1. An image capture apparatus comprising:
an image capture unit configured to capture an image by using a photo detector element which provides an output value varied depending on a light reception volume;
a projector unit configured to project light to an area targeted for image capture by the image capture unit, in synchronization with the image capture by the image capture unit;
a synchronous detection processor configured to obtain a synchronous detection image by subtracting an output value of an image captured with no light projected by the projector unit, from an output value of an image captured with light projected by the projector unit;
an exposure controller configured to control the image capture unit and the projector unit in such a manner as to obtain two or more synchronous detection images under different exposure conditions; and
an image generator configured to select one or more pixels from the rest of pixels at each position in the two or more synchronous detection images under the different exposure conditions excluding a pixel having a lowest output value, and generate a synchronous detection image by using the selected one or more pixels.
2. The image capture apparatus according to claim 1, wherein
the image generator selects one pixel from the rest of the pixels at each position in the two or more synchronous detection images under the different exposure conditions excluding the pixel having the lowest output value, and generates the synchronous detection image by arranging the selected pixels in their respective pixel positions.
3. The image capture apparatus according to claim 2, wherein
the image generator selects the pixel having the highest output value from the pixels at each position in the two or more synchronous detection images under the different exposure conditions, and generates the synchronous detection image by arranging the selected pixels in accordance with their respective pixel positions.
4. The image capture apparatus according to claim 1, wherein
the image generator selects two or more pixels from the rest of the pixels at each position in the two or more synchronous detection images under the different exposure conditions excluding the pixel having the lowest output value, and generates the synchronous detection image by arranging pixels, each synthesized from the selected two or more pixels, in accordance with their respective pixel positions.
5. The image capture apparatus according to claim 1, wherein the exposure controller changes the exposure conditions by controlling at least one of an exposure time and a diaphragm value of the image capture unit.
6. The image capture apparatus according to claim 1, wherein the exposure controller changes the exposure conditions by controlling at least one of a projection volume and a projection time of the projector unit.
7. The image capture apparatus according to claim 1, wherein the exposure controller controls the image capture unit and the projector unit such that an exposure volume of the image capture unit to light projected by the projector unit is constant.
8. An image capture method comprising:
capturing an image by using a photo detector element which provides an output value varied depending on a light reception volume;
projecting light to an area targeted for the image capture in synchronization with the capture of the image;
obtaining a synchronous detection image by subtracting an output value of an image captured with no light projected, from an output value of an image captured with light projected;
controlling the image capture and light projection in such a manner as to obtain two or more synchronous detection images under different exposure conditions in the image capture;
selecting one or more pixels from the rest of pixels at each position in the two or more synchronous detection images excluding a pixel having a lowest output value, and generating a synchronous detection image by using the selected one or more pixels.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus for BTU measurement of natural gas comprising:
at least one reference spherical acoustic resonator containing a reference gas;
a sample gas spherical acoustic resonator containing a natural gas sample;
a first acoustic transmitter adapted to transmit a first acoustic signal into said natural gas sample;
a second acoustic transmitter adapted to transmit a second acoustic signal into said reference gas;
a first acoustic receiver adapted to receive at least a portion of said first acoustic signal;
a second acoustic receiver adapted to receive at least a portion of said second acoustic signal;
data processing means operably connected with a signal output of said first acoustic receiver for determining a specific gravity of said natural gas sample based upon said first acoustic signal received by said first acoustic receiver; and
conversion means for converting said specific gravity of said natural gas sample to a heating value of said natural gas sample.
2. An apparatus in accordance with claim 1 further comprising a second reference spherical acoustic resonator containing a second reference gas.
3. An apparatus in accordance with claim 1 further comprising nitrogen measurement means disposed in said sample gas spherical acoustic resonator for measuring a nitrogen content of said natural gas sample.
4. An apparatus in accordance with claim 3, wherein said nitrogen measurement means is an oxygen sensor.
5. An apparatus in accordance with claim 2 further comprising switching means for switching transmission of said second acoustic signal between said first reference gas and said second reference gas.
6. An apparatus in accordance with claim 1 further comprising control means for controlling BTU content of natural gas operably connected with said data processing means.
7. An apparatus in accordance with claim 6, wherein said control means comprises a SCADA system.
8. A method for real-time measurement of BTU content of natural gas comprising:
introducing a reference gas into a first hollow spherical acoustic resonator;
introducing a natural gas sample into a second hollow spherical acoustic resonator substantially identical to said first hollow spherical acoustic resonator;
transmitting a first acoustic signal through said natural gas sample;
transmitting a second acoustic signal through said reference gas;
measuring a third radial resonance frequency in each of said reference gas and said natural gas;
determining a specific gravity of said natural gas sample; and
determining said BTU content based upon said specific gravity.
9. A method in accordance with claim 8, wherein said reference gas and said natural gas are maintained at a substantially constant temperature and pressure.
10. A method in accordance with claim 8 further comprising determining an oxygen content of said natural gas sample.
11. A method in accordance with claim 8, wherein a frequency of said first acoustic signal and said second acoustic signal is less than about 50 kHz.
12. A method in accordance with claim 10, wherein said first acoustic signal is transmitted through a second reference gas in a third hollow spherical acoustic resonator upon determination of a threshold amount of oxygen in said natural gas sample.
13. An apparatus for Btu measurement of pipeline gas comprising:
a reference gas sphere containing a reference gas;
a sample gas sphere containing a pipeline gas sample;
a sample gas sphere acoustic transmitter adapted to transmit an acoustic signal into said pipeline gas sample;
a sample gas sphere acoustic receiver adapted to receive at least a portion of said acoustic signal exiting from said pipeline gas sample;
a reference gas sphere acoustic transmitter adapted to transmit said acoustic signal into said reference gas disposed within said reference gas sphere;
a reference gas sphere acoustic receiver adapted to receive at least a portion of said acoustic signal exiting from said reference gas;
pressure means for maintaining a substantially constant pressure in said reference gas sphere and said sample gas sphere;
temperature means for maintaining a substantially constant temperature in said reference gas sphere and said sample gas sphere; and
radial frequency measurement means for measuring a radial frequency of said reference gas and said pipeline gas sample.
14. An apparatus in accordance with claim 13, wherein said sample gas sphere acoustic receiver is disposed within a sample gas sphere wall of said sample gas sphere.
15. An apparatus in accordance with claim 13, wherein said sample gas sphere acoustic receiver is disposed within a sample gas sphere wall of said sample gas sphere.
16. An apparatus in accordance with claim 13, wherein said reference gas sphere acoustic transmitter is disposed within a reference gas sphere wall of said reference gas sphere.
17. An apparatus in accordance with claim 13, wherein said reference gas sphere receiver is disposed within a reference gas sphere wall of said reference gas sphere.
18. An apparatus in accordance with claim 13, wherein said sample gas sphere acoustic transmitter is aligned to generate at least one radial frequency.
19. An apparatus in accordance with claim 13, wherein said reference gas sphere transmitter is aligned to generate at least one radial frequency.
20. An apparatus in accordance with claim 13, wherein said sample gas sphere and said reference gas sphere have the same size.
21. An apparatus in accordance with claim 13, wherein said sample gas sphere and said reference gas sphere are substantially identical and have an internal diameter of about 2 inches.
22. An apparatus in accordance with claim 13, wherein said reference gas sphere transmitter and said sample gas sphere transmitter are suitable for propagating acoustic waves having frequencies one of less than and equal to about 50 kHz.
23. A method for determining a Btu content of a pipeline fuel gas comprising the steps of:
filling a first hollow spherical resonator with a reference gas;
filling a second hollow spherical resonator substantially identical to said first hollow spherical resonator with a sample gas;
propagating acoustic waves through each of said reference gas and said sample gas;
measuring a radial mode resonance frequency in each of said first hollow spherical resonator and said second hollow spherical resonator;
determining a specific gravity of each of said reference gas and said sample gas; and
determining a heating value of said sample gas based upon said specific gravity.
24. A method in accordance with claim 23, wherein said first hollow sphere resonator and said second hollow sphere resonator have a diameter of one of less than and equal to about 2 inches.
25. A method in accordance with claim 23, wherein said acoustic waves have frequencies one of less than and equal to about 50 kHz.
26. An apparatus for Btu measurement of pipeline gas comprising:
a reference gas spherical resonator containing a reference gas;
a sample gas spherical resonator containing a pipeline gas sample, said sample gas spherical resonator substantially identical to said reference gas spherical resonator;
propagation means for propagating an acoustic signal through each of said reference gas and said pipeline sample gas;
means for maintaining a constant temperature and a constant pressure inside each of said reference gas spherical resonator and said sample gas spherical resonator;
radial frequency measurement means for measuring a third radial resonance frequency of said reference gas and said pipeline gas sample; and
calculation means for calculating a Btu content of said pipeline sample gas.
27. An apparatus in accordance with claim 26, wherein said propagation means is suitable for propagating acoustic waves having frequencies one of less than and equal to about 50 kHz.
28. An apparatus in accordance with claim 26, wherein said reference gas spherical resonator and said sample gas resonator are substantially equal in size.
29. An apparatus in accordance with claim 26, wherein said reference gas spherical resonator and said sample gas resonator have a diameter of one of less than and equal to about 2 inches.