TELEVISION CAMERA APERTURE CORRECTION SYSTEM

• US 3,789,133 A
• Filed: 10/26/1971
• Issued: 01/29/1974
• Est. Priority Date: 10/26/1971
• Status: Expired due to Term

• Current Assignee: Donald D. Kline
• Original Assignee: Donald D. Kline
• Inventors: Kline, Donald D.
• Primary Examiner(s): Murray, Richard
• Application Number:
  US05/192,259
• Time in Patent Office: 826 Days
• Field of Search: 178/DIG.25,5.4R,7.1
• US Class Current: 348/627
• CPC Class Codes: H04N 5/208 for compensating for attenuation of high frequency components, e.g. crispening, aperture distortion correction

Abstract

A television camera aperture correction system wherein the video signal is applied to a low pass filter. The filtered video signal is substracted from the original video signal, which has been suitably delayed by a delay line to produce a contour signal containing primarily high frequency video signal components. The contour signal is amplified and the low level portion of the contour signal, which is primarily high frequency noise, is removed by a coring circuit. Thereafter the cored contour signal is combined with the filtered video signal to produce a resultant video signal having enhanced high frequency components, but without the attendant high frequency noise increase conventionally associated therewith.

Claims

1. An aperture correction system for a video siGnal comprising a low pass filter, a delay line, said video signal being applied to said low pass filter and said delay line, subtraction means for subtracting the signal produced by said low pass filter from the signal produced by said delay line, amplifier means for amplifying the signal produced by said subtraction means and summing means for summing the signal produced by said amplifier means and the signal produced by said low pass filter.

2. Apparatus according to claim 1 wherein said low pass filter comprises a linear phase low pass filter and said delay line has a delay interval corresponding to the delay time of said low pass filter.

3. Apparatus according to claim 2 wherein said amplifier means includes coring means for attenuating the low level portion of the signal produced by said subtraction means.

4. Apparatus according to claim 3 wherein said coring means does not reduce the amplitude of the high level portion of the signal produced by said subtraction means.

5. An aperture correction system for a video signal comprising a low pass filter, a delay line, said video signal being applied to said low pass filter and said delay line, subtraction means for subtracting the signal produced by said low pass filter from the signal produced by said delay line, and summing means for summing the signal produced by said subtraction means and said video signal.

6. Apparatus according to claim 5 wherein said low pass filter comprises a linear phase low pass filter and said delay line has a delay interval corresponding to the delay time of said low pass filter.

7. Apparatus according to claim 6 further comprising coring means for attenuating the low level portion of the signal produced by said subtraction means.

8. Apparatus according to claim 7 wherein said coring means does not reduce the amplitude of the high level portion of the signal produced by said subtraction means.

9. In a color television camera having three camera tubes, lens means for optically imaging varying spectral portions of an image on said camera tubes and three preamplifiers respectively connected to the outputs of said camera tubes, the improvement comprising:

three low pass filters respectively connected to the outputs of said preamplifiers, aperture correction means for producing a contour signal from the output signal of one of said preamplifiers and summing means for respectively summing the output signals produced by each of said low pass filters with said contour signal.

10. Apparatus according to claim 9 wherein said aperture correction means comprises a delay line connected to the output of said one preamplifier, subtraction means for subtracting the signal produced by the low pass filter associated with said one preamplifier from the signal produced by said delay line and amplifier means for amplifying the signal produced by said subtraction means to form said contour signal.

11. Apparatus according to claim 10 wherein said low pass filters comprise linear phase low pass filters and said delay line has a delay interval corresponding to the delay time of said low pass filters.

12. Apparatus according to claim 11 wherein said amplifier means includes coring means for attenuating the low level portion of the signal produced by said subtraction means.

13. Apparatus according to claim 12 wherein said coring means does not reduce the amplitude of the high level portion of the signal produced by said subtraction means.

14. In a color television camera having three camera tubes, lens means for optically imaging varying spectral portions of an image on said camera tubes and three preamplifiers respectively connected to the outputs of said camera tubes, the improvement comprising three low pass filters respectively connected to the outputs of said preamplifiers, three aperture correction circuits for producing contour signals from the respective output signals of said preamplifiers and summing means for summing each of said contour signals with the output sigNal produced by the respective low pass filter associated therewith.

15. Apparatus according to claim 14 wherein each of said aperture correction circuits comprises a delay line connected to said low pass filter, subtraction means for subtracting the signal produced by said low pass filter from the signal produced by said delay line, amplifier means for amplifying the signal produced by said subtraction means to form said contour signal.

16. Apparatus according to claim 15 wherein said low pass filter comprises a linear phase low pass filter and said delay line has a delay interval corresponding to the delay time of said low pass filter.

17. Apparatus according to claim 16 wherein said amplifier means includes coring means for attenuating the low level portion of the signal produced by said subtraction means.

18. Apparatus according to claim 17 wherein said coring means does not reduce the amplitude of the high level portion of the signal produced by said subtraction means.

19. A method of enhancing the high frequency components of a video signal comprising the steps of attenuating the high frequency components of said video signal, delaying said video signal to be in phase with the attenuated signal, subtracting the attenuated signal from the video signal to form a contour signal, amplifying said contour signal and summing the amplified contour signal and said attenuated signal.

20. The method according to claim 19 wherein the step of amplifying includes attenuating the low level portion of said contour signal.

21. The method according to claim 20 wherein the step of attenuating the low level portion of said contour signal is accomplished without reducing the amplitude of the high level portion of said contour signal.

22. A method of enhancing the high frequency components of a video signal comprising the steps of attenuating the high frequency components of said video signal, delaying said video signal to be in phase with the attenuated signal, subtracting the attenuated signal from the video signal to form a contour signal, and summing the contour signal and said video signal.

23. The method according to claim 22 comprising the step of attenuating the low level portion of said contour signal prior to said step of summing.

24. The method according to claim 23 wherein the step of attenuating the low level portion of said contour signal is accomplished without reducing the amplitude of the high level portion of said contour signal.