CN103606185B - Halation emulation mode in low-light level television imaging - Google Patents

Abstract

The invention discloses the halation emulation mode in a kind of low-light level television imaging, mainly solve traditional experiment research method cost height and inefficient problem.Implementation step is: (1), based on the three-dimensional scenic emulation platform of OGRE, imports the three-dimensional model of intense light source and low-light level television image device, generates three-dimensional low-light scene; (2) in three-dimensional low-light scene, according to the night television system internal electron characteristics of motion, photoelectricity transformation principle and microchannel plate scattering theory, statistics arrives fluoroscopic amount of electrons; (3) to arrive fluoroscopic amount of electrons for foundation, by system voltage principle of signal conversion and grey level quantization principle, the simulation of halation intensity profile is realized.Precision of the present invention is high, it is wide, real-time to adapt to, and can realize the accurate simulation of intense light source imaging in night television system.

Description

Halation emulation mode in low-light level television imaging

Technical field

The invention belongs to computer simulation technique field, the halation emulation mode particularly in a kind of low-light level television imaging, can be used for the low-light scene objects identification field under intense light source.

Background technology

Work as intense light source, as street lamp, car light, flare etc. appear in night television system visual field time, system output image can form halation around this luminous point.Local high light on halation can cover weak signal around, the imaging resolution of direct influential system and signal to noise ratio (S/N ratio); And under the constant same observation condition of the factor such as dimension of light source, observed range, on different model imaging system output image, the size of halation is different.Therefore, the research quantitatively characterizing of halation and emulation mode thereof are for the identification of target under intense light source, and the raising etc. of image resolution ratio and signal to noise ratio (S/N ratio) has important practical value.

In recent years, Chinese scholars has mainly carried out the research of following two aspects to the halation in low-light level television imaging: (1) is by replacing micro-channel tubes with hollow tubular, test under Different Light, the principal element of halation in analyzing influence system output image; (2) by changing light source, change the conditions such as the parameter of image intensifier and test, research affects the factor of halation size.In those references, all do not have the accurate quantification of halation in further Study system output image to characterize, thus cause the problem that the degree of accuracy of low-light level television imaging simulation output image is low and the light source scope of application is little.

Summary of the invention

The object of the invention is to the deficiency for above-mentioned prior art, halation emulation mode in a kind of low-light level television imaging is proposed, to provide the quantitatively characterizing of halation in image, improve the degree of accuracy of low-light level television imaging simulation output image, expand the scope of application of low-light level television imaging simulation light source.

The technical solution realizing the object of the invention is: analyze the electron motion that produced by the intense light source characteristics of motion to microchannel plate according to low-light level television imaging system photoelectricity transformation principle, microchannel plate scattering theory; According to law of conservation of energy, calculate electronics under the different motion state of microchannel plate surface, the electron number that the offset distance of impacting electron and each location of pixels receive; Coupling system voltage signal transfer principle and grey level quantization principle, calculate the gray-scale value that these electronics produce on output image, obtains the space annular spread of these gray-scale values, be halation image.Implementation step comprises as follows:

(1) input intense light source and optical lens, photocathode, electronic lens, microchannel plate, video screen these form the calibrating parameters of low-light level television image devices, utilize the three-dimensional model of 3Dmax Software Create intense light source and low-light level television image device, and this three-dimensional model is imported based in the three-dimensional scenic simulated program of OGRE, generate low-light three-dimensional scenic;

(2) according to the illuminance E of the Facing material reflectivity ρ in low-light three-dimensional scenic and bias light, and the luminance brightness L of intense light source, the luminance brightness L of calculating optical lens surface _a(i, j), wherein (i, j) is the two-dimensional coordinate of optical lens surface bin;

(3) according to the luminance brightness L of optical lens surface _a(i, j), calculates by opto-electronic conversion the electron number n (i, j) that photocathode surface is subject to illumination generation;

(4) according to law of conservation of energy, calculate photocathode surface electronic and arrive microchannel plate hour offset distance s through electronic lens ₁(i, j);

(5) according to microchannel plate scattering theory, the offset distance s (i, j) that the electronics calculating arrival microchannel plate produces after microchannel plate Multiple Scattering; According to the Two dimensional Distribution of image on fluorescent screen vegetarian refreshments, calculate the corresponding fluoroscopic each pixel position (x, y) of this offset distance, and add up the electron number n that each pixel position receives _e(x, y), wherein (x, y) is the two-dimensional coordinate of all pixels in video screen surface;

(6) according to the electron number n that the fluoroscopic each pixel position of correspondence receives _e(x, y), calculates the gray-scale value Gray (x of all pixels on video screen by fluoroscopic electro-optic conversion, y), these gray-scale values form a kind of annular distribution near the two-dimensional coordinate central point on video screen surface, and this annular distribution is halation image, and exports.

The present invention compared with prior art, has following remarkable advantage:

1. the present invention has taken into full account that electronics arrives the different motion state of microchannel plate, is realized the emulation of halation, thus accurately can emulate the halation phenomenon in low-light level television imaging by voltage quantization;

2. the present invention generates low-light three-dimensional scenic under the environment demarcating intense light source and low-light level television image device parameter, therefore for different intense light sources, by changing calibrating parameters to mate the emulation that low-light level television image-forming condition realizes its correspondence, the scope of application of low-light level television imaging simulation light source can be expanded.

The explanation of invention accompanying drawing

Fig. 1 is general flow chart of the present invention;

Fig. 2 is the motion schematic diagram of step 4 electronics between electronic lens and microchannel plate in the present invention.

Embodiment

With reference to Fig. 1, the detailed implementation process of the halation emulation mode in low-light level television imaging of the present invention is as follows:

Step 1. generates low-light three-dimensional scenic.

Input intense light source and optical lens, photocathode, electronic lens, microchannel plate, video screen these form the calibrating parameters of low-light level television image devices, utilize the three-dimensional model of 3Dmax Software Create intense light source and low-light level television image device, and this three-dimensional model is imported based in the three-dimensional scenic simulated program of OGRE, generate low-light three-dimensional scenic.

The luminance brightness of step 2. calculating optical lens surface.

(2a) according to the luminance brightness L of intense light source, according to the illuminance E of photometry formulae discovery intense light source at optical lens surface bin place _i(i, j)

$E_i(i,j)=\frac{{\mathrm{LAcos\θ}}_i{\mathrm{cos\θ}}_j}{l^2}$

Wherein (i, j) is the two-dimensional coordinate of optical lens surface bin, and A represents intense light source area, θ _irepresent the surperficial bin normal in low-light three-dimensional scenic and the angle of intense light source between the incident ray at optical lens surface bin place, θ _jrepresent intense light source surface bin normal and the angle of intense light source between the incident ray at optical lens surface bin place, l represents the distance between intense light source and optical lens surface;

(2b) according to the illuminance E of the Facing material reflectivity ρ in low-light three-dimensional scenic, bias light and intense light source at optical lens surface place illuminance E _i, by the luminance brightness L of reflected light law calculating optical lens surface _a

L _a＝ρ(E _i+E)/π，

(2c) (2a) and (2b) is combined, the luminance brightness L of calculating optical lens surface _a(i, j)

$L_a(i,j)=\mathrm{\ρ}(\frac{{\mathrm{LAcos\θ}}_i{\mathrm{cos\θ}}_j}{l^2}+E)/\mathrm{\π}.$

Step 3. calculates the electron number that photocathode surface produces.

According to the luminance brightness L of optical lens surface _a(i, j), is subject to the electron number n (i, j) of illumination generation according to opto-electronic conversion formulae discovery photocathode surface:

$n(i,j)=\frac{\mathrm{\π}}{4}{\left(\frac{D_f}{f}\right)}^2{L}_a(i,j)\mathrm{\τ}\·S_k,$

Wherein D _frepresent System Optics effective aperture, f represents optical system focal length, and τ represents optical lens transmitance, S _krepresent photocathode sensitivity.

Step 4. calculates offset distance during electronics arrival microchannel plate.

With reference to Fig. 2, being implemented as follows of this step:

(4a), according to law of conservation of energy, photocathode surface electronic arrives microchannel plate speed V through electronic lens is calculated ₁the angle theta of (i, j) and this speed and electronic lens normal ₁(i, j):

$V_1(i,j)=\sqrt{{V_0}^2+\frac{2eu}{m_e}}$

${\mathrm{\θ}}_1(i,j)=arctan\frac{V_0{\mathrm{sin\θ}}_0}{\sqrt{{\left(V_0{\mathrm{cos\θ}}_0\right)}^2+\frac{2eu}{m_e}}},$

Wherein V ₀, θ ₀represent that photocathode surface produces initial velocity and the initial angle of electronics respectively, e represents the quantity of electric charge of Single Electron, m _erepresent the quality of Single Electron, u represents the operating voltage between electronic lens and microchannel plate;

(4b) according to speed V during electronics arrival microchannel plate ₁the angle theta of (i, j) and this speed and electronic lens normal ₁(i, j), by law of conservation of energy calculate its arrive microchannel plate time offset distance s ₁(i, j):

$s_1(i,j)=\frac{\left(V_1\right(i,j\left){\mathrm{cos\θ}}_1\right(i,j)-V_0{\mathrm{cos\θ}}_0)m_e{V}_0{\mathrm{sin\θ}}_{0}D}{eu},$

Wherein, D represents the distance between electronic lens and microchannel plate.

Step 5. adds up the electron number that each pixel position receives.

(5a) speed when arriving microchannel plate according to electronics and the angle theta of electronic lens normal ₁(i, j), by microchannel plate scattering theory, calculates the offset distance s that electronics enters microchannel plate generation primary collision ₂:

$s_2=\frac{2m_e\sqrt{{V_0}^2+\frac{2eu}{m_e}}{\mathrm{sin\θ}}_1(i,j)}{eu},$

Wherein m _erepresent the quality of Single Electron, V ₀represent that photocathode surface produces the initial velocity of electronics, e represents the quantity of electric charge of Single Electron, and u represents the operating voltage between electronic lens and microchannel plate;

(5b) according to offset distance s during electronics arrival microchannel plate ₁(i, j), enter the offset distance s of microchannel plate generation primary collision ₂with collision frequency N, calculate the offset distance s (i, j) that electronics produces after microchannel plate Multiple Scattering:

s(i,j)＝s ₁(i,j)+N·s ₂，

(5c) by s in (4b) ₁s in (i, j) and (5a) ₂expression formula substitute into the expression formula of (5b), calculate the offset distance s (i, j) that electronics produces after microchannel plate Multiple Scattering:

$s(i,j)=\frac{\left(V_1\right(i,j\left)\cos \mathrm{\θ}\right(i,j)-V_0{\mathrm{cos\θ}}_0)m_e{V}_0{\mathrm{sin\θ}}_{0}D}{eu}+\frac{2{\mathrm{Nm}}_e\sqrt{{V_0}^2+\frac{2eu}{m_e}}{\mathrm{sin\θ}}_1(i,j)}{eu},$

Wherein, V ₀, θ ₀represent that photocathode surface produces initial velocity and the initial angle of electronics respectively, m _erepresent the quality of Single Electron, e represents the quantity of electric charge of Single Electron, and u represents the operating voltage between electronic lens and microchannel plate, and D represents the spacing of electronic lens and microchannel plate, N represents the number of times that electronics and the non-perforated wall of microchannel plate collide, and value is natural number.

(5d) according to the Two dimensional Distribution of image on fluorescent screen vegetarian refreshments, offset distance s (the i that the electronics arriving microchannel plate by following formulae discovery produces after microchannel plate Multiple Scattering, j) corresponding fluoroscopic each pixel position (x, y):

$|\sqrt{{\left({\mathrm{xd}}_w\right)}^2+{\left({\mathrm{yd}}_h\right)}^2}-s(i,j)|<\mathrm{\&delta;},$

Wherein, d _wrepresent the width of the single pixel of video screen, d _hrepresent the height of the single pixel of video screen, δ=min (d _w, d _h), s (i, j) represents offset distance;

(5e) the electron number n that each pixel position receives is added up _e(x, y).

Step 6. calculates the gray-scale value of all pixels on video screen.

(6a) according to the electron number n that the fluoroscopic each pixel position of correspondence receives _e(x, y), calculates quantification voltage V (x, y) of each pixel by voltage signal conversion formula:

$V(x,y)=\frac{\mathrm{\&pi;}}{4}{\mathrm{\&tau;}}_e{\left(\frac{D_e}{f_e}\right)}^{2}R\&CenterDot;A_s\&CenterDot;G_v\&CenterDot;v\&CenterDot;G\&CenterDot;k\&CenterDot;n_e(x,y)\&CenterDot;e/a^2,$

Wherein τ _erepresent the transmitance of coupled lens, D _erepresent coupled lens effective aperture, f _erepresent coupled lens focal length, R represents explorer response rate, A _srepresent effective photosensitive elemental area, G _vrepresent vision signal enlargement factor, v represents the operating voltage of electronic lens, and G represents the gain of microchannel plate, and k represents video screen luminous efficacy, and a represents electron optics enlargement factor, n _e(x, y) represents the electron number that each location of pixels receives, and e represents the quantity of electric charge of Single Electron;

(6b) according to quantification voltage V (x, y) of each pixel, the gray-scale value Gray (x, y) of each pixel is calculated:

$Gray(x,y)=\frac{255}{V_{Max}-V_{Min}}V(x,y),$

Wherein, V _maxand V _minrepresent maximal value and the minimum value of the quantification voltage of all pixels respectively;

(6c) gray-scale value of all pixels forms a kind of annular distribution near the two-dimensional coordinate central point on video screen surface, and this annular distribution is the halation image of output.

More than describing is only example of the present invention, does not form any limitation of the invention.Obviously for those skilled in the art; after having understood content of the present invention and principle; all may when not deviating from the principle of the invention, structure; carry out the various correction in form and details and change, but these corrections based on inventive concept and change are still within claims of the present invention.

Claims (6)

1. the halation emulation mode in low-light level television imaging, comprises the steps:

(1) input intense light source and optical lens, photocathode, electronic lens, microchannel plate, video screen these form the calibrating parameters of low-light level television image devices, utilize the three-dimensional model of 3Dmax Software Create intense light source and low-light level television image device, and this three-dimensional model is imported based in the three-dimensional scenic simulated program of OGRE, generate low-light three-dimensional scenic;

(2) according to the illuminance E of the Facing material reflectivity ρ in low-light three-dimensional scenic and bias light, and the luminance brightness L of intense light source, the luminance brightness L of calculating optical lens surface _a(i, j), wherein (i, j) is the two-dimensional coordinate of optical lens surface bin;

(3) according to the luminance brightness L of optical lens surface _a(i, j), calculates by opto-electronic conversion the electron number n (i, j) that photocathode surface is subject to illumination generation;

(4) according to law of conservation of energy, calculate photocathode surface electronic and arrive microchannel plate hour offset distance s through electronic lens ₁(i, j):

(4a) according to law of conservation of energy, photocathode surface electronic arrives microchannel plate speed V through electronic lens is calculated ₁the angle theta of (i, j) and this speed and electronic lens normal ₁(i, j), by following formulae discovery:

$V_1(i,j)=\sqrt{{V_0}^2+\frac{2eu}{m_e}}$

${\mathrm{\&theta;}}_1(i,j)=\arctan \frac{V_0{\mathrm{sin\&theta;}}_0}{\sqrt{{\left(V_0{\mathrm{cos\&theta;}}_0\right)}^2+\frac{2eu}{m_e}}}$

Wherein V ₀, θ ₀represent that photocathode surface produces initial velocity, the initial angle of electronics, e represents the quantity of electric charge of Single Electron, m _erepresent the quality of Single Electron, u represents the operating voltage between electronic lens and microchannel plate;

(4b) according to speed V during electronics arrival microchannel plate ₁the angle theta of (i, j) and this speed and electronic lens normal ₁(i, j), by law of conservation of energy calculate its arrive microchannel plate time offset distance s ₁(i, j)

$s_1(i,j)=\frac{\left(V_1\right(i,j\left){\mathrm{cos\&theta;}}_1\right(i,j)-V_0{\mathrm{cos\&theta;}}_0)m_e{V}_0{\mathrm{sin\&theta;}}_{0}D}{eu}$

Wherein D represents the spacing of electronic lens and microchannel plate;

(5) according to microchannel plate scattering theory, the offset distance s (i, j) that the electronics calculating arrival microchannel plate produces after microchannel plate Multiple Scattering; According to the Two dimensional Distribution of image on fluorescent screen vegetarian refreshments, calculate the corresponding fluoroscopic each pixel position (x, y) of this offset distance s (i, j), and add up the electron number n that each pixel position receives _e(x, y), wherein (x, y) is the two-dimensional coordinate of all pixels in video screen surface;

(6) according to the electron number n that the fluoroscopic each pixel position of correspondence receives _e(x, y), calculates the gray-scale value Gray (x of all pixels on video screen by fluoroscopic electro-optic conversion, y), these gray-scale values form a kind of annular distribution near the two-dimensional coordinate central point on video screen surface, and this annular distribution is halation image, and exports.

2. the halation emulation mode in a kind of low-light level television imaging according to claim 1, the luminance brightness L of the calculating optical lens surface wherein described in step (2) _a(i, j), by following formulae discovery:

$L_a(i,j)=\mathrm{\&rho;}(\frac{{\mathrm{LAcos\&theta;}}_i{\mathrm{cos\&theta;}}_j}{l^2}+E)/\mathrm{\&pi;}$

Wherein A represents intense light source area, θ _irepresent the surperficial bin normal in low-light three-dimensional scenic and the angle of intense light source between the incident ray at optical lens surface bin place, θ _jrepresent intense light source surface bin normal and the angle of intense light source between the incident ray at optical lens surface bin place, l represents the distance between intense light source and optical lens surface.

3. the halation emulation mode in a kind of low-light level television imaging according to claim 1, the electron number n (i, j) being subject to illumination generation by opto-electronic conversion calculating photocathode surface wherein described in step (3), computing formula is as follows:

$n(i,j)=\frac{\mathrm{\&pi;}}{4}{\left(\frac{D_f}{f}\right)}^2{L}_a(i,j)\mathrm{\&tau;}\&CenterDot;S_k$

Wherein D _frepresent System Optics effective aperture, f represents optical system focal length, and τ represents optical lens transmitance, S _krepresent photocathode sensitivity.

4. the halation emulation mode in a kind of low-light level television imaging according to claim 1, wherein described in step (5) according to microchannel plate scattering theory, offset distance s (the i that the electronics calculating arrival microchannel plate produces after microchannel plate Multiple Scattering, j), be calculated as follows:

$s(i,j)=\frac{\left(V_1\right(i,j\left){\mathrm{cos\&theta;}}_1\right(i,j)-V_0{\mathrm{cos\&theta;}}_0)m_e{V}_0{\mathrm{sin\&theta;}}_{0}D}{eu}+\frac{2{\mathrm{Nm}}_e\sqrt{{V_0}^2+\frac{2eu}{m_e}}{\mathrm{sin\&theta;}}_1(i,j)}{eu}$

Wherein, N represents the number of times that electronics and the non-perforated wall of microchannel plate collide, and value is natural number.

5. the halation emulation mode in a kind of low-light level television imaging according to claim 1, the Two dimensional Distribution according to image on fluorescent screen vegetarian refreshments wherein described in step (5), calculate this offset distance s (i, j) corresponding fluoroscopic each pixel position (x, y), by following formulae discovery:

$|\sqrt{{\left({\mathrm{xd}}_w\right)}^2+{\left({\mathrm{yd}}_h\right)}^2}-s(i,j)|<\mathrm{\&delta;}$

Wherein, d _wrepresent the width of the single pixel of video screen, d _hrepresent the height of the single pixel of video screen, δ=min (d _w, d _h).

6. the halation emulation mode in a kind of low-light level television imaging according to claim 1, the gray-scale value Gray (x, y) of all pixels on the calculating video screen wherein described in step (6), calculates as follows:

(6a) quantification voltage V (x, y) of each pixel is calculated according to voltage signal conversion formula

$V(x,y)=\frac{\mathrm{\&pi;}}{4}{\mathrm{\&tau;}}_e{\left(\frac{D_e}{f_e}\right)}^{2}R\&CenterDot;A_s\&CenterDot;G_v\&CenterDot;v\&CenterDot;G\&CenterDot;k\&CenterDot;n_e(x,y)\&CenterDot;e/a^2$

Wherein τ _erepresent the transmitance of coupled lens, D _erepresent coupled lens effective aperture, f _erepresent coupled lens focal length, R represents explorer response rate, A _srepresent effective photosensitive elemental area, G _vrepresent vision signal enlargement factor, v represents the operating voltage of electronic lens, and G represents the gain of microchannel plate, and k represents video screen luminous efficacy, and a represents electron optics enlargement factor;

(6b) according to quantification voltage V (x, y) of each pixel, the gray-scale value Gray (x, y) of each pixel is calculated

$Gray(x,y)=\frac{255}{V_{Max}-V_{Min}}V(x,y)$

Wherein V _maxand V _minrepresent maximal value and the minimum value of the quantification voltage of all pixels respectively.