Television – Image signal processing circuitry specific to television – Special effects
Reexamination Certificate
1999-04-05
2001-03-13
Hsia, Sherrie (Department: 2614)
Television
Image signal processing circuitry specific to television
Special effects
C348S592000
Reexamination Certificate
active
06201581
ABSTRACT:
TECHNICAL FIELD
This invention relates to an image signal processing device and method, a picture synthesizing device, and an editing device which are used for picture synthesis employing a so-called chroma key.
BACKGROUND OF THE INVENTION
Conventionally, in chroma key processing using an editing device at a broadcasting station or the like, picture synthesis is carried out by inserting a background picture into a foreground picture.
Specifically, at a broadcasting station or the like, for example, an announcer is imaged with a screen of blue color as a background (so-called blue back), thereby generating an image signal of a foreground picture. Also, a desired object to be allocated to the background of the foreground picture is imaged, thereby generating an image signal of a background picture.
In an editing device or the like, in response to the operation by an operator, a color to be extracted from the foreground picture is preset by setting a reference signal level with respect to color-difference signals. In the case where picture synthesis is to be carried out by using a soft chroma key, in the editing device, lower limit and upper limit signal levels (that is, threshold values) are set with reference to a center color of the color to be extracted.
The editing device generates a key signal by sequentially comparing the threshold values with the image signal of the foreground picture. Specifically, with respect to the foreground picture generated with the background of blue color screen, the editing device generates a key signal by setting the upper limit and lower limit threshold values so that a value 0 is obtained in the background part while a value 1 is obtained with colors other than the blue color of the background. With respect to other bluish colors, a key signal is generated within a range of the value 1 to the value 0 corresponding to the upper limit and lower limit threshold values so that a value corresponding to the degree of blueness is obtained.
Thus, the conventional editing device generates a key signal by sequentially discriminating the color of the foreground picture, using a two-dimensional color space expressed by color-difference signals (that is, a color space with UV signals as coordinate axes). The editing device synthesizes the foreground picture and the background picture with reference to the key signal thus generated, so as to generate a synthetic picture such that the background picture is inserted in the background of the foreground picture.
Meanwhile, in the conventional editing device, it is difficult to discriminate a portion of a high luminance level and a portion of a low luminance level with the same color. Therefore, with respect to a synthetic picture generated by the conventional editing device, there arises a problem such that the contour of the inserted background picture is displayed in an unnatural manner, thus lowering the definition in comparison with the case where no chroma key processing is carried out.
As a method for solving this problem, it may be considered to express and process each pixel of the foreground picture on a three-dimensional color space. In this method, however, the range of key signal setting must be adjusted on the three-dimensional color space instead of the conventional two-dimensional color space, and therefore the operation to adjust chroma key processing might be complicated.
DISCLOSURE OF THE INVENTION
In view of the foregoing problem, it is an object of the present invention to provide an image signal processing device and method, a picture synthesizing device, and an editing device which enable picture synthesis of high definition with a simple structure and enable desired processing by simple operation.
In an image signal processing device and method according to the present invention, in generating a key signal for synthesizing a foreground picture and a background picture, a polar coordinate of each pixel of the foreground picture is detected in a three-dimensional color space having a center color of a color to be extracted from the foreground picture as an origin, and the key signal is generated in accordance with the distance of the polar coordinate from the origin.
Also, in generating a key signal for synthesizing a foreground picture and a background picture, the value of the key signal is set in accordance with the distance from a predetermined reference color in a three-dimensional color space to each pixel of the foreground picture, and a picture as a result of processing by the key signal and a characteristic setting screen for the key signal are displayed. The n, characteristics of the key signals are changed by information obtained through the characteristic setting screen, and the picture as a result of processing is changed.
In addition, in generating a key signal for synthesizing a foreground picture and a background picture, the value of the key signal is set in accordance with the distance of each pixel of the foreground picture from a reference center color in a three-dimensional color space, and position information of a pixel designated in the foreground picture from a predetermined reference position in the three-dimensional color space.
Also, in generating a key signal for synthesizing a foreground picture and a background picture, a pixel forming the foreground picture is projected on a reference plane set on a three-dimensional color space, thus displaying the position of the pixel forming the foreground picture on the three-dimensional color space.
In addition, in generating a key signal for synthesizing a foreground picture and a background picture, the value of the key signal is set in accordance with the distance from a predetermined reference color in a three-dimensional color space, and each pixel of at least the foreground picture is located at a corresponding position on the three-dimensional color space, thus displaying a picture viewed from a desired viewpoint.
The key signal generating, device and method having such characteristics may be applied to a picture synthesizing device based on the frame unit and an editing device for carrying out editing of a plurality of frames.
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Ando Tatsunobu
Matsuzaki Katsuro
Moriwake Katsuakira
Tsukahara Atsushi
Frommer William S.
Frommer & Lawrence & Haug LLP
Hsia Sherrie
Shallenburger Joe H.
Sony Corporation
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