Signal processing apparatus which suppresses a color signal according to luminance level

• US 7,061,528 B1
• Filed: 04/20/1999
• Issued: 06/13/2006
• Est. Priority Date: 04/24/1998
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Honma, Yoshihiro
• Primary Examiner(s): Yu, Ngoc-Yen
• Assistant Examiner(s): Hannett, James M.
• Application Number:
  US09/295,323
• Time in Patent Office: 2,611 Days
• Field of Search: 348/279, 348/280, 348/272, 348/237, 348/254, 348/234, 348/231.6, 348/223.1, 348/222.1, 348/230.1, 348/229.1
• US Class Current: 348/222.1
• CPC Class Codes: H04N 23/12 with one sensor only
• CPC Class Codes: H04N 9/77 Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase circuits for matrixing H04N9/67

Abstract

To provide a signal processing apparatus and an image pickup signal processing method both of which restrain a color signal from being influenced by band limitation in a color processing system, thereby enabling signal processing which produces an undegraded image, the processing of color-suppressing RGB signals or complementary color signals is performed between a color interpolation circuit and a color-difference matrix circuit. Otherwise, the processing of suppressing a color signal is performed in front of the color interpolation circuit.

Claims

1. A signal processing apparatus which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

interpolation circuit which generates a plurality of color signals for each pixel position of the image pickup element by interpolation based on signals of pixels adjacent to said each pixel position of the image pickup element;

color-difference signal forming circuit for forming color-difference signals based on output of said interpolation circuit;

suppression circuit being provided between said color interpolation circuit and said color-difference signal forming circuit, which suppresses the plurality of color signals generated by said interpolation circuit, if a level of a luminance signal is out of a predetermined range;

wherein it is so constructed that plurality of color signals suppressed which are output from said suppression circuit is regarded as input of said color-difference signal forming circuit.

2. A signal processing apparatus according to claim 1, further comprising gamma correction circuit provided between said suppression circuit and said color-difference signal forming circuit, which performs gamma correction on the plurality of color signals outputted from said suppression circuit.

3. A signal processing apparatus according to claim 2, further comprising luminance signal correcting circuit which corrects the luminance signal on the basis of the plurality of color signals suppressed by said suppression circuit.

4. A signal processing apparatus according to claim 3, wherein said luminance signal correcting circuit corrects the luminance signal before the luminance signal is gamma-corrected.

5. A signal processing apparatus which processes a signal outputted from an image pickup element having complementary color filters, comprising:

interpolation circuit which generates complementary color signals for each pixel position of the image pickup element by interpolation based on signals of pixels adjacent to said each pixel position of the image pickup element;

RGB matrix circuit which generates RGB signals from the complementary color signals interpolated by said interpolation circuit;

color-difference signal forming circuit for forming color-difference signals based on the output by said RGB matrix circuit; and

suppression circuit being provided between said interpolation circuit and said color-difference signal forming circuit, which suppresses the RGB signals generated by said RGB matrix circuit, if a level of a luminance signal is out of a predetermined range;

wherein it is so constructed that RGB signals outputted from said suppression circuit are input into said color-difference signal forming circuit.

6. A signal processing apparatus according to claim 5, further comprising gamma correction circuit provided between said suppression circuit and said color-difference signal forming circuit, which performs gamma correction on the RGB signals outputted from said suppression circuit.

7. A signal processing apparatus according to claim 6, further comprising luminance signal correcting circuit which corrects the luminance signal on the basis of the RGB signals suppressed by said suppression circuit.

8. A signal processing apparatus according to claim 7, wherein said luminance signal correcting circuit corrects the luminance signal before the luminance signal is gamma-corrected.

9. A signal processing apparatus which processes a signal outputted from an image pickup element having complementary color filters, comprising:

interpolation circuit which generates complementary color signals for each pixel position of the image pickup element by interpolation based on signals of pixels adjacent to each said pixel position of the image pickup element;

RGB matrix circuit which generates RGB signals from the complementary color signals; and

suppression circuit being provided between said interpolation circuit and said RGB matrix circuit, which suppresses the complementary color signals interpolated by said interpolation circuit, if a level of luminance signal is out of a predetermined range;

wherein it is so constructed that the color signals outputted from said suppression circuit are inputted into RGB matrix circuit.

10. A signal processing apparatus according to claim 9, further comprising luminance signal correcting circuit which corrects the luminance signal on the basis of the complementary color signals suppressed by said suppression circuit.

11. A signal processing apparatus according to claim 10, wherein said luminance signal correcting circuit corrects the luminance signal before the luminance signal is gamma-corrected.

12. A signal processing apparatus which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

interpolation circuit which generates primary color signals or complementary color signals for each pixel position of the image pickup element by interpolation based on signals of pixels which adjacent to said each pixel position of the image pickup element; and

suppression circuit provided between said image pickup element and said interpolation circuit, which suppresses a color signal outputted from the image pickup circuit, if a level of a luminance signal is out of a predetermined range.

13. A signal processing apparatus according to claim 12, further comprising luminance signal correcting circuit which corrects the luminance signal on the basis of the color signal suppressed by said suppression circuit.

14. A signal processing apparatus according to claim 13, wherein said luminance signal correcting circuit corrects the luminance signal before the luminance signal is gamma-corrected.

15. A signal processing apparatus which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

a color-suppression circuit, provided for primary color signals or complementary color signals obtained from said image pickup element, for color-suppressing said primary color signals or said complementary color signals in accordance with the level of luminance signal;

a gamma-correction circuit which gamma-corrects the output signals suppressed by said suppression circuit; and

A/D conversion circuit for A/D converting primary color signals or complementary color signals obtained from said image pickup element before said color-suppression circuit.

16. A signal processing apparatus according to claim 15, further comprising:

a color-difference signal forming circuit for converting the output signals gamma-corrected by said gamma-correction circuit into color-difference signals.

17. A signal processing apparatus which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

a color-suppression circuit, provided for primary color signals or complementary color signals obtained from said image pickup element, for color-suppressing said primary color signals or said complementary color signals in accordance with the level of luminance signal; and

a color-difference signal forming circuit for converting the output signals color-suppressed by said color-suppression circuit into color-difference signals; and

A/D conversion circuit for A/D converting primary color signals or complementary color signals obtained from said image pickup element before said color-suppression circuit.

18. A signal processing method which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

interpolating a plurality of color signals for each pixel position of the image pickup element by interpolation based on signals of pixels adjacent to said each pixel position of the image pickup element;

forming color-difference signals based on output in interpolating step;

suppressing the plurality of color signals interpolated between said color interpolating step and said forming step, if a level of a luminance signal is out of a predetermined range;

wherein it is so processed that plurality of color signals suppressed which are output from said suppressing step is regarded as input of said forming step.

19. A signal processing method according to claim 18, further comprising:

A/D converting primary color signals or complementary color signals obtained from said image pickup element before said the signals are suppressed in said suppressing step.

20. A signal processing method according to claim 18, further comprising:

performing, between said suppressing step and said forming step, gamma correction on the plurality of color signals outputted from said suppressing step.

21. A signal processing method according to claim 20, further comprising:

correcting luminance signal on the basis of the plurality of color signals suppressed in said suppressing step.

22. A signal processing method according to claim 21, wherein said luminance signal is corrected before the luminance signal is gamma-corrected.

23. A signal processing method which processes a signal outputted from an image pickup element having complementary color filters, comprising:

interpolating complementary color signals for each pixel position of the image pickup element by interpolation based on signals of pixels adjacent to said each pixel position of the image pickup element;

generating RGB signals by performing RGB matrix into complementary color signals interpolated in said interpolating step;

forming color-difference signals based on the output in said RGB matrix step; and

suppressing, between said interpolating step and said forming step, the RGB signals generated in said RGB matrix step, if a level of a luminance signal is out of a predetermined range;

wherein it is so processed that RGB signals outputted in said suppressing step are input into said color-difference signal forming step.

24. A signal processing method according to claim 23, further comprising:

performing gamma correction, between said suppressing step and said forming step, on the RGB signals outputted in said suppressing step.

25. A signal processing method according to claim 24, further comprising:

correcting the luminance signal on the basis of the RGB signals suppressed in said suppressing step.

26. A signal processing method according to claim 25, wherein said luminance signal is corrected before the luminance signal is gamma-corrected.

27. A signal processing method which processes a signal outputted from an image pickup element having complementary color filters, comprising:

interpolating by generating complementary color signals for each pixel position of the image pickup element by interpolation based on signals of pixels adjacent to each said pixel position of the image pickup element;

generating RGB signals by performing RGB matrix into the complementary color signals interpolated in said interpolating step; and

suppressing the complementary color signals interpolated in interpolating step between said interpolating step and said generating step, if a level of luminance signal is out of a predetermined range;

wherein it is so processed that the color signals outputted in said suppressing step are inputted into RGB matrix circuit.

28. A signal processing method according to claim 27, further comprising:

correcting the luminance signal on the basis of the complementary color signals suppressed in said suppressing step.

29. A signal processing method according to claim 28, wherein said luminance signal is corrected before the luminance signal is gamma-corrected.

30. A signal processing method which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

interpolating by generating primary color signals or complementary color signals for each pixel position of the image pickup element by interpolation based on signals of pixels which adjacent to said each pixel position of the image pickup element; and

suppressing, between said image pickup element and said interpolating step, a color signal outputted from the image pickup step, if a level of a luminance signal is out of a predetermined range.

31. A signal processing method according to claim 30, further comprising:

correcting the luminance signal on the basis of the color signal suppressed in said suppressing step.

32. A signal processing method according to claim 31, wherein said luminance signal is corrected before the luminance signal is gamma-corrected.

33. A signal processing method which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

a color-suppressing primary color signals or complementary color signals obtained from said image pickup element in accordance with the level of luminance signal; and

a gamma-correcting the output signals suppressed in said color-suppression step; and

A/D converting primary color signals or complementary color signals obtained from said image pickup element before said the signals are suppressed in said suppressing step.

34. A signal processing method which processes a signal outputted from an image pickup element having filters arranged to use plural kinds of colors, comprising:

suppressing, primary color signals or complementary color signals obtained from said image pickup element, in accordance with the level of luminance signal;

forming color-difference signal by converting the output signals color-suppressed in said color-suppressing step into color-difference signals; and

A/D converting primary color signals or complementary color signals obtained from said image pickup element before said the signals are suppressed in said suppressing step.