JPS58117787A - Chromakey device - Google Patents

Abstract

PURPOSE:To attain a synthesized picture having a shadow corresponding to the content of a picture and providing much more natural feeling, by modulating a key signal with a shadow signal and modulating each component of a luminance signal and a color difference signal with the modulated key signal. CONSTITUTION:A shadow signal SHD inputted to a terminal 18 is applied to multipliers 21, 22 via attenuators 19, 20. A key signal K2 or (1-K2) is applied to the multipliers 21, 22 respectively and the key signal is modulated with the shadow signal and the result is applied to multipliers 9, 10. Instruction signals ADJ1, ADJ2 are applied to the attenuators 19, 20 to change the contrast of the shadow in the front and background picture. Thus, the synthesized picture video data KYD, VID obtained from a mixer 12 have shadow according to the shadow signal SHD.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chromakey device, and particularly to a chromakey device that makes composite images look more natural.

There are various factors contributing to the visual unnaturalness of the composite image formed by image keying. For example, the power of the color of the pack screen, such as blue, appearing on the outline of the foreground in a composite image 2-
Examples include fringes and edge fritters where the outline of the foreground flickers.

However, even if you look at the composite image with these improvements, it still looks unnatural due to the lack of perspective and shadows. Although I created a sense of perspective by blurring the strawberry landscape painting, and used shadow keying to add the shadows of objects in the foreground to the strawberry landscape painting, it still cannot be said to have a sufficiently natural feel. The reason for this is.

Force 2 - In order to avoid fringes and edge frittering, the illumination is made as uniform as possible when photographing the foreground, so the objects in the foreground 1 shine uniformly throughout and are composited as they are. be.

As an example, consider the two scenes shown in FIG.

As shown in Figure 1A, the foreground of the car and the face of the person inside the car are covered with shadows of objects in the foreground that change in various ways. Furthermore, this does not happen with houses and the like in the background because they are far away. However, conventional chromakey devices do not take into consideration the shadows cast on the faces of automobiles and people riding in them. Also, the scene shown in Figure 1B is
It consists of a walking person in the foreground and a house in the background, and in a scene like this, the shadow of an object in the foreground, such as a tree or a building, is supposed to be casting a shadow, but there is only one person. This shadow should appear, darker on the area and lighter on the building. However, conventional chromakey devices do not produce many such shadows.

FIG. 2 shows the overall configuration of a conventional digital chromakey device. In the figure, 1 is an input terminal to which foreground video data FG and "/ID" are supplied.

2 is an input terminal to which background video data BG and VID are supplied, and 3 is an output terminal to which composite image video data KYD and '/ID appear. The foreground image, in which the subject is located in front of a blue back screen, is supplied to the key signal generation circuit 4, and the difference from the back screen color, blue, is calculated for each sample data of the foreground video data.・ is formed on the key signal. This key (it number Ko) is supplied to Keyzorocera+5, and the slice sliced at the reference level is
The key signal r-in and edge timings are adjusted, etc.

Key signal for color cancellation Key signal for Kly mixer! and 3 are formed. The color cancel circuit 6 is for erasing pack color data from the foreground color video data FG, ``11'' ID.

Video data CAN and VID are bordered by the output.

Further, 7 indicates a mixer to which the foreground and background video data are supplied, and the two are combined by cross-fading or the like using the key signal 3 mentioned above.

This Kisa-7 is used for shadow keying and is not used for normal chroma keying.

Background video data BG and VID are sent directly to mixer 8
supplied to The mixer 8 is composed of five multipliers 9 and 10, a phase inversion circuit 11, and an adder 12, as shown in FIG. In other words, the first multiplier 9 outputs the video data CAN and VID from the cancellation circuit 6, and the key signal is multiplied by 2 and supplied to the adder 12, and the first multiplier 10 outputs the background video data. BG, VID and the key signal (/Kg) from the phase inversion circuit 11 are multiplied and supplied to an adder 12, from which composite video data KYD, Y are obtained.

As Jin explained, conventional chromakey devices had the disadvantage that they did not add the changes in light and shadow that would occur in reality, making a single composite image visually unnatural.

The object of the present invention is to eliminate such drawbacks and to realize a nine-cooma key device. This invention provides a shadow signal generating circuit corresponding to the shadow to be superimposed on one composite image.

The shadow to be superimposed is created by modulating the brightness ffi signal with the shadow signal, but in this case, there are restrictions arising from the nature of the daisymelka 2-video signal. In a YUV signal system that transmits a video signal in the form of components of Y data and color difference data U and V, each component is defined as shown in the following equation.

Y=0.299R+0. ! rg7ck+0.7/I
BU=-0,/b9R-0,33/Ck+0JOOBV
= O,SθOR-0,'l/f()-0,
0g 2 B From the above formula, yellow YL (R= G =
/ v B = 0) e cyan CY (R=O9G
=B=/), magenta MG (R=/ eB=0.G=/
), R, G, and B, and the values of Y, U, and V for each color are determined as follows.

R: x=0. ,．． 29? , U=-OJb9.
v=0. ! ;00(): x=0. ! ;g7,
U=-0,33/, v=-0,11/gs: y=
0. //+tυ=0. SOO, v=-θ, 0g2n,:
r=0. ggb, u=-0,! ;, V=0.0g2
CY: Y=0.7θi, u=0. lbq, v=-0
,3M(): Y=0. 'l/, 3, U=0. ．．
33/, V=0. 'l/g Then, by plotting each of the above colors on the coordinates with Y as the vertical axis and U as the horizontal axis, the area of the parallelogram shown as 13 in Figure qA is found, tb, and similarly, Y is the vertical axis. By plotting each of the above-mentioned colors on nine coordinates with V as the horizontal axis, the parallelogram area indicated by 14 in Figure B is found. Conbonen) Y, U
.

The can value of V should only be able to move within regions 13 and 14 shown in FIG. 9 (#). Therefore, if you simply modulate the luminance signal Y into a shadow signal in order to add a change in shadow, the sample data at point There is a risk of this happening. Therefore, in this Q invention, Fig.
As shown in FIG. 2, modulation is performed to change the sample data at point X along a broken line 15 connecting the user's own position and the origin. For example, modulation to change point X to point X7 is performed by reducing both the luminance signal and color difference signal while maintaining the level ratio at point X. In order to realize such modulation, the key signal for each component of the luminance signal and color difference signal may be modulated with a shadow signal.

Hereinafter, one embodiment of the present invention will be described. The mixer 8 in the digital chromakey device shown in FIG. 2 has the configuration shown in FIG. S. In FIG. S, key signal modulation circuits 16 and 17 are provided as shown surrounded by broken lines. These key signal modulation circuits 16 and 11 each have attenuators 19 and 20 that attenuate the level of the shadow signal 8HD from the terminal 18, and the attenuated shadow signal 8HD and key signal are supplied with: or (/-Kl). multipliers 21 and 22, and the multipliers 21 and 22
The modulated key signal appearing at the output of the multiplier - and 10
supplied to The above-mentioned seven tone generators 19 and 20 include:
Instruction signals ADJ and ADJ are supplied from terminals 23 and 24, allowing the density of shadows to be varied in the foreground and background images. The constituent lines in FIG. S are provided for each of the luminance data Y, color difference data U and V, and the key signals after modulation appearing at the outputs of the key signal modulation circuits 16 and 11 are commonly used. therefore,
As shown in Figure C, modulation can be performed for each sample of video data to change the position along 1s15 connecting the original position and the origin. Then, composite image video data KYD, l/ obtained from the mixer 12
It has a round shape depending on ID Iri & shadow signal SHD.

°Like the scene explained at the beginning (Fig. 1 A).

If you want to superimpose a shadow' only on the foreground, use the instruction signal ADJ.
r in G1 of attenuator 19 by 1 and ADJ2
In addition to setting (0<01</), r in G of the attenuator 20 may be set as ((h=/).

In addition, if you want to cast a shadow of one tatami in both the foreground and the background, as in the scene shown in FIG. 1B, each dean of attenuators 19 and 2Q should be
</) is good - 0 By setting 5cckl<a max) together with this, it is possible to make the shadow superimposed on the foreground darker than that of the background.

FIG. 6 shows the entire system of one embodiment of the present invention, and 25 indicates a chromakey device having the above-mentioned mixer. In addition, a television camera 26 photographs an object located in front of the real color puck screen, and its output is digitized for each component to form foreground color video data FG, VID. In addition, from background power 2 - video data BG, V, digital v
'rR27 to be generated from TV camera 2
6 and digital VTR 27 are assumed to be operated by a common synchronizing signal from a synchronizing signal generator 28.

When compositing the scene shown in FIG. 1A, the television camera 26 photographs a car and a person inside the car,
The digital VTR 27 reproduces a video source obtained by photographing the scenery outside the car through the window of the moving car as background video data BG and VID.

This background C video data B(), l/ID is supplied to the shadow signal generation circuit 29. This shadow signal generation circuit 29 generates a shadow signal 8HD by waveform-shaping only the luminance data through a threshold circuit and band-limiting it with a low-pass filter.

According to this shadow signal SHD, it is possible to superimpose a changing shadow on a moving car and a person inside the car,
Even when the scene shown in FIG. 1A is formed as a composite image, it can be made to look more natural. In addition, in FIG. 6, 30 indicates a monitor receiver.

Furthermore, in the case of a fixed shadow that is not related to the content of the image, rather than a moving shadow as described above, a microcomputer can be used to generate the shadow. In the front, buildings and other scenery are photographed using a TV camera, and the output luminance signal is waveform-shaped and band-limited through a threshold circuit. can form shadows that appear on the landscape.

As understood from the above explanation, according to this invention, 1
Since the composite image has a shadow corresponding to the content of the image, one composite image can be made to look more natural than with the conventional glue masking device. Furthermore, according to Jin's invention, the key signal is modulated by the shadow signal, and each component of the luminance signal and color difference signal is modulated by the modulated key signal, so that the video signal after modulation is as shown in Figure q. It is possible to prevent going out of the defined area as shown.

[Brief explanation of the drawing]

Figure 1 is a route map used to explain the conventional glue machine key device,
2 and 3 are block diagrams of a conventional glue μ-makey device and a block diagram of a part thereof; Block diagram of a mixer. Figure tIIJ6 is a block diagram showing the overall system configuration of an embodiment of the present invention. 1... Input terminal for foreground video data, 2... Input terminal for background video data, 7.8... Mixer, 16°17... Attenuator, 29... Shadow signal generation circuit. Agent Masatomo Sugiura

Claims (1)

[Claims] In a chromakey device that modulates a foreground video signal and a background video signal with a key signal and synthesizes the same, the circuit generates a shadow signal corresponding to a shadow superimposed on the foreground or background video signal; A chromakey device comprising: a circuit for adjusting the level of the shadow signal; and a circuit for modulating the shadow signal with the shadow signal from the level adjustment circuit.