Method and apparatus for testing and checking the criteria of a key signal decoder from a chromakey mixer

US4949165A · kind A · utility

Assignee

• BTS Broadcast Television Systems GmbH · DE

Inventors

• Uwe Riemann · Braunschweig, DE
• Gerd Brand · Didderse, DE

Key dates

• Filing date: Feb 11, 1988
• Grant date: Aug 14, 1990
• Expiry date: Feb 11, 2008

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N17/02
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A test pattern generator provides a test pattern signal timed for insertion in the foreground signal of a chromakey mixer to occupy the area of particular shape in any desired part of a monitor screen. The test pattern signal provides a color scan signal which becomes part of the foreground signal within the test pattern area and which is also supplied to the decoder along with the foreground signal. Decoder responds to the color scan signal in the test pattern by substituting the background signal of the portion of the color scan displayed corresponding to colors to which the decoder responds by switching in the background signal. This enables determination of the exact range of response of the decoder while the mixer is operating also of observance of changing of the setting of the response of the decoder so that it can be more accurately set to the desired color range.