JPH02292986A - Generating method for picture synthesizing key signal - Google Patents

Abstract

PURPOSE:To obtain a chroma-key signal that can freely change the viewfield of a foreground photographing camera by setting a background blue panel at the irreducible minimum size and covering electrically the outside of the blue panel with a virtual blue panel when pictures are synthesized with a chroma-key method. CONSTITUTION:A chroma-key reduction blue panel 15 having the irreducible minimum size is set at the center of a studio set 16, and a foreground subject of the panel 15 is photographed by a foreground photographing camera 7. A rotational angle/lens magnification detecting circuit 8 detects the rotational angle of the camera 7 and the zoom magnification of a photographing lens and inputs these detection results to a computer 9 for control of generation of a chroma-key signal. The full address data on a memory 10 having the picture element storage areas in number corresponding to a virtual blue panel 17 that can cover an entire viewfield which is changed by the pan, tilt and zoom of the camera 7 is sent to a magnification/reduction scroll circuit 11 as a virtual blue panel signal 17C. Then a virtual key area signal 18C is inputted to a key signal processing circuit 12 and synthesized with a reduced chroma- key signal 20CC. Thus an output chroma-key signal 19C corresponding to an output chroma-key picture 19.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a method for switching an image output image signal of a foreground subject in a single color background, which is usually blue, and another background image signal depending on the presence or absence of the single color. Regarding a key signal generation method for image synthesis that generates a so-called chroma key signal to synthesize a foreground subject image and another background image, in particular, it is necessary to make an actually provided single-color background panel with a minimum size sufficient to contain the foreground subject. In addition, the field of view of the foreground imaging camera can be changed significantly without being limited by the size of the single-color background panel.

(Summary of the Invention) The present invention enables panning, small chilling, zooming, etc. of a foreground imaging camera without being restricted by the size of a background blue panel for generating an image switching key signal in so-called chroma one-image compositing. In order to do this, the size of the actual background blue panel is kept to the minimum necessary, and in the outer blue panel area, the virtual blue panel signal stored in the frame memory with expanded memory area is stored according to the camera's field of view. It is taken out and appropriated to substantially expand the effective blue panel area.

(Prior Art) In general, in the chromakey method commonly used for partial image synthesis, a generation system for generating key signals for image synthesis, that is, so-called chromakey signals, having a schematic configuration and arrangement as shown in Fig. 6 has been used. . In the conventional configuration shown, a single color background panel, typically blue, surrounds and behind the foreground subject to be inlaid and composited with other background images, i.e.
A blue panel 27 is disposed and an image is taken by a foreground image loss camera 7, and a color image signal of the three primary colors R, G, and B of the captured image is supplied to a chromakey signal generation circuit 14 via a camera processor 13. The chromakey signal generation circuit 14
, the input color image signal is discriminated based on the presence or absence of a color signal component in a narrow hue range that strictly corresponds to the color of the background blue panel 27 to form a chroma key image 3l as shown in the figure. A chroma key signal 31C is generated and supplied to the synthesis circuit 28, with the area corresponding to the foreground object set to the level ``1°'' and the area corresponding to the foreground object set to the level ``1°''. The synthesis circuit 28 expresses the foreground image signal 27S from the camera processor 13 and another background image 29 into which the foreground subject is to be embedded, depending on the level ゜0゛゜ and the level ``゜1゜゜ of the chromakey signal 31C. Background image signal 2
9S and synthesize it to create a synthesized output image 3 as shown in the figure.
Take out o.

(Problem to be Solved by the Invention) In the Chromakey-1S generation system with the conventional configuration described above, the range to be imaged by the foreground imaging camera 7 including the foreground subject, that is, the entire field of view of the camera, is colored in a predetermined single color, that is, blue. I needed to leave it there.

For example, when camera 7 is banged to the right, the entire right side of the background must be blue until the foreground subject moves out to the left of the camera's field of view; conversely, when camera 7 is banged to the left, the foreground subject is blue. The entire left side of the background needed to be blue until it was off to the right side of the camera's field of view. the result,
It is necessary to prepare a blue panel 27 large enough to cover the entire background within which the camera 7 can be panned left and right, or to limit the range in which the camera 7 can be panned according to the size of the blue panel 27. In particular, in order to be able to zoom out the foreground subject using the foreground camera 7, it is necessary to make the entire background in an extremely wide area above, below, left and right of the foreground subject blue, so the range that can actually be zoomed is limited. became extremely narrow. Therefore, for the traditional chromakey method,
An important issue is to be able to freely change the field of view of the foreground imaging camera without being restricted by the size of the blue panel. It was a question.

(Means for Solving the Problems) An object of the present invention is to solve the above-mentioned conventional problems, and to make the blue panel arranged behind the foreground subject as small as possible to match the size of the foreground subject. However, it is an object of the present invention to provide a method for generating a chroma key signal, that is, a key signal for image synthesis, which allows the field of view of a foreground imaging camera to be freely changed.

That is, in the key signal generation method for image synthesis of the present invention, the background blue panel that is actually prepared is reduced to the necessary minimum size, and the background around its periphery is covered by a virtual blue panel that is electrically formed. The imaging output image signal of a foreground overimage camera that images a foreground subject in a single color background and the background image signal of {1!1 are switched by a key signal generated depending on the presence or absence of the single color, and the In compositing the foreground subject image and the other background image, the single-color background is reduced to a size sufficient to include the foreground subject, and the number of background images corresponding to the entire field of view that can be set by the foreground imaging camera is reduced. digitized pixel storage areas are provided vertically and horizontally in an amount exceeding the number of digitized pixels of a predetermined frame, using an enlarged frame I/-frame memory storing the single color image signal in almost all of the digitized pixel storage areas; The unit reproduces the background area of the imaging output image signal that exceeds the reduced single-color background due to a change in the field of view of the foreground imaging camera from the digitized pixel storage area corresponding to the changed field of view of the enlarged frame memory. The key signal is generated by supplementing it with an image signal of one color. (Function) Therefore, according to the present invention, when synthesizing images using the chromakey method, it is possible to reduce the actually prepared background blue panel to the minimum necessary size, and to do so without being restricted by the size of the blue panel. Pan the foreground imaging camera arbitrarily,
It will be possible to tilt or zoom.

(Example) The present invention will be described in detail below with reference to the drawings.

First, FIG. 1 shows a schematic arrangement of a chroma key signal, that is, a key signal generation system for image synthesis according to the method of the present invention.

In the illustrated configuration, a reduced blue panel 15 for chroma keying, which has the minimum necessary size, is arranged in the center of the studio set 16, and the foreground subject located in front of it is imaged by the foreground imaging camera 7. As shown in FIG. 2, the main body of the foreground imaging camera 7 and a support such as a tripod are equipped with a rotary encoder 1 that detects the rotation angle of the camera 7 in the horizontal plane and in the vertical plane, respectively, in the rotation support mechanism of the main body. and 2 are attached, and a potentiometer 3 for detecting the magnification of the zoom lens is also attached to the zoom mechanism. Incidentally, these rotary encoder 2 and potentiometer 3 correspond to the rotation angle/lens magnification detection circuit 8 shown in FIG. Each rotation angle in the horizontal plane and in the vertical plane of the camera 7 is determined by counting the number of pulse outputs proportional to the rotation angle from each reference position of the rotary encoders 1 and 2 using the pulse counter 4. The zoom magnification of the imaging lens is determined by converting the differential output voltage from the reference point of the potentiometer 3 into a digital value using the A/D converter 5. The pulse counter 4 and the A/I) I inverter 5 are connected via a computer bus 6 to a conbuque 9 in the configuration shown in the first figure, so that:
Data regarding the horizontal and vertical rotation angles of the camera 7 and the zoom magnification of the lens are input to the computer 9 at any time, and the generation of the chromakey signal described below is controlled based on these data.

On the other hand, the number of pixels digitized in the horizontal direction on the display screen of the television system standard that finally displays the composite output image using the image output image signal of the foreground imaging camera 7 is expressed as pH, and the number of pixels digitized in the vertical direction is expressed as pV. The number of digitized pixels qll and qV that satisfy the conditions qll>pl+ and qV>pV when Virtual blue panel 17 sized to cover the entire field of view to be changed
An enlarged frame memory 10 having a pixel storage area corresponding to the number of pixels is prepared, and all memory addresses and data of the enlarged frame memory 10 are supplied to the enlarged/reduced scroll circuit 11 as a virtual blue panel signal 17G. Its expansion/
In the reduction scroll circuit 11, under the control of each data related to the above-described field of view change of the camera 7 supplied from the computer 9, the current image including the reduced blue panel of the camera 7 and the foreground object is changed from the entire screen of the virtual blue panel 17 to the current image including the reduced blue panel of the camera 7 and the foreground subject. A virtual key area image 18 corresponding to the visual field is cut out, and a virtual key area signal 18C corresponding to the cut out image 18 is supplied to the key signal processing circuit 12. The key signal processing circuit 12 receives the image pickup output image signals R, G, and B of the foreground image pickup camera 7 as in the conventional configuration shown in FIG.
A reduced chromakey signal 20CC corresponding to the reduced chromakey image 20 is supplied to the chromakey signal generation circuit 14 via the processor 13, and is generated in accordance with the presence or absence of a predetermined blue signal component with respect to the reduced blue panel 15 in exactly the same way as in the past. are also supplied at the same time, and these two types of chromakey signals, namely, the reduced chromakey signal 20CC and the virtual key area signal 18C, are synthesized as described later with reference to FIG.
By the method of the present invention, an output chroma key signal 19C corresponding to the output chroma key image 19 is finally generated in which the entire background including the desired foreground object is colored a predetermined blue color over a wide range.

Next, FIG. 3 shows an example of a detailed configuration including the enlargement/reduction scroll circuit 11 and the key signal processing circuit 12 in the schematic configuration shown in the first figure. In the illustrated configuration, the computer 9 transmits information in the horizontal (}l) direction and the vertical (V
) direction is supplied to the H start address register 21 and ■ start address register 22 respectively and set, and the magnification of the virtual key area 18 with respect to a reference virtual key area of a predetermined size that is used as a reference for zooming. That is, the magnification rate by the zoom of the camera 7 is supplied to the magnification rate register 23 and set.

On the other hand, in each pixel storage area of the enlarged frame memory 10,
A virtual blue panel 17 is configured by storing color signal components representing a predetermined blue color in advance corresponding to the entire background of the outer periphery including the periphery of the reduced blue panel 15 to be actually arranged, and each register 21, 22 ．． Each data corresponding to the current field of view of the camera 7 set at 23 is supplied to the address generation circuit 24, and an address signal generated based on the data is supplied to the address input of the enlarged frame memory 10 to generate a virtual key area signal. Read 18C, analog signal switch 2
It is supplied to the control human power terminal C of No.5. In the analog signal switch 25, the reduced chromakey signal 20CC from the chromakey signal generation circuit 14, that is, the area corresponding to the reduced blue panel 15 in the captured output image signal of the foreground imaging camera 7, as shown in FIG. The area of the foreground subject to be gated and extracted and the background area outside the reduced blue panel 15 are set to the level ``l''.
At the same time, the analog signal corresponding to the reduced blue panel 15 is supplied to the switching input terminal a, and the other switching input terminal b is set to the level ゜゛0゛゛. 1゛゜stitch,
The outer area is set to level ``0'''', and manual switching a and b are switched according to the levels ``I'' and ``O'' of the control signal, and only the area of the foreground subject is set to level ``!''! '', and the output chroma key signal 19C with the entire other background '614M at the level '0' is taken out.

Next, FIG. 4 schematically shows an example of the mode of analog key signal switching and synthesis by the analog signal switch 25 described above during the horizontal scanning line period l in each image shown in FIG. 1. In FIG. 4, the virtual key area signal 18c is shown in the upper part.
The signal waveforms of the reduced chromakey signal 20CC are shown in the middle row, and the output chromakey signal 19G is shown in the lower row, with their timings corresponding to each other. When the virtual key area signal 18C supplied as a control signal to the analog signal switch 25 is at the level "o゛゜," the level "0゜" of the switching input terminal b is taken out as the switching output, so the output chroma key signal ql9c is at the level “It becomes 0゜゛. In addition, virtual key area signal 18C
When the level is "1", the reduced chroma key signal 20CC of the switching input terminal a is taken out as the switching output, so that only the foreground subject area has the level "1" as shown in FIG. An output chroma key signal 19G is obtained in which the entire other background region is at the level ゛°0'゜ based on the reduced blue panel 15 and the virtual blue panel 17.

As a result, even if the foreground image camera 7 is moved left and right, tilted up and down, and zoomed to change the magnification of the imaging lens, the virtual key area signal 18C obtained from the enlarged frame memo is always Since the computer 9 changes the virtual key area signal 18G based on the current field of view data of the camera 7 so as to cover the outer background area of the reduced blue panel l5 for chroma key provided in the studio set 6, the virtual key area signal 18G is actually Without being restricted by the size of the placed blue panel,
Even if the field of view of the camera 7 is freely changed, a chromakey signal can be obtained that can gate and extract only the foreground subject.

Finally, the H start address of the virtual key area image 18, ■Start address and zoom The operation B for calculating each magnification rate will be explained with reference to FIG. 5, which shows images of the virtual blue panel and the virtual key press area.

First, when the zoom magnification of the imaging lens is set to a certain magnification m0 and each rotation angle in both the horizontal and vertical directions is set to zero radian, the virtual key area image 18
Suppose that the image is as shown in the image 32 shown on the right side of FIG. A shaded area 33 in this image 32 is an area corresponding to the reduced blue panel 15. In this setting state, the value set in the magnification register 23 is 1.0, and the H start address and ■ start address are set as shown in the figure.
As x0 and Y0, respectively, the virtual key area image 18 cut out from the virtual blue panel 17 and the reduced chromakey image 20 formed from the captured output image of the camera 7 are superimposed, and the image is slightly wider than the frame of the area 32 corresponding to the reduced blue panel 15. Expanded frame memory 1 that corresponds to the entire internal area from the inside
Each pixel storage area of 0 is set to level "°1", and each pixel storage area in all background areas other than the level "l III jI area" is set to level "0"°. Starting from this set state, when the field of view of the camera 7 is changed, the H start address X1, the start address Y, and the magnification rate M that should be entered in each register 21, 22, and 23 are as follows. Become.

X-L (1+KK-θ./m) Y=Yo (1+Ky'θ,/m)M=+s
/w. Here, θu and θ, are rotation angles in the horizontal plane and vertical plane, respectively, κ8 and K, are proportionality constants, and m is the lens magnification.

(Effects of the Invention) As is clear from the above description, according to the present invention, an image of a foreground subject in a blue background is discriminated and extracted based on the presence or absence of a blue component, and the so-called chromakey image is combined with another background image. When synthesizing images using the method, the actual background blue panel prepared is made as small as possible, and the outside of the background blue panel is covered with an electrically formed virtual blue panel. A remarkable advantage is that the foreground imaging camera can be panned, tilted or zoomed arbitrarily without being restricted by the size of the panel.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a key signal generation system for image synthesis according to the method of the present invention, FIG. 2 is a perspective view showing an example of camera field of view changing means used in the method of the present invention, and FIG. 3 is a diagram according to the present invention. FIG. 4 is a block diagram showing an example of a partial detailed configuration of a key signal generation system for image synthesis according to the method of the present invention; FIG. 6 is a diagram showing an example of the structure of a key area image according to the method of the present invention, and FIG. 6 is a block diagram showing a schematic structure of a conventional key signal generation system for image synthesis. 1.2... Rotary encoder 3... Potentiometer 4... Pulse counter 5... A/D converter 6... Computer bus 7... Foreground imaging camera 8... Rotation angle/lens Magnification detection circuit 9... Computer 10... Enlarged frame memory 11 for virtual blue panel...
- Enlargement/reduction scroll circuit 12...Key signal processing circuit 13...Camera processor 14...Chroma key signal generation circuit 15...Reduction blue panel 16...Studio set l7...Virtual blue panel 17C...Virtual blue panel signal l8...Virtual key area image 18C...
Virtual key area signal l9...Output chroma key image 19C...Output chroma key signal 20...Reduced chroma key image 20CC...Reduced chroma key signal. 21...H start address register 22...■
Start address register 23...Enlargement ratio register 24...Address generation circuit 25...Analog signal switch 27...Blue panel for chroma key 27S...Foreground image signal 28...Composition circuit 29
... Blue scenery image 30 ... Composite output image 31
... Chromakey one image 31G... Chroma key signal 3rd figure 0V Figure 4 Example of the present invention, 3 keys @． Illustration 6 of I1 of Hanawa Painting

Claims (1)

[Claims] 1. The foreground subject image and the foreground subject image are switched by a key signal generated depending on the presence or absence of the single color to switch between an image output image signal of a foreground imaging camera that images a foreground subject in a single color background and another background image signal. When compositing with another background image, the single color background is reduced to a size sufficient to include the foreground subject, and a number of digitized pixel storage areas corresponding to the entire configurable field of view of the foreground imaging camera are created. The field of view of the foreground imaging camera is changed by using an enlarged frame memory which is provided vertically and horizontally in excess of the number of digitized pixels of a predetermined frame, and stores the image signal of the single color in almost all of the digitized pixel storage area. Accordingly, the background area of the image pickup output image signal exceeding the reduced single color background is supplemented by the single color image signal reproduced from the digitized pixel storage area corresponding to the changed field of view of the enlarged frame memory. A key signal generation method for image synthesis, characterized in that a key signal is generated.