Image pickup signal processing apparatus

• US 5,457,494 A
• Filed: 11/20/1989
• Issued: 10/10/1995
• Est. Priority Date: 11/21/1988
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sasaki, Takashi, Suga, Akira, Shiraishi, Akihiko, Matoba, Kazuyuki
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): LEE, MICHAEL
• Application Number:
  US07/438,090
• Time in Patent Office: 2,150 Days
• Field of Search: 358/41, 358/48, 358/44, 358/43, 358/21 R, 358/75, 358/80, 358/32, 358/164, 358/30, 358/34, 358/43, 358/48, 358/166, 358/169, 358/29, 358/27, 358/50, 358/48, 358/47, 358/160
• US Class Current: 348/229.1
• CPC Class Codes: H04N 2209/046 Colour interpolation to calculate the missing colour values
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 25/136 using complementary colours
• CPC Class Codes: H04N 9/646 for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters

Abstract

An image pickup signal processing apparatus for generating a digital luminance signal and digital color difference signals from output signals from a solid-state image pickup element, includes subtracters for generating primary color signals or color difference signals from the output signals from the solid-state image pickup element, and an A/D converter for converting the primary color or color difference signals output from the subtracters into digital signals.

Claims

1. An image pickup signal processing apparatus for generating a digital luminance signal and digital color difference signals from output signals from a solid-state image pickup element, comprising:

operation means for generating primary color signals or color difference signals from the output signals from said solid-state image pickup element;

an A/D converter for converting the output signals of said solid-state image pickup element and the primary color or color difference signals output from said operation means into digital signals, a quantization level of said A/D converter being variably set according to the level of said output signals of said solid-state image pickup element and the output signals having a small level being quantized by a large number of quantization levels;

gamma correction means for gamma correcting the color difference signals output from said A/D converter by using a correction table which provides corrected color difference signals from a luminance signal level included in the output signals of said solid-state image pickup element which is A/D-converted by said A/D converter, and a color difference signal level.

2. An apparatus according to claim 1, wherein DC potentials of the color difference signals input to said A/D converter are set such that zero levels of the color difference signals are located at a middle point of an input range of said A/D converter.

3. An apparatus according to claim 1, wherein an output signal level of said operation means is variably changed in accordance with an input range of said A/D converter.

4. An image pickup signal processing apparatus comprising:

a) image pickup means for photoelectrically converting image pickup light from an object to be photographed and for obtaining complementary color signals;

b) means for generating primary color signals from the obtained complementary color signals;

c) signal processing means comprising an amplifier, for processing the primary color signals, said amplifier variably controlling levels of said primary color signals;

d) an A/D converter having an input range, for A/D-converting the processed primary color signals whose levels are variably controlled in accordance with the input range of said A/D converter;

e) means for generating color difference signals from outputs from said A/D converter; and

f) means for generating a luminance signal from the complementary color signals converted from the outputs of said A/D converter.

5. An image pickup signal processing apparatus comprising:

color image pickup means using a complementary color filter for providing a plurality of different complementary color signals formed by using a differential amplifier which receives outputs from two sample/hold circuits operated to have opposite phases and operated at a period twice of a period of a read clock of said color image pickup means;

an A/D converter for A/D-converting a plurality of different signals each representing a difference between said plurality of different complementary color signals outputted from said color image pickup means;

color signal processing means for processing signals outputted from said A/D converter to generate color difference signals;

a decoder for decoding the signals outputted from said A/D converter to provide the plurality of different complementary color signals outputted from said color image pickup means; and

a luminance signal processing means for processing signals outputted from said decoder to generate a luminance signal.

6. An apparatus according to claim 5, wherein the plurality of different complimentary color signals are formed by using a differential amplifier which receives an output from a sample/hold circuit having the same period as that of a read clock of said color image pickup means and an output from a D/A converter to which is applied a digital signal provided by a decoder for decoding the signals outputted from said A/D converter.

8. An apparatus according to claim 5, wherein the complementary color filter includes Mg, Gr, Cy, and Ye filters.

9. An apparatus according to claim 5, wherein said color image pickup means includes a CCD.

10. An apparatus according to claim 5, wherein the levels of the signals corresponding to the differences of the color signals and supplied to said A/D converter are limited in accordance with an input range of said A/D converter.

7. An image pickup signal processing apparatus comprising:

color image pickup means using a complementary color filter;

an A/D converter for A/D-converting signals corresponding to differences between different color signals output from said color image pickup means;

color signal processing means for forming color signals by using outputs from said A/D converter;

a decoder for decoding original color signals from the outputs from said A/D converter; and

a luminance signal processing unit for forming a luminance signal using an output from said decoder,

wherein said decoder includes switch means for alternately outputting the output from said A/D converter and an inverted output thereof every pixel period and adding means for adding an output from said switch means and an output obtained by delaying the output from said switch means by one pixel.

11. An image pickup signal processing apparatus comprising:

means for time-divisionally A/D converting signals corresponding to differences of complementary color signals provided form image pickup means having a complementary color filter; and

means for generating color difference signals and a luminance signal of primary color signals from the complementary color signals generated by decoding the A/D converted signals, wherein a quantization level of the A/D conversion of said signals is variably set according to an output level of said image pickup means and said signals having a small level are quantized by a large number of quantization levels.

12. An apparatus according to claim 11, wherein the complementary color signals include Mg, Gr, Cy, and Ye, and the color difference signals include R-Y and B-Y.

13. An image pickup signal processing apparatus comprising:

color image pickup means using a complementary color filter;

means for receiving an output from said color image pickup means and separating complementary color signals;

differential amplifying means for receiving a plurality of complementary color signals separated by said separating means;

A/D-converting means for non-linearly A/D-converting an output from said differential amplifying means; and

processing means for performing linear processing of an output from said A/D-converting means,

wherein a signal having a small level is quantized by a large number of quantization levels.

14. An apparatus according to claim 13, wherein said A/D-converting means comprises a resistor voltage-dividing circuit for generating voltage-divided outputs locally having different values, and a plurality of comparators using the voltage-divided outputs as reference values.

15. An apparatus according to claim 13, wherein said color image pickup means includes a CCD.

16. An apparatus according to claim 13, wherein said separating means includes two sample/hold circuits driven by sampling pulses having opposite phases at a period twice that of a read clock of said color image pickup means.

17. An apparatus according to claim 13, wherein said A/D-converting means includes a non-linear circuit for converting an input signal into a non-linear signal and outputting the non-linear signal, and an A/D converter for A/D converting an output from said non-linear circuit.

18. An apparatus according to claim 17, wherein said non-linear circuit comprises time constant elements and generates a constant output when an input level exceeds a predetermined value.

19. An apparatus according to claim 17, wherein said color image pickup means includes a CCD.

20. An image signal processing apparatus including color image pickup means having a complementary color filter for photoelectrically converting light from an object, for generating primary color signals by digitally processing an output of said color image pickup means, comprising:

(a) A/D conversion means for A/D-converting the output of said image pickup means with a predetermined quantization level;

(b) means for changing the quantization level according to a level of the output of said image pickup means so that the output having a small level is quantized by a large number of quantization levels.

21. An apparatus according to claim 20, wherein said complementary color filter includes Mg, Gr, Ye and Cy filters, and the primary color signals include R, G and B.

22. An apparatus according to claim 20, wherein said color image pickup means includes a CCD.

23. An image signal processing apparatus including color image pickup means having a complementary color filter for photoelectrically converting light from an object, for generating primary color signals by digitally processing an output of said color image pickup means, comprising:

A/D conversion means for A/D-converting the output of said image pickup means with a plurality of quantization levels; and

means for changing the quantization levels according to a level of the output of said image pickup means so that the output having a small level is quantized by a larger number of quantization levels.

24. An apparatus according to claim 23, wherein said complementary color filter includes Mg, Gr, Ye and Cy filters, and the primary color signals include R, G and B.

25. An apparatus according to claim 23, wherein said color image pickup means includes a CCD.