CN104156908A - High time resolution frequency domain transient imaging method - Google Patents

Abstract

The invention discloses a frequency-domain transient imaging method with high temporal resolution, comprising the following steps: 1) collecting a group of image sets I _{x, y} (f, φ) for a measured object through a modulation imaging system; 2) Extract the fundamental image and the harmonic image I ⁿ _{x, y} (nf) from the image set I _{x, y} (f, φ) whose frequency is f; 3) for the fundamental image and the harmonic Figure I ⁿ _{x, y} (nf) images are corrected for amplitude and phase; 4) The corrected fundamental wave image and the harmonic image I ⁿ _{x, y} (nf) form a spectrum image set I ^p _{x ,y} (f), and then perform Fourier transform along the frequency f of the spectrum image set to obtain the transient image i _x,y (t). The method extracts high-order harmonic components from the collected image data of limited working frequency to obtain higher frequency information, thereby improving the temporal resolution of transient images.

Description

Frequency domain transient imaging method with high temporal resolution

technical field

The invention relates to the fields of optics and computer vision, in particular to a frequency-domain transient imaging method with high time resolution.

Background technique

For general imaging systems, the speed of light can be considered to be infinite, so the traditional image records the light response of the object under the condition of stable light. But the light transient response of an object contains more information. The technique of collecting information on the optical transient response of an object is called transient imaging. One approach to transient imaging uses ultra-high-speed cameras and requires ultra-short-pulse light sources. This method belongs to the time domain acquisition scheme, and its time resolution depends on the imaging speed of the camera. The disadvantage is that the ultra-high-speed imaging system and light source used are very expensive, and the acquisition process is complicated and time-consuming. Another method is to use a modulated imaging system, which requires the same principle as the TOF (time-of-flight) depth camera. The frequencies are imaged separately. This method belongs to the frequency domain acquisition scheme. The data collected by the imaging system at each operating frequency is the frequency spectrum of the transient image at this frequency. The transient state can be obtained by Fourier transform and related denoising algorithms or by using optimization methods. image. The temporal resolution of frequency-domain transient imaging mainly depends on the operating frequency of the modulated imaging system. Due to the limitations of the hardware system, the modulation imaging system can only work in a limited frequency range, which limits the temporal resolution of the obtained transient images.

Contents of the invention

The purpose of the present invention is to invent a high-time-resolution frequency-domain transient imaging method in order to overcome the technical defect of low temporal resolution of transient images due to the limited frequency range of the modulation imaging system in the prior art.

In order to solve the above-mentioned technical problems, the present invention provides a high-time-resolution frequency-domain transient imaging method, which comprises the following steps: 1) collecting a group of image sets I _{x, y} for the measured object through a modulation imaging system (f, φ); 2) extract the fundamental wave image and the harmonic image I ⁿ _{x, y} (nf) from the image set I _{x, y} (f, φ) whose frequency is f; 3) for the The fundamental image and the harmonic image I ⁿ _{x, y} (nf) are corrected for amplitude and phase; 4) the corrected fundamental image and the harmonic image I ⁿ _{x, y} (nf ) to form a spectrum image set I ^p _x,y (f), and then perform Fourier transform along the frequency f of the spectrum image set to obtain a transient image i _x,y (t).

In the above technical solution, the modulated imaging system in step 1) at least includes a signal generator, a light source and an imaging system.

In the above-mentioned technical scheme, the step of collecting a group of image sets I _{x, y} (f, φ) with a frequency of f to the measured object through the modulation imaging system described in step 1) is: a) the signal generator controls the The light source emits a square wave signal with a frequency f, and controls the shutter of the imaging system to image at the same frequency; b) when the phase difference between the control signal of the light source and the control signal of the shutter of the imaging system is φ, it is obtained image And the image obtained by φ-90° Compose the image set $I_{x,\mathrm{the\; y}}(f,\mathrm{\φ})=I_{x,\mathrm{the\; y}}^r(f,\mathrm{\φ})+j{I}_{x,\mathrm{the\; y}}^i(f,\mathrm{\φ}),$ Where j is an imaginary number symbol.

In the above technical solution, the modulated imaging system in step 1) selects an equally spaced operating frequency from low to high frequency ranges and equidistant phases from 0 to 2π to collect images of the measured object.

In the above-mentioned technical scheme, in step 2), the step of extracting the fundamental wave image and the harmonic image I ⁿ _{x, y} (nf) from the image set I x _{, y} (f, φ) at the frequency of f is:

${{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;nk</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

In the above technical solution, in step 3), before correcting the amplitude and phase of the fundamental wave image and the harmonic image I ⁿ _x,y (nf) image, the modulation imaging system is first calibrated, The steps are:

A) select a diffuse reflection plate with a uniform surface, and place it before the modulation imaging system;

B) collecting data on the diffuse reflector to obtain a set of images C _{x, y} (f, φ);

C) Using a parametric model $C_{x,\mathrm{the\; y}}(f,\mathrm{\&phi;})=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{A}^{\mathrm{no}}\left(\mathrm{nf}\right)\exp \{-j[\mathrm{n\&phi;}-{\mathrm{\&phi;}}_0^{\mathrm{no}}\left(\mathrm{nf}\right)\left]\right\}$ Fitting parameters A ⁿ (nf) and

In the above technical solution, step 4) in the step of forming the spectrum image set I ^p _{x, y} (f) from the corrected fundamental image and the harmonic image I ⁿ _{x, y} (nf), if a frequency If there are multiple images at the point, the fundamental wave image or the image of the lowest harmonic will be kept; if there is no image at a frequency point, then the amplitude linear interpolation and phase linear interpolation will be used to supplement the image at this frequency point.

The present invention has the following beneficial effects: the frequency-domain transient imaging method with high time resolution of the present invention extracts high-order harmonic components from the collected image data of limited working frequency to obtain higher frequency information, thereby improving Temporal resolution of transient images.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is a schematic diagram of the modulation imaging system of the present invention;

Fig. 2 is a flow chart of the high time resolution frequency domain transient imaging method of the present invention.

Detailed ways

A specific embodiment of the present invention will be described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations thereof such as "includes" or "includes" and the like will be understood to include the stated elements or constituents, and not Other elements or other components are not excluded.

As shown in Figure 1, the present invention provides a modulated imaging system, which at least includes: a signal generator, a light source and an imaging system;

As shown in Figure 2, it is a flow chart of a high-time-resolution frequency-domain transient imaging method implemented by the above-mentioned modulated imaging system, and the method includes the following steps:

Step S100: Collect a group of image sets I _{x, y} (f, φ) of the measured object through the modulation imaging system, where f is the working frequency, and φ is the adjustable phase;

More specifically, firstly, the signal generator controls the light source to emit a square wave signal with frequency f, and controls the shutter of the imaging system to form images at the same frequency; if the phase difference between the control signal of the collected light source and the control signal of the shutter of the imaging system is φ the resulting image The image obtained when the phase difference between the control signal of the acquisition light source and the control signal of the shutter of the imaging system is φ-90° Therefore, the acquired image set is j is an imaginary number symbol; wherein, the modulated imaging system selects equally spaced working frequencies from low to high frequency ranges (i.e. working frequency f=nf _s , f∈[f _L , f _H ], where n is a positive integer, f _s is the frequency interval, f _L , f _H are the minimum and maximum modulation frequency of the modulation imaging system respectively) and the phase selection from 0 to 2π is equally spaced (that is, φ=mφ _s , φ _s is the phase interval, m=0, 1,...,K, K=2π/φ _s ) to collect images of the measured object.

Step S102: Extracting a fundamental image and a harmonic image I ⁿ _{x, y} (nf) from the image set I _{x, y} (f, φ) with frequency f, wherein n is a positive integer;

Wherein, the specific method steps of extracting the fundamental wave image and the harmonic image I ⁿ _{x, y} (nf) from the image set I _{x, y} (f, φ) whose frequency is f are:

${{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;nk</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Step S104: correcting the amplitude and phase of the fundamental wave image and the harmonic image I ⁿ _x,y (nf) image;

Before calibration, the modulation imaging system is first calibrated (for a modulation imaging system, the calibration only needs to be performed once), and the amplitudes A ⁿ (nf) and phase shift Then divide ^In _x,y (nf) by The calibration steps are:

1) Select a diffuse reflection plate with a uniform surface and place it before the modulation imaging system;

2) Collect data on the diffuse reflector to obtain a set of images C _{x, y} (f, φ);

3) The parameters A ⁿ (nf) and

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; n\&phi;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; .</span>$

Step S106: Compose the corrected fundamental wave image and harmonic image I ⁿ _x,y (nf) into a spectral image set I ^p _x,y (f), and then perform Fourier transform along the frequency f of the spectral image set to obtain transient image i _x,y (t);

In the process of composing the corrected fundamental wave image and harmonic image I ⁿ _x,y (nf) into a spectrum image set I ^p _x,y (f), if there are multiple images at a frequency point, the fundamental wave image is retained or the image of the lowest harmonic; if there is no image at a frequency point, _use amplitude linear interpolation and phase linear interpolation to complement the image at this frequency point, and finally obtain a spectrum image set I ^p _x,y (f ).

The frequency-domain transient imaging method with high time resolution of the present invention extracts high-order harmonic components from the collected image data of limited working frequency to obtain higher frequency information, thereby improving the time resolution of the transient image .

The following is an example analysis of the frequency-domain transient imaging method with high temporal resolution in the embodiment of the present invention, specifically an example of transient imaging of an object, and the steps are as follows:

Step 200: Set the working frequency of the modulation imaging system to 5MHz-165MHz, interval f _s =1MHz, phase 0-π, interval φ _s =π/200, and acquire a set of images I _x,y (f,φ).

Step 202: For the image set I _{x, y} (f, φ) whose frequency is f, extract the fundamental wave image and the harmonic image;

${{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;nk</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Due to the small amplitude of high-order harmonics, only the third harmonic is selected, that is, the maximum value of n is 3.

Step 204: correcting the fundamental wave image and the harmonic image with calibration parameters;

${{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; .</span>$

Step 206: Use the corrected fundamental wave image and harmonic image to form a spectrum image set I ^p _x,y (f), with a frequency interval of f _s =1 MHz. Among them, the 5-165MHz frequency band adopts the fundamental wave image, the 166-330MHz frequency band adopts the second harmonic image, and the 331-495MHz frequency band adopts the third harmonic image. The images that do not exist in the 0-5MHz frequency band and the 166-495MHz frequency band are complemented by amplitude linear interpolation and phase linear interpolation.

Step 208: Reconstruct the transient image ix _,y (t)=FFT[I ^p _x,y (f)].

Finally, it should be noted that: the above embodiments are only used to illustrate the present invention rather than limit the technical solutions described in the present invention; Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered by the claims of the present invention.

Claims (7)

1. A frequency-domain transient imaging method with high temporal resolution, characterized in that, comprising the following steps: 1) Collect a group of image sets I _{x, y} (f, φ) of the measured object through the modulation imaging system; 2) extract the fundamental image and the harmonic image I ⁿ _{x, y} (nf) from the image set I x _, y (f, φ) whose frequency is f; 3) correcting the amplitude and phase of the fundamental wave image and the harmonic image I ⁿ _x,y (nf); 4) Composing the corrected fundamental wave image and the harmonic image I ⁿ _x,y (nf) into a spectrum image set I ^p _x,y (f), and then do The Fourier transform obtains the transient image i _x,y (t). 2 . The frequency-domain transient imaging method with high time resolution according to claim 1 , wherein the modulated imaging system in step 1) at least includes a signal generator, a light source and an imaging system. 3 . 3. the frequency-domain transient imaging method of high temporal resolution according to claim 2, is characterized in that, described in step 1) is collected a group of image sets I _{x, y} ( f, φ) steps are: a) the signal generator controls the light source to emit a square wave signal at a frequency f, and controls the shutter of the imaging system to image at the same frequency; b) collecting the image obtained when the phase difference between the control signal of the light source and the control signal of the shutter of the imaging system is φ And the image obtained by φ-90° Compose the image set $I_{x,\mathrm{the\; y}}(f,\mathrm{\&phi;})=I_{x,\mathrm{the\; y}}^r(f,\mathrm{\&phi;})+j{I}_{x,\mathrm{the\; y}}^i(f,\mathrm{\&phi;}),$ Where j is an imaginary number symbol. 4. the frequency-domain transient imaging method of high temporal resolution according to claim 1, is characterized in that, described in step 1) the modulation imaging system selects from low to high frequency range selection equidistant operating frequency and from 0 Phases up to 2π select equidistant phases to collect images of the measured object. 5. the frequency-domain transient imaging method of high temporal resolution according to claim 1, is characterized in that, in step 2) from the image collection I _{x that described frequency is f, y} (f, φ) extracts The steps of the fundamental image and the nth harmonic image I ⁿ _{x, y} (nf) are: ${{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;nk</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$ 6. according to the frequency-domain transient imaging method of high temporal resolution described in any one of claim 1-5, it is characterized in that, step 3) in to described fundamental wave image and described harmonic image I ⁿ Before _{x, y} (nf) correct the amplitude and phase, the modulation imaging system is first calibrated, and the steps are: A) select a diffuse reflection plate with a uniform surface, and place it before the modulation imaging system; B) collecting data on the diffuse reflector to obtain a set of images C _{x, y} (f, φ); C) Using a parametric model $C_{x,\mathrm{the\; y}}(f,\mathrm{\&phi;})=\underset{\mathrm{no}=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{A}^{\mathrm{no}}\left(\mathrm{nf}\right)\exp \{-j[\mathrm{n\&phi;}-{\mathrm{\&phi;}}_0^{\mathrm{no}}\left(\mathrm{nf}\right)\left]\right\}$ Fitting parameters A ⁿ (nf) and 7. the frequency-domain transient imaging method of high temporal resolution according to claim 1, is characterized in that, step 4) described fundamental wave image after correction and described harmonic wave image I ⁿ _{x, y} (nf ) in the step of forming the spectrum image set I ^p _{x, y} (f), if there are multiple images at a frequency point, then keep the fundamental image or the image of the lowest harmonic; if there is no image at a frequency point, then use the amplitude Linear interpolation and phase linear interpolation complement the image at this frequency point.