Method and apparatus for processing component signals to preserve high frequency intensity information

• US 5,008,741 A
• Filed: 04/07/1989
• Issued: 04/16/1991
• Est. Priority Date: 04/07/1989
• Status: Expired due to Term

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Knierim, David L., Brown, Gary L.
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): VU, KIM Y
• Application Number:
  US07/334,829
• Time in Patent Office: 739 Days
• Field of Search: 358/31, 358/32, 358/16, 358/21
• US Class Current: 348/675
• CPC Class Codes: H04N 9/69 for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83

Abstract

A video signal in component form is processed by generating two chroma component signals which have a selected bandwidth and are GAMMA corrected, generating a linear luminance component signal which has a greater bandwidth than the chroma component signals and is not GAMMA corrected, and GAMMA correcting the linear luminance component signal to provide a GAMMA-corrected luminance component signal having a greater bandwidth than the GAMMA-corrected chroma component signals.

Claims

1. A method of processing a video signal in component form, comprising:

(a) generating two chroma component signals which have a selected bandwidth and are GAMMA corrected,

(b) generating a linear luminance component signal which has a greater bandwidth than the chroma component signals and is not GAMMA corrected, and

(c) GAMMA correcting the linear luminance component signal by combining the linear luminance component signal and the chroma component signals to provide a GAMMA-corrected luminance component signal having a greater bandwidth than the GAMMA-corrected chroma component signals.

2. A method according to claim 1, wherein step (a) comprises generating three GAMMA-corrected primary color component signals and applying the GAMMA-corrected color component signals to an encoding matrix that outputs chroma component signals.

3. A method according to claim 2 wherein step (b) comprises removing the GAMMA correction of the GAMMA-corrected color component signals to provide linear color component signals and applying the linear color component signals to a luminance matrix that outputs a luminance component signal.

4. A method according to claim 1, wherein step (a) comprises generating three linear primary color component signals, GAMMA correcting the linear color component signals, and applying the GAMMA-corrected color component signals to an encoding matrix that outputs chroma component signals.

5. A method according to claim 4, wherein step (b) comprises applying the linear primary color component signals to a luminance matrix that outputs a luminance component signal.

6. A method according to claim 1, wherein step (c) comprises generating a GAMMA-corrected luminance component signal Y such that Y'"'"' is substantially equal to ##EQU4## where Y'"'"' is the linear luminance component signal and CR and CB are the GAMMA-corrected chroma component signals.

7. A method according to claim 1, wherein step (c) comprises generating a GAMMA-corrected luminance component signal Y such that Y'"'"' is substantially equal to Y**GAMMA, where Y'"'"' is the linear luminance component signal.

8. Apparatus for processing a video signal in component form, comprising:

means for providing two chroma component signals which have a selected bandwidth and are GAMMA corrected,

means for providing a linear luminance component signal which has a greater bandwidth than the chroma component signals and is not GAMMA corrected, and

means for GAMMA correcting the linear luminance component signal by combining the linear luminance component signal and the chroma component signals to provide a GAMMA-corrected luminance component signal having a greater bandwidth than the GAMMA-corrected chroma component signals.

9. Apparatus according to claim 8, wherein the means for providing the two chroma component signals comprise means for providing linear primary color component signals, means for GAMMA correcting the linear primary color component signals, an encoding matrix connected to receive the GAMMA-corrected color component signals and to output chroma component signals, and low pass filter means for receiving the chroma component signals from the matrix and limiting them to said selected bandwidth.

10. Apparatus according to claim 9, wherein the means for providing the linear luminance signal comprise a luminance matrix connected to receive the linear primary color component signals and to output a luminance signal.

11. Apparatus according to claim 8, wherein the means for providing the two chroma component signals comprise means for providing GAMMA-corrected primary color component signals and an encoding matrix connected to receive the GAMMA-corrected color component signals and to output chroma component signals.

12. Apparatus according to claim 11, wherein the means for providing the linear luminance component signal comprise means for removing the GAMMA-correction of the GAMMA-corrected primary color component signals to provide linear color component signals, and a luminance matrix connected to receive the linear color component signals and output a luminance signal.

13. A method of processing a video signal in component form, comprising:

(a) generating two chroma component signals which have a selected bandwidth and are GAMMA corrected,

(b) generating a linear luminance component signal which has a greater bandwidth than the chroma component signals and is not GAMMA corrected,

(c) low pass filtering for limiting the linear luminance signal, whereby the linear luminance signal is limited to a bandwidth greater than said selected bandwidth, and

(d) GAMMA correcting the bandwidth-limited linear luminance component signal to provide a GAMMA-corrected luminance component signal having a greater bandwidth than the GAMMA-corrected chroma component signals.

14. A method according to claim 13, wherein step (a) comprises generating three GAMMA-corrected primary color component signals and applying the GAMMA-corrected color component signals to an encoding matrix that outputs chrome component signals.

15. A method according to claim 14, wherein step (b) comprises removing the GAMMA correction of the GAMMA-corrected color component signals to provide linear color component signals, and applying the linear color component signals to a luminance matrix that outputs a luminance component signal.

16. A method according to claim 13, wherein step (a) comprises generating three linear primary color component signals, GAMMA correcting the linear color component signals, and applying the GAMMA-corrected color component signals to an encoding matrix that outputs chroma component signals.

17. A method according to claim 16, wherein step (b) comprises applying the linear primary color component signals to a luminance matrix that outputs a luminance component signal.

18. A method according to claim 14, wherein the encoding matrix also outputs a GAMMA-corrected luminance component signal, and step (b) comprises removing the GAMMA correction of the GAMMA-corrected luminance component signal.

19. A method according to claim 13, wherein step (c) comprises combining the linear luminance component signal and the chroma component signals to provide the GAMMA-corrected luminance component signal.

20. A method according to claim 19, wherein step (c) comprises generating a GAMMA-corrected luminance component signal Y such that Y'"'"' is substantially equal to ##EQU5## where Y'"'"' is the linear luminance component signal and CR and CB are the GAMMA-corrected chroma component signals.

21. A method according to claim 13, wherein step (c) comprises generating a GAMMA-corrected luminance component signal Y such that Y'"'"' is substantially equal to Y**GAMMA, where Y'"'"' is the linear luminance component signal.

22. Apparatus for processing a video signal in component form, comprising:

means for providing two chroma component signals which have a selected bandwidth and are GAMMA corrected,

means for providing a linear luminance component signal which has a greater bandwidth than the chroma component signals and is not GAMMA corrected,

means for lowpass filtering the linear luminance component signal whereby the linear luminance signal is limited to a bandwidth greater that the selected bandwidth, and

means for GAMMA correcting the linear luminance component signal to provide a GAMMA-corrected luminance component signal having a greater bandwidth than the GAMMA-corrected chroma component signals.

23. Apparatus according to claim 22, wherein the means for providing the two chroma component signals comprise means for providing linear primary color component signals, means for GAMMA correcting the linear primary color component signals, an encoding matrix connected to receive the GAMMA-corrected color component signals and to output chroma component signals, and low pass filter means for receiving the chroma component signals from the matrix and limiting them to said selected bandwidth.

24. Apparatus according to claim 23, wherein the means for providing the linear luminance signal comprise a luminance matrix connected to receive the linear primary color component signals and to output a luminance signal.

25. Apparatus according to claim 22, wherein the means for providing the two chroma component signals comprise means for providing GAMMA-corrected primary color component signals and an encoding matrix connected to receive the GAMMA-corrected color component signals and to output chroma component signals.

26. Apparatus according to claim 25, wherein the means for providing the linear luminance component signal comprise means for removing the GAMMA-correction of the GAMMA-corrected primary color component signals to provide linear color component signals, and a luminance matrix connected to receive the linear color component signals and output a luminance signal.