CN106292128A - A kind of formation method based on polarization extinction - Google Patents

Abstract

The invention discloses a kind of formation method based on polarization extinction, the i.e. front at camera lens and arrange a polaroid being perpendicular to camera optical axis, polaroid can uniformly rotate before camera lens；When polaroid uniform rotation, camera is continuously shot, and obtains the polarization image under different polarization angle；Take camera the first two field picture of obtaining of shooting as reference picture, constantly make extinction state differentiation with reference picture by shoot the image got after camera every time, obtain final delustring image, i.e. 180 ° of width delustring images obtained of polaroid rotation.It is high that the present invention has picture contrast, and the details of target clearly waits remarkable advantage, more conducively human eye or other scopes to the observation of object and detection, and principle is simple, and effect is obvious.

Description

A kind of formation method based on polarization extinction

Technical field

The invention belongs to technical field of imaging, a kind of formation method based on polarization extinction.

Background technology

Owing to object reflection light is too strong or body surface direct reflection, the image photographed can present a piece of bright The white of eye, strong interference human eye or other scopes are to the observation of object or detection.Therefore in this feelings Under condition, some headend equipment is needed to eliminate high light, beneficially human eye in the case of not affecting object detection information Or object observed or detects by other scopes.For this situation, people's design achieves various Eliminating the system of high light, ubiquitous system is to add an attenuator between scope and object to reduce light By force.But, the image entirety light intensity step-down that this system obtains, contrast reduction, target detail resolution is also Can reduce.

Also having a kind of technology is exactly polarization extinction system, utilizes polaroid to carry out the mechanism of delustring as shown in Figure 1: When light source meets Brewster's angle θ_BTime incident, reflection light is complete line polarized light, adjusts analyzer azimuth, When polarization azimuth is orthogonal with the polarization direction of reflection light, due to the light blocking effect of polaroid, reflect light Polaroid can not be passed through completely, thus reach the purpose of delustring；When light source deviates brewster angle incidence, reflection Light is partial polarized light, adjusts analyzer azimuth and can only eliminate partially reflective light, as long as meeting angle of incidence at cloth Scholar can effectively weaken the high light impact on target acquisition near this special angle.

Above-mentioned extinction coefficient is widely used scene, and the normally used extinction method of this system mainly has feedback to disappear Light, optical extinction etc..Feedback delustring is to utilize circuit feedback signal to be adjusted, thus reaches to eliminate high light Purpose.Document 1 (ZHANGJ H, LIU L G, ZHU H N, et al.The High Resolution Polarization Nulling Measurement System with Magneto-optical Modulator [J] .Journal of Optoelectronics-Laser.2001,12 (10): 1041-1042.) disclose in A kind of method utilizing novel mangneto manipulator and drive circuit to be modulated polarized light, its advantage is quick In real time, shortcoming is high to optically activ material requirement, system design complexity；Optical extinction is that the character utilizing light is to by force Light eliminates, and principle is simple, and the suitability is wide, and effect is also apparent from.Document 2 (CN103345099A) In disclose a kind of formation method based on polarized light delustring, by shoot several angles polarization image, to often Width polarization image delimit the pixel window of 3*3, the data in window compared with threshold value set in advance Relatively, by obtaining final delustring image after image co-registration, the extinction effect that this method obtains with preset Threshold value closely related, and the execution time of algorithm is long, and camera can only shoot the polarization of several special angle every time Image, has certain limitation.Document 3 (CN102998667A) disclose a kind of based on polarization remote sensing The rough water sun glitter stripping means of detection, utilizes polarization imaging based on liquid crystal variable retarder to visit Survey instrument and carry out rough water polarization imaging detection, obtain polarization intensity image, and then calculate degree of polarization image with inclined Shake angle image, is calculated the mesh separated under sun glitter background based on time series analysis and image fusion technology Mark thing, although this method is notable to the peeling effect of sun glitter, but systematic cost is higher, apparatus expensive, And can be used only in the sun glitter stripping field that polarization remote sensing detects, there is certain limitation.

Summary of the invention

It is an object of the invention to provide a kind of formation method based on polarization extinction, high light can be eliminated well and do Disturbing, beneficially human eye or other scopes are to the observation of target and detection.

The technical solution realizing the object of the invention is: a kind of formation method based on polarization extinction, it is achieved step Rapid as follows:

Step 1, arranges a polaroid being perpendicular to camera optical axis in the front of camera lens, and polaroid is in phase Can uniformly rotate before machine camera lens；

Step 2, when polaroid uniform rotation, camera is continuously shot, and obtains the polarization under different polarization angle Image；

Step 3, takes camera the first two field picture of obtaining of shooting as reference picture, shoots after camera every time The image got constantly is made extinction state differentiate with reference picture, obtains final delustring image, i.e. polaroid rotation Turn 180 ° of width delustring images obtained.

Compared with prior art, its remarkable advantage is the present invention: it is strong that (1) utilizes the polarization characteristic of reflection light to eliminate Light, and utilizes compared with attenuator carries out the existing method of delustring, has picture contrast high, and the details of target is clear Clear waiting remarkable advantage, more conducively human eye or other scopes to the observation of object and detection, principle is simple, Effect is obvious.(2) polaroid uniform rotation makes camera be continuously shot, and can obtain the inclined of different polarization angle Shake image, and is not only the polarization image of several angle, as 0 °, 60 °, 120 ° or 0 °, 45 °, 90 °, 135°.(3) polaroid is every turns half-turn, utilizes delustring method of discrimination can obtain a width delustring image, the soonest Speed.(4) suitability is strong, can apply to the multiple occasion needing to eliminate high light interference.Such as to gleams of light are reflecting on waves in the river Lake surface, observe immersed body；For the headstock under strong illumination, identify its license plate number；To occurring, minute surface is anti- The object penetrated, observes its surface information；The water surface affected by sun glitter is taken photo by plane, exploration ships or Person's floater etc..

Below in conjunction with the accompanying drawings the present invention is described in further detail.

Accompanying drawing explanation

Fig. 1 is polarization extinction schematic diagram.

Fig. 2 is the flow chart of present invention formation method based on polarization extinction.

Fig. 3 (a) be by strong illumination license plate number delustring before image, Fig. 3 (b) is the figure after utilizing delustring of the present invention Picture.

Fig. 4 (a) is the image before the water surface delustring that affected by sun glitter, after Fig. 4 (b) is for utilizing delustring of the present invention Image.

Fig. 5 (a) is the image before simulation museum exhibit historical relic delustring, after Fig. 5 (b) is for utilizing delustring of the present invention Image.

Fig. 6 (a) is the image before simulating floater delustring of taking photo by plane, after Fig. 6 (b) is for utilizing delustring of the present invention Image.

Detailed description of the invention

In conjunction with Fig. 2, present invention formation method based on polarization extinction, it is achieved step is as follows:

Step 1, arranges a polaroid being perpendicular to camera optical axis in the front of camera lens, and polaroid is fixed In gear central authorities, gear is fixed on support, utilizes motor driven gear at the uniform velocity to rotate, thus drives phase Polaroid uniform rotation before machine camera lens.Visible light wave range black-white CCD camera chosen by camera, and frame frequency is f_pFrame/ Second, the gray level image that image is M*N of shooting gained, fp >=10, M, N are width and the height of image, unit For pixel.Motor drives the gear uniform rotation studding with polaroid, and camera can adopt any polarization angle Polarization image, and be not only the polarization image of several special angle, such as conventional 0 °, 60 °, 120 ° Or 0 °, 45 °, 90 °, 135 °.If camera frame frequency is 15 frames/second, the image of shooting gained is 640*480 Gray level image, Fig. 3 (a) be by strong illumination license plate number delustring before image.

Step 2, while polaroid uniform rotation, camera is continuously shot, and obtain under different polarization angle is inclined Shake image.The every half-turn that turns of polaroid, polarization angle at the uniform velocity changes from 0 ° to 180 °, if arranging motor Rotating speed (i.e. the rotating speed of polaroid) is per second to turn over 180 °, the most per second turns half-turn, then polaroid often turns over 180 °/f_p Camera photographs piece image, wherein, and f_pFrame frequency for camera.It it is 180 °s/sec as arranged motor speed, i.e. The rotating speed of polaroid is 180 °s/sec, and while polaroid uniform rotation, camera is continuously shot, and obtains different inclined Polarization image under angle of shaking.The every half-turn that turns of polaroid, polarization angle at the uniform velocity changes, the most partially from 0 ° to 180 ° The sheet that shakes often turns over 180 °/15=12 ° camera and photographs piece image, and wherein, 15 is the frame frequency of camera.Improve phase The frame frequency of machine or the rotating speed of the motor that slows down can control polaroid often turn over 1 ° of camera adopt more several Polarization image.The angle, θ that camera shooting piece image polarization turns over can represent by equation below:

$\mathrm{\θ}=\frac{{\mathrm{\θ}}_v}{f_p}$

Wherein, θ_vFor the polaroid angle turned over per second, f_pFor the frame frequency of camera used, θ is that camera often shoots one The angle that width polarization turns over.θ is the least, represents that polaroid often turns over half-turn camera and photographs more polarization Image, final delustring image is more accurate.

Step 3, takes camera the first two field picture of obtaining of shooting as reference picture, shoots after camera every time The image got constantly is made extinction state differentiate with reference picture, obtains final delustring image, i.e. polaroid rotation Turn 180 ° of width delustring images obtained.Wherein extinction state method of discrimination implementation process is as follows:

The gray value of each pixel position of the new two field picture that camera is obtained and reference picture respective pixel The grey scale pixel value of some position compares, and takes less as the new gray scale of this pixel position in reference picture Value, when the gray value of each pixel position of reference picture no longer changes, reference picture now is The final image after delustring, extinction state discrimination formula is as follows:

$W_{{\mathrm{\θ}}_1}(i,j)=I_{{\mathrm{\θ}}_1}(i,j)$

$W_{{\mathrm{\θ}}_2}(i,j)=\min (I_{{\mathrm{\θ}}_2}(i,j),W_{{\mathrm{\θ}}_1}(i,j))$

$W_{{\mathrm{\θ}}_3}(i,j)=\min (I_{{\mathrm{\θ}}_3}(i,j),W_{{\mathrm{\θ}}_2}(i,j))$

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$W_{{\mathrm{\θ}}_{n-1}}(i,j)=\min (I_{{\mathrm{\θ}}_{n-1}}(i,j),W_{{\mathrm{\θ}}_{n-2}}(i,j))$

$W_{{\mathrm{\θ}}_n}(i,j)=\min (I_{{\mathrm{\θ}}_n}(i,j),W_{{\mathrm{\θ}}_{n-1}}(i,j))$

Wherein,Representing the first two field picture that camera is adopted, corresponding polaroid angle is θ₁, (i j) represents i-th The pixel of row jth row,Represent the gray scale of the i-th row jth row pixel in the first two field picture that camera is adopted Value,For the ash of the i-th row jth row pixel in the reference picture that the first two field picture adopted by camera obtains Angle value；The second two field picture adopted for cameraIn the gray value of the i-th row jth row pixelWithAfter comparing relatively, take in both less as the new gray value of this pixel position in reference pictureThe 3rd two field picture adopted for cameraIn the gray value of the i-th row jth row pixel WithAfter comparing relatively, take in both less as the new gray value of this pixel position in reference pictureThe (n-1)th two field picture adopted for cameraIn the gray value of the i-th row jth row pixelWithAfter comparing relatively, take in both less as this pixel position new in reference picture Gray valueRepresent along with the uniform rotation of polaroid, in the n-th frame image that camera is adopted The gray value of the i-th row jth row pixel,ForWithAfter comparing relatively, take in both less As the new gray value of this pixel position in reference pictureIfI.e. join Examine image no longer to change, thenFor the delustring image finally given.

Utilize the extinction effect comparison diagram of other several groups of scenes experiments that the present invention does respectively as Fig. 3 (a), Fig. 3 (b), Shown in Fig. 4 (a), Fig. 4 (b), Fig. 5 (a), Fig. 5 (b), Fig. 6 (a), Fig. 6 (b), as can be seen from the figure delustring After image and delustring before contrast substantially, extinction effect is notable, and target is clear, effectively eliminates high light interference.

Claims (4)

1. a formation method based on polarization extinction, it is characterised in that realize step as follows:

Step 1, arranges a polaroid being perpendicular to camera optical axis in the front of camera lens, and polaroid is in phase Can uniformly rotate before machine camera lens；

Step 2, when polaroid uniform rotation, camera is continuously shot, and obtains the polarization under different polarization angle Image；

Step 3, takes camera the first two field picture of obtaining of shooting as reference picture, shoots after camera every time The image got constantly is made extinction state differentiate with reference picture, obtains final delustring image, i.e. polaroid rotation Turn 180 ° of width delustring images obtained.

Formation method based on polarization extinction the most according to claim 1, it is characterised in that in step 1, Visible light wave range black-white CCD camera chosen by camera, and frame frequency is f_pFrame/second, the image of shooting gained is M*N's Gray level image, f_p>=10, M, N are width and the height of image, and unit is pixel.

Formation method based on polarization extinction the most according to claim 1, it is characterised in that in step 2, The every half-turn that turns of polaroid, polarization angle at the uniform velocity changes from 0 ° to 180 °, if the rotating speed arranging polaroid is per second Turn over 180 °, the most per second turn half-turn, then polaroid often turns over 180 °/f_pCamera photographs piece image, wherein, f_pFrame frequency for camera；The angle, θ equation below that camera shooting piece image polarization turns over represents:

$\mathrm{\θ}=\frac{{\mathrm{\θ}}_v}{f_p}$

Wherein, θ_vFor the polaroid angle turned over per second, f_pFor the frame frequency of camera used, θ is that camera often shoots one The angle that width polarization turns over.

Formation method based on polarization extinction the most according to claim 1, it is characterised in that in step 3, Extinction state method of discrimination implementation process is as follows:

The gray value of each pixel position of the new two field picture that camera is obtained and reference picture respective pixel The grey scale pixel value of some position compares, and takes less as the new gray scale of this pixel position in reference picture Value, when the gray value of each pixel position of reference picture no longer changes, reference picture now is The final image after delustring, extinction state discrimination formula is as follows:

$\begin{array}{c}{W}_{{\mathrm{\θ}}_1}(i,j)=I_{{\mathrm{\θ}}_1}(i,j)\\ W_{{\mathrm{\θ}}_2}(i,j)=\min (I_{{\mathrm{\θ}}_2}(i,j),W_{{\mathrm{\θ}}_1}(i,j))\\ W_{{\mathrm{\θ}}_3}(i,j)=\min (I_{{\mathrm{\θ}}_3}(i,j),W_{{\mathrm{\θ}}_2}(i,j))\\ \·\\ \·\\ \·\\ \·\\ \·\\ \·\\ W_{{\mathrm{\θ}}_{n-1}}(i,j)=\min (I_{{\mathrm{\θ}}_{n-1}}(i,j),W_{{\mathrm{\θ}}_{n-2}}(i,j))\\ W_{{\mathrm{\θ}}_n}(i,j)=\min (I_{{\mathrm{\θ}}_n}(i,j),W_{{\mathrm{\θ}}_{n-1}}(i,j))\end{array}$

Wherein,Representing the first two field picture that camera is adopted, corresponding polaroid angle is θ₁, (i j) represents The pixel of the i-th row jth row,Represent the ash of the i-th row jth row pixel in the first two field picture that camera is adopted Angle value,For the i-th row jth row pixel in the reference picture that the first two field picture adopted by camera obtains Gray value；The second two field picture adopted for cameraIn the gray value of the i-th row jth row pixel WithAfter comparing relatively, take in both less as the new gray value of this pixel position in reference pictureThe 3rd two field picture adopted for cameraIn the gray value of the i-th row jth row pixel WithAfter comparing relatively, take in both less as the new gray value of this pixel position in reference pictureThe (n-1)th two field picture adopted for cameraIn the gray value of the i-th row jth row pixelWithAfter comparing relatively, take in both less as this pixel position new in reference picture Gray valueRepresent along with the uniform rotation of polaroid, in the n-th frame image that camera is adopted The gray value of the i-th row jth row pixel,ForWithAfter comparing relatively, take in both less As the new gray value of this pixel position in reference pictureIfI.e. join Examine image no longer to change, thenFor the delustring image finally given.