value of the voltage that controls the brightness when the input signal is minimum. Contrast tracking
Offset voltage for each signal of red (r), green (g), and blue (b). The four elements for white balance adjustment are the above-mentioned four elements. In addition to these four elements, the contrast VR and the brightness VR which are normally open to the operator are added. The white balance adjustment is intended to prevent color shift even if the operator adjusts the brightness by moving the contrast VR and the brightness VR.

The white balance adjustment method is performed as follows. Brightness VR and contrast VR are maximized. The input signal is set to 0, and the black level is adjusted for each color of red (r), green (g), and blue (b) so that the desired chromaticity of white is obtained on the low luminance side. Red (r), green (g), blue (b) so that the input signal is maximized and the picture level is at the maximum brightness and the desired white chromaticity.
Adjust for each color. The brightness VR is minimized, and the brightness tracking is adjusted so that the chromaticity of white does not change even when the brightness VR is turned. Brightness VR is maximized and the picture-level is adjusted again. The contrast tracking is adjusted so that the contrast VR is minimized and the chromaticity of white does not change even if the contrast VR is turned. With the above work, the white balance adjustment for one chromaticity of white is completed.

As described above, the white balance adjustment is a very complicated work and requires a special instrument and skill, so that it cannot be performed by a general operator.

Therefore, in the present invention, white balance adjustment is performed once for white having a reference chromaticity, and the red at this time is adjusted.
The gain and offset data of the video signals of the (r), green (g), and blue (b) signals are stored in the memory.

Here, the case of displaying white having a chromaticity other than that adjusted will be described below. First, the operator inputs the color temperature T and the MPCD value n. Coordinate conversion is performed from the data of color temperature T and MPCD value n, and UC
Convert to coordinates (u, v) on the S chromaticity diagram. The UCS chromaticity diagram is a coordinate conversion of the CIE chromaticity diagram. The point where the isochromatic temperature line is orthogonal to the blackbody radiation locus and (1 / T) are almost equally spaced on the blackbody radiation locus. It is suitable for obtaining the color temperature at two points that are lined up with. The coordinates on the UCS chromaticity diagram are represented by (u, v). FIG. 8 shows the black body radiation locus and the isothermal temperature line on the UCS chromaticity diagram.

The above conversion is performed by an approximate value according to JIS Z 8725, Appendix 1. Exponential function approximation was performed for one coordinate axis u, linear approximation for the other coordinate axis v, and exponential function approximation was performed for the reciprocal a of the slope of the isochromaticity line. The above conversion is given by the following equations (1) and (2).

[0025]

[Equation 1]

Next, the coordinates (u, v) on the UCS chromaticity diagram
Is converted into coordinates (x, y) on the CIE chromaticity diagram. The conversion is given by equations (3) and (4). x = 3u / 2 (u-4v + 2) ... (3) y = v / (u-4v + 2) ... (4) Next, the coordinates (x, y) on the CIE chromaticity diagram are red and green. , Convert to blue signal ratio. The conversion formula is given by the formulas (5), (6) and (7). R = 0.41464x-0.14811-0.082178 {1- (x + y)} ... (5) G = -0.090442x + 0.25043y + 0.015582 {1- (x + y)} ... (6) B = 0.41464x-0.14811-0.082178 {1- (x + y)} (7) However, R, G, and B are signal ratios of red, green, and blue, respectively.

Further, R, G, B are converted into a signal ratio with 1 as a whole. The conversion formulas are given by the formulas (8), (9) and (10). r = R / (R + G + B) ………… (8) g = G / (R + G + B) ………… (9) b = B / (R + G + B) …… (10) By the above, the operator set. The chromaticity data (color temperature and MPCD value) could be converted into r, g, b ratio.

From this ratio, the gain and offset of the video signal after calculation interpolation are obtained. Hereinafter, one of red, green, and blue signals will be considered. First, gain interpolation is performed. The gain is given by equation (11). G ′ = s / s ′ × G (11) where G ′ is the gain after the arithmetic interpolation, s ′ is the signal ratio after the arithmetic interpolation, G is the initial value of the gain, and s is the initial value of the signal ratio.

Next, the brightness is interpolated. Regarding the gain, G was converted to G ', but the offset is the same as before conversion as it is. In this case, the offset is the black level. The black level is by no means the point where the brightness is zero. The fact that the black level has not changed even though the gain G has changed to G ′ means that the point at which the luminance is 0 has shifted. 0 brightness
Brightness tracking adjusts the point.
Here, it is assumed that the gain is changed from G to G ′, the offset is VBL, and the brightness position at the point of zero brightness is x ₀ . If the horizontal axis is the brightness VR and the vertical axis is the brightness control voltage, the deviation of the brightness control voltage at the brightness 0 point when only the gain is adjusted is given by the following equation (12). To be y′−y = (G′−G) x ₀ (12) where y ′ is the brightness control voltage at the point where the brightness is 0 after gain correction and y is the brightness control voltage before gain correction. Is.

Since the brightness control voltage has increased by (y'-y) at the point of zero brightness, the cutoff voltage is decreased by (y'-y). This is shown in equation (13). VBL '- (y'-y) = VBL- (G'-G) x 0 ......... (13) where, VBL' is voltage after offset correction, the VBL offset is the voltage before correction voltage .

As described above, both the gain and the offset are calculated and interpolated, and the white balance is adjusted for the white color having the chromaticity designated by the operator.

Next, a concrete embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a schematic configuration of a CRT display device of the present invention. In the figure, CRT 1 is a normal color CRT, and red, green, and blue video signals 9 are supplied to video amplifiers 600 (601, 602, 60) for each color.
Amplified up to about 50 Vpp in 3), cathode 10 of each electronic system
The electric potential between the grid 11 and the grid 11 is adjusted, the electron beam is deflected by the deflection yoke 12 connected to the deflection circuit 13, and the CRT is displayed.
Display an arbitrary figure on the tube surface of 1.

In this embodiment, the gain control circuit 100 (101, 102,
For 103), the arithmetic interpolation unit 200 sets a gain for changing the chromaticity of white for each color. Also,
For the image amplifier 600 (601, 602, 603), the arithmetic interpolation unit 200 sets an offset for changing the chromaticity of white for each color of red (r), green (g), and blue (b). To do. The gain and the offset are variable according to the data of the memory 300 in which the white balance data adjusted by the adjusting unit 4 is stored and the chromaticity data input from the white chromaticity input switch 500. .

Gain control circuit 100 (101, 102,
103) is composed of a multiplication circuit, and the relationship between the input signal Vi, the output signal Vo, and the control input α is given by the equation (14). Vo = α · kVi (14) However, k is a constant, and the gain control input α (0 to 0
5V variable) to control the gain. The gain control input α is added from the arithmetic interpolation unit 200.

Video amplifier 600 (601, 602, 60
3) is composed of an adder circuit, and the relationship between the input signal Vi ′, the output signal Vo ′ and the control input β is given by the equation (15). Vo '= mVi' + nβ (15) However, m and n are constants, and the offset can be controlled by the offset control input β. The offset control voltage is applied from the arithmetic interpolation unit 200.

As shown in FIG. 9, the arithmetic interpolator 200 includes an arithmetic processing unit 201 and an F / F (flip-flop) 20.
2, D / A (D / A converter) 203, memory 300
(White balance adjustment data storage device 301 and white balance calculation interpolation data storage device 302).

FIG. 10 is a flowchart for converting chromaticity into the RGB color system. FIG. 11 shows the subroutine of the flowchart of FIG. First, the operator wants to set white chromaticity data (color temperature data and MPC
Enter the D value). The arithmetic interpolation unit 200 converts the color temperature data input by the operator into the signal ratio data (r + g + b = 1) of red (r), green (g), and blue (b). In particular,
The conversion is performed according to the equations (1) to (10).

As described above, the white chromaticity data set by the operator can be converted into the r, g, b signal ratio. From the data of the r, g, b signal ratio, red (r), green
Obtain the gain and offset of each of the (g) and blue (b) signals. The gain is given by equation (14) and the offset is given by equation (15).

As shown in FIG. 12, the white chromaticity input switch 500 is composed of a color temperature input switch 501, an MPCD input switch 502, and switches 503, 504 and 505 for storing data after white balance calculation interpolation. .

The operation of the chromaticity input switch 500 will be described. Press the color temperature input switch 501 to change the color temperature.
When the MPCD input switch 502 is pressed, the MPCD value changes (using a see-saw type switch, the left side is changed in the + direction and the right side is changed in the − direction). First, use the color temperature input switch 501 to check the white on the blackbody radiation locus in real time on the screen and stop it at the desired position, and then use the MPCD input switch 502 to change in real time the changes in the color matching temperature lines. Check on the screen and stop. White balance calculation interpolation data storage switch 503
504 and 505, when double-clicked between 0.2 seconds and 1.0 seconds, memorize the data of the white chromaticity of the display screen at that time, and press once to store the memorized data. The white chromaticity of the data is displayed.

FIG. 13 shows another embodiment of chromaticity input. In this embodiment, a numerical input key is provided so that the chromaticity itself can be input by the ten keys, and the color temperature data can be input first, and then the MPCD can be input. For example, 9300K first, then 27MPCD
Enter, and so on. It is also possible to directly achieve the desired white chromaticity by interpolation calculation. Also,
The number of switches for storing data after white balance calculation interpolation can be increased as needed.

[0042]

As described in detail above, according to the present invention,
Once the white balance is adjusted, the operator can easily achieve the desired white chromaticity on the screen by the arithmetic interpolation function, so that the readjustment of the white balance is not necessary and it is displayed on the CRT. It is also possible to reduce the difference in color between the image and the actual publication.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a CRT display device of the present invention.

FIG. 2 is a diagram for explaining a hue of light.

FIG. 3 is a diagram conceptually showing a relationship among hue, saturation, and brightness of light.

FIG. 4 is a diagram showing a CIE chromaticity diagram.

FIG. 5 is a diagram for explaining color temperature.

FIG. 6 is a diagram showing a color temperature locus of blackbody radiation.

FIG. 7 is a diagram showing a black body radiation locus and isochromatic temperature lines on a CIE chromaticity diagram.

FIG. 8 is a diagram showing a blackbody radiation locus and isochromatic temperature lines on the UCS chromaticity diagram.

FIG. 9 is an internal detailed diagram of a calculation interpolation unit.

FIG. 10 is a flowchart of arithmetic interpolation.

11 is a flowchart of the flowchart of FIG.

FIG. 12 is a diagram showing an example of a white chromaticity input switch.

FIG. 13 is a diagram showing another embodiment of the white chromaticity input switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CRT display device 4 White balance adjusting unit 9 Video signal 14 Deflection circuit 100 Gain control circuit 200 Computation interpolation unit 300 Memory 500 White chromaticity selection switch 600 Video amplifier

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kikuo Tomita 5-2-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Omika factory

Claims (5)

[Claims] 1. A chromaticity as a reference in a CRT display device for inputting and amplifying red, green, and blue video signals, performing scanning according to horizontal and vertical synchronizing signals, and displaying an image on a CRT tube surface. From the chromaticity input means, storage means for storing the gain, ratio and offset data of the video signal in the white balance adjustment performed for the white color, chromaticity input means for inputting the chromaticity of white, When the desired white chromaticity is input, the input white chromaticity red,
A CRT display device comprising: a calculation unit that performs interpolation calculation of green, blue gain, ratio, and offset based on the data in the storage unit. 2. The CRT display device according to claim 1, wherein a color temperature and an MPCD value are input to the chromaticity input means. 3. The CRT display device according to claim 1, wherein the arithmetic means transits a temperature on a black body radiation locus during color temperature input and a temperature on a constant color temperature during MPCD value input. A CRT display device characterized by: 4. The CRT display device according to claim 1, wherein the calculation means calculates U from the color temperature and the MPCD value.
The coordinate conversion to the CS chromaticity diagram is performed by linear approximation for one coordinate axis and exponential approximation for the reciprocal of the gradient of the other coordinate axis and the color temperature line, and the color temperature and MP are calculated.
A CRT display device characterized by performing interpolation calculation for deriving a signal ratio of red, green, and blue from a CD value. 5. A white balance adjustment is performed in advance on white having a reference chromaticity, and gain, ratio, and offset data of red, green, and blue video signals in the white balance adjustment at that time are stored in a storage means. Incidentally, when the operator inputs the desired white chromaticity, the interpolation calculation of the gain, ratio and offset of the input white chromaticity of red, green and blue is performed based on the data in the storage means. By running
A white balance adjustment method for a CRT display device for performing white balance adjustment.