Method for obtaining line synchronization information items from a video signal, and apparatus for carrying out the method

• US 6,271,888 B1
• Filed: 08/19/1998
• Issued: 08/07/2001
• Est. Priority Date: 08/27/1997
• Status: Expired due to Fees

• Current Assignee: Deutsche Thomson-Brandt Gmbh (Vantiva SA)
• Original Assignee: Deutshe Thomson-Brandt GmbH
• Inventors: Lares, Roland, Rothermel, Albrecht
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): DESIR, JEAN WICEL
• Application Number:
  US09/136,264
• Time in Patent Office: 1,084 Days
• Field of Search: 348/521, 348/525, 348/500, 348/530, 348/531, 348/533, 348/538, 348/540, 348/610, 348/614, 348/607, 348/629, 348/21, 348/845.3, 386/24, 382/279, 375/365, 375/366, 375/368
• US Class Current: 348/521
• CPC Class Codes: H04N 5/10 Separation of line synchronising signal from frame synchronising signal or vice versa

Abstract

A method for obtaining line synchronization information items from a video signal is proposed. To that end, the following improvement measures are proposed:

a) an accurate determination of the position of a line synchronization pulse is effected by carrying out a convolution operation between the video signal for the video line and a pattern function. The exact position is then established by analysis of the result function (φ_sv(k)) of the convolution operation.

B) time-domain filtering of the established positions of the line synchronization pulses is carried out, in which a linear or non-linear estimation for the purpose of determining the corrected positions of the line synchronization pulses is carried out in each case.

The invention also relates to an apparatus for carrying out the method.

Claims

1. Method for obtaining line synchronization information items from a video signal, comprising the following method steps:

a) determining the position of a line synchronization pulse by convolving the video signal for the respective video line with a pattern function, and carrying out analysis of the result function of the convolution operation;

b) filtering the positions of line synchronization pulses in the temporal direction, wherein an estimation for the determination of a correction position of a line synchronization information item is carried out.

2. Method according to claim 1, in which an idealized line synchronization pulse is used as the pattern function.

3. Method according to claim 1, in which the analysis of the result function of the convolution operation comprises the step of determination of the maximum or minimum of the result function, the maximum or minimum indicating the position of the line synchronization pulse.

4. Method according to claim 3, comprising the step of forming the first derivative of the result function, and determining the zero of the first derivative, which then specifies the position of the maximum or minimum.

5. Method according to claim 4, in which the step of determining the zero of the first derivative comprises the step of carrying out a linear regression and determining the point of intersection between the regression line and the abscissa of the coordinate system.

6. Method according to claim 4, in which the determination of the maximum or minimum of the result function is made dependent on whether the first derivative has at the zero at least a gradient which is greater or less than a predetermined minimal or maximal value.

7. Method according to claim 1, in which the estimation is carried out with a knowledge base which consists of the positions of a number of preceding line synchronization pulses.

8. Method according to claim 1 in which the estimation comprises the step of forming a linear regression of the positions of the line synchronization pulses.

9. Method according to claim 7, comprising the step of establishing whether an abrupt sudden change has occurred in the case of the positions of the line synchronization pulses, and if so, switching off or changing to a different range the knowledge base of estimation during the time-domain filtering of the positions of the line synchronization pulses.

10. Apparatus for obtaining line synchronization information items from a video signal comprising the following components:

a) a line sync signal identification unit, in which the exact position of a line sync pulse is determined by convolution of the video signal for a video line with a pattern function and subsequent analysis of the result function of the convolution operation; and

b) a filter device, in which the positions of the line synchronization pulses are filtered in the temporal direction, an estimation for a corrected position of a line synchronization pulse taking place.

11. Apparatus according to claim 10, having a sudden position change identification unit, in which it is determined whether an abrupt sudden change has occurred in the case of the specific positions of the line synchronization pulses, and which causes the filter device, after an identified sudden change, to switch off its knowledge base, for the estimation or change it over to a different range.

12. Apparatus according to claim 10, in which the line synchronization signal identification unit comprises an MTA filter (Moving Time Average filter) for the convolution operation.

13. Apparatus according to claim 11, in which the line synchronization signal identification unit comprises an MTA filter (Moving Time Average filter) for the convolution operation.