JPS6010893A - Key signal detecting circuit in chromakey system - Google Patents

Abstract

PURPOSE:To obtain a key signal detecting circuit in a chromakey system with a simple circuit and accurate color adjustment by detecting a chromakey signal by a color difference signal. CONSTITUTION:The color difference signal (B-Y) as shown in (b-1) is waveform- shaped by a comparator and a waveform-shaped signal (B-Y)' waveform-shaped as shown in (b-2) is fed directly to an AND gate 2. On the other hand, a color difference signal (R-Y) shown in (b-3) is waveform-shaped by a window comparator and a waveform-shaped color difference signal (R-Y)' as shown in (b-4) is obtained and this color difference signal (R-Y)' is inverted and fed to an AND gate 2. Through the constitution above, the color difference signals (B-Y)' and (R-Y)' are fed to the AND gate 2, the inverted color difference signals (R-Y)' and (B-Y)' are ANDed at the AND gate 2 and the key signal is outputted from the AND gate 2 only when the (B-Y)' is at a low level and the (R-Y)' is at a high level.

Description

Detailed Description of the Invention The present invention provides a key signal in a chromakey system that combines a first image signal and a second image signal by inserting a second image signal into a portion of a predetermined hue of a first image signal. Regarding a detection circuit.

A conventional detection circuit of this kind is shown in FIG.
As shown in . , the waveform-shaped primary color signals R' and G' are inverted, and the waveform-shaped primary color signal B' is directly supplied to the AND gate 1 operated by three people, and the AND gate 1 detects the blue signal to obtain the key signal. Ta.

However, when using the conventional chromakey signal detection circuit as described above, it is difficult to adjust the color because saturation and hue information is not included, although it requires an AND gate by three people to detect the key signal. Moreover, there was a drawback that accurate color adjustment was not possible.

The present invention has been made in view of the above, and the present invention solves the above-mentioned drawbacks by detecting a chromakey signal using a color difference (t), and enables accurate gray adjustment with a simple circuit. The purpose is to provide circuits.

The present invention will be explained below with reference to Examples.

FIG. 2(a) is a block diagram showing the configuration of an embodiment of the present invention.

2 is a two-person AND gate.

As shown in (b-1) of Figure 2 (bl), the color difference signal (B-Y
) is waveform-shaped by a comparator, and the waveform-shaped color difference signal (B-Y)' shown in (b-2) of FIG. 2 is waveform-shaped.
is directly supplied to AND gate 2. On the other hand, Fig. 2(b)
As shown in (b-3) of Figure 2, the color difference signal (R-Y) is waveform-shaped by a window comparator, and the waveform of (b-3) of Figure 2 fh is obtained.
-4) Obtain the waveform shaped color difference signal (RY)' shown in
The waveform-shaped color difference signal (RY)' is inverted and then supplied to the AND gate 2.

In one embodiment of the present invention configured as described above, the waveform-shaped color difference signal (B-Y
)' and the waveform-shaped color difference signal (R-Y) shown in (b-4) of FIG. ' and the waveform-shaped color difference signal (t3-Y)' are ANDed in the AND gate 2, and the waveform-shaped color difference signal (B-Y)' is at a low level and the waveform-shaped color difference signal (R-Y)' is at a high level. A key signal is output from AND gate 2 only in the case of level.

Note that although the above example illustrates the detection of a green light, detection of a red light may also be performed in the same manner.

As explained above, according to the present invention, the key signal is detected using the color difference signal, so the gate circuit for detection is simple, and since hue and saturation information is included, color adjustment is accurate. There is an effect that can be done.

[Brief explanation of the drawing]

Figure 1 (a), (b) 9 tc+ and (d+ are diagrams for explaining the conventional key signal detection circuit, Figure 2 (a)
) is a block diagram showing the configuration of an embodiment of the present invention, No. 21
m(b-1), (b-2), (b-3), and (b-4) are waveform diagrams for explaining one embodiment of the present invention. 2...and gate. Patent applicant Pioneer Corporation

Claims (1)

[Claims] In a multi-port masking system that inserts a second image signal into a portion of a predetermined hue of the first image signal and synthesizes the first image signal and the second image signal, two images of the first image signal are combined. 1. A key signal detection circuit comprising a logic operation means for performing a logic operation on a color difference signal, and an output of the logic operation means is used as a key signal for switching between a first image signal and a second image signal.