JPS6118919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to solve the unnaturalness of fitting when performing screen composition and to improve the quality of the composite screen in special effects of color television using chroma key back. This is related to the soft chromakey method aimed at.

Usually, in special effects for color television, a chromakey signal generator is used to obtain a key signal of a hue corresponding to a chromakey back (generally blue) using R, G, and B signals from a color camera. In this case, the chromakey signal generator is configured, for example, as shown within the dotted line frame in FIG. 1, and is well known. To explain the operation of this chromakey signal generator, the R.
The G and B signals are applied to a hue matrix circuit as shown in FIG. 3 to obtain the A circuit and B signals. To explain FIG. 3, the hue matrix consists of variable resistors 35 and 37 that rotate in conjunction and have terminals at an angle of 120 degrees from each other, and as shown in the figure, each terminal receives R, G, and B signals. are applied respectively. The slider 36 of the variable resistor 35 is located at the B (blue) terminal, and the slider 38 of the variable resistor 37 is arranged at an angle of 180 degrees with the slider 36, and is located at the terminal R.
and terminal G. Now, when an image as shown in FIG. 4a is captured by a color camera, signals as shown in FIG. 5 are output to the R, G, and B terminals. In Fig. 4a, B indicates the blue color of the chroma key back (background), G indicates green, and R indicates the blue color of the chroma key back (background).
indicates a red object and W indicates a white object. A diagonal line 39 indicates the shadow of the R object and indicates that the saturation is half that of B. Line 40 also indicates the signal obtained on scanning line 40 in FIG. Therefore, in FIG. 5, A shows the signal waveform of the R signal, B shows the G signal, and C shows the B signal. This kind of signal is converted into hue matrix 1
When the voltage is applied to the variable resistor 35, the A signal is outputted through the slider 36 of the variable resistor 35 with the waveform shown in FIG.
The B signal is outputted through the slider 38 in the waveform shown in E of the figure (half of the composite signal of the R (red) signal in A and the G (green) signal in B). The A signal D and B signal E thus obtained are subjected to signal processing in the subtraction circuit 2, resulting in the waveform of the [A-B] signal A as shown in FIG. This [A-B] signal A is L.
High-frequency noise is removed by a low-pass filter (PF) 3, and the signal is applied to a stretch amplifier circuit 5 through a delay line 4. [A] input to the stretch amplifier circuit 5
-B] Signal A is sliced at the stretch level 42 as shown in FIG.
It is output as a chromakey signal C as shown in G in the figure.

However, the chromakey signal obtained in this manner has a sharp signal waveform as shown in FIG. 5C. Since this chromakey signal is converted from an analog signal to a digital signal, noise from color cameras, uneven color of chromakey back, uneven lighting, etc.
Due to the effects of shadows, scratches in the chroma key back, etc., jitter may occur on the edges of the chroma key signal or the outline of the composite screen, or it may not be possible to extract the image sufficiently, or the chroma key back may become foggy depending on the contrast and hue of the image to be inserted. The composition of the screen was unnatural and the quality could not be said to be sufficient, with details such as hair being noticeable and details such as hair being lost.

The present invention provides a novel soft chromakey method that eliminates the drawbacks of the conventional methods as described above, and embodiments thereof will be described below with reference to the drawings.

In the block diagram of FIG. 1, R, G, and B signals from a color camera or the like are added to the hue matrix 1 as described above to obtain A and B signals.
The A signal and B signal are processed by the subtraction circuit 2 to obtain the [A-B] signal A shown in FIG. 6 etc., and the chromakey signal C is obtained. As described above, the operation up to this point is the same as the process of obtaining a conventional chromakey signal, and in the figure, the area within the dotted line frame indicates the same type of chromakey signal generator as the conventional one.

On the other hand, [A-B] signal A removes noise in high frequency components through L, P, and F7, and extracts only the signal components above the black level in the positive direction linear clipper circuit 8, and further delays them. By correcting the phase with line 9 and amplifying it with video amplification circuit 10, a signal waveform of an achromatic signal (b) as shown in FIG. 6 (b) is obtained. This signal includes details at a low level of the chromakey signal as a signal component. After this achromatic signal B is sufficiently amplified by the video amplifier circuit 11, the shadow level is adjusted by the shadow adjuster 12, and then transmitted to the white clip circuit 13, where signal components exceeding a specified level are cut out, as shown in Figure D. It is output as a shadow signal like this. This shadow signal D is non-added to the chroma key signal C in a NAM circuit (non-addition circuit) 14, and is amplified in a video amplification circuit 15 to obtain a soft chroma key signal E. Therefore, the chroma key signal C is used as a key signal for a large area portion, and the shadow signal D is used as a key signal for the outline and shadow portions of the image. Therefore, the shadow adjuster 12
This makes it possible to easily adjust shadow reproduction, non-reproduction, image omission, etc. The soft chroma key signal E obtained in this way is used as a gate signal for the linear gate amplifier circuit 30, and a video signal of an image of only yellow Y as shown in FIG. Obtained at By linearly gating the video signal on the chroma key back side in Figure 6, there is no contour jitter, and
A chroma key back-side inset signal chi in which the shadow part of the chroma key back is well reproduced is obtained.

Next, a method for obtaining a video signal to be inserted into a portion other than the chromakey back will be described. In FIG. 1, the achromatic signal LO is applied to an achromatic circuit 22 via an achromatic regulator. This achromatic signal L is outputted by the achromatic adjusters 23, 24, and 25 into a signal waveform as shown in FIG. A signal N corresponding to the G signal and a signal L corresponding to the B signal are obtained by adjusting their levels. On the other hand, the R, G, and B signals from the color camera are phase-adjusted by delay lines 16, 17, and 18b, amplified by video amplification circuits 19, 20, and 21, and then applied to the achromatic circuit 22. In this achromatic circuit 22, the R, G, and B signals are converted into the R, G, and B signals by subtracting the signal R, the signal N, and the signal L, which are equal to the hue component of the chroma key back section, from each of the input R, G, and B signals. Correspondingly, signals W, W and F as shown in FIG. 6, which do not include the signal component of the chroma key back portion in the R, G, B signals, are obtained. These signals wo, signal wa and signal ka are transmitted to video amplification circuits 26, 27 and 2.
8 and amplified by color encoder 29.
added to. The color encoder 29 processes the input signal to obtain a color video signal as shown in FIG. This color video signal is an ideal inset signal that maintains the image quality of the original signal without damaging details such as hair, and also eliminates chroma key back fog.

When the chromakey back-side inset signal and color video signal obtained in this manner are displayed as images as shown in FIGS. 7a and 7b. Figure a shows an image of the inset signal on the chroma key back side, and the background shows yellow Y, and there is no signal in the area of black background 43, in other words, it is a black area. Furthermore, the shaded area 39 indicates yellow, which is the background color with reduced saturation.
FIG. 1B shows an image corresponding to a color video signal, which is inserted into a portion other than the chroma key back. In this figure, G indicates a green area, R indicates a red area, and W indicates a white area. A black background 44 indicates a black area where no signal exists. Therefore, by combining the chroma key back side inset signal and the color video signal, the seventh
An image as shown in Figure c can be obtained. The image obtained in this way has shadows, has no unnatural contours due to inset, and is a composite image with intact details.

Next, another embodiment for obtaining a color video signal to be inserted into a portion other than the chroma key back will be described. FIG. 2 is a block diagram showing another embodiment for obtaining color video signals. In the same figure, li,
Nu and Lu indicate the same achromatic signals as Ri, Nu and Lu in FIG. The polarity of these achromatic signals R, N, and R is inverted by inverters 31, 32, and 33, and
It is added to the color encoder 29. Each signal applied to the color encoder 29 is processed and outputted as an NTSC signal with a waveform as shown in FIG. 6, with its polarity inverted. On the other hand, the 6th
The NTSC original signal from a color camera, etc., as shown in Figure 4, is applied to the mixing circuit 34, and mixed with the achromatic signal applied from the other side, thereby producing a color video signal that does not contain the signal component of the chromakey back portion. You can get it. In this case, the mixing circuit 3 is replaced with the inverters 31, 32 and 33.
Even if 4 is replaced with a subtraction circuit, the same effect as described above can be obtained.

As described above, the present invention uses a chromakey bag to generate a chromakey signal by obtaining the hue from R, G, and B signals from a television camera, etc., and adds this to a linear gate amplifier to generate a chromakey signal. When compositing the screen, the [A-B] signal is
After removing high-frequency noise through the P/F, a key signal (achromatic signal) that retains the details of the low-level part is created by removing the noise below the black level, and the key signal and the chromakey signal are decoded by the NAM circuit. By adding, a soft chromakey signal is obtained,
Also, from the achromatic signal, a signal (R/G/B signal or NTSC signal) equal to the signal component of the chromakey back part included in the R/G/B signals of a color camera, etc. is created, and this signal is used for the color camera. This is characterized in that a color video signal that does not include the signal component of the chromakey back portion is obtained by subtracting the signal from the original signal (R, G, B signal or NTSC signal).

As a result, in the present invention, when compositing images, jitter due to noise in the outline of the composite part is eliminated, detail parts are not damaged, the fog of the chroma key back is not noticeable, and the shadow of the chroma key back is reduced. It is possible to provide a high-quality composite image, such as by being able to reproduce parts of the image and creating a feeling as if the composite screen were inserted in a natural state without using electrical methods.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment showing the configuration for explaining this method, and FIG. 2 is a schematic diagram showing another embodiment for obtaining a color video signal that does not include the chroma key back signal component in FIG. 1. Fig. 3 is a circuit diagram of the hue matrix, Fig. 4 is an image example for explaining this method, Fig. 5 is a signal waveformer of a chroma key signal generator, and Fig. 6 is an explanation of this method. FIG. 7 is an output image diagram for explaining this method. In the figure, 1 is a hue matrix, 2 is a subtraction circuit,
5 is a stretch amplifier circuit, 8 is a positive linear clipper circuit, 12 is a shadow adjuster, 13 is a white clip circuit, 14 is a NAM circuit, 22 is an achromatic circuit, 23, 24, 25 is an achromatic adjuster, 29
3 is a color encoder, 30 is a linear gate amplifier circuit, 31, 32, 33 are inverters, and 34 is a mixing circuit.

Claims (1)

[Claims] 1. After removing high-frequency noise from the [A-B] signal created from the R, G, and B signals of a color camera through L, P, and F, signal components below the black level are removed. A key signal (achromatic signal) that retains the details of the low level part obtained through a linear clipper circuit, and a chromakey signal obtained by passing the [A-B] signal through a stretch amplifier circuit.
A soft chromakey method characterized by obtaining a soft chromakey signal through non-additive processing in the NAM circuit. 2. A patent characterized in that a key signal (achromatic signal) that retains details is applied to the NAM circuit through an adjustment circuit that adjusts the signal level and a white clip circuit that removes signal components larger than the set level. A soft chromakey method according to claim 1. 3 The [A-B] signal created from the R, G, and B signals of a color camera is passed through L, P, and F to remove high-frequency noise, and then passed through a linear clipper circuit to remove signal components below the black level. The obtained key signal (achromatic signal) that retains the detail of the low level part is passed through an adjustment circuit that adjusts the signal level to create a signal equal to the signal component of the chroma key back part included in the R, G, and B signals of the color camera. Soft chroma keying is characterized in that by subtracting this signal from the R, G, and B original signals of a color camera, or by inverting and mixing one of the signals, a color video signal that does not include the signal component of the chroma key back part is obtained. method. 4 The [A-B] signal created from the R, G, and B signals of the color camera is passed through L, P, and F to remove high-frequency noise, and then passed through a linear clipper circuit to remove signal components below the black level. The obtained key signal (achromatic signal) that retains the details of the low level part and the chromakey signal obtained by passing the [A-B] signal through a stretch amplifier circuit are combined.
A soft chromakey signal is created by non-addition in the NAM circuit, and a video signal is obtained by linearly gating the color video signal to be inserted into the chromakey back side using the soft chromakey signal, while the color camera's R・Create a signal equal to the signal component of the chromakey back part included in the G/B signal, and use this as the R/G/
A color video signal that does not contain the signal component of the chroma key back part is obtained by subtracting from the original signal B or by mixing one signal with phase inversion, and by mixing the same color video signal and the linearly gated video signal. A soft chroma key method characterized by obtaining signals for inset composite screens.