Method for obtaining signals in electronic devices by means of interpolation between interpolation point values

• US 6,072,544 A
• Filed: 03/17/1997
• Issued: 06/06/2000
• Est. Priority Date: 03/21/1996
• Status: Expired due to Fees

• Current Assignee: Deutsche Thomson-Brandt Gmbh (Vantiva SA)
• Original Assignee: Deutsche Thomson Brandt Gmbh
• Inventors: Heizmann, Friedrich, Gleim, Guenter, Rekla, Bernd
• Primary Examiner(s): LEE, MICHAEL
• Application Number:
  US08/822,155
• Time in Patent Office: 1,177 Days
• Field of Search: 348/745-747, 348/806-807, 315/368.12, 315/368.13, 315/368.11
• US Class Current: 348/745
• CPC Class Codes: H04N 3/2335 with calculating means
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen
• CPC Class Codes: H04N 9/28 Arrangements for convergence or focusing

Abstract

A method is proposed for obtaining signals in electronic devices by means of interpolation between interpolation point values (W0 to W12), the interpolation point values (W0 to W12) being distributed linearly over a region. A number of interpolation values are calculated in each case at a specific interval between the interpolation point values (W0 to W12). The calculation of the interpolation values is then performed as follows: Firstly, a correction step value (a to 1) is determined in each case for an interval bounded by two interpolation point values (W0 to W12) by linear interpolation between these interpolation point values (W0 to W12) . These correction step values (a to 1) are calculated for all intervals. The calculation of the interpolation value in the current interval is then performed such that apart from the correction step value (a to 1) for the current interval use is also made at least of the correction step value (a to 1) of the preceding and/or of the following interval. As a result, the interpolation curve is laid smoothly through the intervals, and pronounced discontinuities in the gradient of the interpolation curve are avoided.

Claims

1. A method for interpolation, comprising the steps of:

defining interpolation intervals between each adjacent pair of a plurality of original interpolation values;

designating a set of interpolation locations within each said interpolation interval;

assigning a correction step value between each said pair of original values relating to a linear rate of change defined by the respective magnitudes of the original values and their respective distances from said interpolation locations;

calculating interpolation values for each said interpolation location in a given interpolation interval based upon said assigned step values for said given interpolation interval and said interpolation intervals before and after said given interpolation interval; and

,

generating an output signal from said original values and said interpolation values.

2. A method according to claim 1, comprising the step of using the correction step value of the interpolation intervals before or after said given interval only in subregions of said given interval during said calculating step.

3. A method according to claim 1, comprising the step of weighting the correction step values of the interpolation intervals before and after the given interpolation interval in accordance with the location of the interpolation value being calculated during said calculating step.

4. A method according to claim 3, comprising the step of weighting the correction step value for the interpolation interval before said given interval with a weighting value that decreases with increasing distance of the location of the interpolation value being calculated.

5. A method according to claim 3, comprising the step of weighting the correction step value for the interpolation interval after said given interpolation interval with a weighting value that increases with decreasing distance of the location of the interpolation value being calculated.

6. A method according to claim 2, comprising the step of weighting the correction step value for the interpolation interval before said given interpolation interval with a weighting value that is reduced decrementally during a transition from one location of an interpolation value to be calculated to the next location of an interpolation value to be calculated.

7. A method according to claim 2, comprising the step of weighting the correction step value for the interpolation interval after said given interval with a weighting value that is increased incrementally during any change from one location of an interpolation value being calculated to the next location of an interpolation value being calculated.

8. A method according to claim 2, comprising the step of maintaining a weight of the correction step value for the current interval constant when calculating the interpolation values within the given interval.

9. A method according to claim 1, comprising the step of adding a starting value to at least the first interpolation value of the first interpolation location of a first given interval.

10. A method according to claim 9, further comprising the step of adding contributions of weighted correction step values of the first interval in the case of a fictional calculation of interpolation values for an interval situated before the first interval to obtain a starting value.

11. A method according to claim 1, further comprising the step of adding additional weighted correction step values of the first interval, which originate from a fictional calculation of interpolation values for an interval situated before the first interval to the interpolation values in the first interval of the region.

12. A method according to claim 11, further comprising the step of decreasing weights of the additional correction step values of the first interval with increasing distance of the position of the interpolation value currently to be calculated within the first interval from the boundary of the region.

13. A method according to claim 1 further comprising the step of adding additional weighted correction step values, which originate from a fictional calculation of interpolation values for an interval situated after the last interval to the interpolation values in the last interval of the region.

14. A method according to claims 13, further comprising the step of increasing the weights of the additional correction step values of the last interval with decreasing distance of the position of the interpolation values currently to be calculated within the last interval from the boundary of the region.

15. A method according to claim 13, further comprising the step of calculating the last interpolation values of the last interval, by adding an amount thereto in order to keep the gradient of the interpolation curve constant.

16. A method according to claim 1 further comprising the step of adding at least one interpolation point value at each boundary of a region defined by said interpolation intervals to expand the region.

17. A method according to claim 16, further comprising the step of interpolating starting from the three most closely neighbouring interpolation point values to determine additional interpolation point values in each case.

18. A method according to claim 17, further comprising the step of calculating the first additional interpolation point value according to the formula:

space="preserve" listing-type="equation">im01=3W0-3W1+W2

wherein W0, W1 and W2 are the three most closely neighbouring interpolation point values.

19. A method according to claim 17, further comprising the step of calculating the second additional interpolation point value according to the formula:

space="preserve" listing-type="equation">im13=3W12-3W11+W10

wherein W10, W11, W12 are the three most closely neighbouring interpolation point values.

20. A method according to claim 1, further comprising the step of calculating the interpolation values in each case using a computing rule which is independent of the result of a preceding calculation of an interpolation value.

21. A method according to claim 1 further comprising the step of calculating the interpolation values in each case using a recursive computing rule, use being made in each case of the result of the preceding calculation of an interpolation value.

23. Method according to claim 1, further comprising the step of generating correction voltages for convergence adjustment in a video projector from said output signals.

24. Method according to claim 1, further comprising the step of generating a waveform from said original values and said interpolation values.

22. An apparatus for generating correction voltages for convergence adjustment in a video projector, said device including:

means for defining interpolation intervals between each adjacent pair of a plurality of original interpolation values;

means for designating a set of interpolation locations within each said interpolation interval;

means for assigning a correction step value between each said pair of original values relating to a linear rate of change defined by the respective magnitudes of the original values and their respective distances from said interpolation locations;

means for calculating interpolation values for each said interpolation location in a given interpolation interval based upon said assigned step values for said given interpolation interval and said interpolation intervals before and after said given interpolation interval; and

, means for generating an output signal from said original values and said interpolation values.