Television – Image signal processing circuitry specific to television – Special effects
Reexamination Certificate
1998-05-11
2001-05-01
Hsia, Sherrie (Department: 2614)
Television
Image signal processing circuitry specific to television
Special effects
C348S591000, C348S592000
Reexamination Certificate
active
06226048
ABSTRACT:
TECHNICAL FIELD
The present Invention relates to an image signal processing apparatus suitably applicable, for example, to an editing system and particularly to composing image signals by generating a key signal with reference to a signal level for a chrominance signal without causing an incongruous feeling even if a picture having little luminance signal component is processed.
BACKGROUND ART
In the editing system, it has been a conventional practice to make various processing for image signals by the key signal which is generated with reference to the luminance signal as a standard.
Specifically, the editing system of this type extracts the luminance signal form an image signal which is an object of processing and makes the gain of the luminance signal variable after clamping it to generate the key signal. Further, with reference to the key signal, an image signal of background and the image signal to be processed are mixed each other, thereby causing the image as the object of processing (see
FIG. 14B
) to be fit into the image of background (see
FIG. 14A
) for producing a composed image (see FIG.
14
C), for example.
In the meantime, the editing system may generate the key signal taking an image signal produced by the computer graphics as the object of processing. In such an image signal as produced by the computer graphics, there may sometimes be included a picture of blue color, etc. having little luminance signal components.
If the key signal is generated with the luminance signal as a standard in connection with the picture of blue color, etc. having little luminance components, the key signal will be generated in thinner form. Consequently, when processing the picture produced by the computer graphics by the key signal, the edition processed picture will be displayed played in the thinner shape. This will make the edited picture to cause a sense of incongruity.
Thus, when letters of Y and C in
FIG. 14B
are displayed in white and blue, respectively, there is an inconvenience that, as is shown in
FIG. 14C
, the letter C will be composed to be thinner than the letter Y in the composed picture.
DISCLOSURE OF INVENTION
The present invention has been made in consideration of the foregoing point and aims to propose an image signal processing apparatus which is capable an image signal without causing the incongruous feeling even if the picture having little luminance signal component is processed.
The present invention comprises a signal level detector circuit for outputting a signal level detecting signal by detecting a signal level a the chrominance signal and a signal level corrector circuit for correcting a signal level of the signal level detecting signal to generate a key signal according to the chrominance signal.
If the signal level detecting signal is obtained by detecting the signal level of the chrominance signal and the key signal is then generated with reference to the chrominance signal from the signal level detecting signal, it will be possible to raise the signal level of the key signal for an area where the luminance signal is low level, thereby allowing the picture composition to be performed satisfactorily on such area.
REFERENCES:
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Frommer William S.
Frommer Lawrence & Haug LLP.
Hsia Sherrie
Shallenburger Joe H.
Sony Corporation
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