JP3305794B2 - Primary color conversion method and apparatus for multi-primary color display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing circuit for displaying a television signal, and more particularly to a signal processing circuit for converting a three-primary color television signal using a simple primary combination and a negative signal clip. The present invention relates to a primary color conversion method and apparatus for converting a signal into a signal for multi-primary color display.

[0002]

2. Description of the Related Art In the current color television transmission system or its display device, transmission from three primary colors or display based on three primary colors has been put to practical use, and there is a prior art of multi-primary color display exceeding the three primary colors. Did not.

[0003]

For example, the current color television standard comprises three primary color points: red (R), green (G) and blue (B). When these primary color points are displayed on the xy chromaticity diagram, for example, it is as shown in FIG. The current standard method can also represent colors outside the triangle RGB of FIG. 7, and if any color is represented by the signal levels r, g, and b of the three primary color points R, G, and B, Point A is a color in which the value of r is negative.

However, on the receiver side, there is no emission color whose level corresponds to a negative value. Therefore, if the three primary color points are equal on the receiving side and the transmitting side, a triangle like point A on the chromaticity diagram is used. Colors located outside the circle cannot be correctly reproduced. The following two methods can be considered as a method for improving this. (I) A color with high saturation on the receiver side is defined as three primary color points. (Ii) Add a highly saturated color to make the receiver more multi-primary. In order to reproduce a wide color range by the method (i), it is necessary to use a very high-saturation color. Since a high-saturation color usually has a low luminance, the method (ii) is practically used. It is advantageous.

As an example, consider the display of six primary colors as shown in FIG. The new primary colors are O, P, Q, S, T, U. 6
The primary colors are considered because the current display is three primary colors, and it is considered that it is practically easy to make the integral multiple of the primary colors. The signal levels of the six primary colors are o, p, q,
When the color of s, t, u is represented by the three primary color system and the signal levels of the three primary colors are r, g, b, respectively, R, G, B, O, P, Q, S, T, U is 1 × 3
(The elements are the tristimulus values of light), the equation (1)
Holds.

## EQU00001 ## o.O + p.P + q.Q + s.S + t.T + u.U = r.R + g.G + b.B (1) Since equation (1) is a 6-element, 3 simultaneous equation, it is solved without adding any conditions. It is not possible.

Accordingly, an object of the present invention is to provide
It is possible to convert a color television signal, which is a primary color system, into a signal for multi-primary color display, and to accurately reproduce a high-saturation color. An object of the present invention is to provide a primary color conversion method and apparatus for multi-primary color display capable of solving the three simultaneous equations.

[0007]

In order to achieve the above object, a first invention of a multi-primary-color display primary color conversion method according to the present invention is a luminance signal Y of a transmitted color television signal and two color difference signals. C ₁ and C ₂ are converted into three primary color signals R, G and B via an inverse matrix circuit, and the positions of the input three primary color signals R, G and B obtained by the conversion on the chromaticity diagram are determined. Judgment is made, and based on the judgment result, three primary colors are selected from among the multi-primary colors exceeding the three primary colors provided on the chromaticity diagram, and the input color signal is represented by a primary combination thereof, and the multi-primary colors on the receiving side are selected. It is characterized in that it is prepared for display.

A second invention of the primary color conversion method is a method for converting the luminance signals Y and 2 of the transmitted color television signal.
The two color difference signals C ₁ and C ₂ are converted into three primary color signals R, G and B via an inverse matrix circuit, and multi-primary color signals exceeding the three primary colors separately provided on the chromaticity diagram on the receiving side are respectively converted into the three primary color signals. It calculates and outputs as a primary combination of the primary color signals R, G and B, selects three primary colors from among the multiple primary colors exceeding the three primary colors, and outputs the primary combination of the other primary colors negative. Sometimes, the output is made zero and a correction signal is prepared, and the correction signal is added to the output of the primary combination of the three selected primary colors and output, so that the receiving side can display multi-primary colors. It is characterized by having made it.

Further, a first invention of the present invention, which is a primary color conversion device for multi-primary color display, is a luminance signal Y of a transmitted color television signal and two color difference signals C ₁ and C _1.
An inverse matrix circuit that inversely converts ₂ to the original three primary colors R, G, and B signals, and three primary colors separately provided on the chromaticity diagram so that colors with higher saturation can be accurately reproduced on the receiving side. , Each of which calculates and outputs a primary combination of the three primary colors R, G and B signals, and an input three primary colors R and G obtained by the inverse matrix circuit. A chromaticity diagram position determining circuit for determining where the G and B signals are located on the chromaticity diagram; and a multi-primary color exceeding three primary colors separately provided on the chromaticity diagram based on the determining circuit. In order to prepare for three primary color selection circuits for selecting three primary colors and for displaying multiple primary colors on the receiving side, only the primary combination result of the selected three primary colors with the three primary colors R, G and B signals is used. Extracted from the output of the multi-primary-color signal primary combination calculation circuit And an output circuit for outputting.

A second invention of the primary color conversion device is a device for converting the luminance signals Y and 2 of the transmitted color television signal.
An inverse matrix circuit for inversely converting the three color difference signals C ₁ and C ₂ into the three primary colors R, G and B signals, and a chromaticity diagram for accurately reproducing even more saturated colors on the receiving side. A multi-primary-color signal primary combination calculating circuit for separately calculating and outputting each of the multi-primary color signals exceeding the three primary colors as a primary combination of the three primary colors R, G and B signals; Three primary colors are selected from the primary colors, and when the primary combination output obtained by the multi-primary signal primary combination calculation circuit of the other primary colors becomes negative, the output is made zero and a correction signal is prepared. In order to prepare for multi-primary color display on the receiving side, the correction signal prepared above is added to the output of the primary combination obtained by the multi-primary signal primary combination calculation circuit of the selected three primary colors. And an output circuit for outputting. Things.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. First, the transmitted luminance signal Y and two color difference signals C ₁ and C ₂ of the color television signal of the three primary color system are converted into three primary color signals R, G and B by a usual inverse matrix circuit. The first aspect of the present invention is a method and an apparatus for switching the primary color points between primary color points of three or more primary colors on the receiving side for each pixel in accordance with the input color of the three primary color signals.

FIG. 2 shows six primary colors, of which four areas (triangular OPQ, PSQ, TQ) which can be displayed in a combination of three primary colors.
This is a first embodiment in which the color range is divided into OQ, TQU).
For example, if the input color signal is within the range of the triangular OPQ on the chromaticity diagram, when s = t = u = 0.0 in equation (1), the solution of o, p and q> 0.0 is obtained, so that it is accurate. Color reproduction is performed. o, p, q, s, t, u from r, g, b
The conversion to can be performed by the hardware configuration shown in FIG.

In FIG. 1, the input levels of the R, G, and B signals of the three primary colors are r ', g', and b 'because the R, G, and B signals of the color signals whose gamma characteristics of the display device on the display side have been corrected. The color component of B is corrected by the gamma characteristic γ, and after the primary color conversion, the gamma characteristic is corrected before output to the display device. The determiner 1 determines the position of the input color signal on the chromaticity diagram, for example, on the xy chromaticity diagram, for example, which of the four triangular regions shown above. Based on the result of the determination, it is selected which of the three sets of coefficient units k (six sets) are used or not used.

On the chromaticity diagram, which side of an arbitrary color is on a given straight line is determined by, for example, checking whether the color is on the left or right of the straight line PQ on the xy chromaticity diagram shown in FIG. Is the equation (2) that displays the straight line PQ on the chromaticity diagram

K ₁ · r + k ₂ · g + k ₃ · b = 0 (2) The coefficients k ₁ , k ₂ , and k ₃ are determined, and these coefficients are multiplied by the r, g, and b components of the input color signal, respectively. The primary combination is taken, and the judgment is made based on the sign of the result of the combination. The hardware configuration for this determination is as shown in FIG.
Is the content of the determining unit 1 shown in FIG.

That is, in FIG. 3, signals r, g, and b are signals obtained by multiplying the R, G, and B components of the input television signal by a gamma coefficient, and a set of coefficients k ₁ , k ₂ , and k ₃ is: For example, on the chromaticity diagram shown in FIG. 2, a group of multiplication coefficients for determining on which side the input color signal exists with respect to the straight line PQ, similarly, a set of coefficients k ₄ , k ₅ and k ₆ and a coefficient k _7, k _8, k ₉
Is for the straight lines OQ and QT, in this case the coefficient set of coefficients k ₁₀ , k ₁₁ and k ₁₂ is an unused set.

The linear combination of each of the multiplication outputs of the set of coefficients is determined as 0 or 1 by the decision units 2 to 5 depending on the positive or negative.
These outputs actuate or deactivate the coefficient unit group k shown in FIG. 1, and more specifically, perform the following operations (a) to (d).

(A) When the input color is on the left of the straight line PQ, it is determined to be a triangle PSQ.

O = t = u = 0.0 p · P + q · Q + s · S = r · R + g · G + b · B (3)

(B) The input color is a straight line OQ on the right of the straight line PQ.
When it is above, it is determined that it is a triangular OPQ, and the coefficient unit k is

S = t = u = 0.0 o · O + p · P + q · Q = r · R + g · G + b · B (4)

(C) When the input color is a straight line QT under the straight line OQ
Is judged to be a triangular OQT, and the coefficient unit k is

P = s = u = 0.0 o · O + q · Q + t · T = r · R + g · G + b · B (5)

(D) When the input color is below the straight line QT, it is determined that the input color is a triangular TQU.

O = p = s = 0.0 t · T + q · Q + u · U = r · R + g · G + b · B (6)

Next, a second embodiment according to the second invention of the present application will be described. FIG. 4 shows the configuration of the second embodiment. In the first embodiment, the scale of the hardware increases because the coefficient unit k is changed for each pixel in accordance with the input color, but the scale of the hardware is small in FIG. 4 because the coefficient is fixed. With this configuration, some colors in the hexagonal OPSQUT may not be completely reproduced,
There is no problem in practical use.

In this figure, the negative clip and inverted output N.D.
C. Works as follows. That is, input x
When (the left side of the figure) is positive, “x” is output on the right side and “0” is output below. When the input x is negative, "0" is output on the right side and "x" is output below.

The principle operation of FIG. 4 will be described below. Equation (1) can be transformed into equation (7), which is a ternary system of three with unknowns o, p, and q, with s, t, and u as dependent variables.

## EQU00007 ## o.O + p.P + q.Q = r.R + g.G + b.Bs.S.T.T.T.U.U (7)

When s, t, and u are simply represented by linear combinations of r, g, and b, o, in principle, due to the constraint of equation (7),
For many colors inside a hexagonal OPSQUT, where all values of p, q, s, t, u should be 0 or positive,
Any value will be negative. Therefore, correct color reproduction cannot be performed. In FIG. 4, in order to improve this, the negative clip and inverted output N.D. C. Is used. This circuit outputs "0" when s, t, and u are negative, and adds the correction term to o, p, and q, so that the above problem can be greatly improved.

The coefficient of the coefficient unit k shown in FIG.
O, p, q, s, for most colors inside the QUT
It is determined in advance so that all the values of t and u become 0 or positive. FIG. 5 shows a hardware configuration when FIG. 4 is applied to four primary colors.

Next, in order to more specifically understand the present invention, R, G, B, O, P, Q, S, T, and U are specifically given numerical values on a chromaticity diagram, and FIG. The hardware configuration shown in FIG. 4 will be described. As an example, consider the following chromaticity point case.

R (0.393, 0.212, 0.019), G (0.365, 0.701, 0.112), B (0.192, 0.087, 0.958), O (0.640, 0.360, 0.000), P (0.332, 0.620, 0.048), Q (0.153, 0.024, 0.823), S (0.028, 0.398, 0.574), T (0.705, 0.295, 0.000), U (0.169, 0.007, 0.824) (8)

In equation (8), each primary color is a tristimulus value X, Y,
It is represented by Z and shown on the xy chromaticity diagram as shown in FIG.

In the first embodiment (FIG. 1), for the input colors r, g, and b, the area is determined as follows and the signal level is calculated. (A) -0.7949 · r + 0.0569 · g + 0.0487 · b> 0.0

[Mathematical formula-see original document] o = t = u = 0.0 p = 0.9623 · r + 1.0837 · g + 0.0568 · b q = 0.6681 · r + 0.0226 · g + 1.1182 · bs = 1000. b (9)

(B) When −0.7949 · r + 0.0569 · g + 0.0487 · b <0.0 and −0.0082 · r + 0.5452 · g + 0.0552 · b> 0.0

S = t = u = 0.0 o = 0.6182 · r−0.0442 · g−0.0378 · b p = −0.0173 · r + 1.1538 · g + 0.1168 · b q = 0.0238 · r + 0.0687 · g + 1.1577 · b (10)

(C) When −0.0082 · r + 0.5452 · g + 0.0552 · b <0.0 and 0.0511 · r + 0.5820 · g + 0.0557 · b> 0.0

P = s = u = 0.0 o = 0.5274 r + 6.0051 g + 0.5745 b q = 0.0228 r + 0.1360 g + 1.1645 bt = 0.0745 r-4.9629 g-0.5023 b (11)

(D) When 0.0511 · r + 0.5820 · g + 0.0557 · b <0.0

O = p = s = 0.0 q = 2.0815 · r + 23.579 · g + 3.4070 · bt = 0.5994 · r + 1.0138 · g + 0.0694 · bu u = −2.0562 · r−23.414 · b−2.2398 · b (12)

In the second embodiment (FIG. 4), the following calculations are performed.

F (x) = x, x> 0.00, x <0.0 g (x) = 0, x> 0.0 x, x <0.0 s ₁ = −0.9182 · r + 0.0825 · g + .1979 · bt ₁ = 0.2936 · r -1.8885 · g-0.3339 · b u ₁ = -0.1249 · r-1.3786 · g + 0.7049 · b o = -0.2972 · r + 2.3798 · g + 0.4522 · b-0.6147 · g ( s ₁ ) + 1.2189 · g (t ₁ ) + 0.0547 · g (u ₁ ) p = 0.9378 · r + 0.5533 · g−0.1118 · b + 0.9741 · g (s ₁ ) −0.2325 · g (t ₁ ) −0.0593 · g (u ₁ ) q = 0.7335 · r + 1.4264 · g + 0.3273 · b + 0.6406 · g (s ₁ ) + 0.0136 · g (t ₁ ) + 1.0047 · g (u ₁ ) s = f (S ₁ ) t = f (t ₁ ) u = f (u ₁ ) (13)

For some color samples, (9)-
A description will be given of what value expression (13) produces. (E) When r = -0.5, g = 1.0, b = 1.0 (C1 in FIG. 6)

In the first embodiment, −0.7949 · r + 0.0569 · g +
Since 0.0487 · b = 0.503> 0.0, it is determined as (a), and from equation (9),

O = 0.0, p = 0.657, q = 0.807, s = 0.637, t = 0.0, u = 0.0 (14)

In the second embodiment, s ₁ = 0.740, t ₁ = −2.367, and u = −0.637.

## EQU15 ## When o = 0.062, p = 0.559, q = 0.741, s = 0.740, t = 0.0, u = 0.0 (15) (f) When r = 1.0, g = 1.0, b = 1.0 (FIG. 6) C2)

In the first embodiment, −0.7949 · r + 0.0569 · g + 0.0487 · b = −0.689 <0.0−0.0082 · r + 0.5452 · g + 0.0552 · b = 0.592> 0.
Since it becomes 0, it is determined as (b) and from equation (10)

## EQU16 ## o = 0.536, p = 1.253, q = 1.250, s = 0.0, t = 0.0, u = 0.0 (16)

In the second embodiment, s ₁ = −0.638, t ₁ = −1.926, and u = −0.799.

(17) o = 0.536, p = 1.253, q = 1.250, s = 0.0, t = 0.0, u = 0.0 (17) (g) When r = 1.0, g = −0.05, b = 1.0 (FIG. 6) C3)

In the first embodiment, −0.0082 · r + 0.5452 · g + 0.0552 · b = −0.030 <0.0 0.0511 · r + 0.5820 · g + 0.0557 · b = 0.028> 0.0
Is determined as (c), and from equation (11)

(18) o = 0.285, p = 0.0, q = 0.132, s = 0.0, t = 0.272, u = 0.0

In the second embodiment, s ₁ = −0.903, t ₁ = 0.355 and u ₁ = 0.015

[Equation 19] o = 0.184, p = 0.020, q = 0.117, s = 0.0, t = 0.355, u = 0.015 (19) (h) When r = 0.2, g = −0.14, b = 1.0 C4)

In the first embodiment, 0.0511 · r + 0.5820 · g + 0.
[0557] Since b = −0.016 <0.0, it is determined as (d) and from equation (12)

## EQU20 ## o = 0.0, p = 0.0, q = 0.522, s = 0.0, t = 0.047, u = 0.627 (20)

In the second embodiment, s ₁ = 0.003, t ₁ = −0.011, and u = 0.773.

## EQU21 ## o = 0.046, p = 0.001, q = 0.274, s = 0.003, t = 0.0, u = 0.773 (21)

As shown in this example, the present invention employs a triangle R
Even for colors outside the GB, the three primary color signals can be converted to multi-primary color signals.

Although the present invention has been described in detail with reference to the embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes are possible.

[0044]

According to the primary color conversion method of the present invention, the color outside the triangle formed by the three primary color points R, G, and B on the xy chromaticity diagram with the color signal of the color television signal in the three primary color system. The color of the degree point can be accurately reproduced, the color with high saturation is displayed correctly, and the hardware configuration of the conversion method is relatively simple.

[Brief description of the drawings]

FIG. 1 shows an example of a hardware configuration according to a first embodiment of the present invention.

FIG. 2 shows an example of area division on a chromaticity diagram with six primary colors displayed

FIG. 3 is a configuration example of a first embodiment determiner 1;

FIG. 4 is an example of a hardware configuration according to a second embodiment of the present invention;

FIG. 5 is a configuration example of another embodiment (4 primary colors) of the present invention.

FIG. 6 is a specific example of a chromaticity diagram for displaying six primary colors.

FIG. 7: Display of a current standard method using a chromaticity diagram

FIG. 8 is an example of a chromaticity diagram for displaying six primary colors.

[Explanation of symbols]

1-5 Judgment unit γ Gamma correction γ ^-1 Inverse gamma correction k coefficient unit k ₁ -k ₁₂ coefficient unit NC negative clip and inverted output

Claims (5)

(57) [Claims] 1. A luminance signal Y and two color difference signals C ₁ and C ₂ of a transmitted color television signal are converted into three primary color signals R, G and B via an inverse matrix circuit, and are obtained by the conversion. Input three primary color signals R, G and B
Is determined at what position on the chromaticity diagram, and based on the determination result, three primary colors are selected from among multiple primary colors beyond the three primary colors separately provided on the chromaticity diagram, and input by primary combination of these. A primary color conversion method for displaying multiple primary colors, wherein the primary color conversion method represents a color signal and prepares for multiple primary color display on a receiving side. 2. A luminance signal Y of a transmitted color television signal and two color difference signals C ₁ and C ₂ are converted into three primary color signals R, G and B via an inverse matrix circuit, and are converted on the receiving side. Separately, a multi-primary signal exceeding three primary colors provided on the chromaticity diagram is calculated and output as a linear combination of the three primary signals R, G and B, and three primary colors are selected from among the multiple primary colors exceeding the three primary colors. Select the other primary colors
When the output of the next combination becomes negative, the output is made zero and a correction signal is prepared, the correction signal is added to the output of the primary combination of the selected three primary colors, and the resultant signal is output. A multi-primary-color display primary color conversion method characterized by being prepared for the multi-primary color display. 3. In the case where the color television signal is transmitted after being subjected to inverse gamma correction in consideration of the gamma correction of the display device on the receiving side, the three primary color signals R and G are converted prior to the primary color conversion.
3. The primary color conversion method for multi-primary color display according to claim 1, wherein gamma correction is performed on each of B and B, and the output multi-primary color signal is subjected to inverse gamma correction. 4. transmitted color television signal has a luminance signal Y and two color difference signals C ₁ and C ₂ of the original three primary colors R, reverse matrix circuit for inversely converting the G and B signals, the receiving side In order to accurately reproduce even a highly saturated color, each of the multi-primary signals exceeding the three primary colors separately provided on the chromaticity diagram is calculated as a linear combination of the three primary colors R, G and B signals. And a multi-primary-color signal primary combination calculating circuit for outputting the three primary colors R and G obtained by the inverse matrix circuit.
And a chromaticity diagram position determination circuit for determining the position of the B and B signals on the chromaticity diagram; and 3 out of multi-primary colors exceeding three primary colors separately provided on the chromaticity diagram based on the determination circuit. Three primary color selection circuits for selecting three primary colors, and in order to prepare for multi-primary color display on the receiving side, only the result of the primary combination of the selected three primary colors with the three primary colors R, G and B signals is used. An output circuit for extracting and outputting from an output of a multi-primary-color signal primary combination calculation circuit, and a primary-color conversion device for multi-primary-color display. 5. transmitted color television signal has a luminance signal Y and two color difference signals C ₁ and C ₂ of the original three primary colors R, reverse matrix circuit for inversely converting the G and B signals, the receiving side In order to accurately reproduce even a highly saturated color, each of the multi-primary signals exceeding the three primary colors separately provided on the chromaticity diagram is calculated as a linear combination of the three primary colors R, G and B signals. And a multi-primary-signal primary-join calculation circuit for selecting and outputting three primary colors from among the multi-primary colors exceeding the three primary colors, and obtaining the primary connections obtained by the multi-primary-signal primary-join calculation circuit for the other primary colors When the output becomes negative, a correction circuit for setting the output to zero and preparing a correction signal is provided.
1 obtained by the multi-primary-color signal primary combination calculation circuit of the two primary colors
An output circuit for adding the prepared correction signal to the output of the next combination and outputting the added signal, and a primary color conversion device for multi-primary color display.