JPH0782307B2 - Color conversion device - Google Patents

Description

The present invention relates to an image processing device, and more particularly to a color conversion device for a multivalued color image used in a coloring simulator for industrial products such as cars and a makeup simulator.

[Conventional technology]

Conventionally, there have been the following techniques for performing this type of color conversion. The first method is to find the coordinates of the boundary line of the area whose color is to be changed, and paint the inside of this boundary line with a different color, and this method is mostly used in devices that handle graphic images. .

The second method uses the chroma key technology used in television studios and the like. (For example, Watanabe,
Suzuki, Suzuki "Digital Line Soft Chromakey" Television Society of Japan 1981 National Convention 10-6).

FIG. 5 shows a block diagram of a color conversion device using this chroma key technology. This device is composed of 50 cursor generators, 70 soft key signal generators, and 80 combining circuits.
A color image is input after being divided into three components of a luminance signal (I _Y ) and two color difference signals (I _RY , I _BY ) of _RY and _BY . The luminance signal is output as it is as the output luminance signal O _Y , and the two color difference signals I _RY and I _BY are converted by the value of the soft key signal K generated by the 70 soft key generation section in the synthesizing circuit of 80. It is combined with the subsequent target color difference signals C _RY and C _BY and output as output color difference signals O _RY and C _BY . When the cursor displayed in the output image by the cursor / timing generator 52 is moved to the representative point of the part whose color is to be changed by operating the positioner 51, the cursor is generated by the timing signal from the cursor / timing generator 52. The input color difference signal at the position of is stored in the registers 71 and 72. In the component difference calculator of 73 and 74, input color difference signal and register 7
The absolute value of the difference from the reference color difference signal (R _RY , R _BY ) from 1,72 is calculated, and the coefficient is multiplied by this in multipliers 75,76, and the two multiplication results are calculated by the soft key signal generator 77. Add and obtain the soft key signal K through the limiter appropriately. Since this soft key signal represents the difference between the color component of the input signal and the color component of the cursor portion, the smaller the value of K in the synthesizing circuit 80, the target color difference signal C _{RY with} respect to the input signals I _RY and I _BY . If a large proportion of, C _BY is combined, only the color part near the cursor part will be C _RY , C
Converted to another color specified by _BY .

[Problems to be solved by the invention]

The conventional color conversion device described above has the following drawbacks. First, in the first closed area filling method, it is extremely difficult to detect a boundary between a color-changing portion and a non-color-changing portion from a color video signal having a delicate color change input by a video camera or the like. Even if it can be detected well, there is a step in the color and brightness of the boundary, which makes it very unnatural. Further, since the process of obtaining the portion inside the closed region from the coordinate data of the boundary line is complicated, real-time processing at the data rate displayed by the cathode ray tube is extremely difficult. Further, since the color-changed portion is replaced with a certain uniform data, the nuances of the shade and color of the original image are lost.

For example, when changing the body color of a car photographed with a video camera from red to blue, even with the same red, there are shades (the brightness changes) depending on how the light hits, and there are also parts that appear bright red. However, since there is a part that looks a little dark red (there is a change in color saturation), such changes in brightness and color saturation remain as in the original image, and if only the hue is changed from red to blue, the original The nuances of the image are lost.

Compared to the first method, the method using the second soft key is that the color correlation is calculated without detecting the closed region, so that real-time processing is possible and that the luminance change remains in the original image. Although improved, the drawback remains that the nuance of changes in color saturation is lacking. In addition, since the color correlation is calculated in a form in which the color saturation and the hue are combined, for example, when the hue is the same red but the color saturation is different depending on the light condition, the color may not be converted.

A register for receiving the hue data from the color separation means and storing a hue value at any one point on the screen is provided as a means for obtaining the predetermined reference hue data, and the output of the register is used as it is or on the screen. The hue values of the dots are sequentially read from the register to obtain an average value, which is used as the predetermined reference hue data.

According to another feature of the present invention, the color image data is input, the color image data is decomposed into three components of luminance, color saturation and hue, and the luminance data is output as first image output data. Color separation means for outputting the saturation data to the color saturation conversion means described later and hue data for the soft key generation means and the hue conversion means described later, respectively, and the hue data from the color separation means and the predetermined reference hue data. In response to this, the soft key generating means for outputting the soft key data proportional to the absolute value of the phase difference represented by both data and having the maximum and minimum values limited to the hue conversion means and the color saturation conversion means described later. And the color saturation data from the color separation means, the soft key data from the soft key generation means, and any color saturation control data. And a color saturation conversion means for outputting output color saturation data obtained by changing the gain of the color saturation data according to the color saturation control data as second image output data, and a hue from the color separation means. Data, arbitrary hue data, and a soft key signal from the soft key generating means are input, and the hue data from the color separating means and the arbitrary hue data are input according to the value of the soft key signal. The output hue data with different composition ratio
And a hue conversion unit that outputs the image output data as the image output data.

[Means for solving problems]

In order to eliminate the above drawbacks, the present invention inputs color image data, decomposes the color image data into three components of luminance, color saturation, and hue to convert the luminance data and the color saturation data into first and second data. Upon receiving the color separation means for outputting as the second video output data and outputting the hue data to the soft key generation means and the hue conversion means described later, the hue data from the color separation means and the predetermined reference hue data. Soft key generating means for outputting to the hue exchanging means soft key data whose maximum and minimum values are limited in proportion to the absolute value of the phase difference represented by both data, and the hue data from the color separating means. And any hue data and soft key data from the soft key generating means are input, and the color from the color separating means is input according to the value of the soft key data. It is and a hue conversion means for outputting the output color data obtained by changing the synthesis ratio between the data and the arbitrary hue data as third video output data.

〔Example〕

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. This device comprises a color separation circuit 10, a soft key generation circuit 20, a hue conversion circuit 30, a register 40, and a cursor generation circuit 50. 1
The portions 0, 20, and 30 are the portions described in the first claim, and the register 40 is provided to obtain the reference color difference signal R _H from the input video signal as described in the second aspect. This is unnecessary when R _H is set externally.
Further, the cursor generation circuit 50 is provided to improve the operability of the work of which position on the screen the hue value is stored in the register 40.

The input video signal is input to the color separation circuit 10 as 8-bit digital data of R, G, and B, where the luminance signal O _Y , the color saturation signal O _S, and the input hue signal I _H are divided into 8 types. bit·
Converted to digital data. First, the first color conversion circuit 11
At O _Y = 0.30 ・ R ＋ 0.59 ・ G ＋ 0.11 ・ B, R−Y = R
-O _Y , B-Y = B-O _Y digital operation is performed and R, G, B
Signal to Y, RY, BY signals and then in the second color conversion circuit 12 Is digitally converted by giving the data showing the angle from the BY coordinate of the vector OA in the BY, RY coordinate system as shown in FIG. into a saturation signal O _S and hue signal I _H. These digital operations can be easily realized by using commercially available ROM and adder. Here, the input is R, G, B signals, but NTS
Even in the case of inputting C signal, Y, RY, BY signal, etc., it can be converted into luminance, color saturation and hue components by performing similar digital calculation.

O _Y and O _S signal but is outputted as it is to the outside as the first and second components of the output video signal, I _H signal portions having a value close to the reference hue signal R _H is replaced by the hue set value C _H Is output. This process will be described below.

When the cursor displayed on the screen by the cursor display signal from the cursor timing generation circuit 52 is moved to the representative point of the part whose color is to be changed by operating the positioner 51, the timing from the cursor timing generation circuit 52 The signal is sent to the register 40, and the input hue value at the cursor position is stored in the register 40, and this value is sent to the soft key generation circuit 20 as the reference hue signal R _H. In the soft key generation circuit 20, first, in the hue difference detection circuit 21, the absolute value of the phase difference between I _H and R _H is multiplied by a gain coefficient α (a fixed value or a value that can be controlled from the outside) K ′.
Is calculated, and then this K ′ is given a third value in the clipping circuit 22.
Clip processing with the input / output relationship shown in the figure
Create the key signal K. The hue conversion circuit 30 is composed of an adder and a multiplier, and receives the hue data input from the color separation circuit 10.
I _H , arbitrary hue data C _H set externally, and the soft key signal K from the soft key generation circuit 20 are input, and O _H = K I _H + (1-K) C _H and outputs as the third component of the third output video signal by calculating an output color signal O _H by digital calculation. In this example, the output video signal is output in the form of luminance, color saturation, and hue, but R, G, B signals and NTSC signals can also be obtained by providing a conversion circuit in the subsequent stage. As described above, the area on the screen having a hue close to the hue value of the point on the screen designated by the cursor is converted into an arbitrary hue set from the outside.

FIG. 4 is a block diagram of another embodiment of the present invention. This apparatus has a color saturation conversion circuit 60 added to the apparatus of FIG. 1 described above, and since the configuration and operation of the other parts are the same as those of the apparatus of FIG. 1, only the different parts will be described. The color saturation conversion circuit 60 receives an input color saturation signal I _S from the color separation circuit 10 (same as the _OS signal in FIG. 1), a soft key signal K from the soft key generation circuit 20, and an external signal. Optional color saturation control signal C _S (-127 ≤ C _S ≤ +127
, 8-bit digital signal), and _OS = (1 + C _S
· K) · by I _S (provided that C _S · K> -1) becomes digital operation seeking output color saturation data O _S. As a result, the degree of change in the color saturation can be set as it is in the original image, and the brightness (color saturation) of the desired color to be changed can be arbitrarily set externally by the C _S signal.

〔The invention's effect〕

As described above, since the present invention uses the soft chroma key technology, there is an effect that the boundary between the part where the color is converted and the part where the color is not converted is smooth and natural color conversion can be performed.
Further, since the luminance and the color saturation of the original image are not changed, there is an effect that only the color can be converted without impairing the nuances of the original image such as the shade and the brightness of the color.

In addition, the present invention uses a soft gain for color saturation of the original image.
Since it can be controlled by both the key signal and external data, in addition to the above effect, the effect of freely controlling the brightness (color saturation) of the target color to be changed without impairing the nuance of the original image is there.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory view of the principle of a second color separation circuit in FIG. 1, and FIG. 3 is a clip in FIG. FIG. 4 is a block diagram showing the operation of the circuit, FIG. 4 is a block diagram of another embodiment of the present invention, and FIG. 5 is a block diagram of a color conversion device using the conventional chroma key technology. 10 …… color separation circuit, 11 …… first color separation circuit, 12 …… second
Color separation circuit, 20 ... Soft key generation circuit, 21 ... Hue difference detection circuit, 22 ... Clip circuit, 30 ... Hue conversion circuit, 40 ... Register, 50 ... Cursor generation circuit, 51 ...
Positioner, 52 ... Cursor / timing generation circuit,
60: color saturation conversion circuit, 70: soft key generator,
71,72 ... Register, 73,74 ... Component difference calculation unit, 75,76 ...
… Multiplier, 77… Soft key signal generator.

Claims (2)

[Claims] 1. Color image data is input, and the color image data is decomposed into three components of luminance, color saturation and hue, and luminance data and color saturation data are output as first and second image output data. However, the color separation means for outputting the hue data to the soft key generation means and the hue conversion means, which will be described later, and the hue data from the color separation means and the predetermined reference hue data are received, and the absolute phase difference represented by the two data is received. A software that is proportional to the value and is limited to the maximum and minimum values.
The soft key generation means for outputting the key data to the hue conversion means described below, the hue data from the color separation means, an arbitrary hue data and the soft key data from the soft key generation means are input, Hue conversion means for outputting, as third video output data, output hue data obtained by changing the composition ratio of the hue data from the color separation means and the arbitrary hue data according to the value of the soft key data. A color conversion device having. 2. Color image data is input, the color image data is decomposed into three components of luminance, color saturation and hue, and the luminance data is output as first image output data, the color saturation data being described later. Color separation means for outputting the hue data to the soft key generation means and the hue conversion means, which will be described later, to the color saturation conversion means, and both data by receiving the hue data from the color separation means and the predetermined reference hue data. The soft key generation means for outputting the soft key data, which is proportional to the absolute value of the phase difference represented by the above, and whose maximum and minimum values are limited, to the hue conversion means and the color saturation conversion means described later, and the color separation. Receiving the soft saturation data from the means, the soft key data from the soft key generating means, and any color saturation control data, the soft key data and the color The output color saturation data obtained by changing the gain of the color saturation data according to Wado control data second
Color saturation conversion means for outputting as image output data of
Hue data from the color separation means, arbitrary hue data, and a soft key signal from the soft key generation means are input, and hue data from the color separation means is input according to the value of the soft key signal. A color conversion device comprising: a hue conversion unit that outputs, as third image output data, output hue data that has a changed composition ratio with the arbitrary hue data.