JP3557135B2 - Image adjustment circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image adjustment circuit that performs color adjustment for a color image signal.
[0002]
[Prior art]
In a color TV, a normal hue is determined by a phase difference from a color burst signal included in a color TV signal. That is, a normal color composite signal contains a specific color burst signal, and the color data is demodulated based on the phase difference between the color burst signal and the color signal. When the hue adjustment is performed, the phase of each hue is rotated with respect to the phase of the color burst signal. That is, as shown in FIG. 5, in the normal case, the position of each color is determined by setting the phase of the color burst signal to 180 °, BY to 0 °, and RY to 90 °. The hue is adjusted by rotating the position of each color with respect to the position of the color burst according to the adjustment signal. In the example shown in the figure, each color is originally made to correspond to the phase drawn by the solid line, but is rotated clockwise according to the hue adjustment signal so that each color is made to correspond to the phase drawn by the broken line. . Thus, the color corresponding to the same color signal is changed, and the hue adjustment is performed.
[0003]
[Problems to be solved by the invention]
As described above, conventionally, the hue adjustment is performed by changing the phase of the color burst, but the color burst cannot be used in the digital signal processing. Therefore, in the processing of the digital signal, it is necessary to always calculate the phase from the input BY and RY and rotate the phase in accordance with the hue adjustment signal.
[0004]
That is, in FIG. 5, a color separated by θ from the BY axis is represented by {sin θ} ² + {cos θ} ² = 1 when the color density is constant. Changing the hue means shifting the phase. For example, the phase is temporarily rotated by θ ′. In this case, the point of θ with respect to BY is represented by {sin (θ + θ ′)} ² + {cos (θ + θ ′)} ² = 1. Therefore, calculations must be performed on each data so that this equation applies. This means that for each point, θ = tan ⁻¹ {(RY) / (BY)} must always be calculated, and a point shifted by θ ′ which is data for hue adjustment must be calculated. It is. This operation has a problem that the amount of operation is large and the circuit scale becomes very large.
[0005]
The present invention has been made in view of the above problems, and has as its object to provide an image adjustment circuit capable of reducing the amount of calculation for hue adjustment.
[0006]
[Means for Solving the Problems]
The present invention relates to an image adjustment circuit that performs color adjustment on a color image signal including color difference signals RY and BY, and has a complementary relationship between RY and BY corresponding to hue adjustment data. , The amplitudes of the red component and the blue component are changed complementarily by multiplying the amplitude magnifications of the red and blue components, and the amplitude magnifications of the RY and BY are uniquely determined for the hue adjustment data, In addition, the relationship ( amplitude magnification of RY ) ² + (amplitude magnification of BY) ² = (constant value A) is satisfied .
[0007]
As described above, the hue can be adjusted by changing the amplitudes of the blue component and the red component according to the hue adjustment data. Such amplitude adjustment can be easily performed by multiplying the input digital data by a predetermined coefficient or the like, and the color tone can be adjusted by reducing the amount of calculation.
[0009]
Further, it is preferable to have a hue conversion table for supplying the amplitude magnification for the RY and BY according to the hue adjustment data. The amplitude magnification can be read according to the hue adjustment data.
[0012]
Further, it is preferable that the amplitude magnification of RY and BY is represented by a two's complement.

[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter, referred to as embodiments) will be described with reference to the drawings.
[0014]
FIG. 1 is a block diagram illustrating the configuration of the image adjustment circuit according to the present embodiment. The color signal is, for example, a color digital signal of the NTSC system and includes three signals of Y (luminance), BY, and RY. Of these signals, the Y signal has nothing to do with hue adjustment, so that RY and BY are input to this circuit. RY is input to the multiplier 10, and BY is input to the multiplier 12. The multipliers 10 and 12 are supplied with the amplitude magnifications from the operation coefficient table 14, respectively. The input RY and BY are multiplied by the respective amplitude magnifications, and the multiplication results are adjusted in hue. It is output as RY and BY.
[0015]
Here, adjustment data K indicating the ratio of red is input to the operation coefficient table 14, and the amplitude magnifications of RY and BY corresponding to the adjustment data K are output. FIG. 2 shows the contents of the operation coefficient table 14. As described above, the adjustment data K is data of 32 stages from 00h to 1Fh.
[0016]
These 32 levels of data are basically
(Equation 1)
(Amplitude magnification of RY) ² + (amplitude magnification of BY) ² = 2
It is determined based on the formula. Here, this is basically because a certain degree of approximation is included. Particularly, K = 00h is limited by the upper limit value of the magnification.
[0017]
As described above, the amplitude magnification having a complementary relationship can be determined by the above-described equation (Equation 1). With the complementary amplitude magnification, as described later, a vector of a certain color is adjusted to be rotated.
[0018]
By using such an operation coefficient table 14, the operation for hue adjustment can be performed only by multiplying the inputted RY and BY by the corresponding amplitude magnification, and the amount of operation is extremely small. Can be.
[0019]
Next, the contents of the amplitude magnification in the calculation coefficient table 14 will be described. As described above, the amplitude magnification is determined by the equation (RY amplitude amplitude) ² + (BY amplitude amplitude) ² = 2 (it is not always necessary to be 2 and may be a constant A). ing.
[0020]
In particular, when the constant is set to “2”, there is a point that “amplitude magnification = 1”, so that there is an advantage that calculation for determining the amplitude magnification becomes easy.
[0021]
On the other hand, if y = RY and x = BY, a function F (a function corresponding to FIG. 5) indicating the relationship between the hue and the phase after the multiplication in the multipliers 10 and 12 is:
(Equation 2)
F = (kr · y) ² + (kb · x) ²
It is represented by
[0022]
kr and kb are coefficients uniquely determined by the adjustment data K supplied from the outside, and the function F is
(Equation 3)
F = ay ² + bx ²
It is expressed as Here, a and b are constants of a = kr ² and b = kb ² , and 0 ≦ kr ≦ √A and 0 ≦ kb ≦ √A.
[0023]
Therefore, the relationship between the hue and the phase of the function F by the calculation of the present embodiment is as shown in FIG. That is, when the value of K is reduced, the amplitude magnification kb of BY is reduced, and the amplitude magnification kr of RY is increased. As a result, the ellipse becomes larger in the RY direction, the RY increases, and the BY decreases accordingly. In this way, color tone adjustment for enhancing red and color tone for enhancing blue can be performed.
[0024]
By changing the amplitudes of RY and BY with such amplitude magnifications kf and kb, the phase θ from the BY axis with respect to the color is changed, as if the color vector is rotated. Looks like it has been adjusted. That is, when kr is large and kb is small, RY is large, BY is small, and the color vector moves counterclockwise around the coordinate 0.
[0025]
Such an adjustment is different from the rotation based on θ ′ described as a conventional example, but a pseudo color tone adjustment can be performed, and the amount of calculation can be very small.
[0026]
FIGS. 4A, 4B, and 4C show signal amplitudes based on color adjustment. In this figure, the amplitude value is shown for each color of the color bar. From the left, “white”, “yellow”, “cyan”, “green”, “magenta”, “red”, “blue”, and “black” are shown. Is the place where the amplitude value is 2's complement and 0. In this example, the left side (a) is an example of the input side, and the upper right side (b) shows the amplitude value of each color when the phase is rotated by θ ′ as in the conventional example. On the other hand, the lower right part (c) is obtained by changing BY and RY according to the present embodiment. As described above, according to the present embodiment, it is possible to adjust the color tone of each color such as bluish or reddish.
[0027]
In this embodiment, as shown in FIG. 2, all coefficients can be calculated by ²ⁿ . Therefore, the multiplication can be configured with a shift register and an adder. That is, multiplication of 2 can be performed by bit shifting. Further, it is preferable that all the digital data is represented by two's complement and operated. In addition, it is preferable that the calculation result is output after the number of bits is adjusted to a predetermined number.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to adjust the color tone by changing the amplitude of the color difference signal at the amplitude magnification corresponding to the hue adjustment data. Further, since it is only necessary to change the amplitude of the color difference signal at a uniquely determined amplitude magnification, the circuit configuration can be simplified and the circuit scale can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an embodiment.
FIG. 2 is a diagram showing contents of an operation coefficient table coefficient.
FIG. 3 is a diagram illustrating a change in hue.
FIG. 4 is a diagram illustrating the amplitude of each color.
FIG. 5 is a diagram showing a conventional hue adjustment.
[Explanation of symbols]
10, 12 multiplier, 14 operation coefficient table.

Claims (3)

An image adjustment circuit that performs color adjustment on a color image signal including the color difference signals RY and BY ,
According to the hue adjustment data, the amplitudes of the red and blue components are complementarily changed by multiplying RY and an amplitude magnification complementary to BY,
The RY and BY amplitude magnifications are uniquely determined with respect to the hue adjustment data, and (RY amplitude magnification) ² + (BY amplitude magnification) ² = (constant ) An image adjustment circuit, which satisfies the relationship of value A) . The circuit according to claim 1 ,
Image adjusting circuit and having a color conversion table for supplying an amplitude ratio to the R-Y and B-Y in accordance with the hue adjustment data. The circuit according to claim 1 ,
The image adjustment circuit according to claim 1, wherein the amplitude magnification of RY and BY is represented by a two's complement.

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