JPH084342B2 - Video signal processing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to hue correction and saturation improvement processing of a full-color image in an RGB video signal, and a color television, a monitor television, and a television screen which receive the RGB video signal as an input. It can be widely applied to video printers and the like for making hard copies.

2. Description of the Related Art Conventionally, general color televisions drive a CRT by inputting a composite video signal such as NTSC and decoding the composite video signal into RGB which is the three primary colors of light. In a composite video signal such as NTSC, video information is handled by dividing it into three elements of luminance, hue, and saturation, so a decoder that demodulates NTSC into RGB is, for example, an RGB video that is freely demodulated by a variable resistor or the like. The brightness, hue and saturation of the signal can be adjusted. for that reason,
In color televisions currently on the market, the saturation tends to be set higher in order to make the output image look more vivid than the original image.

However, many recent color TVs have an RGB input terminal, and the frequency of use has increased with the development of new media equipment, but it is difficult to increase the saturation of the image input with RGB, so RGB The resolution of the input image is high, but the vividness is often inferior to NTSC. The same applies to video printers, and NTSC as an input signal is insufficient in terms of resolution, and RGB is not vivid. Further, complementary color inks C (cyan), M (magenta),
In order to compensate for the low saturation of Y (yellow), it is effective to positively increase the saturation of the video signal. Also, in the case of a video printer, the hue due to the spectral characteristics of the C, M, and Y inks used is usually inconsistent with the complementary color of RGB, so RGB is calculated by the matrix calculation as shown in equation (1).
After GB is converted into R'G'B 'having a hue suitable for the color reproduction system of the recording means, C, M, and Y are obtained by further complementary color conversion (JP-A-60-146574).

R '= a00 * R + a01 * G + a02 * B G' = a10 * R + a11 * G + a12 * B B '= a20 * R + a21 * G + a22 * B (1) The coefficient of this matrix improves the saturation at the same time as the element that corrects the hue. The above-mentioned NT
The result is the same as the one with higher saturation in SC.

Problems to be Solved by the Invention In the conventional example, after RGB is digitally converted by three sets of A / D converters, hardware by a multiplier, LUT (look-up table) and adder / subtractor, or software by a CPU is used. Although the above-mentioned matrix calculation is performed by software calculation, software has a drawback that processing takes a very long time and printing time becomes long, and hardware has a drawback that processing time is short but cost is high. . Further, in each case, three sets of high-speed A / D converters are required, which greatly increases the cost.

In addition, it is difficult to obtain a resistance value having an accurate value as calculated by implementing the matrix operation of the equation (1) by an analog operation using a general resistance matrix. Since the balance is lost, it is difficult to realize in terms of calculation accuracy.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a video signal processing device which can perform hue correction and saturation improvement at the same time by a resistance matrix that is extremely low in cost and does not easily lose white balance.

Means for Solving the Problems In the present invention, a video signal composed of RGB is inputted, and signals R, G, and B of the video signal, which are inverted respectively, −R, −
An inverting buffer group for outputting G, -B, a first resistor group having the same resistance value connected to the R input to the R output, the G input to the G output, and the B input to the B output, and G or- G
A second resistor group having the same resistance value connected from the input to the R output, the G or −G input to the G output, and the B or −B input to the B output, and the B or −B input to the R output, G
Or a third resistor group having the same resistance value connected from -G input to G output, B or -B input to B output, and R or -R input to G output, B or -B input to B Output, a fourth group of resistors having the same resistance value connected from the R or -R input to the R output, and B or -B input to G output, B or -B input to B output, R or -R A fifth resistor group having the same resistance value connected from the input to the R output, and connected from the R or -R input to the B output, from the R or -R input to the R output, and from the G or -G input to the G output And a sixth resistor group having the same resistance value,
G or -G input to B output, R or -R input to R
The video signal processing device is provided with a seventh resistor group having the same resistance value and connected from the output, G or -G input to the G output.

Action The present invention has the above-mentioned configuration, in which the first resistor group is R,
It acts as an element to set the saturation and hue of G and B as they are, and for the R output, the second resistor outputs the component from G or -G and the third resistor outputs the component from B or -B. Give, R
Change the hue and saturation of the output. The signal level of the R output is changed by the second resistor and the third resistor, but the second resistor and the third resistor are G or -G for the G output.
, B output is connected to B or -B,
The signal level of the R output cancels the change without changing the hue of the G output and the B output.

Similarly, the fourth resistor and the fifth resistor cancel the signal level change of the G output with respect to the B output and the R output while changing the hue and saturation of the G output, and the sixth resistor The seventh resistor cancels a change in the signal level of the B output with respect to the R output and the G output while changing the hue and saturation of the B output.

Therefore, in the present invention, in the case of a black and white signal (R = G = B), the circuit configuration is completely symmetrical with respect to RGB, so that the output is also R '= G' = B 'and the same black and white signal. Therefore, if the first, second, third, fourth, fifth, sixth, and seventh resistors have the same value, the hue is corrected without impairing the white balance even if there is no absolute accuracy. The saturation can be improved.

First Embodiment A first embodiment of the video signal processing device of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a video signal processing device of the present invention. 1, 2, and 3 are buffers with a gain of 1, 4, 5,
6 is a gain-1 inverting buffer, 7, 8 and 9 are first resistors connected from R input to R output, G input to G output, B input to B output, 10, 11 and 12 are G Or -G input to R output, G or -G input to G output, B or-
Second resistor group connected from B input to B output, 13, 1
4, 15 is a third resistor group connected from B or −B input to R output, G or −G input to G output, B or −B input to B output, 16, 17, 18 is R or − Fourth resistor group connected from R input to G output, B or -B input to B output, R or -R input to R output, 19, 20, 21
Is the fifth connected from B or -B input to G output, B or -B input to B output, R or -R input to R output
Resistor group 22, 23, 24 is a sixth resistor group connected from R or -R input to B output, R or -R input to R output, G or -G input to G output, 25, 26 and 27 are G
Alternatively, a seventh group of resistors 28, 29, 30 connected from -G input to B output, R or -R input to R output, and G or -G input to G output are amplifiers of gain k.

In a normal RGB signal system, when R = G = B, an achromatic color is obtained, and a luminance signal representing brightness is defined by equation (2).

Y = R / 3 + G / 3 + B / 3 (2) Therefore, the primary color signals (RGB) are converted into color difference signals (Y, R-Y, B-
If the matrix to be converted to Y) is A, A defined by is expressed by equation (3), and the inverse matrix is expressed by equation (4).

Further, when the saturation coefficient for changing the saturation is α, the matrix B for changing the saturation of the color difference signal can be defined by the equation (5).

Equation (5) shows that when α = 0, it is monochrome, when 0 <α <1, there is no saturation, and when α = 1, there is no change in saturation.
When α> 1, the saturation is improved.

From the above matrix, RGB with saturation changed from RGB signal
When C is a matrix to be converted into a signal, C = A BA, and therefore, from the formulas (3), (4), and (5), formula (6) is obtained.

Further, the matrix giving the coefficient for correcting the hue can be set as D from the equation (1).

However, a00 + a01 + a02 = 1 a10 + a11 + a12 = 1 a20 + a21 + a22 = 1 a00> 0, a11> 0, a22> 0 Here, the matrix for simultaneously performing hue correction and saturation improvement is represented by the product of matrix C and matrix D, and this is expressed as E
Then a + b + c = 1, a> 0 d + e + f = 1, e> 0 g + h + i = 1, i> 0 Further, the signs of the coefficients b, c, d, f, g, and h are <b>,
It will be written as <c>, <d>, <f>, <g>, and <h>. For example, <b> G in the block diagram of FIG.
Is positive, it is connected to the output + G of the buffer 2, and if the coefficient b is negative, it is connected to the output -G of the buffer 5, and the same applies to other signals.

Next, the input / output characteristics of the video signal processing device of this embodiment shown in FIG. 1 are shown in equation (9).

R '= k ・ Pa ・ R / P + k ・ Pb ・ G / P + k ・ Pc ・ B / P G' = k ・ Pd ・ R / P + k ・ Pe ・ G / P + k ・ Pf ・ B / P
(9) B '= k ・ Pg ・ R / P + k ・ Ph ・ G / P + k ・ Pi ・ B / P However, P = 1 / r + 1 / rb + 1 / rc + 1 / rd + 1 / rf + 1 / rg + 1 / rh Pa = 1 / r + 〈d > / Rd + <f> / rf + <g> / rg + <h> / rh Pb = <b> / rb Pc = <c> / rc Pe = 1 / r + <b> / rb + <c> / rc + <g > / Rg + <h> / rh Pd = <d> / rd Pf = <f> / rf Pi = 1 / r + <b> / rb + <c> / rc + <d> / rd + <f> / rf Pg = <G> / rg Ph = <h> / rh Here, when Equation (9) is compared with Equation (8) and solved, Equation (10) is obtained.

r / rb = | b | / a + e + i-2, r / rc = | c | / a + e + i-2 r / rd = | d | / a + e + i-2, r / rf = | f | / a + e + i-2 r / rg = | g | / a + e + i-2, r / rh = | h | / a + e + i-2 k = a + | b | + | c | + | d | + e + | f | + | g | + | h | + i-2 / a + B + c + d + e + f + g + h + i-2 (10) If r is appropriately determined from the relation of the above equation (10), rb,
rc, rd, rf, rg, rh and k can be calculated. The gain coefficient k is generally greater than 1. Output RGB rather than input RGB
Amplifiers 28, 2 if the level of
9 and 30 are not necessary.

If this embodiment is applied to a video printer as an example, not only the hue of RGB is corrected according to the hue of recording ink (CMY), but also the saturation of RGB image is adjusted according to the saturation of NTSC image. It is possible to obtain good results by improving the saturation of the CMY ink after the complementary color conversion and improving the saturation considerably considerably in order to compensate for the insufficient saturation of the ink.

EFFECTS OF THE INVENTION According to the present invention, a masking circuit using a resistance matrix that does not disturb the balance of white color can be configured while using analog processing.
It is possible to correct the hue of the RGB video signal and increase the saturation. Therefore, from the viewpoint of the conventional cost, RG
Hue correction can be introduced to the video printer that recorded CMY with the inverted signal of B with almost no cost increase.
You can print more faithful images.

Also, since the saturation can be increased at the same time, the elements that were generally inferior even when compared to the image with the NTSC signal with enhanced saturation are eliminated, and it is possible to project a more beautiful image than NTSC in all respects. . Further, when applied to a video printer, it becomes possible to compensate for the lack of saturation of the complementary color ink within the range of color reproduction by the ink. Since NTSC is not sufficient in terms of resolution as an input signal of a video printer, the effect of vividly printing in RGB is extremely large.

[Brief description of drawings]

1 to 6 are block diagrams of respective parts of the video signal processing device in the embodiment of the present invention. 1, 2, 3 ... Buffer, 4, 5, 6 ... Inversion buffer, 7, 8, 9 ... First resistor group, 10, 11, 12 ... Second resistor group, 13, 14 , 15 …… Third resistor group, 16, 1
7, 18 …… Fourth resistor group, 19, 20, 21 …… Fifth resistor group, 22, 23, 24 …… Sixth resistor group, 25, 26, 27 ……
Seventh resistor group, 28, 29, 30 ... Amplifier

Claims (2)

[Claims] 1. A signal -R,-, wherein R, G, and B of the video signal are inverted, with an RGB video signal as an input.
An inverting buffer group for outputting G, -B, a first resistor group having the same resistance value connected to the R input to the R output, the G input to the G output, and the B input to the B output, and G or- G
A second resistor group having the same resistance value connected from the input to the R output, the G or −G input to the G output, and the B or −B input to the B output, and the B or −B input to the R output, G
Or a third resistor group having the same resistance value connected from -G input to G output, B or -B input to B output, and R or -R input to G output, B or -B input to B Output, a fourth group of resistors having the same resistance value connected from the R or -R input to the R output, and B or -B input to G output, B or -B input to B output, R or -R A fifth resistor group having the same resistance value connected from the input to the R output, and connected from the R or -R input to the B output, from the R or -R input to the R output, and from the G or -G input to the G output And a sixth resistor group having the same resistance value,
G or -G input to B output, R or -R input to R
A video signal processing device comprising a seventh resistor group of the same resistance value connected from the output, G or -G input to the G output. 2. An amplifier having an amplification degree of 1 or more for amplifying a signal from the first, second, third, fourth, fifth, sixth and seventh resistor groups. The video signal processing device as set forth in claim 1.