WO2022185691A1 - フォトンカウンティング装置、フォトンカウンティング方法およびフォトンカウンティング処理プログラム - Google Patents
フォトンカウンティング装置、フォトンカウンティング方法およびフォトンカウンティング処理プログラム Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
- H04N25/618—Noise processing, e.g. detecting, correcting, reducing or removing noise for random or high-frequency noise
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
- H04N25/77—Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
- H04N25/772—Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components comprising A/D, V/T, V/F, I/T or I/F converters
- H04N25/773—Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components comprising A/D, V/T, V/F, I/T or I/F converters comprising photon counting circuits, e.g. single photon detection [SPD] or single photon avalanche diodes [SPAD]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
- G01J2001/4413—Type
- G01J2001/442—Single-photon detection or photon counting
Definitions
- the present disclosure relates to a photon counting device, a photon counting method, and a photon counting processing program.
- Patent Documents 1 and 2 describe a photon counting device using a CMOS (Complementary Metal Oxide Semiconductor) image sensor.
- CMOS Complementary Metal Oxide Semiconductor
- photoelectrons generated according to the number of input photons are accumulated as charges.
- the charge accumulated in the photoelectric conversion element is converted into a voltage and amplified by an amplifier.
- a voltage output from the amplifier is converted into a digital value by an A/D converter.
- the photon counting device determines the number of photons of the pixels forming the image sensor based on the digital value output from the A/D converter.
- Non-Patent Documents 1 to 3 describe techniques related to photon counting using a CMOS image sensor.
- readout noise which is random noise, occurs in the amplifier when the voltage amplified by the amplifier is read out.
- the readout noise is large, the probability distribution of observed photoelectrons becomes broad. Therefore, the readout noise of each pixel is desired to be small.
- pixel readout noise may have a certain range of variation. In this case, there is a possibility that the accuracy of photon counting may decrease in pixels with high readout noise.
- An object of one aspect of the present disclosure is to provide a photon counting device capable of suppressing deterioration in photon counting accuracy.
- An example of a photon counting device includes a plurality of pixels including a photoelectric conversion element that converts input light into electric charge, an amplifier that amplifies the electric charge converted by the photoelectric conversion element and converts it into a voltage, and an amplifier of the plurality of pixels.
- a / D converter that converts the voltage output from to a digital value, a first derivation unit that derives a provisional value of the number of photons of each pixel in a plurality of pixels based on the digital value, a first probability and a first a second derivation unit for deriving a deterministic value of the number of photons in the target pixel, which is one of the plurality of pixels, based on a probability of 2, wherein the first probability is associated with the photon number distribution of light.
- the second probability is the observation probability for each photoelectron number in the target pixel based on the probability distribution of the number of photoelectrons, and the second probability is the number of photoelectrons in the provisional value of the target pixel based on the probability distribution of the number of photoelectrons accompanying the readout noise of the target pixel. is the observed probability of
- the first derivation unit derives the provisional value of the number of photons in each pixel based on the magnitude of the digital value corresponding to the amount of charge generated in each pixel. For example, pixels with high readout noise may have large errors in the derived interim values.
- the second derivation unit derives a definitive value of the number of photons when the target pixel exhibits the provisional value, based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light and the probability distribution of the number of photoelectrons associated with readout noise. .
- the definite value of the number of photons is derived in consideration of the magnitude of the readout noise in the target pixel. Therefore, it is possible to reduce the influence of readout noise on the derivation of the deterministic value, thereby improving the accuracy of photon counting.
- An exemplary second derivation unit calculates a probability for each number of photoelectrons when the target pixel indicates a provisional value by multiplying the first probability and the second probability, and calculates a definite value based on the calculated probability. may decide.
- the most probable number of photons can be obtained by setting the number of photoelectrons that indicates the maximum value among the probabilities for each number of photoelectrons when the target pixel indicates a provisional value.
- An example of the probability distribution of the number of photoelectrons associated with the photon number distribution of light is the Poisson distribution, the super-Poisson distribution, the sub-Poisson distribution, the photon number distribution indicated by the photon number squeezed state, the photon number distribution indicated by the quantum entangled photon state, and multimode. It may be any one of a squeezed photon number distribution, a Bose-Einstein distribution, a logarithmic normal distribution, a uniform distribution, or a mixed distribution. With this configuration, the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light can be appropriately described.
- the probability distribution of the number of photoelectrons accompanying the readout noise of the target pixel may be a normal distribution.
- the probability distribution of the number of photoelectrons associated with readout noise can be appropriately described.
- the second derivation unit calculates an average value of provisional values of the peripheral pixels, with two or more pixels included in a partial region around the target pixel among the plurality of pixels as peripheral pixels, and considers the average value. may be used to calculate the first probability. In this configuration, the reliability of the first probability is increased by considering the average value of the number of photoelectrons in the peripheral pixels.
- An example of the average value may be a weighted average including readout noise of peripheral pixels in the weighting. With this configuration, it is possible to obtain a highly reliable average value of the number of photoelectrons in peripheral pixels with small readout noise.
- An example of the average value may be a weighted average that includes the distance between the target pixel and each of the surrounding pixels. With this configuration, it is possible to obtain an average value with increased reliability of the number of photoelectrons of neighboring pixels closer to the target pixel.
- An example of the average value may be a weighted average including a weight that reduces the error from the average value of the number of photons of the surrounding pixels. By using such a weighted average, an improvement in the accuracy of calculating the average value can be expected.
- the second derivation unit may calculate the average value of the provisional values based on the data of the provisional values in a plurality of frames. By using provisional values in a plurality of frames in this manner, an improvement in the accuracy of calculation of the average value can be expected.
- An exemplary second derivation unit includes a definite value derived from a pixel having readout noise equal to or greater than a predetermined value among the plurality of pixels as a target pixel, and a pixel having readout noise less than the predetermined value among the plurality of pixels. Photon-counting data for a plurality of pixels may be created with the provisional values. With this configuration, calculation for deriving the observation probability is not required for pixels having readout noise less than a predetermined value.
- An exemplary second derivation unit calculates a definite value derived from a pixel having a provisional value less than a predetermined value among the plurality of pixels as a target pixel, and a pixel having a provisional value equal to or greater than the predetermined value among the plurality of pixels. Photon-counting data for a plurality of pixels may be created with the provisional values. With this configuration, calculation for deriving the observation probability is not required for pixels having a provisional value equal to or greater than a predetermined value.
- the example second derivation unit may have a noise map indicating the readout noise of each of the plurality of pixels. That is, the second derivation unit may derive the second probability by referring to data including the noise map.
- An example photon counting method includes: deriving a provisional value of the number of photons for each of the plurality of pixels based on digital values corresponding to the plurality of pixels output from a two-dimensional image sensor having a plurality of pixels; deriving a deterministic value of the number of photons in the target pixel, which is one of the plurality of pixels, based on the first probability and the second probability; deriving the deterministic value includes: As the probability of , the observation probability for each number of photoelectrons in the target pixel is obtained based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light. determining an observation probability for each number of photoelectrons in the provisional value of the target pixel based on the distribution.
- a provisional value of the number of photons in each pixel is derived based on the magnitude of the digital value corresponding to the amount of charge generated in each pixel. For example, pixels with high readout noise may have large errors in the derived interim values. Further, based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light and the probability distribution of the number of photoelectrons associated with readout noise, a definitive value of the number of photons when the target pixel exhibits the provisional value is derived. In this way, the definite value of the number of photons is derived in consideration of the magnitude of the readout noise in the target pixel. Therefore, it is possible to reduce the influence of readout noise on the derivation of the deterministic value, thereby improving the accuracy of photon counting.
- An example of deriving a definite value is to calculate the probability for each number of photoelectrons when the target pixel indicates the provisional value by multiplying the first probability and the second probability, and determine based on the calculated probability. value may be determined.
- the most probable number of photons can be obtained by setting the number of photoelectrons that indicates the maximum value among the probabilities for each number of photoelectrons when the target pixel indicates a provisional value.
- An example of deterministic value is derived from the probability distribution of the number of photoelectrons accompanying the photon number distribution of light, such as Poisson distribution, super-Poisson distribution, sub-Poisson distribution, photon number distribution indicated by photon number squeezed state, quantum entangled photon state , a multimode squeezed photon number distribution, a Bose-Einstein distribution, a logarithmic normal distribution, a uniform distribution, or a mixed distribution.
- the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light can be appropriately described.
- a normal distribution may be used as the probability distribution of the number of photoelectrons associated with the readout noise of the target pixel to derive an example of the definite value. With this configuration, the probability distribution of the number of photoelectrons associated with readout noise can be appropriately described.
- An example of deriving a definite value is to use two or more pixels included in a partial region around the target pixel among a plurality of pixels as peripheral pixels, calculate the average value of the provisional values of the peripheral pixels, and calculate the average value may be calculated in consideration of the first probability.
- the reliability of the first probability is increased by considering the average value of the number of photoelectrons in the peripheral pixels.
- An example of deriving a definite value may use a weighted average including the readout noise of surrounding pixels in the weighting as the average value. With this configuration, it is possible to obtain a highly reliable average value of the number of photoelectrons in peripheral pixels with small readout noise.
- An example of deriving a definite value may use a weighted average that includes the distance between the target pixel and each of the surrounding pixels as the average value. With this configuration, it is possible to obtain an average value with increased reliability of the number of photoelectrons of neighboring pixels closer to the target pixel.
- An example of deriving a definite value may use a weighted average that includes a weight that reduces the error from the average value of the number of photons of surrounding pixels as the average value. By using such a weighted average, an improvement in the accuracy of calculating the average value can be expected.
- Deriving the definitive value of one example may be performed by calculating an average value of the provisional values based on the data of the provisional values in multiple frames. By using provisional values in a plurality of frames in this manner, an improvement in the accuracy of calculation of the average value can be expected.
- An example method is to calculate a definite value derived from a plurality of pixels having readout noise of a predetermined value or more as a target pixel, and a provisional value of a pixel having a readout noise of less than a predetermined value among the plurality of pixels. may further include generating photon counting data for the plurality of pixels by. With this configuration, calculation for deriving the observation probability is not required for pixels having readout noise less than a predetermined value.
- An example method is to calculate a definite value derived from a plurality of pixels having a provisional value less than a predetermined value as a target pixel, and a provisional value of a pixel having a provisional value greater than or equal to the predetermined value among the plurality of pixels. may further include generating photon counting data for the plurality of pixels by. With this configuration, calculation for deriving the observation probability is not required for pixels having a provisional value equal to or greater than a predetermined value.
- Deriving the deterministic value may refer to a noise map indicating the readout noise of each of a plurality of pixels.
- the second probability may be derived based on data including noise maps.
- An example photon counting processing program is a program that causes a computer to execute photon counting processing based on digital values corresponding to a plurality of pixels output from a two-dimensional image sensor having a plurality of pixels, wherein the digital value is Based on, a first derivation process for deriving a provisional value of the number of photons of each pixel in a plurality of pixels, and a target pixel, which is one of the plurality of pixels, based on the first probability and the second probability a second derivation process for deriving a definitive value of the number of photons, and the first probability is the observation probability for each number of photoelectrons in the target pixel based on the probability distribution of the number of photoelectrons accompanying the distribution of the number of photons of light. and the second probability is an observation probability for each number of photoelectrons in the provisional value of the target pixel based on the probability distribution of the number of photoelectrons accompanying the readout noise of the target pixel.
- the photon counting device and the photon counting method it is possible to suppress a decrease in photon counting accuracy.
- FIG. 1 is a diagram showing the configuration of an example of a photon counting device.
- FIG. 2 is a schematic diagram showing a pixel group of 3 rows ⁇ 3 columns.
- FIG. 3 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 4 is a schematic diagram for explaining the definite value derivation unit.
- FIG. 5 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 6 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 7 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 8 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 9 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 1 is a diagram showing the configuration of an example of a photon counting device.
- FIG. 2 is a schematic diagram showing a pixel group of 3 rows ⁇ 3 columns.
- FIG. 3 is a diagram showing the
- FIG. 10 is a diagram comparing the probabilities of FIGS.
- FIG. 11 is a schematic diagram for explaining a definite value derivation unit.
- FIG. 12 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 13 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 14 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 15 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 16 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 17 is a schematic diagram for explaining a definite value derivation unit.
- FIG. 18 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 12 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 13 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 14 is a diagram showing the probability distribution of the number of photo
- FIG. 19 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 20 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 21 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 22 is a flow chart showing the operation of an example photon counting device.
- FIG. 23 is a diagram showing the process of deriving a definite value from a pixel value. It is a figure which shows a photon counting processing program.
- FIG. 25 is a diagram for explaining an example of photon counting results.
- FIG. 26 is a diagram for explaining an example of photon counting results.
- FIG. 27 is a schematic diagram showing another form of peripheral pixels.
- FIG. 28 is a schematic diagram showing another form of peripheral pixels.
- FIG. 28 is a schematic diagram showing another form of peripheral pixels.
- FIG. 29 is a schematic diagram showing another form of peripheral pixels.
- FIG. 30 is a schematic diagram showing another form of peripheral pixels.
- FIG. 31 is a diagram for explaining another example of weighted averaging.
- FIG. 32 is a diagram for explaining another example of weighted averaging.
- FIG. 33 is a diagram for explaining another example of weighted averaging.
- photon counting refers to counting the number of photoelectrons generated in each pixel of the image sensor, and counting the number of photons considering the quantum efficiency (QE) of the image sensor. including both. Photon counting like these is also called photon number resolving. In general, photon counting also includes both detection of photoelectrons generated at each pixel of the image sensor and detection of photons incident on each pixel of the image sensor.
- FIG. 1 is a diagram showing the configuration of an example photon counting device.
- an exemplary photon counting device includes a CMOS image sensor 10 as a two-dimensional image sensor, and a computer (controller) 20 connected to the CMOS image sensor 10 .
- the CMOS image sensor 10 includes multiple pixels 11 and an A/D converter 15 .
- the plurality of pixels 11 are two-dimensionally arranged. That is, the plurality of pixels 11 are arranged in row direction and column direction.
- Each pixel 11 has a photodiode (photoelectric conversion element) 12 and an amplifier 13 .
- the photodiode 12 stores photoelectrons generated by the input of photons as charges.
- the amplifier 13 converts the charge accumulated in the photodiode 12 into a voltage and amplifies the converted voltage.
- the amplified voltage is transferred to the vertical signal line 16 line by line (row) by switching the selection switch 14 of each pixel 11 .
- Each vertical signal line 16 is provided with a CDS (correlated double sampling) circuit 17 .
- the CDS circuit 17 removes noise that varies between pixels and temporarily stores the transferred voltage.
- the A/D converter 15 converts the voltage output from each amplifier 13 in the plurality of pixels 11 into a digital value.
- the A/D converter 15 may be provided in each pixel 11 .
- the A/D converter 15 converts the voltage stored in the CDS circuit 17 into a digital value.
- the converted digital values are output to the computer 20 respectively.
- the digital value may be sent to a horizontal signal line (not shown) and output to the computer 20 by switching the column selection.
- the CMOS image sensor 10 outputs to the computer 20 a digital value corresponding to the number of photons input (the number of photoelectrons generated). It should be noted that when the voltage amplified by the amplifier 13 is read out, readout noise, which is random noise, is generated within the amplifier 13 .
- the computer 20 is physically configured with storage devices such as RAM and ROM, processors (arithmetic circuits) such as CPU and GPU, and communication interfaces. Examples of the computer 20 include personal computers, cloud servers, smart devices (smartphones, tablet terminals, etc.), microcomputers, and FPGAs (field-programmable gate arrays).
- the computer 20 functions as a storage unit 21, a conversion unit 22, a data processing unit 23, and a control unit 24 by executing a program stored in the storage device with a processor of the computer system.
- the computer 20 may be arranged inside the camera device including the CMOS image sensor 10, or may be arranged outside the camera device.
- a display device 25 and an input device 26 may be connected to the computer 20 .
- Display device 25 is, for example, a display capable of displaying the photon counting results obtained by computer 20 .
- the input device 26 may be a keyboard, mouse, or the like for the user to input measurement conditions. Note that the display device 25 and the input device 26 may be touch screens. Display device 25 and input device 26 may be included in computer 20 . Also, the display device 25 and the input device 26 may be provided in a camera device including the CMOS image sensor 10 .
- the storage unit 21 stores data for converting the digital value output from the CMOS image sensor 10 into the number of photons. For example, the storage unit 21 stores gain and offset values for each of the pixels 11 as a lookup table. The storage unit 21 also stores the readout noise of each of the plurality of pixels 11 as a lookup table (noise map).
- a digital value [DN] output from the A/D converter 15 described above is expressed by the following equation (1). Therefore, the offset value [DN] is indicated as a digital value output when no light is input. Therefore, in one example, a plurality of digital values are acquired from a plurality of dark images acquired by the CMOS image sensor 10 in a state where no light is input, and the acquired digital values are averaged for each pixel 11. An offset value is obtained. Also, when acquiring the gain [DN/e] of each pixel 11, a plurality of frame images are acquired by the CMOS image sensor 10 with a sufficient amount of light. Then, the average optical signal value S[DN] and the standard deviation N[DN] of the digital values in each pixel 11 are obtained. The gain is derived from the average optical signal value S and the standard deviation N, since it is expressed as N 2 /S.
- the readout noise is defined, for example, as fluctuations in digital values, and can be expressed as a value converted into the number of electrons. Therefore, by obtaining the standard deviation of the digital value for each pixel 11 in a plurality of dark images (for example, 100 frames or more) and dividing the obtained standard deviation by the gain of the pixel 11, the readout noise for each pixel 11 is obtained.
- the offset value, gain and readout noise for each pixel may be obtained during the manufacturing process of the photon counting device.
- the conversion unit 22 refers to the table stored in the storage unit 21 and converts the digital values for each of the plurality of pixels 11 output from the A/D converter 15 into the number of photons (the number of photoelectrons).
- the number of photons per pixel 11 can be obtained by dividing the number of photoelectrons by the quantum efficiency. When the quantum efficiency is 100%, the number of photoelectrons and photons are the same.
- the data processing unit 23 creates a two-dimensional image showing the number of photons in each pixel 11 based on the number of photons output from the conversion unit 22 .
- the two-dimensional image may be an image in which each pixel is drawn with luminance corresponding to the number of photons.
- the created two-dimensional image can be output to the display device 25 .
- the data processing unit 23 may also create a histogram or the like that is a plot of the number of pixels against the number of photons.
- the control unit 24 can centrally control each functional unit of the computer 20 and the CMOS image sensor 10 .
- the conversion unit 22 will be described in detail below.
- a group of pixels arranged in 3 rows ⁇ 3 columns may be referred to as a partial area of the image sensor composed of a plurality of pixels.
- FIG. 2 is a schematic diagram showing a pixel group of 3 rows ⁇ 3 columns.
- the readout noise corresponding to each pixel 11 constituting the pixel group is indicated by the symbol "R i " (i indicates the position of the pixel).
- the conversion unit 22 can appropriately refer to the gain, offset value, and readout noise of each pixel 11 by referring to the lookup table held by the storage unit 21 .
- An example conversion unit 22 includes a provisional value derivation unit 22a (first derivation unit) and a fixed value derivation unit 22b (second derivation unit).
- the provisional value deriving unit 22a derives a provisional value of the number of photons of each pixel 11 among the plurality of pixels 11 based on the digital value.
- the provisional value derivation unit 22a the number of photoelectrons obtained by dividing the value obtained by subtracting the offset value from the measured digital value by the gain is converted to a provisional value of the number of photons (first provisional value) for each pixel 11.
- the first provisional value may be referred to as a pixel value.
- the provisional value derivation unit 22a may derive an integer value of the number of photons estimated from the pixel value as a provisional value (second provisional value).
- the second provisional value may be referred to as the provisional number of photons.
- the provisional number of photons may be obtained by rounding the pixel value to the nearest whole number.
- the pixel value may be converted into the provisional photon number by setting a predetermined threshold range for the pixel value. For example, the threshold range corresponding to 5 photoelectrons is greater than or equal to 4.5e and less than 5.5e.
- the provisional value (for example, the number of provisional photons) of each pixel 11 constituting the pixel group is indicated by the symbol "k i " (i indicates the position of the pixel).
- the definite value derivation unit 22b derives (determines) the definite value of the number of photons of each of the plurality of pixels 11. For example, the definite value deriving unit 22b takes one of the plurality of pixels 11 as a target pixel and derives the definite value of the number of photons in the target pixel. By setting each of a plurality of pixels constituting the two-dimensional image sensor as a target pixel, a definite value of the number of photons in all pixels is derived.
- the definite value derivation unit 22b derives the first probability and the second probability, and based on the derived first probability and the second probability, calculates the definite value of the number of photons in the target pixel.
- the first probability is the observation probability for each number of photoelectrons in the target pixel based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light, and is expressed by the following equation (3).
- the first probability in one example is based on the probability distribution of the number of photoelectrons accompanying optical shot noise and follows the Poisson distribution.
- the first probability is the probability (observation probability) that the number of photons in the target pixel is observed to be k when the average number of photons in the target pixel is ⁇ , and is obtained for each number of photoelectrons.
- the photon number k is a provisional photon number assumed by the definite value derivation unit 22b. That is, the number of photons k can be said to be a provisional value (third provisional value) of the number of photons in the target pixel.
- the third provisional value may be referred to as the assumed number of photons.
- the average number of photons may be an average of provisional values of peripheral pixels.
- Peripheral pixels may be defined as two or more pixels included in a partial region around the target pixel among the plurality of pixels.
- the central pixel 11c may be defined as the target pixel, and the pixel group of 3 rows ⁇ 3 columns may be the peripheral pixels.
- the average number of photons in the target pixel is the average value of the provisional values of the pixels 11 forming the peripheral pixels.
- the provisional value of the target pixel among the surrounding pixels may be the assumed number of photons. That is, in FIG.
- k0 when deriving the average number of photons of pixel 11c, k0 may be the assumed number of photons.
- the provisional values of the peripheral pixels excluding the target pixel may be either the pixel value or the provisional number of photons. Either the pixel value or the provisional number of photons may be used as the provisional value of the target pixel instead of the assumed number of photons.
- the definite value derivation unit 22b may refer to a noise map indicating the readout noise of each of the plurality of pixels 11, and calculate a weighted average including the readout noise of surrounding pixels in the weighting as the average number of photons.
- the weight W i (i indicates the position of the pixel) based on the readout noise is expressed by the following equation (4), for example. That is, an example weight W i may be the inverse power of the read noise R i .
- the provisional value is more likely to be reflected in the average number of photons for pixels with smaller readout noise, and the provisional value is less likely to be reflected in the average number of photons for pixels with greater readout noise.
- the confidence ⁇ can increase or decrease the influence of readout noise on the weights W i . That is, the greater the reliability ⁇ , the greater the influence of the readout noise on the weight Wi. In one example, ⁇ 0. Note that if the value of the reliability ⁇ becomes too large, it is conceivable that a correct definite value will not be derived. Thus, in one example, the reliability ⁇ may be less than 20.
- the reliability ⁇ may be a value preset in the definite value derivation unit 22b, or may be a value that can be set by the user of the photon counting device 1.
- Equation (5) The average number of photons ⁇ based on the weighted average is given by Equation (5) below.
- the second probability is the observation probability for each number of photoelectrons in the provisional value of the target pixel based on the probability distribution of the number of photoelectrons associated with the readout noise of the target pixel, and is expressed by Equation (6) below.
- the provisional value of the target pixel may be a pixel value.
- the second probability follows a normal distribution (Gaussian distribution).
- x is the pixel value [e] of the target pixel
- R is the readout noise [e-rms] of the target pixel. That is, the second probability is the probability (observation probability) that the number of photons of the target pixel is observed to be k in the provisional value (for example, pixel value) of the target pixel, and is obtained for each number of photoelectrons.
- the definite value derivation unit 22b calculates the probability for each number of photoelectrons when the target pixel indicates the provisional value, and calculates the number of photons based on the calculated probability. determine the definite value of That is, the definite value deriving unit 22b as an example calculates the probability for each assumed photon number when the target pixel exhibits the provisional value based on the following equation (7) while changing the assumed number of photons of the target pixel, The value of the assumed number of photons with the highest probability is output as the confirmed value of the number of photons.
- the range of the assumed number of photons calculated by the definite value derivation unit 22b may be determined based on the provisional value and the average number of photons of the target pixel.
- the assumed photon number range may be the minimum range that includes the provisional value of the target pixel and the average photon number.
- the average number of photons may be calculated without including the provisional value of the target pixel.
- the range of the assumed number of photons may be a range from 0 to the maximum provisional value of the peripheral pixels.
- the above equation (7) may be modified as follows for ease of calculation. That is, the log of both sides of the above equation (7) is taken, and the following equation (8) is derived.
- Equation (8) above may be approximated as in Equation (9) below.
- the definite value deriving unit 22b which is an example, can derive the definite value of the number of photons based on the following equation (9).
- FIG. 3 is a diagram showing the probability distribution of the number of photoelectrons.
- FIG. 3 shows the probability distribution of the number of photoelectrons when the pixel value of the target pixel is 4.2 [e] and the average number of photons of the target pixel is 2.5 photons.
- the first probability distribution when the assumed number of photons is 3 photons is indicated by a thick line L1
- the second probability distribution when the assumed number of photons is 3 photons is indicated by a dashed line L2.
- a solid line L3 indicates the probability distribution of the product of the first probability and the second probability when the assumed number of photons is 3 photons.
- the second probability when the assumed number of photons is 3 photons and the pixel value is 4.2 [e] is indicated by the dashed line L4. ], ie, P(3
- the definite value deriving unit 22b uses the provisional values of the surrounding pixels as clues to derive the most probable number of photons in the target pixel as the definite value of the target pixel.
- the fixed value derivation unit 22b will be further described below using specific numerical values.
- three examples are described: an example in which the readout noise of the target pixel is large, an example in which the readout noise of the target pixel is small, and an example in which the amount of light to the two-dimensional image sensor is large.
- a group of pixels arranged in 3 rows and 3 columns is described as peripheral pixels, but in the following, for the sake of simplicity of explanation, the peripheral pixels are arranged in 1 row and 3 columns. described as. In this case, the center pixel is the target pixel.
- FIG. 4 shows an example when the readout noise of the target pixel is large.
- (a) of FIG. 4 shows the pixel value [e] of each pixel 11 .
- (b) of FIG. 4 shows the provisional number of photons of each pixel 11 .
- (c) of FIG. 4 shows the readout noise of each pixel 11 .
- (d) of FIG. 4 shows the weight of each pixel 11 in the weighted average.
- the pixel values [e] of the three pixels 11 are respectively "1.1", “4.2” and "0.3”, and the provisional photon numbers of the three pixels are respectively "1". , "4" and "0".
- the readout noise [e-rms] of the three pixels is "0.2", "2.0” and "0.4", respectively.
- the reliability ⁇ is "2”
- the weights of the three pixels are "25", "0.25", and "6.25".
- the definite value derivation unit 22b derives the probability of the assumed number of photons under the pixel value of 4.2 [e] based on the above equation (9) while changing the assumed number of photons.
- 5 to 9 are diagrams showing the probability of the number of photoelectrons in the case of the example of FIG. 5 to 9 show the Poisson distribution according to the average number of photons and P(k
- FIG. 5 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "0". In the example of FIG. 5, since the assumed number of photons is "0", the average number of photons of the target pixel is approximately 0.79 [e]. Also, in FIG. 5, the probability that the assumed number of photons is "0" when the pixel value is 4.2 is shown at the position of the number of photoelectrons of 4.2 [e].
- FIG. 6 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "1". In the example of FIG. 6, since the assumed number of photons is "1", the average number of photons of the target pixel is approximately 0.80. Also, in FIG. 6, the probability that the assumed number of photons is "1" when the pixel value is 4.2 is shown at the position of the number of photoelectrons of 4.2 [e].
- FIG. 7 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "2". In the example of FIG. 7, since the assumed number of photons is "2", the average number of photons of the target pixel is approximately 0.81. In FIG.
- FIG. 8 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "3". In the example of FIG. 8, since the assumed number of photons is "3", the average number of photons of the target pixel is approximately 0.82. In FIG. 8, the probability that the number of assumed photons is "3" when the pixel value is 4.2 is shown at 4.2[e].
- FIG. 9 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "4". In the example of FIG. 9, since the assumed number of photons is "4", the average number of photons of the target pixel is approximately 0.83. In FIG. 9, the probability that the assumed number of photons is "4" when the pixel value is 4.2 is shown at 4.2[e].
- FIG. 10 is an enlarged view of the position where the number of photoelectrons is 4.2 [e] in FIGS. 5 to 9 for comparison. As shown in FIG. 10, in the example of FIG. 4, the probability is highest when the assumed number of photons is "1".
- the deterministic value derivation unit 22b which is an example, compares the probabilities obtained by the calculation result of Equation (9), and derives 1[e] as the deterministic value of the number of photons of the target pixel.
- FIG. 11 shows an example when the readout noise of the target pixel is small.
- (a) of FIG. 11 shows the pixel value [e] of each pixel.
- (b) of FIG. 11 shows the provisional number of photons for each pixel.
- (c) of FIG. 11 shows the readout noise [e-rms] of each pixel.
- (d) of FIG. 11 shows the weight of each pixel in the weighted average.
- the pixel values [e] of the three pixels are "1.1", “4.2", and “0.3”, respectively, and the provisional photon numbers of the three pixels are "1", It is derived as "4" and "0".
- the readout noise [e-rms] of the three pixels is "0.2", “0.3” and "0.4", respectively.
- the reliability ⁇ is "2”
- the weights of the three pixels are "25", “11.1", and "6.25".
- the definite value derivation unit 22b derives the probability of the assumed number of photons when the pixel value is 4.2 based on the above equation (9) while changing the assumed number of photons.
- 12 to 16 are diagrams showing the probability of the number of photoelectrons in the case of the example of FIG. 11.
- FIG. 12 to 16 show the Poisson distribution according to the average number of photons and P(K0
- the assumed number of photons k is "0"
- the average number of photons of the target pixel is approximately 0.59.
- FIG. 12 also shows the probability that the assumed number of photons is "0" when the pixel value is 4.2.
- the probability that the assumed number of photons is "0" when the pixel value is 4.2 is shown at the position of the number of photoelectrons of 4.2 [e].
- FIG. 13 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "1".
- the average number of photons of the target pixel is approximately 0.85.
- the probability that the assumed number of photons is "1" when the pixel value is 4.2 is shown at the position of the number of photoelectrons of 4.2 [e].
- FIG. 14 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "2". In the example of FIG. 14, since the assumed number of photons is "2", the average number of photons of the target pixel is approximately 1.11. Also, in FIG.
- FIG. 15 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "3". In the example of FIG. 15, since the assumed number of photons is "3", the average number of photons of the target pixel is approximately 1.38. Also, in FIG. 15, the probability that the assumed number of photons is "3" when the pixel value is 4.2 is shown at the position of the number of photoelectrons of 4.2 [e].
- FIG. 16 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "4". In the example of FIG.
- the average number of photons of the target pixel is approximately 1.64. Also, in FIG. 16, the probability that the assumed number of photons is "4" when the pixel value is 4.2 is shown at the position of the number of photoelectrons of 4.2 [e].
- the probability of the assumed number of photons other than "4" is almost zero. Therefore, the definite value derivation unit 22b derives "4" as the definite value of the number of photons of the target pixel.
- FIG. 17 shows an example in which the amount of light for a two-dimensional image sensor is large.
- (a) of FIG. 17 shows the pixel value of each pixel.
- (b) of FIG. 17 shows the provisional number of photons for each pixel.
- (c) of FIG. 17 shows the readout noise of each pixel.
- (d) of FIG. 17 shows the weight of each pixel in the weighted average.
- the pixel values of the three pixels are "108.4", "92.6” and “95.1” respectively, and the provisional photon numbers of the three pixels are "108" and "93” respectively. , “95”.
- the readout noises of the three pixels are "0.2", "2.0", and “0.4", respectively.
- the reliability ⁇ is "2”
- the weights of the three pixels are "25", "0.25", and "6.25".
- the definite value derivation unit 22b derives the probability of the assumed number of photons when the pixel value is 4.2 based on the above formula while changing the assumed number of photons.
- 18 to 21 are diagrams showing the probability of the number of photoelectrons in the case of the example of FIG. 17.
- FIG. 18 to 21 show the Poisson distribution according to the average number of photons and P(K0
- the assumed number of photons is "92"
- the average number of photons of the target pixel is approximately 105.29.
- the probability that the assumed number of photons is "92" when the pixel value is 92.6 is shown at the position of the number of photoelectrons 92.6 [e].
- FIG. 19 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "93".
- the average number of photons of the target pixel is approximately 105.30.
- the probability that the assumed number of photons is "93" when the pixel value is 92.6 is shown at the position of the number of photoelectrons 92.6 [e].
- FIG. 20 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "94”. In the example of FIG. 20, since the assumed number of photons is "94", the average number of photons of the target pixel is approximately 105.31. In FIG.
- FIG. 21 is a diagram showing the probability of the number of photoelectrons when the assumed number of photons is "95".
- the probability that the assumed number of photons is "95” when the pixel value is 92.6 is shown at the position of the number of photoelectrons of 92.6 [e].
- FIG. 22 is a flowchart showing the operation of the photon counting device (photon counting method).
- photons incident on the pixels 11 of the CMOS image sensor 10 are converted into charges by the photodiodes 12 (step S11).
- the converted charges are converted into voltage by the amplifier 13 (step S12).
- the voltage is converted into a digital value by the A/D converter 15 and output to the computer 20 (step S13).
- the provisional value derivation unit 22a of the conversion unit 22 derives a provisional value from the digital value based on the gain and offset value of each pixel obtained by referring to the table of the storage unit 21 (step S14).
- the definite value derivation unit 22b derives the definite value of the number of photons from, for example, equation (9) based on the provisional value of each pixel and the readout noise (step S15).
- FIG. 23 (a) of FIG. 23 is a diagram showing readout noise of each pixel 11 in a two-dimensional image sensor having pixels of 4 rows ⁇ 4 columns.
- FIG. 23(b) is a diagram showing the process of deriving a definite value from the pixel value of each pixel.
- the definite value derivation unit 22b determines the definite value of the number of photons for each of the plurality of pixels 11 by the method described above. That is, the definite value derivation unit 22b creates photon counting data composed of definite values of the number of photons in each pixel 11 based on the definite values derived from each of the plurality of pixels 11 as the target pixel.
- FIG. 23 is a diagram showing readout noise of each pixel 11 in a two-dimensional image sensor having pixels of 4 rows ⁇ 4 columns.
- FIG. 23(b) is a diagram showing the process of deriving a definite value from the pixel value of each pixel.
- the pixel value of each pixel 11 is converted into a provisional value and further converted into a definite value.
- 1[e] is derived as the provisional value
- 1[e] is derived as the final value.
- the provisional value and the final value are different values.
- the peripheral pixels are a pixel group of 3 rows ⁇ 3 columns centering on the target pixel. Pixels included in an area corresponding to three columns of pixels are peripheral pixels. When the pixel 11a with a pixel value of 1.2[e] is the target pixel, four pixels in the region R are peripheral pixels. As described above, the number of photons is measured for each of a plurality of pixels. The measurement result (photon counting data) is output to the display device 25 as, for example, image data (step S16).
- FIG. 24 is a diagram showing a recording medium 100 storing a program P1 for causing a computer to execute photon counting processing.
- a photon counting processing program P1 stored in the recording medium 100 includes a provisional value derivation module P22a, a definite value derivation module P22b, a data processing module P23, and a control module P24.
- Provisional value derivation module P22a Functions (processes) realized by executing the provisional value derivation module P22a, the fixed value derivation module P22b, the data processing module P23, and the control module P24 are respectively the provisional value derivation unit 22a (first derivation processing), the determination This is the same as the function (processing) of the value derivation unit 22b (second derivation processing), data processing unit 23, and control unit 24.
- the photon counting processing program P1 is recorded in the program recording area of the recording medium 100.
- the recording medium 100 is composed of a recording medium such as a CD-ROM, DVD, ROM, semiconductor memory, or the like.
- the photon counting processing program P1 may be provided via a communication network as a computer data signal superimposed on a carrier wave.
- one example of the photon counting device 1 includes a plurality of photodiodes 12 that convert input light into electric charges and amplifiers 13 that amplify the electric charges converted by the photodiodes 12 and convert them into voltages.
- the first probability is the observation probability for each number of photoelectrons in the target pixel based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light
- the second probability is the probability of the number of photoelectrons associated with the readout noise of the target pixel. It is the observation probability for each number of photoelectrons in the provisional value of the target pixel based on the distribution.
- the provisional value derivation unit 22a derives the provisional value of the number of photons in each pixel 11 based on the magnitude of the digital value corresponding to the amount of charge generated in each pixel 11. For example, a pixel 11 with large readout noise may have a large error included in the derived provisional value.
- the definite value deriving unit 22b derives the definite value of the number of photons when the target pixel exhibits the provisional value, based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light and the probability distribution of the number of photoelectrons associated with readout noise. do.
- the definite value of the number of photons is derived in consideration of the magnitude of the readout noise in the target pixel. Therefore, it is possible to reduce the influence of readout noise on the derivation of the deterministic value, thereby improving the accuracy of photon counting.
- the definite value deriving unit 22b calculates the probability for each assumed number of photons when the target pixel indicates the provisional value by multiplying the first probability and the second probability, and determines the probability based on the calculated probability. determine the value.
- the most probable number of photons can be obtained by setting the number of assumed photons that indicates the maximum value among the probabilities for each number of assumed photons when the target pixel indicates a provisional value.
- the probability distribution of the number of photoelectrons accompanying the photon number distribution of light in one example is based on the Poisson distribution. With this configuration, the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light can be appropriately described. In addition, the probability distribution of the number of photoelectrons accompanying the readout noise of the target pixel in one example is based on the normal distribution. With this configuration, the probability distribution of the number of photoelectrons associated with readout noise can be appropriately described.
- the definite value deriving unit 22b calculates the average value of the provisional values of the surrounding pixels, with two or more pixels 11 included in a partial region around the target pixel among the plurality of pixels 11 as surrounding pixels. A first probability is calculated taking into account the values. More specifically, the fixed value deriving unit 22b calculates the number of photoelectrons in the target pixel based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons of light, using the average value of the provisional values of the surrounding pixels as the average number of photons in the target pixel. Derive the observation probability for each In this configuration, the reliability of the first probability is increased by considering the average value of the number of photoelectrons in the peripheral pixels.
- the definite value derivation unit 22b as an example has a noise map indicating the readout noise of each of the plurality of pixels 11.
- the definite value derivation unit 22b can derive the second probability by referring to data including the noise map.
- the definite value derivation unit 22b can refer to the noise map to calculate the weighted average.
- the definite value derivation unit 22b which is an example, calculates a weighted average including the readout noise of the peripheral pixels in the weighting as the average value. With this configuration, it is possible to obtain a highly reliable average value of the number of photoelectrons in peripheral pixels with small readout noise.
- An example of the average value is a weighted average that includes the distance between the target pixel and each of the surrounding pixels. With this configuration, it is possible to obtain an average value with increased reliability of the number of photoelectrons of neighboring pixels closer to the target pixel.
- the definite value deriving unit 22b may derive the same value as the provisional number of photons of the target pixel as the definite value of the target pixel when the readout noise of the target pixel is small. That is, the definite value derivation unit 22b calculates the definite value derived from pixels having readout noise equal to or greater than a predetermined value among the plurality of pixels as target pixels, and the pixels having readout noise less than the predetermined value among the plurality of pixels.
- Photon counting data for a plurality of pixels may be generated based on the provisional value of .
- the definite value derivation unit 22b may derive the provisional value as the definite value for pixels with readout noise of less than 0.4 [e-rms].
- the definite value derivation unit 22b may perform the above calculation for deriving the definite value only for pixels with readout noise of 0.4 [e-rms] or more.
- the definite value derivation unit 22b can determine the pixels from which the provisional values are derived as definite values and the pixels from which the above calculations for deriving the definite values are executed.
- the provisional value deriving unit 22b calculates a definite value derived from a pixel having a provisional value less than a predetermined value among a plurality of pixels as a target pixel, and a provisional value Photon counting data for a plurality of pixels may be generated based on the interim values of pixels having values.
- the definite value derivation unit 22b may derive the provisional value as the definite value for pixels whose provisional value is equal to or greater than the set value. In other words, the definite value derivation unit 22b may perform the above-described calculation for deriving the definite value only for pixels whose provisional value is less than the set value.
- the definite value derivation unit 22b may set the range of the number of assumed photons so that the provisional value is substantially derived as the definite value for the pixels whose provisional value is equal to or greater than the set value. That is, the definite value derivation unit 22b may set a range obtained by adding the provisional value of the target pixel to the range from 0 to the set value as the range of the assumed number of photons. For example, when the set value is 10 [e], the range of assumed photon numbers is "0, 1, 2, ..., 8, 9, 10, 93" in the example of Fig. 17 .
- FIGS. 25 and 26 are examples showing the output results of one example of the photon counting device.
- FIG. 25(a) is an image formed as a result of photon counting by EMCCD (Electron Multiplying Charge Coupled Device). The image has a brightness corresponding to the number of photons measured.
- FIG. 25(b) is an image formed based on the digital values obtained by the photon counting device described above. The image has luminance according to the digital value.
- FIG. 25(c) is an image formed based on the provisional values obtained by the photon counting device described above. The image has luminance according to the provisional value.
- FIG. 25(d) is an image formed based on the determined values obtained by the photon counting device described above. The image has luminance according to the determined value.
- EMCCD Electrom Multiplying Charge Coupled Device
- the background light is 0 [photon/pix/frame]
- the signal is 1 [photon/pix/frame]
- the exposure time is 200 [ms] (5 [fps])
- the wavelength is 532 [nm].
- numbers, squares, and combinations of three rectangles are drawn by signals. Note that the reliability ⁇ is 10.
- noise occurs over the entire image due to the influence of readout noise in particular.
- the signal portion of FIG. 25(c) is drawn more clearly than the signal portion of the EMCCD shown in FIG. 25(a). This is considered to be due to the EMCCD having multiplication noise.
- the background portion of FIG. 25(c) contains more noise than the EMCCD background portion. This is considered to be caused by pixels with large readout noise being included in the plurality of pixels forming the two-dimensional image sensor.
- FIG. 25(d) which shows the image reflecting the deterministic value
- the clarity of the signal portion is the same as in FIG. 25(c).
- the noise in the background portion of FIG. 25(d) is less than the noise in the background portion of FIG. 25(c), and the amount of noise is comparable to that of the EMCCD.
- FIG. 26 shows a dark image obtained by a photon counting device.
- FIG. 26(a) is an image formed based on the digital values obtained by the photon counting device described above.
- FIG. 26(b) is an image formed based on the provisional values obtained by the photon counting device described above.
- FIG. 26(c) is an image formed based on the determined values by the photon counting device described above.
- noise occurs over the entire image due to the influence of readout noise in particular.
- (b) of FIG. 26 a lot of noise is observed due to pixels with large readout noise.
- (c) of FIG. 26 showing the image reflecting the final values the amount of noise is reduced compared to (b) of FIG. 26 showing the image reflecting the provisional values.
- peripheral pixels are formed by a pixel group of 3 rows ⁇ 3 columns centered on the target pixel, but the configuration of the peripheral pixels may be determined arbitrarily. 27, 28, 29 and 30 show other examples of peripheral pixels. In both figures, a pixel 11c serving as a target pixel and other pixels 11 are shown.
- FIG. 27 shows an example in which the peripheral pixels are a pixel group configured in a square shape.
- the peripheral pixels shown in (a) of FIG. 27 are composed of a pixel group of 3 rows ⁇ 5 columns.
- the peripheral pixels shown in (b) of FIG. 27 are composed of a pixel group of 5 rows ⁇ 5 columns.
- the central pixel 11c is the target pixel, but the other pixels 11 may be the target pixels.
- the peripheral pixels may be formed by a group of pixels arranged in N rows ⁇ M columns or M rows ⁇ N columns, where N is an integer of 1 or more and M is an integer of 2 or more.
- FIG. 28 shows an example in which peripheral pixels are a group of pixels configured line-symmetrically and point-symmetrically.
- the peripheral pixels shown in FIG. 28(a) are composed of five cross-shaped pixels.
- the peripheral pixels shown in FIG. 28(b) are composed of eleven cross-shaped pixels.
- a pixel 11c which is the target pixel, is located at the intersection of the pixels arranged in the row direction (pixel row) and the pixels arranged in the column direction (pixel column). are arranged, the target pixel may be another pixel 11 .
- one pixel row and one pixel column intersect has been shown, one or more pixel rows and one or more pixel columns may intersect with each other.
- the peripheral pixels shown in (c) of FIG. 28 have a shape in which the pixels at the four corners of the pixel group configured in a square shape (5 rows ⁇ 5 columns) are removed.
- the peripheral pixels shown in (d) of FIG. 28 have a shape in which the pixels around the four corners of the group of pixels configured in a square shape (5 rows ⁇ 5 columns) are removed.
- the peripheral pixels shown in (e) of FIG. 28 have a shape in which the pixels around the four corners of the group of pixels configured in a square shape (7 rows ⁇ 7 columns) are removed.
- the peripheral pixels shown in (f) of FIG. 28 have a shape in which the pixels around the four corners of the group of pixels configured in a square shape (7 rows ⁇ 5 columns) are removed.
- the peripheral pixels shown in (g) of FIG. 28 are composed of pixels 11 corresponding to diagonal positions in a group of pixels configured in a square shape (3 rows ⁇ 3 columns).
- the peripheral pixels shown in (h) of FIG. 28 are composed of pixels 11 corresponding to diagonal positions in a group of pixels configured in a square shape (5 rows ⁇ 5 columns).
- FIG. 29 shows an example in which pixels separated from each other are included in a group of pixels in which peripheral pixels are line-symmetrically and point-symmetrically configured.
- the peripheral pixels shown in (a) of FIG. 29 are composed of nine pixels 11 spaced apart from each other in a pixel group of 5 rows ⁇ 5 columns.
- the peripheral pixels shown in FIG. 29B are composed of 16 peripheral pixels 11 and a central pixel 11c in a pixel group of 5 rows ⁇ 5 columns.
- the peripheral pixels shown in FIG. 29(b) are composed of four corner pixels and a cross-shaped pixel group including the center pixel 11c in a pixel group of 5 rows ⁇ 5 columns.
- the peripheral pixels shown in (b) of FIG. 29 are composed of a group of pixels in the 1st row, a group of pixels in the 3rd row, and a group of pixels in the 5th row in a group of pixels of 5 rows ⁇ 7 columns.
- the peripheral pixels shown in (a) of FIG. 30 are composed of pixels 11 arranged to form a swastika shape in a square (5 rows ⁇ 5 columns) pixel group.
- the peripheral pixels shown in FIG. 30(b) are composed of a triangular pixel group. In this example, one of the vertices of the triangle is the target pixel, but another pixel 11 may be the target pixel.
- the peripheral pixels shown in (c) of FIG. 30 are composed of pixels 11 forming a spiral shape in a square (5 rows ⁇ 5 columns) pixel group.
- the peripheral pixels shown in (d) of FIG. 30 are a plurality of diagonally continuous pixel groups in a rectangular (7 rows ⁇ 7 columns) area, and include a plurality of pixel groups separated from each other. In the illustrated example, the pixels 11 at the four corners are included in the peripheral pixels.
- each peripheral pixel illustrated in FIGS. 27-30 may be expanded based on the regularity. For example, expansion includes increasing the number of consecutive pixels in the row direction, increasing the number of consecutive pixels in the column direction, increasing the number of consecutive pixels in the diagonal direction, and the like.
- the respective peripheral pixels illustrated in FIGS. 27 to 30 may overlap each other. When overlapping peripheral pixels that are different from each other, one or both of the peripheral pixels may be expanded. In addition, for peripheral pixels that have a different shape when inverted vertically or horizontally, the original peripheral pixels and the inverted peripheral pixels may be superimposed.
- FIG. 31 is a diagram for explaining another example of weighted averaging.
- FIG. 31 shows a noise map based on the readout noise described in the above embodiment and a map of weights based on the noise map (hereinafter sometimes referred to as noise weights).
- the modified example of FIG. 31 includes a distance weight as a weight for the weighted average.
- the distance weight is weighted average weighting based on the distance between the target pixel and each of the surrounding pixels.
- the distance weight is set based on the distance between the center of the pixel 11c, which is the target pixel, and the center of each of the surrounding pixels, so that the smaller the distance, the larger the weight.
- a mask used as a Gaussian filter may be used as a distance weight.
- the product of the noise weight and the distance weight is used to weight the weighted average.
- FIG. 32 is a diagram for explaining still another example of weighted averaging.
- FIG. 32 shows a noise map based on readout noise and a weight map based on the noise map described in the above embodiments.
- the modified example of FIG. 32 includes a 1/0 weight as the weight of the weighted average.
- the 1/0 weighting is weighting in which a value of 1 or 0 set for each peripheral pixel is used as a weighting element.
- the product of the noise weight and the 1/0 weight is used to weight the weighted average. Therefore, in pixels where the 1/0 weight element is 1, the noise weight is used as it is for the weighting of the weighted average.
- the weighting of the weighted average is 0 for a pixel whose 1/0 weight element is 0.
- the provisional values of pixels whose 1/0 weight element is 0 are not used in the calculation for calculating the average number of photons.
- defective pixels included in a plurality of pixels forming a two-dimensional image sensor may be detected, and the 1/0 weight of the detected defective pixels may be set to zero. In this case, the output of the defective pixel is not used for calculating the average number of photons.
- the 1/0 weight can be used to form an arbitrary shape of surrounding pixels, as shown in FIG. FIG. 33 shows a noise map, a map of weights based on the noise map, and a 1/0 weight.
- the 1/0 weight of FIG. 33 five pixels forming a cross have a weight of 1, and the remaining four pixels have a weight of zero.
- the product of the noise weight and the 1/0 weight is used for weighting the weighted average, so that the peripheral pixels have substantially the same shape as the peripheral pixels shown in FIG. 28(a). In this way, by setting the 1/0 weight of arbitrary pixels in the rectangular area to 1 and setting the 1/0 weight of the remaining pixels to 0, the shape of the surrounding pixels can be arbitrarily set.
- the first probability is derived based on the probability distribution of the number of photoelectrons accompanying optical shot noise, which is represented by the Poisson distribution. It may be derived based on the probability distribution of the number of photoelectrons associated with the distribution of the number of photons.
- the first probability may be derived based on the probability distribution according to the light source.
- the light source is a non-coherent light source such as an LED or a thermal photon source
- the first photon number distribution based on the super-Poissonian distribution (Super-poissonian), which is a photon number distribution with larger photon number fluctuations than the Poisson distribution. Probabilities may be derived.
- Super-poissonian super-Poissonian
- the first probability may be derived based on a sub-Poissonian distribution, which is a photon number distribution in which fluctuation in the number of photons is smaller than that of the Poisson distribution.
- the first probability may be derived based on the photon number distribution exhibited by the photon number squeezed state (e.g., Fock state) such as a single photon source, or spontaneous parametric down conversion (spontaneous parametric down
- the first probability may be derived based on the photon number distribution exhibited by the entangled photon state (for example, NOON state) generated by the conversion, SPDC) or the like.
- a first probability may be derived based on. Also, if the light source is a thermal light source or a pseudo-thermal light source, even if the first probability is derived based on the Bose-Einstein distribution good. In addition, a log-normal distribution that has a shape with a longer tail for larger numbers, a uniform distribution that has a uniform probability for each photon number, and multiple photon number distributions. The first probability may be derived based on a combined distribution, such as a Mixture of multiple photon distribution.
- the weights used when calculating the average number of photons using weighted averaging are not limited to the examples in the above embodiment.
- the weights obtained as follows may be used.
- the true average number of photons may be the arithmetic mean of the true number of photons of the peripheral pixels.
- the expected value E[( ⁇ * ⁇ ) 2 ] of the squared error between ⁇ * and ⁇ is minimized. It suffices to calculate w such that First, the expected value E[ ⁇ * ] of ⁇ * is obtained.
- the pixel value x follows the probability distribution p(x) shown in Equation (10).
- Equation (17) the average number of photons ⁇ * by weighted averaging is given by equation (18).
- Equation (17) cannot be calculated as it is because the true average number of photons ⁇ is included in the equation (17). Therefore, in one example, assuming that the average number of photons calculated as an unweighted average of the surrounding pixels is ⁇ , wi derived based on Equation (17) may be used as the weight.
- w i derived based on equation (17) may be solved self-consistently. That is, the average number of photons is obtained by substituting the derived weight wi into equation (18) (first step), and the weight wi is derived from equation (17) using this average number of photons (first 2 step) may be repeated until convergence.
- the solution of equation (19) may be used as the average number of photons, expecting that the weighted average average number of photons ⁇ * approximates the true average number of photons ⁇ .
- equation (20) when the function on the right side is a contraction map.
- the average number of photons of the target pixel may be derived based on data of provisional values of multiple frames. That is, the definite value derivation unit 22b may acquire the data of the provisional values of the pixels for a plurality of frames, and derive the average number of photons based on the acquired data. For example, the definite value derivation unit 22b may derive the average number of photons of the target pixel for each acquired frame, and obtain the first probability using the average value of the derived average number of photons as ⁇ .
- the definite value derivation unit 22b derives the average number of photons of the target pixel by using the obtained data of the provisional values for the plurality of frames as one population, and obtains the first probability using the derived average number of photons as ⁇ .
- the fixed value derivation unit 22b may calculate the average value of the provisional values for each pixel between the acquired frames, and derive the average number of photons using this average value as the provisional value of each pixel. As described above, by calculating the average number of photons based on the data of the provisional values in a plurality of frames, improvement in the calculation accuracy of the average number of photons can be expected.
- the definite value derivation unit 22b may derive, as the definite value, the number of photons that is considered to have the smallest error from the true number of photons. That is, the definite value derivation unit 22b may derive the expected value of the number of photons as the definite value. For example, the definite value deriving unit 22b sets the observation probability for each number of photoelectrons in the target pixel based on the probability distribution of the number of photons as the first probability, and the probability distribution of the number of photoelectrons accompanying the readout noise of the target pixel.
- the expected value of the number of photons of the target pixel can be derived based on the first probability and the second probability. For example, when the probability for each assumed number of photons when the target pixel indicates a provisional value is given by Equation (21), the expected value k exp of the number of photons is given by Equation (22) below.
- the range of the assumed number of photons k calculated by the definite value derivation unit 22b may be the data range of the probability distribution of the number of photons.
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Abstract
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- 入力された光を電荷に変換する光電変換素子と前記光電変換素子によって変換された電荷を増幅して電圧に変換するアンプとを含む複数の画素と、
前記複数の画素の前記アンプから出力される電圧をデジタル値に変換するA/Dコンバータと、
前記デジタル値に基づいて、前記複数の画素における各画素のフォトン数の暫定値を導出する第1導出部と、
第1の確率及び第2の確率に基づいて、前記複数の画素のうちの一つである対象画素におけるフォトン数の確定値を導出する第2導出部と、を備え、
前記第1の確率は、前記光のフォトン数分布に伴う光電子数の確率分布に基づく、前記対象画素における光電子数ごとの観測確率であり、
前記第2の確率は、前記対象画素の読み出しノイズに伴う光電子数の確率分布に基づく、前記対象画素の前記暫定値における光電子数ごとの観測確率である、フォトンカウンティング装置。 - 前記第2導出部は、前記第1の確率と前記第2の確率との積によって、前記対象画素が前記暫定値を示す場合の光電子数ごとの確率を算出し、算出された確率に基づいて前記確定値を決定する、請求項1に記載のフォトンカウンティング装置。
- 前記光のフォトン数分布に伴う光電子数の確率分布は、ポアソン分布、超ポアソン分布、サブポアソン分布、光子数スクイーズド状態が示すフォトン数分布、量子もつれ光子状態が示すフォトン数分布、マルチモードスクイーズド状態の光子数分布、ボーズ=アインシュタイン分布、対数正規分布、一様分布、又は混合分布である、請求項1又は2に記載のフォトンカウンティング装置。
- 前記対象画素の前記読み出しノイズに伴う光電子数の確率分布は、正規分布である、請求項1~3のいずれか一項に記載のフォトンカウンティング装置。
- 前記第2導出部は、前記複数の画素のうち、前記対象画素の周囲の一部領域に含まれる2以上の画素を周辺画素として、前記周辺画素における前記暫定値の平均値を算出し、前記平均値を考慮して前記第1の確率を算出する、請求項1~4のいずれか一項に記載のフォトンカウンティング装置。
- 前記平均値は、前記周辺画素の前記読み出しノイズを重み付けに含む加重平均である、請求項5に記載のフォトンカウンティング装置。
- 前記平均値は、前記対象画素と前記周辺画素のそれぞれとの距離を重み付けに含む加重平均である、請求項5又は6に記載のフォトンカウンティング装置。
- 前記平均値は、前記周辺画素のフォトン数の平均値との誤差を小さくするような重みを重み付けに含む加重平均である、請求項5に記載のフォトンカウンティング装置。
- 前記第2導出部は、複数フレームにおける前記暫定値のデータに基づいて、前記暫定値の前記平均値を算出する、請求項5~8のいずれか一項に記載のフォトンカウンティング装置。
- 前記第2導出部は、前記複数の画素のうち所定の値以上の前記読み出しノイズを有する画素を前記対象画素として導出された前記確定値と、前記複数の画素のうち前記所定の値未満の前記読み出しノイズを有する画素の前記暫定値とによって、前記複数の画素についてのフォトンカウンティングデータを作成する、請求項1~9のいずれか一項に記載のフォトンカウンティング装置。
- 前記第2導出部は、前記複数の画素のうち所定の値未満の前記暫定値を有する画素を前記対象画素として導出された前記確定値と、前記複数の画素のうち前記所定の値以上の前記暫定値を有する画素の前記暫定値とによって、前記複数の画素についてのフォトンカウンティングデータを作成する、請求項1~10のいずれか一項に記載のフォトンカウンティング装置。
- 前記第2導出部は、前記複数の画素のそれぞれの前記読み出しノイズを示すノイズマップを有する、請求項1~11のいずれか一項に記載のフォトンカウンティング装置。
- 複数の画素を有する2次元イメージセンサから出力される前記複数の画素に対応するデジタル値に基づいて、前記複数の画素における各画素のフォトン数の暫定値を導出することと、
第1の確率及び第2の確率に基づいて、前記複数の画素のうちの一つである対象画素におけるフォトン数の確定値を導出することと、を備え、
前記確定値を導出することは、
前記第1の確率として、光のフォトン数分布に伴う光電子数の確率分布に基づき、前記対象画素における光電子数ごとの観測確率を求めることと、
前記第2の確率として、前記対象画素の読み出しノイズに伴う光電子数の確率分布に基づき、前記対象画素の前記暫定値における光電子数ごとの観測確率を求めることとを含む、フォトンカウンティング方法。 - 前記確定値を導出することは、前記第1の確率と前記第2の確率との積によって、前記対象画素が前記暫定値を示す場合の光電子数ごとの確率を算出し、算出された確率に基づいて前記確定値を決定する、請求項13に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記光のフォトン数分布に伴う光電子数の確率分布として、ポアソン分布、超ポアソン分布、サブポアソン分布、光子数スクイーズド状態が示すフォトン数分布、量子もつれ光子状態が示すフォトン数分布、マルチモードスクイーズド状態の光子数分布、ボーズ=アインシュタイン分布、対数正規分布、一様分布、又は混合分布を利用する、請求項13又は14に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記対象画素の前記読み出しノイズに伴う光電子数の確率分布として、正規分布を利用する、請求項13~15のいずれか一項に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記複数の画素のうち、前記対象画素の周囲の一部領域に含まれる2以上の画素を周辺画素として、前記周辺画素における前記暫定値の平均値を算出し、前記平均値を考慮して前記第1の確率を算出する、請求項13~16のいずれか一項に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記平均値として、前記周辺画素の前記読み出しノイズを重み付けに含む加重平均を用いる、請求項17に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記平均値として、前記対象画素と前記周辺画素のそれぞれとの距離を重み付けに含む加重平均を用いる、請求項17又は18に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記平均値として、前記周辺画素のフォトン数の平均値との誤差を小さくするような重みを重み付けに含む加重平均を用いる、請求項17に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、複数フレームにおける前記暫定値のデータに基づいて、前記暫定値の前記平均値を算出する、請求項17~20のいずれか一項に記載のフォトンカウンティング方法。
- 前記複数の画素のうち所定の値以上の前記読み出しノイズを有する画素を前記対象画素として導出された前記確定値と、前記複数の画素のうち前記所定の値未満の前記読み出しノイズを有する画素の前記暫定値とによって、前記複数の画素についてのフォトンカウンティングデータを作成することを更に含む、請求項13~21のいずれか一項に記載のフォトンカウンティング方法。
- 前記複数の画素のうち所定の値未満の前記暫定値を有する画素を前記対象画素として導出された前記確定値と、前記複数の画素のうち前記所定の値以上の前記暫定値を有する画素の前記暫定値とによって、前記複数の画素についてのフォトンカウンティングデータを作成することを更に含む、請求項13~21のいずれか一項に記載のフォトンカウンティング方法。
- 前記確定値を導出することは、前記複数の画素のそれぞれの前記読み出しノイズを示すノイズマップを参照する、請求項13~23のいずれか一項に記載のフォトンカウンティング方法。
- 複数の画素を有する2次元イメージセンサから出力される前記複数の画素に対応するデジタル値に基づいて、フォトンカウンティングの処理をコンピュータに実行させるプログラムであって、
前記デジタル値に基づいて、前記複数の画素における各画素のフォトン数の暫定値を導出する第1導出処理と、
第1の確率及び第2の確率に基づいて、前記複数の画素のうちの一つである対象画素におけるフォトン数の確定値を導出する第2導出処理と、
をコンピュータに実行させ、
前記第1の確率は、光のフォトン数分布に伴う光電子数の確率分布に基づく、前記対象画素における光電子数ごとの観測確率であり、
前記第2の確率は、前記対象画素の読み出しノイズに伴う光電子数の確率分布に基づく、前記対象画素の前記暫定値における光電子数ごとの観測確率である、フォトンカウンティング処理プログラム。
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JP2020038129A (ja) * | 2018-09-04 | 2020-03-12 | 浜松ホトニクス株式会社 | 平均光子数の推定方法及び平均光子数の推定装置 |
JP2020096646A (ja) * | 2016-12-05 | 2020-06-25 | キヤノン株式会社 | 放射線撮影装置、放射線撮影システム、放射線撮影方法、及びプログラム |
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Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006352716A (ja) * | 2005-06-17 | 2006-12-28 | Casio Comput Co Ltd | 撮像装置及び撮像方法 |
JP2020096646A (ja) * | 2016-12-05 | 2020-06-25 | キヤノン株式会社 | 放射線撮影装置、放射線撮影システム、放射線撮影方法、及びプログラム |
WO2019102637A1 (ja) | 2017-11-24 | 2019-05-31 | 浜松ホトニクス株式会社 | フォトンカウンティング装置およびフォトンカウンティング方法 |
WO2019102636A1 (ja) | 2017-11-24 | 2019-05-31 | 浜松ホトニクス株式会社 | フォトンカウンティング装置およびフォトンカウンティング方法 |
JP2020038129A (ja) * | 2018-09-04 | 2020-03-12 | 浜松ホトニクス株式会社 | 平均光子数の推定方法及び平均光子数の推定装置 |
Non-Patent Citations (2)
Title |
---|
DAKOTA A. STARKEY ET AL.: "Determining Conversion Gain and Read Noise Using a Photon-Counting Histogram Method for Deep Sub-Electron Read Noise Image Sensors", JOURNAL OF THE ELECTRON DEVICES SOCIETY, vol. 4, 3 May 2016 (2016-05-03), pages 129 - 135, XP011607396, DOI: 10.1109/JEDS.2016.2536719 |
JIAJU MA ET AL.: "Photon-number-resolving megapixel image sensor at room temperature without avalanche gain", OPTICA, vol. 4, 12 December 2017 (2017-12-12), pages 1474 - 1481 |
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