CN102497512A - Zigzag scanning high resolution imaging system and method - Google Patents

Abstract

The invention discloses a zigzag scanning high resolution imaging system and method, relating to the field of imaging. High resolution imaging can be realized by adopting the system and the method. The system comprises an image acquisition device, an image acquisition control device, an image processing device and a display device, wherein the image acquisition device comprises two linear array CCD (charge coupled device) cameras; the two linear array CCD cameras are used for scanning and shooting an object to be imaged respectively at inclination angles of theta and -theta relative to the horizon, so that the image acquisition device and the object to be imaged form zigzag scanning and the scanned contents mutually disjoint; theta is more than 0 and less than 90 degrees; the image acquisition control device controls the image acquisition processes of the CCD cameras; the image processing device rebuilds the acquired image data; and the display device is used for displaying the obtained high resolution image. The system is simple to realize in the engineering and is very economical and is convenient to maintain; and the images with higher resolution can be obtained by utilizing the conventional imaging device.

Description

A kind of broken-line type scanning high-resolution imaging system and method

Technical field

The present invention relates to the high-resolution imaging field, relate in particular to a kind of broken-line type scanning high-resolution imaging system and method.

Background technology

In recent years, line array CCD had been widely used in fields such as space flight, remote sensing, safety and industrial detection because it has high integration, high-resolution, high accuracy and highly sensitive characteristic.The spatial resolution that how to improve the line array CCD imaging has become a hot research problem.To this hot issue, many scholars have proposed various effective solutions.According to different research starting points, these methods can be summarized as two big types, promptly based on the method for image-forming principle with based on the method for sampling configuration.The former mainly is the angle from image-forming principle, the focal length through increasing optical system or reduce the CCD pixel dimension and improve the CCD pixel resolution.But the increase of optical system focal length can bring difficult problems such as design difficulty increase, the increasing of camera volume and weight and expense increase, and because the restriction of factors such as physical structure, manufacturing, sensitivity and signal to noise ratio, CCD device pixel dimension can not be done too for a short time; The latter through changing the sample mode of CCD, utilizes Image Reconstruction Technology to realize high resolution imaging then from the CCD sampling configuration.Many research work have been done about method both at home and abroad, the typical hyper mode sampling that has French SPOT-5HRG camera to adopt, the single line battle array that height mode is sampled and the Beijing Space Electromechanical Research Institute the proposes inclination 45 degree Sampling techniques that the Chinese Academy of Space Technology is studied etc. represented based on sampling configuration.

The key of hyper mode sampling imaging technology is how accurately two identical line array CCDs to be integrated in the device; Make the displacement that they stagger 0.5 pixel along the pixel orientation, the displacement of the individual pixel of the n+0.5 that staggers along the scanning direction (n is a positive integer).This method of sampling require to stagger between the two CCD error of displacement is no more than the distance of 1/10～1/20 pixel, is that 10 μ m are example with the pixel size, then requires two offset errors between the line array CCD must be controlled between 0.5 μ m～1 μ m.Therefore; The realization of hyper mode Sampling techniques depends on accurate device integrated technology, in the actual integrating process of CCD, the control of the offset error between two CCD is had high requirement; If error can not be controlled in the suitable scope, will cause bigger influence to image resolution ratio.

Height mode sampling imaging technology is similar basically with hyper mode, and difference is the height mode method of sampling except adopting the wrong drainage technique of pixel, and also the scanning frequency with line array video camera is doubled.But too high scanning frequency can cause other hardware device (motor encoder, motion control card, image pick-up card etc.) can't satisfy too fast capture speed; And these hardware devices of upgrading will cause very big economic expense to adapt to high-speed data acquisition and motion control; And some equipment is because its performance bottleneck can't be accomplished upgrading at all, and therefore relying on the raising line scanning frequency is not a good solution.

The single line battle array inclination 45 degree Sampling techniques that the Beijing Space Electromechanical Research Institute proposes are a kind of brand-new sampling configurations.Through with line array CCD rotation 45 degree, make picture pick-up device along becoming the direction of miter angle to sample with the orientation of line array CCD pixel, improve the spatial resolution of image, and overcome the CCD dislocation registration problems that exists in hyper mode and the height mode Sampling techniques.But also there is tangible drawback in this method; For example the imaging visual field (View ofField) of video camera narrows down; The image information of obtaining tails off; Spatial resolution that the more important thing is this mode hypograph does not increase significantly, and is merely 1.19 times in theory, can not satisfy the requirement of high-resolution imaging.

Summary of the invention

The technical problem that the present invention solves is how to obtain high-definition picture.

In order to overcome the above problems, the present invention provides a kind of broken-line type scanning high-resolution imaging system and method, equipment is changed under the less demanding situation, and under the little situation of visual field influence, can be improved camera resolution.

Embodiments of the invention adopt following technical scheme:

A kind of broken-line type scanning high-resolution imaging system comprises:

Image collecting device; Form by two linear array CCD cameras; Said two linear array CCD cameras and level are treated imaging object and are scanned capture with cant angle theta and-θ angle respectively; 0＜θ＜90 ° wherein make image collecting device and treat to be the zigzag scanning shape between the imaging object, and scans content is mutually disjointed;

The IMAQ control device, control CCD image of camera gatherer process;

Image processing apparatus is rebuild the view data that collects;

Display unit is used to show the high-definition picture that obtains.

Embodiments of the invention also provide a kind of broken-line type scanning high-resolution imaging method, comprising:

A) camera space layout is arranged two identical linear array CCD cameras and level respectively with cant angle theta and-θ angle, 0＜θ＜90 ° wherein make image collecting device and treat to be the zigzag scanning shape between the imaging object, and scans content is mutually disjointed;

B) trigger capture, the IMAQ control device is controlled the gatherer process of two cameras respectively, and they send the capture triggering signal to two line-scan digital cameras simultaneously, and two line-scan digital cameras make public simultaneously;

C) A/D conversion, line array CCD converts light signal into analog electrical signal and transfers to image pick-up card, and image pick-up card is accomplished the A/D conversion, and analog electrical signal is converted into the data image signal input image processing unit;

D) geometric correction of imagery is carried out geometric correction by image processing apparatus to the data image signal of importing.

A kind of broken-line type scanning high-resolution imaging system and method that the embodiment of the invention provides; Adopt two linear array CCD cameras and level to arrange with cant angle theta and-θ angle respectively; 0＜θ＜90 ° wherein make image collecting device and treat to be the zigzag scanning shape between the imaging object, and the scans content mode of mutually disjointing; Be not reduced under the picture situation in the visual field, improving the spatial resolution of imaging.

Description of drawings

When combining accompanying drawing to consider; Through with reference to following detailed, can more completely understand the present invention better and learn wherein many attendant advantages easily, but accompanying drawing described herein is used to provide further understanding of the present invention; Constitute a part of the present invention; Illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute to improper qualification of the present invention, wherein:

Fig. 1 is the system architecture diagram of high-resolution imaging system of the present invention;

Fig. 2 is the specific embodiments figure of high-resolution imaging of the present invention system;

Fig. 3 is the imaging visual field sketch map of line-scan digital camera;

Fig. 4 is the two-dimensional space sampling sketch map of line-scan digital camera;

Fig. 5 is the location of pixels distribution map in the distorted image that obtains that tilts to sample;

Fig. 6 is the location of pixels distribution map in the correcting image that conversion obtains through pixel coordinate.

Embodiment

Followingly describe with reference to Fig. 1-6 pair embodiments of the invention.

Embodiment one:

Present embodiment relates to a kind of broken-line type and scans the high-resolution imaging system, and Fig. 1 is for realizing the system architecture diagram of high-resolution imaging.Image collecting device 1 comprises linear array CCD camera 11 and linear array CCD camera 12, according to rearranging with the angled mode of level, make image collecting device and treat to be the zigzag scanning shape between the imaging object, and scans content is mutually disjointed; Communication acquisition control device 2 comprises image pick-up card 21 and image pick-up card 22, sends triggering signal to camera 11 and camera 12 respectively, triggers the camera capture, and converts the analog electrical signal of camera output into data image signal; 3 pairs of image pick-up cards of image processing apparatus 21 are rebuild with the view data of image pick-up card 22 outputs and are spliced; Obtain complete high-definition picture, image processing apparatus 3 can be programmable logic device or the computer processing system with image processing function; Via display unit 4 high resolution digital image is shown at last.

Fig. 2 is concrete embodiment figure, establishes camera 11 and camera 12 and scans capture with cant angle theta and-θ angle respectively, and L is the pixel spacing of camera CCD; Sampling interval along the camera scanning direction is L * N; N＞0 is a coefficient, regulates the size of the sampling interval of camera scanning direction.The sampling matrix of camera 11 and camera 12 is respectively so:

$M_1=[{\mathrm{<figure-callout\; id="11"\; label="V"\; filenames="HDA0000121323830000011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{11},V_2]=\left[\begin{array}{cc}L\cos \mathrm{\&theta;}& 0\\ L\sin \mathrm{\&theta;}& L\&times;N\end{array}\right]$

$M_2=[{\mathrm{<figure-callout\; id="12"\; label="V"\; filenames="HDA0000121323830000011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{12},V_2]=\left[\begin{array}{cc}L\cos \mathrm{\&theta;}& 0\\ L\sin \mathrm{\&theta;}& L\&times;N\end{array}\right]$

Then the sampling density of camera 11 and camera 12 is:

${\mathrm{\&rho;}}_1={\mathrm{\&rho;}}_2=\frac{1}{\det \left|M_1\right|}=\frac{1}{\det \left|M_2\right|}=\frac{1}{N{L}^2\cos \mathrm{\&theta;}}$

The number of the pixel of gathering on the sampling density representation unit area, image spatial resolution is directly proportional with collection density.Can find out that from formula N is more little, the θ angle is big more, and sampling density is just big more, thereby the spatial resolution of image is just high more.To reduce N can realize through the scanning frequency that improves camera, but mention as preamble, and improving scanning frequency is not a good solution.The present invention makes line array CCD cant angle theta angle carry out scanning sample to object through the locus of adjustment camera, and is as shown in Figure 3.Can see that from figure the sampling of tilting makes the imaging visual field of camera be reduced to D cos θ by original D, and the θ angle is big more, the imaging visual field of camera is more little.When θ is 5 when spending, it is big that the visual field becomes, but resolution is improved and diminished.When θ is 85 when spending, the visual field diminishes, but resolution is greatly improved.Therefore; Take all factors into consideration the resolution and the visual field of imaging system, the present invention has adopted two identical line array CCDs, and tiltangle is taken as 60 degree; The visual field of each camera is original 1/2; Sampling density is doubled, and the image that two cameras are collected is respectively proofreaied and correct and spliced, and can obtain full resolution pricture and keep the visual field constant.

As shown in Figure 4, there is an angle all the time in the scanning process of camera, and the scan line of line-scan digital camera to be form with column or row export image to, the image that therefore obtains certainly exists geometric distortion.Image processing apparatus carries out geometric correction to the data image signal of input, is one step of key of realizing high-resolution imaging, mainly comprises two steps:

(1) pixel coordinate conversion: set up the pixel coordinate of distorted image and the mapping relations between the sample point coordinate on the corresponding actual object, each pixel coordinate of image is proofreaied and correct according to mapping relations.

Shown in Figure 4 is the two-dimentional sample space of camera, and each dot is represented a sampled point among the figure, the note do S (x, y) (x=1,2 ..., m; Y=1; 2 ..., n); Shown in Figure 5 is the actual position of spatial sampling point in distorted image; The pixel coordinate conversion is exactly through the pixel value in the distorted image is redistributed coordinate position, makes that the distribution of sampled point of sample space of pixel distribution and camera of image is consistent, thereby obtains correcting image as shown in Figure 6.Make that distorted image is that (u, v), correcting image is that (i j), then can realize the pixel coordinate conversion through following formula to f to g

(2) picture element interpolation: its pixel distribution of image that conversion obtains through preliminary coordinate is irregular; The parity that is embodied in the horizontal ordinate value in the image is not simultaneously; These positions do not have pixel value, therefore also need utilize the pixel distribution regularization of the method for picture element interpolation with image.As shown in Figure 6, the pixel position of the little box indicating interpolation of black, the present invention adopts linear interpolation method to accomplish interpolation, as shown in the formula

$f(2i-\mathrm{1,2}j)=\frac{1}{4}(f(2i-\mathrm{2,2}j)+f(2i,2j)+f(2i-\mathrm{1,2}j-1)+f(2i-\mathrm{1,2}j+1));$

$f(2i,2j-1)=\frac{1}{4}(f(2i-\mathrm{1,2}j-1)+f(2i+\mathrm{1,2}j-1)+f(2i,2j-2)+f(2i,2j)).$

After the view data that according to the method described above camera 11 and camera 12 is collected is proofreaied and correct, at last also need with this two width of cloth independently full resolution pricture splice, thereby when improving resolution, keep the visual field of imaging system constant.

After accomplishing the correction and splicing of image, just obtained complete high-definition picture, just can export image to display unit 4 and show this moment.

Embodiment two:

Present embodiment has carried out experiment simulation to the high-resolution imaging method that embodiment one describes, and verifies the actual imaging effect of this method.

Experiment porch is Matlab 7.9.0, at first chooses one 480 * 480 gray level image simulation and treats imaging object, samples according to the method for sampling of describing in the instance one then.If the pixel spacing L=10 of camera CCD, along the spacing of camera scanning direction for

then the sampling matrix of camera 11 and camera 12 do

Single line-scan digital camera is at pixel spacing L=10; Tiltangle=0, the sampling matrix during sweep span

is:

$[V_1,V_2]=\left[\begin{array}{cc}10& 0\\ 0& 10\&times;\sqrt{3}\end{array}\right],$

The line scanning direction that is camera is vertical with the orientation of CCD pixel, and the resolution of image is 48 * 28.

The figure that the present invention is obtained splices, and image resolution ratio is 96 * 56.

Can find out that the present invention can utilize the low camera of differentiating to realize high-resolution imaging really.

Embodiment three:

Present embodiment is expanded the high-resolution imaging system that embodiment one describes, and an open high-resolution imaging framework is provided.

Through two linear array CCD cameras (11,12) of upgrading (as the single line array CCD camera is upgraded to the super-resolution camera), can reach higher image resolution ratio;

Through increasing tiltangle, the number of corresponding expansion linear array CCD camera (11,12) also can obtain higher resolution simultaneously.

As stated, embodiments of the invention have been carried out explanation at length, but as long as not breaking away from inventive point of the present invention and effect in fact can have a lot of distortion, this will be readily apparent to persons skilled in the art.Therefore, such variation also all is included within protection scope of the present invention.

Claims (6)

1. a broken-line type scans high-resolution imaging system, comprising: image collecting device, form by two linear array CCD cameras; The IMAQ control device, control CCD image of camera gatherer process; Image processing apparatus is rebuild the view data that collects; Display unit is used to show the high-definition picture that obtains; It is characterized in that; Said two linear array CCD cameras and level are treated imaging object and are scanned capture with cant angle theta and-θ angle respectively; 0＜θ＜90 ° wherein make image collecting device and treat to be the zigzag scanning shape between the imaging object, and scans content is mutually disjointed.

2. a kind of according to claim 1 broken-line type scanning high-resolution imaging system is characterized in that said θ is 60 °.

3. a kind of according to claim 1 broken-line type scanning high-resolution imaging system, it is characterized in that: said image processing apparatus is made up of two image pick-up cards, and each capture card is respectively controlled a CCD image of camera gatherer process.

4. like the said a kind of broken-line type scanning high-resolution imaging system of one of claim 1 to 3, it is characterized in that: said image processing apparatus is programmable logic device or the computer processing system with image processing function.

5. a broken-line type scanning high-resolution imaging method is characterized in that, may further comprise the steps:

A) camera space layout is arranged two identical linear array CCD cameras and level respectively with cant angle theta and-θ angle, 0＜θ＜90 ° wherein make image collecting device and treat to be the zigzag scanning shape between the imaging object, and scans content is mutually disjointed;

B) trigger capture, the IMAQ control device is controlled the gatherer process of two cameras respectively, and they send the capture triggering signal to two line-scan digital cameras simultaneously, and two line-scan digital cameras make public simultaneously;

C) A/D conversion, line array CCD converts light signal into analog electrical signal and transfers to image pick-up card, and image pick-up card is accomplished the A/D conversion, and analog electrical signal is converted into the data image signal input image processing unit;

D) geometric correction of imagery is carried out geometric correction by image processing apparatus to the data image signal of importing.

6. like the said a kind of broken-line type scanning high-resolution imaging method of claim 5; It is characterized in that; The said step d) geometric correction of imagery; Specifically comprised for two steps: at first set up the pixel coordinate of distorted image and the mapping relations between the sample point coordinate on the corresponding actual object, each pixel coordinate of image is proofreaied and correct according to mapping relations; Utilize of the pixel distribution regularization of the method for picture element interpolation again, and image is spliced, obtain high-resolution digital picture image.

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