阅读说明：本技术 反射式散射光场成像中的背向干扰滤除方法及成像系统 (Backward interference filtering method in reflective scattered light field imaging and imaging system ) 是由 刘红林 韩申生 于 2019-01-09 设计创作，主要内容包括：本发明公开了一种反射式散射光场成像中的背向干扰滤除方法及成像系统,该方法通过获得目标物的自相关从而恢复目标物的像,该方法不仅可以用在反射模式中滤除背向干扰,也可以推广到其他模式中滤除其它类型的干扰,且不受目标物静止与否的限制,相应的,一种生物软组织内的目标物成像系统结构简单易于实施。(The invention discloses a method for filtering back interference in reflection type scattered light field imaging and an imaging system, wherein the method recovers an image of a target object by obtaining autocorrelation of the target object, the method can be used for filtering back interference in a reflection mode, can also be popularized to other modes for filtering other types of interference, is not limited by whether the target object is static or not, and accordingly, the target object imaging system in biological soft tissue has a simple structure and is easy to implement.)

1. A method for filtering backward interference in reflective scattered light field imaging is characterized by comprising the following steps:

step one, obtaining a scattered light field distribution graph twice, projecting incident light to an object to be imaged, and at t₁And t₂Respectively exposing and shooting the object to be imaged by a camera at any time, obtaining two scattered light field distribution diagrams of the two objects to be imaged and ensuring tau₂＜t₂-t₁＜τ₁In which τ is₁Is the comprehensive decoherence time of the diffuse reflection on the surface of the medium and the shallow back scattering light, namely the decoherence time of the back interference light, tau₂Is the decoherence time of the scattering signal carrying the target information, wherein the time of two exposures is less than tau₂；

Step two, calculating the difference of the speckles of the two exposures, wherein the speckles of the two exposures are respectively expressed as:

S(t₁)＝O*PSF(t₁) + R formula-1, and

S(t₂)＝O*PSF(t₂) + R, formula-2,

wherein O is an object, PSF is a point spread function of the scattering medium, and R is a light intensity distribution of the backward disturbance light;

the difference between the speckles of the two exposures is:

ΔS＝S(t₂)-S(t₁)＝O*[PSF(t₂)-PSF(t₁)]formula-3;

and step three, extracting the autocorrelation of the target object, and performing autocorrelation on the formula-3 in the step two to obtain the autocorrelation of the target object:

and step four, recovering the image of the target object, and recovering the image of the target object through the autocorrelation of the target object obtained in the step three.

2. The method of claim 1, wherein: the incident light and the camera are arranged on the same side of the object to be imaged.

3. The method of claim 1, wherein: and the point spread function in the second step is the point spread function of the scattering medium, and the spatial statistical distribution of the point spread functions corresponding to different scattering media is one of Gaussian distribution, Poisson distribution or Lorentzian distribution.

4. The method according to claim 1, wherein in step four, the image of the object is restored by using a phase restoration method, a Gerchberg-Saxton iteration method, a wiener filter method, a regular filter method, an L ucy-Richardson algorithm, or a blind deconvolution method.

5. An imaging system of a target object in a biological soft tissue, comprising the biological soft tissue (1), an incident light (2), a camera (3) and a computer (4) with an image recovery function, characterized in that: the incident light (1) and the camera (3) are on the same side of the biological soft tissue, the camera (3) is in signal connection with a computer (4), and the computer (4) performs image restoration on a target (5) by using the method according to any one of claims 1 to 4.

Technical Field

The invention relates to image processing, in particular to a method for filtering backward interference in reflective scattered light field imaging and an imaging system.

Background

When targets in scattering media such as biological soft tissue and the like are imaged in a reflection mode, the surface layer of the medium can generate diffuse reflection and backscattering, the proportion of the components is often far greater than that of signal light carrying information after being reflected from the targets, and the components are distributed irregularly generally and are difficult to filter by methods such as subtracting direct current background and the like. This causes great difficulty in image restoration.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for filtering back interference in reflective scattered light field imaging and an imaging system.

The purpose of the invention is realized by adopting the following technical scheme:

a method for filtering back interference in reflective scattered light field imaging comprises the following steps:

step one, obtaining a scattered light field distribution graph twice, projecting incident light to an object to be imaged, and at t₁And t₂Respectively exposing and shooting the object to be imaged by a camera at any time, obtaining two scattered light field distribution diagrams of the two objects to be imaged and ensuring tau₂＜t₂-t₁＜τ₁In which τ is₁Is the comprehensive decoherence time of the diffuse reflection on the surface of the medium and the shallow back scattering light, namely the decoherence time of the back interference light, tau₂Is the decoherence time of the scattering signal carrying the target information, wherein the time of two exposures is less than tau₂；

Step two, calculating the difference of the speckles of the two exposures, wherein the speckles of the two exposures are respectively expressed as:

S(t₁)＝O*PSF(t₁) + R formula-1, and

S(t₂)＝O*PSF(t₂) + R, formula-2,

wherein O is a target; PSF is the point spread function of the scattering medium; r is the distribution of optical elements such as the intensity and polarization of the backward disturbance light, which is taken as the intensity distribution in this example; s is speckle distribution, which may be speckle distribution corresponding to light intensity, polarization, or other optical elements, and S is the speckle distribution of light intensity in this example.

The difference between the speckles of the two exposures is:

ΔS＝S(t₂)-S(t₁)＝O*[PSF(t₂)-PSF(t₁)]formula-3;

and step three, extracting the autocorrelation of the target object, and performing autocorrelation on the formula-3 in the step two to obtain the autocorrelation of the target object:

and step four, recovering the image of the target object, and recovering the image of the target object through the autocorrelation of the target object obtained in the step three.

Preferably, the incident light and the camera are arranged on the same side of the object to be imaged.

Preferably, the point spread function in the second step is a point spread function of the scattering medium, and the spatial statistical distribution of the point spread functions corresponding to different scattering media is one of gaussian distribution, poisson distribution or lorentzian distribution.

Preferably, in step four, the phase restoration method, the Gerchberg-Saxton iteration method, the wiener filtering method, the regular filtering method, the L ucy-Richardson algorithm or the blind deconvolution method is adopted to restore the image of the target object.

In addition, the system for imaging the target object in the biological soft tissue comprises the biological soft tissue, incident light, a camera and a computer with an image recovery function, wherein the incident light and the camera are arranged on the same side of the biological soft tissue, the camera is in signal connection with the computer, and the computer performs image recovery on the target object by adopting the method.

Compared with the prior art, the invention has the beneficial effects that: the method and the system are not limited by a static target object, are also suitable for a moving target object, provide the efficiency of image restoration, can be used for filtering back interference in a reflection mode, can also be popularized to other modes for filtering other types of interference, and have important reference significance for auxiliary detection or restoration in the medical and biological research fields.

Drawings

FIG. 1 is a schematic view of a system for imaging a target within biological soft tissue.

In the figure: 1. biological soft tissue; 2. incident light; 3. a camera; 4. a computer; 5. an object.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

When imaging a target object in a scattering medium such as biological soft tissue, brownian thermal motion is inevitable, and other forms of motion are possible, because the scattering particles in the medium are not absolutely stationary.

The light interacts with the scattering medium and the decoherence times of the different components differ, for example, the decoherence time of multiply scattered light is significantly shorter than that of lesser and singly scattered light, the decoherence time of surface diffuse reflected light is generally relatively longer, and the decoherence time of superficial back-scattered light is also generally longer than that of multiply scattered light. The scattered light carrying the target information is mostly light that has undergone multiple scattering. And can thus be distinguished by the difference in the decoherence time.

Specifically, the method for filtering the back interference in the reflective scattered light field imaging comprises the following steps.

Step one, obtaining a speckle distribution map of a twice scattered light field: projecting incident light toward an object to be imaged at t₁And t₂Time of day is respectively exposed by cameraShooting an object to be imaged, obtaining two scattered light field distribution maps of two objects to be imaged and ensuring tau₂＜t₂-t₁＜τ₁In which τ is₁Is the comprehensive decoherence time of the diffuse reflection on the surface of the medium and the shallow back scattering light, namely the decoherence time of the back interference light, tau₂Is the decoherence time of the scattering signal carrying the target information, wherein the time of two exposures is less than tau₂。

And step two, calculating the difference of the speckles of the two exposures. The speckles of the two exposures are respectively expressed as:

S(t₁)＝O*PSF(t₁) + R formula-1, and

where O is the target, PSF is the point spread function of the scattering medium, and R is the intensity distribution of the back-interference light.

The difference between the two is:

ΔS＝S(t₂)-S(t₁)＝O*[PSF(t₂)-PSF(t₁)]formula-3.

And step three, extracting the autocorrelation of the target object. The autocorrelation of the target object can be obtained by the autocorrelation of the formula-3 in the second step

And step four, recovering the image of the target object, and recovering the image of the target object through the autocorrelation of the target object obtained in the step three.

In step four, the phase recovery method, the Gerchberg-Saxton iteration method, the wiener filtering method, the regular filtering method, the L ucy-Richardson algorithm or the blind deconvolution method is adopted to recover the image of the target object.

The method is immune to the movement of the target object and is not limited by the movement.

When the object O moves, the formulas-1 and-2 become formulas-5 and-6, respectively:

and

the autocorrelation of the difference between the two can still be described by equation-4.

The method can be used for filtering the backward interference in the reflection mode and can also be popularized to other modes for filtering other types of interference.

Referring to fig. 1, an imaging system of a target object in biological soft tissue comprises biological soft tissue 1, incident light 2, a camera 3 and a computer 4 with an image recovery function, wherein the incident light 1 and the camera 3 are arranged on the same side of the biological soft tissue, the camera 3 is in signal connection with the computer 4, and the computer 4 performs image recovery on a target object 5 by adopting the method.

The imaging system is not only suitable for biological soft tissue, but also suitable for imaging underwater, ground glass or other targets in or behind media.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various exemplary embodiments and with various alternatives and modifications as will be apparent to those skilled in the art from the above description and concepts, and all such modifications and variations are intended to be included within the scope of the following claims.