JP2505300B2 - Color image signal color correction device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color tone correction device for a color image signal of a digital signal processing system, and particularly when a relatively high level of processing is required for broadcasting. The present invention relates to a suitable color tone correction device.

[Outline of Invention]

The present invention has three types of R (red), G (green), and B (blue).
When color tone correction of a color video signal composed of primary color signal components is performed by digital processing, in parallel with the three colors of R, G and B, the complementary colors of Cy (cyan), Ma (magenta) and Ye (yellow) For each color video signal component,
An object of the present invention is to provide a color video signal correction device which requires a small number of digital multipliers and adders and requires a small digital circuit scale when the color tone can be adjusted independently. Is.

First, according to the present invention, in a color video signal composed of RGB three primary color video signals, from a different point of view, it is composed of an achromatic color component, a primary color component and a complementary color component. Is determined by the one of the input RGB three-color signal components whose level shows the maximum value. Its (primary color signal) level is the level of the signal showing the maximum value and the signal showing the intermediate value (level Is given as a difference with the level of the signal which is neither the maximum nor the minimum), and for the complementary color signal component, the color is the one whose level shows the minimum value, and that level shows the intermediate value level. It is characterized in that it is given by the level difference between the signal and the minimum value level and is given at λ level.

Then, based on this knowledge, in the present invention, the color of the input color video signal is calculated from the combination of the respective colors of the signal having the highest level and the signal having the lowest level among the RGB signal components of the input color video signal. The level difference between the maximum level signal and the intermediate level value signal as the level of the primary color signal component, and the level difference between the intermediate level signal and the minimum level signal as the level of the complementary color signal component. Then, the primary color signal component and the complementary color signal component are selected and multiplied by a predetermined hue and saturation adjustment coefficient determined by the determined color, and the multiplication result is also determined according to the determination result. A predetermined color tone correction function is provided by adding each color signal component of RGB that is a different combination.

[Prior Art] As a color correction device (also called a masking circuit) for a color video signal, a linear matrix circuit as shown in FIG. 4 is conventionally known.

This circuit, as is clear from FIG.
˜43, RG, GB, BR color difference signals are created from the R, G, B signals, and these color difference signals are multiplied by appropriate predetermined coefficients K1 to K6 by coefficient multiplication circuits 44 to 49, respectively, and thereafter, The adder circuits 50 to 55 add the original R, G, and B signals to obtain a video signal subjected to predetermined color correction.

According to this conventional color image signal color correction apparatus, it is possible to adjust the color tone while maintaining white balance, that is, while keeping the achromatic color signal achromatic.

However, in this conventional apparatus, for example, when the coefficient K1 to be multiplied by the RG signal is changed, R,
The color tone of the G image and the color tone of all complementary colors of Cy, Ye, and Ma also change, and even if you try to adjust only the color tone of the image of any specific color, this is not easy. there were.

Then, as a method improved by addressing the problems of such a conventional device, there is a "matrix device" disclosed in Japanese Patent Publication No. 49-41690.

FIG. 5 is a block diagram showing a configuration when the device disclosed in this publication is embodied by a digital system. Hereinafter, a color correction device for a digital system color video signal shown in FIG. 5 will be described. .

In the apparatus of FIG. 5, each RGB signal of the input color video signal is first input to the 6-color separation circuit 61.

This conventional 6-color separation circuit 61 is provided with, for example, the R shown in FIG.
The extraction circuit for separating the signals will be described as an example. The comparison circuit 81 compares the levels of the RG signal and the RB signal based on the original signal, and the signal of the lower level is selected by the selector.
The signal is selected by 82, and the negative component of the selected signal is removed by the clipping circuit 83 and output as the R'signal.

Therefore, the 6-color separation circuit 61 separates a color video signal having a ratio of R, G, and B signals of 0.8: 1.0: 0.2 as follows, for example, as shown in FIG. Equal to

0.8R + 1.0G + 0.2B = 0.2 (R + G + B) +0.6 (R + G)
+ 0.2G where (R + G + B); white (R + G); Ye 'G;G' Therefore, at this time, the color of this video signal is a mixture of Ye 'and G'at a ratio of 0.6: 0.2. And
Primary color signals for color correction R ', G', B'having a signal level ratio of 0.0: 0.2: 0.0 respectively
Similarly, the complementary color signals for color correction Cy ′, Ma ′, and Ye ′ whose signal levels are respectively in the ratio of 0.0: 0.6: 0.0 are output.

Similarly, for a color video signal in which the ratio of R, G, and B signals is 0.8: 1.0: 0.2, it is determined as 0.8R + 0.4G + 0.4B = 0.4 (R + G + B) + 0.4R and used for color correction. Only the output level of the primary color signal R'is 0.
At 4, the other color correction signals are output at the level 0.

Next, the color correction primary color signals R ', G', B'and the color correction complementary color signals Cy ', Ma', Ye 'output from the 6-color separation circuit 61 in this way are respectively The signals are supplied to the multiplication circuits 62 to 65, where they are multiplied by the predetermined correction coefficients K1 to K12, and then added and subtracted to the original RGB signals by the addition and subtraction circuits 66 to 74, respectively, to perform the predetermined correction. Will be output as an RGB signal.

Here, for example, the meaning of multiplying the above Ye 'signal by the above coefficient K1 and then adding it to the R signal and subtracting it from the G signal is shown in Maxwell 2 of FIG.
Explaining with a color diagram, this means that the position of the Ye color is moved in the direction of the solid arrow, and the hue of the Ye color is changed by the coefficient K1.

In addition, it is possible to multiply the Ye ′ signal by the above coefficient K2 and add it to the R signal and the G signal.
This means that the Ye color position is moved in the direction of the dashed arrow to change the saturation of this Ye color by the coefficient K2.

Similarly, each of the color correction primary color signals R ', G', B'and the color correction complementary color signals Cy ', Ma' has a coefficient K3.about.
By multiplying K12 and then adding and subtracting it to the R and G signals, the hue and saturation of each of R, G, B, Cy, and Ma can be adjusted. According to the device shown in FIG. 5, as shown in Table 1,
For each of the colors R, G, B, Cy, Ma and Ye, the hue and saturation can be adjusted independently.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, for each color signal of the input color video signal, the hue and saturation thereof can be adjusted independently independently, while the RGB color signals of the input color video signal are adjusted independently. In addition to a circuit for separating and extracting each component of the color correction primary color signals R ', G', B'and the color correction complementary color signals Cy ', Ma', Ye 'from the components, 12 multipliers and 21 Since many adders and subtractors are required, the circuit scale becomes enormous, and there are problems in cost and size and weight reduction.

An object of the present invention is to reduce the cost of hardware, reduce the size of the device, and reduce the operating power without increasing the amount of hardware when the above-described color correction device capable of independent correction of six colors is made into a digital circuit. The present invention provides a color tone correction device for various color video signals.

[Means for solving the problem]

In order to achieve the above object, a means for detecting a color signal having a maximum level and a color signal having a minimum level from a digitized RGB color video signal, and determining the color of an input signal according to the result, the maximum Using the intermediate level color signal obtained as the detection result of the minimum level color signal and the minimum level color signal, the difference signal between the maximum level color signal and the intermediate level color signal, and the intermediate level color signal and the minimum level color signal A means for creating a signal of a difference from a color signal, a signal of a difference between these two types,
It is provided with means for multiplying a coefficient determined according to the color of the input signal given as the above-mentioned judgment result, and means for adding the output of this means to the RGB signal which is a different combination depending on the judged color. is there.

[Action]

The color of the color image composed of the three primary colors of RGB is determined by the combination of the signal with the highest level and the signal with the lowest level among the three types of RGB signals, and one primary color and one complementary color (one of these or Both may be level 0)
And the level of this primary color signal is the difference between the maximum level signal and the intermediate level signal of the three RGB signals, and the complementary color signal level is the intermediate level signal and the minimum level signal. Since these are the differences from the signals, it is possible to construct a color tone correction device capable of performing 6-color independent correction by calculating these signals and using only a small number of multipliers and adders / subtractors.

〔Example〕

Hereinafter, a color tone correction device for a color image signal according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the present invention. In the figure, three terminals R _IN , G _IN , and B _IN are three types of digital signals R, G, and B which constitute a color video signal to be color-corrected. The supplied input terminals R _OUT , G _OUT , and B _OUT are output terminals from which the corrected R, G, and B signals are taken out.

Input terminals R _IN , G _IN , B _IN supplied to R, G, B 3
The seed digital signal is input to the comparison circuits 1 to 3 and RG
Signal levels are compared between each other, between GB, and between BR.

The color determination circuit 4 determines a color signal having the highest signal level, a color signal having the lowest signal level, and a color signal having a level between them, that is, a color signal having an intermediate level, based on the comparison results of the comparison circuits 1 to 3. Of. At this time, since the signal levels may be the same, a predetermined priority order is set between RGB, and the determination is performed according to this. In this embodiment, this priority order is set to RG.
The order is B.

The determination result of the color determination circuit 4 is the nine selectors 5 to 7 and 14
Used to control ~ 17 and 31, 32.

First, the selector 5 functions to select a color signal having the maximum level from the R, G and B signals based on the judgment result of the color judgment circuit 4 and supply it to the positive input of the subtraction circuit 8. .

Next, the selector 6 also selects a color signal having an intermediate level from the R, G, and B signals based on the determination result of the color determination circuit 4, and further subtracts it from the subtraction input of the subtraction circuit 8 and further subtracts it. It serves to feed the positive input of the circuit 9.

Further, the selector 7 also selects the color signal having the minimum level from the R, G, B signals based on the judgment result of the color judgment circuit 4, and inputs it to the subtraction input of the subtraction circuit 8 and further to the subtraction circuit 9. It works to supply to the positive input.

As a result, the subtracting circuit 8 first outputs a signal representing the level of the primary color component of the input color video signal, and the output is supplied to the two multiplying circuits 10 and 11.

On the other hand, the subtracting circuit 9 outputs a signal representing the level of the complementary color component of the input color video signal, and this output is supplied to the two multiplying circuits 12 and 13.

Next, the selectors 14 and 15 know from the judgment result of the color judgment circuit 4 the color signal having the maximum level among the R, G, and B signals, and select from among the registers 18 to 20 the color of this maximum level. 1 of the register that stores the coefficients K1 to K3 for saturation adjustment corresponding to the signal and 1 of the register that stores the coefficients K4 to K6 for hue adjustment that also correspond to the maximum level color signal. They serve to select each and supply the coefficient outputs of these selected registers to the multiplication circuits 10 and 11, respectively.

Further, the selectors 16 and 17 do not include a color signal showing the minimum value among the R, G, and B signals, which is the determination result of the color determination circuit 4 (R is Cy, G is Ma, and B is Ye. ) Knowing complementary colors,
From registers 24 to 29, register 1 which stores the coefficients K7 to K9 for saturation adjustment corresponding to this complementary color signal,
Similarly, it selects the registers 1 in which the coefficients K10 to K12 for hue adjustment corresponding to complementary colors are stored, and supplies the coefficient outputs of these selected registers to the multiplication circuits 12 and 13, respectively.

Therefore, from the multiplication circuits 10 and 11, a signal obtained by multiplying the primary color component by the saturation adjustment coefficient corresponding to the color of this primary color and a signal similarly multiplied by the hue adjustment coefficient are output, respectively, while the multiplication is performed. The circuits 12 and 13 respectively output a signal obtained by multiplying the complementary color component by the saturation adjustment coefficient corresponding to the color of this complementary color, and a signal similarly multiplied by the hue adjustment coefficient.

Of these outputs, the output of the multiplication circuit 10 is first supplied to the selector 31 controlled by the color determination circuit 4,
By the selection operation by the selector 31, the input terminals R _IN and G
Of the original R, G, B signals supplied from _IN , B _IN , the signal of the color judged to be the primary color by the color judgment circuit 4 is added via 1 of the addition circuits 33 to 35. It

Next, the output of the multiplication circuit 11 and the output obtained by inverting the polarity of the multiplication circuit 11 are supplied to the selector 31 which is also controlled by the color determination circuit 4, and the input operation of the input terminal R is performed by the selection operation of the selector 31. Of the original R, G, B signals supplied from _IN , G _IN , B _IN , two signals other than the color judged to be the primary color by the color judgment circuit 4 are added to the addition circuit.
Addition is performed via the remaining two adder circuits of 33 to 35 excluding the adder circuit to which the output of the multiplier circuit 10 is supplied.

Therefore, as a result, by changing the coefficients stored in the registers 18 to 23, the independent adjustment of the saturation and the hue of the primary colors shown in Table 1 can be obtained.

On the other hand, the outputs of the multiplication circuits 12 and 13 are first supplied to the addition circuit 39 and the subtraction circuit 40, respectively, and the addition circuit 39 adds them, and the subtraction circuit 40 outputs the output of the multiplication circuit 12 from the output of the multiplication circuit 12. Deducted. After that, these adder circuits 39
The output of the subtraction circuit 40 and the output of the subtraction circuit 40 are supplied to the selector 32 which is controlled by the color determination circuit 4, and R, G which form a complementary color determined by the color determination circuit 4 and which does not include a color signal having the minimum level. , B signal (R and G for Ye, G and B for Cy, R for Ma
And B) via the respective 1's in the adder circuits 36-38.

Therefore, as a result, by changing the coefficients stored in the registers 24 to 29, the independent adjustment of the saturation and the hue of the complementary color shown in Table 1 can be obtained.

Next, the operation of this embodiment will be described in detail with a specific example.

As described above, among the coefficients to be stored in the registers 18 to 29, first, the coefficients K1 to K3 are for adjusting the saturation of the R, G, and B primary colors, and the coefficients K4 to K6 are the hues of the respective primary colors. The coefficients K7 to K9 are for adjusting the saturation of each complementary color of Ye, Cy, and Ma, and the coefficients K10 to K12 are also for adjusting the hue of each complementary color.

Now, suppose that the digital color video signal supplied from the input terminals R _IN , G _IN , and B _IN is a signal in which R: G: B = 0.8: 0.4: 0.4.

Then, the color determination circuit 4 determines that the colors of the input signal are R and Ma because the level of the R signal is the maximum and the level of the G signal is the minimum (note that the G signal and the B signal are at this time). Have the same level, but G
The signal level is the minimum).

As a result, the selectors 5, 6, 7 are switched so as to select the R, G, B signals, respectively, and the RB signal having a signal level value of 0.4, that is, the primary color signal component R'of the video signal is output from the subtraction circuit 8. It is output and supplied to the multiplication circuit 10. On the other hand,
The output of the subtraction circuit 9 becomes level 0, and the complementary color signal component is not output.

At this time, since the judged color is R in the selectors 14 and 15, the coefficient K1 for saturation adjustment for R color and the coefficient K4 for hue adjustment are stored in the registers 18 to 23. The registers 18 and 21 are controlled so as to be selected. As a result, the multiplication circuits 10 and 11 output signals obtained by multiplying the primary color components by the saturation adjustment coefficient for R color and the hue adjustment coefficient, that is, R ×
The K1 signal and the R × K4 signal will be output.

Further, at this time, since the color of the video signal is R, the output of the multiplying circuit 10 is added to the R signal via the adding circuit 33, and the output of the multiplying circuit 11 and the output of the inverting circuit 30 are respectively The selector 31 is switched so as to add to the G signal and the B signal via the adder circuits 34 and 35.

Therefore, at this time, the R signal of the video signal includes the primary color signal component R ′ of the video signal and the saturation adjustment coefficient K1 for the R color.
Is added to the B signal, and a correction amount obtained by multiplying the primary color signal component R ′ by the hue adjustment coefficient K4 for R color is added to the B signal, and the correction amount is added from the G signal. In the end, at this time, the saturation of the R signal is K1 minutes, the hue is K4 minutes, and the corrected R, G, and B signals of the digital color video signal are output terminals R _OUT , It will be obtained from G _OUT and B _OUT , and by adjusting these coefficients K1 and K4, the saturation and hue of the R signal can be adjusted completely independently of the signals of other colors.

 Next, it is assumed that a color video signal having a color signal level ratio of R: G: B = 0.8: 0.8: 0.4 is input.

Then, at this time, the color determination circuit 4 determines that the colors of the input signal are R and Ye since the level of the R signal is the maximum and the level of the B signal is the minimum (the levels of the R signal and the G signal). Are equal to each other, but the level of the R signal is the maximum for the above reason).

As a result, the selectors 5, 6, 7 are now R,
The subtraction circuit 9 outputs the GB signal having a signal level value of 0.4, that is, the complementary color signal component Ye 'of the video signal, which is supplied to the multiplication circuits 12 and 13. On the other hand, the output of the subtraction circuit 8 becomes level 0, and the primary color signal component is not output.

Then, at this time, since the determined color is Ye, the selectors 16 and 17 store the coefficient K7 for saturation adjustment for Ye color and the coefficient K10 for hue adjustment in the registers 24-29. The registers 24 and 27 are controlled to be selected, and as a result, the multiplication circuits 12 and 13 output signals obtained by multiplying the complementary color components by the saturation adjustment coefficient for Ye color and the hue adjustment coefficient, that is, Ye.
The × K7 signal and the Ye × K10 signal are output.

Further, at this time, since the color of the video signal is Ye, the output of the multiplication circuit 12 and the output of the multiplication circuit 13 are added together.
From the result of addition in 39 and the output of the multiplication circuit 12, the multiplication circuit 13
The selector 32 is switched so that the result obtained by subtracting the output of 1 is added to the R signal via the adder circuit 36 and added to the G signal via the adder circuit 37.

Therefore, at this time, the R signal of the video signal includes the complementary color signal component Ye ′ of the video signal and the saturation adjustment coefficient K7 for the Ye color.
The result is multiplied by the hue adjustment coefficient K10, and the corrected amount is added, and the G signal is multiplied by the correction signal component Ye ′ by the hue adjustment coefficient K7 for Ye color.
The correction amount obtained by subtracting the result of multiplying K10 will be added, and at this time, in this case, Ye is the color, the saturation is K7 minutes, and the hue is K10 minutes. The R, G, and B signals of the signal are obtained from the output terminals R _OUT , G _OUT , and B _OUT , and by adjusting the coefficients K7 and K10, the saturation and hue of the Ye color can be changed to those of other colors. Can be adjusted independently.

In this embodiment, as is clear from the description of the above example, when the input signal consists of only one of the primary color and complementary color signals, the output of the other is zero. On the other hand, when the primary color and the complementary color are mixed, the above operation is
It will be obtained independently of each other and in parallel.

Therefore, according to this embodiment, 10 adder / subtractor circuits and
It is possible to obtain a digital color tone correction device capable of performing color correction independently of six colors by using four multiplication circuits.

Next, another embodiment of the present invention will be described with reference to FIG.

The embodiment of FIG. 2 is different from the embodiment of FIG. 1 described above in that the subtraction circuits 101 to 103 first calculate respective signal components of RG, GB and BR from an input signal, and a color judgment circuit. Four
Determines the color of the input video signal based on the sign of these components, and based on this determination result, the RG, GB, and BR signal components are further converted into absolute values by the absolute value conversion circuits 104 to 106, and the difference absolute value signal is obtained. The output obtained by the conversion to is selected by the selectors 107 and 108 and used as the primary color component signal and the complementary color component signal.

At this time, the selectors 107 and 108 are, for example, the color determination circuit 4
Thus, when it is determined that the level of the G signal is maximum and the level of the B signal is minimum, the output of the absolute value conversion circuit 104, that is, | RG |, and the output of the absolute value conversion circuit 106, that is, | BR | Works like selecting and.

Therefore, also in this embodiment, the basic operation is the same as that of the embodiment shown in FIG. 1 and the obtained effect is also the same, and therefore the detailed description thereof will be omitted.

Further, FIG. 3 is also another embodiment of the present invention. The difference of the embodiment of FIG. 3 from the embodiment of FIG. 1 is that the addition / subtraction circuits 39 and 40 and the selector 32 are replaced by an inversion circuit. circuit
110, selectors 111 and 112, and addition circuits 113 to 115 are used.

As a result, the output of the multiplying circuit 13 is output to the signal of one of the two colors of the R, G, and B signals which are in the complementary color relationship, which is determined by the color determination circuit 4, and the output of the multiplication circuit 13 is set to the other signal. The switching of the selector 112 is controlled so that the outputs of the multiplication circuit 13 whose polarities are inverted by the inversion circuit 110 are added via the addition circuits 113 to 115, respectively, and the multiplication circuit 12
The selector 111 is switch-controlled so as to add the output of 1 to both signals of two colors of the R, G, and B signals which are in a complementary color relationship with each other.

The operation of the embodiment shown in FIG. 3 is basically the same as that of the embodiment shown in FIGS. 1 and 2, and the effects are also the same, so a detailed description thereof will be omitted.

It is needless to say that those skilled in the art can easily understand the configurations embodying the idea of the present invention in addition to the above embodiments, and the technical scope of the present invention is not limited to the above embodiments. Yes.

By the way, recently, quite a lot of technologies using high-speed DPS (Digital Signal Processor) for image processing have been seen. In such a case, how to reduce the number of operations to improve the processing speed is a problem. become.

However, even in such a case, the present invention is extremely effective, and if the color image signal is processed by using the above-mentioned algorithm according to the present invention, for example, by the procedure shown in the flowchart of FIG. Compared to the case of using the algorithm of the technology, it is about 1/3, and it is possible to easily obtain a significant speedup and to effectively use DPS.

〔The invention's effect〕

According to the present invention, an apparatus capable of independent correction of 6 colors, which is similar to the color tone correction apparatus for digital color image signals according to the prior art, can be reliably realized with, for example, a circuit scale of 1/3. It is possible to easily provide a compact and lightweight color tone correction device for color video signals.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a color tone correction device for a color video signal according to the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a further embodiment of the present invention. Block diagrams showing another embodiment, FIGS. 4 and 5
FIG. 6 is a block diagram for explaining a conventional technique, FIG. 6 is a diagram for explaining a color correction operation, FIG. 7 is a block diagram for showing a conventional example of a 6-color separation circuit, and FIG. 8 is a diagram showing a relationship of color signal levels. FIG. 9 is a block diagram showing another embodiment of the present invention. 1-3 ... comparison circuit, 4 ... color judgment circuit, 5-7, 14-
17, 31, 32, 107, 108, 111, 112 ... Selector, 8,
9, 33-40, 101-103, 113-115 ... Addition / subtraction circuit, 10-
13 ... Multiplier circuit, 18-29 ... Register.

Claims (1)

(57) [Claims] 1. A color image signal color tone correcting device for inputting a digital color image signal composed of three types of image signal components of red, green and blue and independently adjusting hue and saturation for each color. The color video signal component showing the maximum level, the color video signal component showing the intermediate level, and the color video showing the minimum level are detected by detecting the respective levels of the above-mentioned three types of video signal components of red, green, and blue. Means for determining the signal component, and based on the result of the determination, subtracting the color video signal component indicating the intermediate level from the color video signal component indicating the maximum level to obtain the primary color of the input color video signal. The input color image signal is obtained by subtracting the color image signal component showing the minimum level from the primary color level signal showing the component level and the color image signal component showing the intermediate level. Means for creating a complementary color level signal representative of the level of the complementary color component of the component, each of these primary color level signal and a complementary color level signal,
The primary color level correction signal and the complementary color level correction signal are multiplied by a predetermined coefficient selected according to the color combination of the color video signal component showing the maximum level and the color video signal component showing the minimum level. Means for outputting the primary color level correction signal and the complementary color level correction signal in accordance with the color combination of the color video signal component showing the maximum level and the color video signal component showing the minimum level. A color video signal characterized by being provided with means for adding to each color signal component of the video signal, and by independently adjusting the hue and saturation for each color by adjusting the predetermined coefficient. Color correction device.