Chromakey effect apparatus

• US 4,396,939 A
• Filed: 06/04/1981
• Issued: 08/02/1983
• Est. Priority Date: 06/09/1980
• Status: Expired due to Term

• Current Assignee: Nippon Electric Company Limited (NEC Corporation)
• Original Assignee: Nippon Electric Company Limited (NEC Corporation)
• Inventors: Kitahama, Isamu
• Primary Examiner(s): Richardson, Robert L.
• Application Number:
  US06/270,464
• Time in Patent Office: 789 Days
• Field of Search: 358/21, 358/22, 358/26, 358/35, 358/17, 358/19
• US Class Current: 348/587
• CPC Class Codes: H04N 9/75 Chroma key

Abstract

A chromakey effect apparatus including a color-killing subcarrier-generating circuit which generates a color-killing subcarrier which completely kills color even when the hue or saturation of the chromakey area is changed and which also kills the color while simultaneously converting the color. Furthermore, the apparatus is capable of both chromakeying only the chromakey area even when there are many portions having the same color as the chromakey area, and also chromakeying a desired portion even when the desired portion includes a part having different colors. In addition, the apparatus is capable of inserting another television signal into only a desired portion of the chromakey area and of converting the color of the remaining portion of the chromakey area.

Claims

1. A color killing subcarrier generating circuit for a chromakey effect apparatus which generates a color killing subcarrier, comprising:

means for extracting the subcarrier from a television signal containing the chromakey area;

means for receiving a reference subcarrier and for shifting the phase of the reference subcarrier in response to a phase control voltage;

gain control means for controlling the amplitude of the reference subcarrier delivered from said phase shifting means in response to a gain control voltage;

phase comparator means for comparing the phase of the subcarrier delivered from said extracting means with the phase of the reference subcarrier delivered from said phase shifting means;

first supplying means for supplying the compared result to said phase shifting means as said phase control voltage;

means for comparing the amplitude of the subcarrier delivered from said extracting means with the amplitude of the reference subcarrier delivered from said phase shifting means; and

second supplying means for supplying the compared result of said comparing means to said gain control means as said gain control voltage.

2. A color killing subcarrier generating circuit as claimed in claim 1, further comprising means for receiving red, green and blue channel television signals containing a chromakey area and for producing a chromakey signal and sample pulse generating means responsive to said chromakey signal, for generating a sample pulse corresponding to said chromakey area;

said first supplying means including a sample holding circuit for holding the output of said phase comparator means at the timing of said sample pulse, and

said second supplying means including a sample holding circuit for holding the output of said comparing means at the timing of said sample pulse.

3. A chromakey effect apparatus comprising:

means for receiving red, green and blue channel television signals containing a chromakey area and for producing a chromakey signal;

means for generating an area signal to restrict a desired region on a television picture;

gate means responsive to said area signal for passing the chromakey signal;

color killing subcarrier generating means for generating a color killing subcarrier to cancel the color of the chromakey area;

adder means for adding said color killing subcarrier to the television signal containing the chromakey area at the timing of the key signal fed from said gate means; and

means for keying another television signal into the television signal fed from said adder means at the timing of the key signal supplied from said gate means.

6. A chromakey effect apparatus as claimed in claim 3, 4, or 5, further comprising means receiving said area signal for producing a border signal.

4. A chromakey effect apparatus comprising:

means for receiving red, green and blue channel television signals containing a chromakey area and for producing a chromakey signal;

means for generating an area signal to restrict a desired region on a television picture;

color killing subcarrier generating means for generating a color killing subcarrier to cancel the color of the chromakey area;

first adder means for adding said color killing subcarrier to the television signal containing the chromakey area at the timing of the chromakey signal;

second adder means for adding said area signal to said chromakey signal; and

means for keying another television signal into the television signal fed from said first adder means at the timing of the key signal supplied from said second adder means.

5. A chromakey effect apparatus comprising:

means for receiving television signals containing a chromakey area and for producing a chromakey signal;

means for generating an area signal to restrict a desired region on a television picture;

first and second gate means responsive to said area signal and operative alternatively for passing said chromakey signal;

color killing subcarrier generating means for generating a color killing subcarrier to cancel the color of the chromakey area;

color conversion subcarrier generating means for generating a color conversion subcarrier having a predetermined phase and an amplitude;

adder means for adding the color killing subcarrier to the television signal containing the chromakey area at the timing of the output of said first gate means, and adding the color conversion subcarrier to said television signal at the timing of the output of said second gate means; and

means for keying another television signal into the television signal fed from said adder means at the timing of the output of said first gate means.