Auxiliary signal to assist conversion of a letterbox standard aspect ratio television signal to a wide aspect ratio signal

US5268751A · kind A · utility

Assignee

• Deutsche Thomson-Brandt GmbH · DE

Inventors

• Erich Geiger · St. Georgen im Schwarzwald, DE
• Hans-Joachim Platte · Hemmingen, DE
• Martin Plantholt · Hemmingen, DE
• Dietrich Westerkamp · Hannover, DE
• Uwe Riemann · Braunschweig, DE
• Dietmar Hepper · Hannover, DE

Key dates

• Filing date: Apr 15, 1992
• Grant date: Dec 7, 1993
• Expiry date: Apr 15, 2012

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N7/007
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

In the process of generating a compatible 4:3 letterbox format television signal, a wide aspect ration 16:9 progressive scan television signal is vertically transcoded from 575 to 431 image lines, converted to line interlaced form and horizontally compressed. A vertically transcoded interlaced luminance component is converted back to progressive scan form via interpolation, and subtracted from a vertically transcoded original progressive scan luminance component to produce a difference (helper) signal. The difference signal is time compressed and multiplexed into upper and lower edge bar regions of the letterbox format. The compatible letterbox signal also is encoded with additional information including vertical high frequency information and horizontal high frequency information separated during the transcoding and compression processes, respectively. The encoding includes modulating the color subcarrier frequency with luminance information, and intraframe averaging. The difference signal and encoded additional information are used by a 16:9 widescreen receiver to produce a 16:9 progressive scan image display with the transcoded number of lines and good resolution.