JPS6158078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television special effect generating device, and more particularly to a chromakey effect generating device.

A chromakey effect generating device is a device that uses hue differences in color signals to fit images, and until now, the problem has been that unnaturalness remains at the boundaries of the fitted images. A chroma key generator that has improved on these points is disclosed in "Soft Chroma Key" on pages 65 to 72 of the April 1973 issue of "Broadcasting Technology", which uses a linear gate and a color erasing circuit. has achieved its purpose.

FIG. 1 is a block diagram of a conventional chromakey generating device described in the above-mentioned literature, and is composed of a conventional chromakey generating section 1, a soft key generating section 2, and a color erasing section 3. In particular, the color erasing section 3 generates in advance a cancel subcarrier signal for canceling the color signal of a portion into which another image is inserted. How to create this cancel subcarrier signal is as shown in Figure 9 of the above-mentioned document.The background for creating a chroma key signal (chroma key back part), for example, the phase and amplitude of the subcarrier corresponding to the blue back color are stored in memory. I am creating a cancel subcarrier based on Saseko's memories. Therefore, if the saturation or hue of the chroma key back changes, it becomes impossible to completely erase the color, making it impossible to obtain a high-quality chroma key effect. This restricts the movement of a camera that captures background images, which is extremely disadvantageous in actual program production.

Furthermore, although the configuration shown in FIG. 1 allows color conversion to change the hue and saturation of the key back portion using the color erasure function, it also has the disadvantage that color erasure and color conversion cannot be performed at the same time.

Next, the conventional apparatus has a drawback that if there is a part of the same color as the chroma key back part other than the chroma key back part to which chroma keying is desired, this part will also be chroma keyed. For this reason, until now, for example, when a camera takes an image of a person with their back to the chroma key back part, and another image is inserted into this chromakey back part, this person must not wear anything of the same color as the chroma key back part. .

Furthermore, the conventional apparatus has the disadvantage that if a foreign substance is included in the area that requires chroma keying, chroma keying cannot be performed on this area. For example, when the chroma key back area is small, chroma keying cannot be performed to the outside of the chroma key back area. As another example, if the chroma key back part contains characters of other colors, chroma keying cannot be performed.

Accordingly, a first object of the present invention is to provide a chromakey generating device that can simultaneously perform color erasing and color conversion to obtain unprecedented effects.

A second object of the present invention is to provide a chromakey generating device that can reliably perform chromakey only using the chromakey back portion even if there is a portion of the same color as the chromakey back portion other than the chromakey back portion.

A third object of the present invention is to provide a chromakey generating device that can reliably perform chromakey on a desired portion even if the portion to be chromakey has a color different from the chromakey back portion.

A fourth object of the present invention is to provide a chroma key generation device that can obtain a monitor image signal in which the area where chroma keying is allowed can be clearly and visually confirmed.

Next, the present invention will be described in detail with reference to the drawings of an embodiment of the present invention. First, FIG. 2 is a block diagram of a color erasing section, that is, a section that generates a cancel subcarrier according to the present invention. In FIG. 2, the chroma key signal from the chroma key signal input terminal 4 is supplied to a sample pulse generation circuit 5, where a sample pulse having a delay width of about 1 μs by about 1 μs from the start of the chroma key signal is generated. from input terminal 6
The NTSC signal is sent to bandpass filter 7,
Here, subcarrier components are extracted. A continuous subcarrier with constant amplitude is supplied to the input terminal 8, which approximately corresponds to the color of the chromakey back part. and is sent to a gain control circuit 12 whose amplitude changes depending on the control voltage.

The subcarrier extracted by the bandpass filter 7 and the subcarrier passed through the 90° delay device 10 are multiplied by a multiplier 13, and the result is sent to a sample and hold circuit 14. Sample hold circuit 1
4, the output of the multiplier 13 is taken out at the timing of the sample pulse mentioned above, and this output is supplied to the phase adjustment circuit 9 as a control voltage. This feedback loop works so that the phase of the output subcarrier of the phase adjustment circuit 9 becomes equal to the phase of the subcarrier of the keyback portion of the NTSC signal from the terminal 6.

On the other hand, the subcarrier extracted by the bandpass filter 7 and the subcarrier from the phase adjustment circuit 9 are multiplied by a multiplier 11, and the output thereof is sent to a sample and hold circuit 15. The sample hold circuit 15 takes out the result at the timing of the sample pulse and sends it to the gain control circuit 12 as a control voltage. This feedback loop has the amplitude of the output subcarrier of the gain control circuit 12 at the terminal.
It works to make the amplitude equal to the subcarrier amplitude of the key back part of the NTSC signal. Here multiplier 1
1 may be a subtracter, as long as the amplitude of the subcarrier extracted by the filter 7 can be compared with the constant amplitude of the subcarrier from the terminal 8.

FIG. 3 is a diagram for explaining the operation of the cancel subcarrier generating section in FIG. 2, and FIG. This is a color bar signal. b
denotes the output subcarriers of the bandpass filter 7, each amplitude corresponding to each of the color bars of a. C is a chroma key signal and corresponds to blue among the color bar signals of a. The sample pulse e obtained from the sample pulse generation circuit is the output of the multiplier 13, and d is the output of the multiplier 11. The cancel subcarrier obtained with the configuration shown in Figure 2 accurately follows the hue and saturation of the chromakey back area, and does not impose restrictions on the movement of the camera that captures the chromakey back area. I won't receive it.

FIG. 4 is a diagram showing an embodiment of the present invention, in which a chroma key signal is input to a terminal 4, which is led to a chroma key signal output terminal 19 via a chroma key signal gate 17 and an adder circuit 18. Cancel subcarrier generation circuit 100 shown in FIG.
The output of the chroma key signal and the chromakey signal from the gate 17 are sent to a color cancellation subcarrier generation circuit 20, where the phase of the cancel subcarrier is inverted for a certain period of the chromakey signal to generate a color cancellation subcarrier. On the other hand, the chromakey signal from the terminal 4 is sent to the color conversion subcarrier generation circuit 22 via the color conversion key signal gate 21 which operates in a complementary manner to the chromakey signal gate 17. The color conversion subcarrier generating circuit 22 converts the cancel subcarrier from the cancel subcarrier generating circuit 100 into a color conversion subcarrier having a predetermined phase and intensity based on the hue and saturation control signals from the control input terminal 23. Including chromakey back part from terminal 6
The NTSC signal, the color cancellation subcarrier, and the color conversion subcarrier are summed in an adder circuit 32, where the color of the chromakey portion is completely erased, and the color of the color conversion portion is converted.
An NTSC signal is created and output from the output terminal 24. As described above, in the present invention, color erasure and color conversion can be performed simultaneously.

The chromakey signal gate 17 and the color conversion key signal gate 21 operate complementarily. That is, when the gate 17 is closed, the gate 21 operates as if it is open, but the control signals for the gates 17 and 21 are generated by the frame signal generation circuit 25. This frame signal is a signal that specifies a frame of any size at any location on the television screen, and it creates a sawtooth wave with a vertical scanning period and horizontal scanning synchronization, and slices this at a predetermined level. You can easily make it if you do it. A control signal for determining the horizontal and vertical position and size of the frame is supplied to the frame signal generating circuit 25 from a terminal 26. Of course, by reversing the polarity of the frame signal, the area in which chroma keying can be performed can be reversed. FIG. 5 is a diagram showing an example of an effect screen, and a more detailed explanation will be given with reference to this. In Figure 5, a white background 101 and a green circle 102
, blue circles 103 and 104, and red circle 10
There are 5. Now, when limiting the portion of the blue circles 103 and 104 to be chroma keyed, that is, the portion into which another image is inserted, to the blue circle 104, a frame signal corresponding to the frame 106 is generated. If the chroma key signal gate 17 is opened only when the area is inside the frame 106, the chroma key signal from the terminal 4 will be transmitted to the circle 103,1.
Even if the signal corresponds to both circles 104, only circle 104 will be chroma-keyed. Furthermore, if it is desired to change the color of the blue circle 103 at this time, the color conversion subcarrier generation circuit 22 can arbitrarily change the hue and saturation of the subcarrier, thereby converting it into any color. That is, in the present invention, even if there is a color other than the chroma key back part that is the same as the chroma key back part, the part to be chroma keyed can be specified by the frame signal, so that only the desired part can be chroma keyed.

Returning to FIG. 4, the frame signal supplied to the chromakey signal gate 17 passes through the switch 27, and when the contact is switched from p to q as shown in the figure, the frame signal is applied to the adder circuit 18. Here, when the contact q is selected, the gate 17 is in a passing state. By adding a frame signal to the adder circuit 18, the area outside or inside the frame can be forcibly set as an area to be chroma keyed. The outside or inside of the frame can be selected by changing the polarity of the frame signal. That is, according to the present invention, it is also possible to insert another image into an area beyond the chromakey back area. Alternatively, even if the chroma key back portion contains a portion with a different hue, another image can be inserted into the chroma key back portion without fail. This switching of switch 27 is performed by a control signal applied to input terminal 28. Here, we will explain the effect when the frame signal is switched to the contact point q by the switch 27 so that another image can be reliably inserted even if the chroma key back part contains a part with a different hue. This will be explained using Figure 7. a is chroma key back 108
When inserting another image in a place other than the person 109 in a video including a person 109, another hue portion 110 is included in the chroma key back 108. b is a diagram showing a chromakey signal on line L of a, and it is not possible to insert another image into the portion 110 as it is. Here, by creating a frame signal as shown in c and adding it to the chroma key signal in the adder circuit 18 via the switch 27, the chroma key signal shown in d is finally obtained, and the other images are displayed in the portion 110 as desired. It will be inserted. In this case, the person 109 and other hue portions 11 on screen a are erased by the color erasing operation.
The colors of the chroma key back except for 0 disappear, and in this case, the effect of color conversion does not appear on the effect screen after inserting another image.

In FIG. 4, the output of the frame signal generation circuit 25 is also sent to a border generation circuit 29, where a border signal corresponding to the frame is generated. The color-erased and color-converted NTSC signal and border signal from the adder circuit 32 are added together by the adder circuit 30 and sent to the monitor output terminal 31. As shown in FIG. 6, the screen obtained from the monitor output terminal 31 has a border 107 so that the frame portion can be clearly seen. According to the present invention, various chroma key effects can be performed accurately while referring to a monitor screen.

Note that the generation stage of the chroma key signal supplied to the input terminal 4 in FIGS. 2 and 4 corresponds to block 1 in FIG. 1, and this is well known from the above-mentioned literature. The description is omitted.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional chroma key generator.
FIG. 2 is a configuration diagram of a cancel subcarrier generating section according to the present invention, FIG. 3 is a screen and waveform diagram for explaining the operation of FIG. 2, and FIG. 4 is an explanatory diagram showing an embodiment of the present invention. , FIG. 5 and FIG. 6 are diagrams for explaining the effect screen according to the present invention, and FIG. 7 is a diagram for explaining the effect obtained by adding the frame signal and the chromakey signal.

Claims (1)

[Claims] 1 means for generating a frame signal that limits a desired area on a television screen; first and second gate means controlled by the frame signal and operating complementary to each other to receive a chromakey signal; color-cancelling subcarrier signal generation means for canceling the signal; color conversion subcarrier signal generation means for generating a subcarrier with a desired phase and amplitude; addition means for adding the subcarrier signal and the color-converted subcarrier signal at the timing of the output of the second gate means; A chromakey effect generating device characterized by keying a digital signal.