JPS5853829B2 - Edge chromakey device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an edge chromakey device that performs chromakey processing on the entire area of an image portion edged with a predetermined color for forming a chromakey signal in a color image.

Chroma key devices, which are used to inlay and synthesize different color images during the production of television broadcast programs, have become so frequently used that they can be called essential devices in television studios.However, with conventional chroma key devices, In principle, any color can be used as the background color for chroma keying during color image composition, but instead of using blue, which is the opposite color to skin color, which has the strictest color reproduction conditions in color images of broadcast programs. It is generally used as a background color for chroma keying, and a chroma key signal is formed in which a color image in a portion that can be distinguished from the blue background is replaced with another color image.

That is, the chromakey signal shown in FIG. 1S is formed in correspondence with the chromakey blue part in the original color image shown in FIG. 1A, and the other color image shown in FIG. It was inserted into the chromakey blue portion of the original color image shown in FIG. 1a to form a composite color image as shown in FIG. 1d.

However, in such conventional chromakey devices, the second
As shown in Figure a, if characters, figures, etc. are drawn in another color or an achromatic color in the chromakey blue part of the original color image, the parts of the characters or figures have a hue different from the chromakey blue. As shown in FIG. 1, there is no inlay of other color images as shown in FIG. Text and figures will remain as they were and be displayed.

On the other hand, as a screen composition method often used in recent television program production, an original color image with the title of the program written in the blue chromakey area, as shown in Figure 2a, is used, and another color image is For example, once the title of a program is sent out without being inserted, a composite color image is sent out as a display of the program title, and if necessary, another color image is inserted into the blue chromakey area as shown in Figure 1d. However, in such cases, parts such as title characters written in a part of the chroma key in the original color image are also transmitted along with the surrounding chroma key blue part.
In order to be able to replace the image with another color image, as shown in FIG. 2C, the text of the title was changed in brightness from the surrounding chromakey blue, for example, in brighter blue.

Therefore, if another color image shown in FIG. 2e is inserted into the original color image shown in FIG. However, if the color image shown in FIG. 2C is displayed as a program title, there is a drawback in that the color effect is significantly impaired.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, and to color the original color image by changing the characters, figures, etc. written in the chromakey blue part of the original color image to be subjected to chromakey processing to any color or achromatic color. Even in a full color configuration, if there is a chroma key blue area before and after those characters or figures, an edge chroma key device can be used that can uniformly apply chroma key processing to the entire area of the image surrounded by the chroma key blue. It is about providing.

That is, the border chroma key device of the present invention includes a pair of gate means that alternately open and close during each successive horizontal scanning period, and a pair of gate means that respond continuously for approximately one horizontal scanning period to each successive falling edge of a square wave signal train. circuit means, each of which gates an input chroma one-shape wave signal train corresponding to a color having a predetermined hue and saturation degree in a color image signal by the pair of gate means for each successive horizontal scanning period. A pair of intermittent chroma one-sided wave signal trains are alternately taken out every horizontal scanning period, and each of the pair of circuit means is made to respond to the pair of intermittent chroma one-sided wave signal trains, and the pair of circuit means is The present invention is characterized in that the color image signal is subjected to chromakey processing by a logical sum of the response output signal and the input chromakey one-sided wave signal sequence.

In the following, the invention will be described in detail by way of example embodiments with reference to the drawings.

First, the basic aspect of the operation of the border chroma key device of the present invention will be explained with reference to FIG. 3. As shown in FIG. A chromakey signal is formed on the image in the same manner as in the conventional method, and for example, the horizontal scanning line A shown in FIG.
- A square wave signal train shown in FIG. 3C is formed as the chromakey signal on A', and the first rise of the square wave and the last fall of the square wave in the square wave chroma key signal train for each horizontal scanning period. , and uniformly gates the rising and falling edges of these signal waveforms without interruption.
A gate signal with a synthesized square waveform as shown in Figure d is newly formed, and a section as shown in Figure 3e is synthesized to cover the entire image area surrounded by chromakey blue in the same way as shown in Figure 1a. The composite color image shown in FIG. 2d is obtained using the composite chromakey signal.

An example of the configuration of the border chromakey device of the present invention, which operates in the basic manner as described above, is shown in FIG. 4, and signal waveforms of various parts thereof are shown in FIGS. 5a to 5i, respectively.

In the configuration shown in FIG. 4, a chromakey signal a formed in exactly the same way as a conventional chromakey device is guided from the input terminal to gates 1 and 2, and a horizontal drive pulse HD is supplied from the input terminal to the flip-flop 3. , form square wave signals S and C whose polarities are inverted with mutually opposite phases in each successive horizontal scanning period, and apply these square wave signals S and C to gates 1 and 2, respectively, to control the gates. 1 and 2 are alternately opened and closed during each successive horizontal scanning period.

Therefore, from these gates 1 and 2, intermittent chroma key signals d and e are obtained in which chroma key signals are obtained alternately every -horizontal scanning period (IH) in each successive horizontal scanning period.

The intermittent chromakey signals d and e at IH intervals are applied to the retrigger monostable multivibrators 4 and 5, respectively, and the monostable multivibrators 4 and 5 are activated by the falling edge of the signal waveform of the intermittent chromakey signals d and e. Trigger each.

Therefore, when a trigger pulse is applied again during the operation cycle after being once triggered, the retrigger monostable cell vibrator starts the specified periodic operation continuously from the time when the trigger pulse is reapplied. If the operating cycles of the retrigger monostable multi-by-breaks 4 and 5 are both set to the IH period, that is, 63.5 microseconds or slightly shorter, the above-mentioned chroma one-sided wave signal train d + e every IH is applied, it is triggered at the first falling edge of the intermittent chroma one-wave signal train every alternate IH period, and the polarity is reversed at the last fall of the intermittent chroma one-wave signal train in the next IH period. long-term square wave output signal f
and g are obtained.

When those long-term square wave output signals f and g are supplied to the AND gate 6 and the logical product of these square wave output signals f and g is calculated, An IH same-period square wave signal train rising at the falling edge and falling at the last falling edge is obtained.The square wave signal train and the input chromakey signal a are supplied to the OR gate 7, and these signals are When calculating the logical sum of
is obtained.

Note that for each signal waveform in the above description, respective phase delays and the like have been omitted in order to simplify the description.

In addition, in the configuration example shown in FIG. 4, a retrigger monostable multivibrator is used as the edge chromakey device of the present invention to detect the last fall in the chromakey one-sided wave signal train for each successive horizontal scanning period. The configuration of the device of the present invention is not limited to this example. For example, each time a falling edge occurs in the above-mentioned chroma one-sided wave signal train, the subcarrier oscillator, clock pulse oscillator, etc. are reset, and the subcarrier The wave number and the number of clock pulses are counted, and the counted value is stored until the end of the horizontal scanning period, and the position of the last falling edge is calculated using the stored counted value in the next horizontal scanning period. In any case, the desired chroma key signal can be determined by making the signal waveform fall at the time of the IH period delay or, in some cases, using a frame memory or the like and one frame delay. Configure it so that you can get it.

As is clear from the above description, according to the present invention, the following remarkable effects can be obtained.

(1) Even if you write characters or figures of any desired color or achromatic color in the chromakey blue part of the original color image to which chromakey processing is to be applied, the entire area surrounded by the chromakey blue will remain in the same way as before. A color image can be replaced with another color image, and an easy-to-see, high-quality color screen can be constructed without any visual restrictions on the color composition of the original color image.

(2) In extreme cases, for example, as shown in Figure 6 a and d, vertical lines drawn in chromakey blue can be placed before and after letters, figures, etc. drawn in any desired color or achromatic color as described above. If there is a single line, diagonal line, curve, etc., the entire color image part divided by the chroma key blue line can be replaced with another color image. Therefore, when producing a television program, the image This eliminates the need to use a large chroma keyboard that covers the entire area of the subject that needs to be inset, and simply places thin chroma keyboards on the left and right sides of the subject. It is possible to extremely reduce the possibility that the blue color of the chroma keyboard will be reflected on the subject and deteriorate the color composition, skin tone, etc. of a color image.

(3) Furthermore, as shown in Figure T a and b, for example, in a color screen where a human figure appears in the blue sky outside the window, the entire scene within the window frame is It can be used for special effects such as replacing it with a color image.

[Brief explanation of drawings]

Figures 1a to d are diagrams sequentially showing the operational aspects of a conventional chromakey device, and Figures 2a to 2e are diagrams showing the operational aspects of the edge chromakey device of the present invention in comparison with the conventional device, respectively. Diagrams shown in Figures 3a and 3e are diagrams sequentially showing the basic aspects of the operation of the device of the present invention, Figure 4 is a block diagram showing an example of its configuration, and Figure 5a = i is the same. A waveform diagram showing the signal waveforms of each part, Fig. 6a-
d is a diagram showing other aspects of the operation of the device of the present invention,
FIGS. 7a and 7b are diagrams respectively showing still other embodiments. 1.2...Gate, 3...Flip-flop, 4.5...Retrigger monostable multivibrator, 6...AND gate, 7... ...OR gate.

Claims (1)

[Claims] 1. A pair of gate means that alternately open and close during each successive horizontal scanning period, and a pair of circuit means that respond continuously for approximately one horizontal scanning period to each successive falling edge of a square wave signal train. and an input chroma one-wave signal train corresponding to a color having a predetermined hue and saturation in the color image signal is gated by the pair of gate means and alternately for each successive horizontal scanning period. Forming a pair of intermittent chroma one-sided wave signal trains extracted every one horizontal scanning period, causing each of the pair of circuit means to respond to the pair of intermittent chroma one-way wave signal trains, and producing response outputs of the pair of circuit means. 1. A border chromakey device, characterized in that the color image signal is subjected to chromakey processing by a logical product of the signals and the input chromakey one-sided wave signal sequence. 2. The pair of circuit means is a pair of retrigger monostable multivibrators that maintain an on state for approximately one horizontal scanning period in response to each successive fall of a square wave signal train. The edge chromakey device according to scope 1.