CN108805948A - The orthographic projection method and device of image - Google Patents
The orthographic projection method and device of image Download PDFInfo
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- CN108805948A CN108805948A CN201810510489.5A CN201810510489A CN108805948A CN 108805948 A CN108805948 A CN 108805948A CN 201810510489 A CN201810510489 A CN 201810510489A CN 108805948 A CN108805948 A CN 108805948A
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T11/00—2D [Two Dimensional] image generation
- G06T11/003—Reconstruction from projections, e.g. tomography
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Abstract
The application provides a kind of orthographic projection method and device of image, and method includes：The concentric ring using picture centre as the center of circle is divided an image into, determines the coordinate and pixel value of the sampled point on each concentric ring；It obtains under each rotation angle, the coordinate and pixel value of every ray and the intersection point of each concentric ring；Under each rotation angle, for every ray, the projection value of this ray is determined using the pixel value of the intersection point on this ray intercept corresponding with concentric ring where the intersection point.Since picture centre is overlapped with the rotation center of radiographic source, therefore for same ray under different rotation angles, the intercept by the same concentric ring is identical, calculates an intercept, the repeated and redundant that distance can be eliminated calculates, and promotes image rectification and iterative approximation efficiency；And since the calculation amount of this case is small, image rectification and iterative reconstruction process are realized using multiple ray source modules so extending also to.
Description
Technical field
This application involves technical field of image processing more particularly to a kind of orthographic projection method and devices of image.
Background technology
Orthographic projection process is CT (Computed Tomography, computerized tomography) image rectifications and iterative reconstruction process
In a key link.Include radiographic source and detector in usual CT equipment, the ray of radiographic source transmitting passes through testee
Afterwards, it can be received by a detector, when carrying out Image Acquisition, radiographic source and detector are using rotation center as the center of circle, every default
The rotation of angle interval is primary, and the CT images of testee are acquired in this rotary course until rotating a whole loop knot beam.
In the related art, orthographic projection process is to calculate ray through passing by one's way under each rotation angle of x-ray source (view)
On diameter, the product of the distance between pixel value identical point and the pixel value, and all products obtained on the ray are summed.
However, under each rotation angle, the distance between pixel value identical point will calculate one time on every ray, meter
Calculation amount is very big, is taken very much so as to cause CT image rectifications and iterative reconstruction process.
Invention content
In view of this, the application provides a kind of orthographic projection method and device of image, to solve existing realization method image
The problem that correction and iterative reconstruction process take.
According to the embodiment of the present application in a first aspect, provide a kind of orthographic projection method of image, the method includes：
Described image is divided into the concentric ring using picture centre as the center of circle, and determines sampled point on each concentric ring
Coordinate and pixel value, described image center are overlapped with the rotation center；
It obtains under each rotation angle, the coordinate and pixel value of every ray and the intersection point of each concentric ring；
Under each rotation angle, for every ray, the pixel value using the intersection point on this ray and the intersection point institute
The projection value of this ray is determined in the corresponding intercept of concentric ring.
According to the second aspect of the embodiment of the present application, a kind of Orthographic projection device of image is provided, described device includes：
It determines sampling point module, for described image to be divided into the concentric ring using picture centre as the center of circle, and determines every
The coordinate and pixel value of sampled point on a concentric ring, described image center are overlapped with the rotation center；
It determines intersection point module, obtains under each rotation angle, the coordinate and picture of every ray and the intersection point of each concentric ring
Element value；
Projection value module is determined, under each rotation angle, for every ray, utilizing the intersection point on this ray
Pixel value and the intersection point where the corresponding intercept of concentric ring determine the projection value of this ray.
Using the embodiment of the present application, after dividing an image into using picture centre as the concentric ring in the center of circle, determine each same
Sampled point on thimble and pixel value, and obtain under each rotation angle, the coordinate of every ray and the intersection point of each concentric ring
And pixel value, then under each rotation angle, for every ray, the pixel value using the intersection point on this ray and the friendship
The corresponding intercept of concentric ring where point determines the projection value of this ray.Based on foregoing description it is found that due to picture centre with penetrate
The rotation center of line source and detector overlaps, therefore same ray is under different rotation angles, by the same concentric ring
Intercept it is identical, calculated for every ray and once pass through the corresponding intercept of each concentric ring, the weight of distance can be eliminated
Multiple redundant computation, promotes image rectification and iterative approximation efficiency；And since the calculation amount of the application is small, so can also extend
Image rectification and iterative approximation are realized to using multiple ray source modules.
Description of the drawings
Fig. 1 is that the application is a kind of using prior art acquisition ray projection value signal shown according to an exemplary embodiment
Figure；
Fig. 2A is a kind of embodiment flow of the orthographic projection method of image of the application shown according to an exemplary embodiment
Figure；
Fig. 2 B are that a kind of a certain ray shown in A illustrated embodiments is under different rotary angle and same according to fig. 2 by the application
The intersection point schematic diagram of thimble；
Fig. 2 C are that the one kind of the application according to fig. 2 shown in A illustrated embodiments a certain ray under a certain rotation angle passes through
The corresponding intercept schematic diagram of two concentric rings；
Fig. 3 is the embodiment flow of the orthographic projection method of another image of the application shown according to an exemplary embodiment
Figure；
Fig. 4 is a kind of hardware structure diagram of CT equipment of the application shown according to an exemplary embodiment；
Fig. 5 is a kind of example structure of the Orthographic projection device of image of the application shown according to an exemplary embodiment
Figure；
Fig. 6 is the example structure of the Orthographic projection device of another image of the application shown according to an exemplary embodiment
Figure.
Specific implementation mode
Example embodiments are described in detail here, and the example is illustrated in the accompanying drawings.Following description is related to
When attached drawing, unless otherwise indicated, the same numbers in different drawings indicate the same or similar elements.Following exemplary embodiment
Described in embodiment do not represent all embodiments consistent with the application.On the contrary, they be only with it is such as appended
The example of consistent device and method of some aspects be described in detail in claims, the application.
It is the purpose only merely for description specific embodiment in term used in this application, is not intended to be limiting the application.
It is also intended to including majority in the application and "an" of singulative used in the attached claims, " described " and "the"
Form, unless context clearly shows that other meanings.It is also understood that term "and/or" used herein refers to and wraps
Containing one or more associated list items purposes, any or all may be combined.
It will be appreciated that though various information, but this may be described using term first, second, third, etc. in the application
A little information should not necessarily be limited by these terms.These terms are only used for same type of information being distinguished from each other out.For example, not departing from
In the case of the application range, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as
One information.Depending on context, word as used in this " if " can be construed to " ... when " or " when ...
When " or " in response to determination ".
Fig. 1 is that the application is a kind of using prior art acquisition ray projection value signal shown according to an exemplary embodiment
Figure, as shown in Figure 1, O points are the radiographic source of CT equipment, semicircle camber line is the detector of CT equipment, and three dotted lines are radiographic source O points
The ray of transmitting, A points, B points, C points and D points are four points on same ray under a certain rotation angle, it is assumed that
A points are identical as the pixel value of B points, and C points are identical as the pixel value of D points, to need first to calculate the distance between A points and B points,
And the distance between C points and D points, ray projection value u=P of this ray under the rotation angle is then calculated againA×dAB+
PC×dCD。
It follows that under each rotation angle, it is required for first calculating on primary every ray between pixel value identical point
Distance, then calculate the ray projection value of every ray again, it is assumed that under each rotation angle, need to calculate on every ray
The pixel number of distance is Npixel, the number of lines of penetrating of radiographic source is Nchannels, number of revolutions Nviews, then it is directed to and calculates distance
The data volume of this process is Npixel×Nchannels×Nviews.It will be appreciated by persons skilled in the art that described above penetrates
Pixel value identical point on line refers to the pixel value being approximately considered when the sampled point on ray is closeer between adjacent 2 points
It is identical.
Fig. 2A is a kind of embodiment flow of the orthographic projection method of image of the application shown according to an exemplary embodiment
Figure, which can apply in CT equipment, and in the embodiment of the present application, CT equipment may include radiographic source and detector, penetrate
The ray of ray emission is received by a detector after testee, and radiographic source and detector are using rotation center as the center of circle, with pre-
If angle rotates, the image of testee is collected.As shown in Figure 2 A, the orthographic projection method of the image includes the following steps：
Step 201：The concentric ring using picture centre as the center of circle is divided the image into, and determines adopting on each concentric ring
The coordinate and pixel value of sampling point, the picture centre are overlapped with radiographic source rotation center.
In one embodiment, in image the distance between neighboring concentric ring be less than image pixel wide, neighboring concentric ring
The distance between can be equal, can not also be equal.
For the process of the coordinate and pixel value that how to determine the sampled point on each concentric ring, following Fig. 3 are may refer to
The description of illustrated embodiment is not described in detail first.
Step 202：It obtains under each rotation angle, the coordinate and pixel value of every ray and the intersection point of each concentric ring.
For being obtained in step 202 under each rotation angle, the coordinate and picture of every ray and the intersection point of each concentric ring
The process of element value refers to the description of following embodiment illustrated in fig. 3, is not described in detail first.
Step 203：Under each rotation angle, for every ray, using the intersection point on this ray pixel value and
The corresponding intercept of concentric ring where the intersection point determines the projection value of this ray.
In one embodiment, since the distance between neighboring concentric ring is less than the pixel wide of image, it is hereby ensured that
Ray is approximately the same with the pixel value of two intersection points of two neighboring concentric rings after two neighboring concentric rings, so as to
Using the product of the pixel value of an intersection point in two intersection points intercept corresponding with concentric ring where the intersection point as the intersection point institute
In the contribution that concentric ring adds up the ray.It follows that can be by the pixel value of all intersection points on this ray and each friendship
The sum of products of the corresponding intercept of concentric ring where point, is determined as the projection value of this ray, specific formula is as follows：
Wherein, uiFor the projection value of i-th ray, m is the quantity of concentric ring, IVkFor i-th ray and k-th of concentric ring
Intersection point pixel value, dkPass through the corresponding intercept of k-th of concentric ring for i-th ray.
In one embodiment, it is overlapped with the rotation center of radiographic source and detector due to picture centre, every ray
Under different rotation angles, the intercept by the same concentric ring is identical, to, under different rotary angle, every ray with
The distance between intersection point of two neighboring concentric rings can be multiplexed, i.e., intercept can be multiplexed.
It can obtain from the above analysis, it is assumed that under each rotation angle, the pixel number for calculating distance is needed on every ray
For Npixel, the number of lines of penetrating of radiographic source is Nchannels, number of revolutions Nviews, then it is directed to and calculates distance (i.e. intercept) this mistake
The data volume of journey is Npixel×Nchannels, since the calculating data volume of the prior art is Npixel×Nchannels×Nviews, therefore
The computation rate of this case is the N of the prior artviewsTimes.
In an exemplary scenario, Fig. 2 B be a certain ray under different rotary angle with the intersection point schematic diagram of concentric ring,
As shown in Figure 2 B, picture centre and rotation center are O points, and radiographic source and detector rotate on the annulus shown in dotted line,
Under rotation angle ɑ 1, the intersection point of the ray and two neighboring concentric rings is respectively C points and D points, at rotation angle ɑ 2, the ray
Intersection point with two neighboring concentric rings is respectively A points and B points, and the distance between A points and B points are AB, between C points and D points away from
From for CD, can obtain, AB=CD.It will be appreciated by persons skilled in the art that the distance between concentric ring shown in above-mentioned Fig. 2 B
It is merely illustrative, does not represent the distance between concentric ring in practice.
It is obtained by above-mentioned, before executing step 203, it may be predetermined that every ray is corresponding by each concentric ring
Intercept, that is, can arbitrarily choose a rotation angle, under the rotation angle of selection, for away from picture centre it is nearest first
A concentric ring determines every ray by should using the radius and picture centre of first concentric ring to the distance of every ray
The corresponding intercept of concentric ring；Since second concentric ring, for each concentric ring, by every ray and the concentric ring, and
With the concentric ring at a distance from two intersection points of adjacent concentric ring, it is determined as the corresponding intercept of the concentric ring；Wherein, concentric with this
The radius of the adjacent concentric ring of ring is less than the radius of the concentric ring.
Wherein, for by every ray and the concentric ring, and two intersection points of the concentric ring adjacent with the concentric ring
Distance, the process for being determined as the corresponding intercept of the concentric ring can be there are two types of calculation：
The first is：Utilize the radius of the concentric ring, the radius of the concentric ring adjacent with the concentric ring and picture centre
To the distance of every ray, every ray and the concentric ring, and two intersection points of the concentric ring adjacent with the concentric ring are calculated
Distance；It is for second：Using every ray and the concentric ring, and two intersection points of the concentric ring adjacent with the concentric ring
Coordinate calculates at a distance from every ray and the concentric ring, and two intersection points of the concentric ring adjacent with the concentric ring.
Pass through the corresponding intercept of first concentric ring to calculate a certain ray in Fig. 2 C below, and passes through second concentric ring
It is illustrated for corresponding intercept：
1, it is directed to first concentric ring：
The intersection point of ray and first concentric ring is B points, the radius of first concentric ring between neighboring concentric ring away from
From OB=R, subtended angle of the ray with respect to center of circle O is β, and the distance of radiographic source to the center of circle is RF, can obtain, the ray is same by first
The corresponding intercept of thimble is：
2, it is directed to second concentric ring：
(1) intersection point of ray and second concentric ring is A points, and the radius of first concentric ring (inner ring circle) is R, second
The radius of concentric ring (outer ring circle) is R1, can be obtained, the ray and second concentric ring, and adjacent with second concentric ring the
The distance of two intersection points of one concentric ring (ray passes through the corresponding intercept of second concentric ring)：
(2) by above-mentioned steps 202 can get the ray respectively with first concentric ring, the intersection point of second concentric ring
B, the coordinate of intersection point A, to be obtained using the coordinate of intersection point A and the coordinate of intersection points B, the ray is concentric by second
The corresponding intercept of ring.
In the present embodiment, after dividing an image into using picture centre as the concentric ring in the center of circle, determine on each concentric ring
Sampled point and pixel value, and obtain under each rotation angle, the coordinate and pixel of every ray and the intersection point of each concentric ring
Value, then under each rotation angle, for every ray, using where the pixel value and the intersection point of the intersection point on this ray
The corresponding intercept of concentric ring determines the projection value of this ray.Based on foregoing description it is found that due to picture centre and radiographic source and
The rotation center of detector overlaps, therefore same ray is under different rotation angles, by the intercept of the same concentric ring
It is identical, it is calculated for every ray and once passes through the corresponding intercept of each concentric ring, the repeated and redundant of distance can be eliminated
It calculates, promotes image rectification and iterative approximation efficiency；And since the calculation amount of the application is small, so extending also to use
Multiple ray source modules realize image rectification and iterative reconstruction process.
Fig. 3 is the embodiment flow of the orthographic projection method of another image of the application shown according to an exemplary embodiment
Figure is based on the basis of above-mentioned Fig. 2A illustrated embodiments, how to determine the coordinate and pixel of the sampled point on each concentric ring
How value, and obtain under each rotation angle, every ray with for the coordinate and pixel value of the intersection point of each concentric ring into
Row exemplary illustration, as shown in figure 3, the orthographic projection method of the image includes the following steps：
Step 301：For each concentric ring, number of samples is determined according to the radius of the concentric ring and number of revolutions, and
The sampled point of number of samples is chosen on the concentric ring.
In one embodiment, it after dividing an image into multiple concentric rings, can be fitted on the smaller concentric ring of radius
When reducing number of samples, and in order to reach between different rotary angle, the purpose of rotational invariance, on each concentric ring
Number of samples can be divided exactly by number of revolutions.For example, the radius of all concentric rings can be divided into multiple ranges, each range
A corresponding number of samples, and each corresponding number of samples of range can be divided exactly by number of revolutions；It can also be directed to each
Concentric ring pre-sets a number of samples that can be divided exactly by number of revolutions.
It should be noted that other than determining number of samples according to the radius and number of revolutions of concentric ring, it can be with root
Number of samples is determined according to computational accuracy, and computational accuracy if necessary is high, and determining number of samples can be more greatly.
In one embodiment, on each concentric ring, the sampled point of the corresponding number of samples of the concentric ring, sampled point are chosen
Coordinate can beJ=0,1 ... N-1, wherein RiIt is i-th
The radius of a concentric ring, N are the corresponding number of samples of i-th of concentric ring.
For the process of above-mentioned steps 301, due to picture size size all same, can be previously obtained in image every
The coordinate of sampled point on a concentric ring, and be recorded in storage medium, to which the sampled point of record can be directly read every time
Coordinate, without every time calculate one time.
Step 302：The pixel value of each sampled point is determined using the pixel value of image.
In one embodiment, since the coordinate of each sampled point may not fully be overlapped with the coordinate of pixel,
It needs to calculate the pixel value of each sampled point using the pixel value (i.e. the pixel value of image) of neighbouring pixel, for example, being directed to
Each sampled point can obtain every by linear interpolation mode, using the pixel value of pixel near the sampled point into row interpolation
The pixel value of a sampled point.It will be appreciated by persons skilled in the art that linear interpolation mode can be realized by the relevant technologies,
This will not be detailed here by the application.
Step 303：For each rotation angle, using the linear equation of corresponding every ray under the rotation angle and often
The radius of a concentric ring determines the intersection point of every ray and each concentric ring.
For another example shown in above-mentioned Fig. 2 C, to calculate under a certain rotation angle, for the intersection point of certain ray and a certain concentric ring
It illustrates：
It is possible, firstly, to establish pixel coordinate system on the image, the coordinate system is using picture centre as origin, horizontal direction X
Axis, vertical direction are Y-axis, and the subtended angle β by the rotation angle ɑ and ray of ray with respect to center of circle O can obtain ray and the angle of X-axis
For ɑ-β, and then the linear equation that can obtain ray is：
y-YF=tan (alpha-beta) × (x-XF)
Wherein, (XF, YF) be radiographic source coordinate.
Then, k is enabled0=tan (alpha-beta) can obtain ray and concentric ring by the radius r of above-mentioned linear equation and concentric ring
Intersecting point coordinate is：
Alternatively,
Wherein, ray and each concentric ring be there are two intersection point,
Each rotation can be previously obtained due to picture size size all same for the process of above-mentioned steps 303
Under angle, the coordinate of every ray and the intersection point of each concentric ring, and be recorded in storage medium, to can directly read every time
The coordinate of the intersection point of record is taken, without calculating one time every time.
Step 304：The pixel value of each intersection point is determined using the pixel value of sampled point.
In one embodiment, it can be first directed to each concentric ring, determine the angle of the sampled point and X-axis on the concentric ring,
And the angle is numbered the sampled point on the concentric ring according to sequence from small to large, it is then directed to each intersection point again,
It determines the intersection point and the angle of X-axis, and the concentric ring where the intersection point is divided into preset quantity part, and determine per a corresponding
Central angle；The volume of sampled point is corresponded to where determining the intersection point with the angle of X-axis and the central angle using the intersection point on concentric ring
Number, and determine using the pixel value of the corresponding sampled point of the number pixel value of the intersection point；Wherein, preset quantity is the intersection point institute
The quantity of sampled point on concentric ring.
Assuming that the number of samples of the sampled point on a certain concentric ring is N, after being ranked up according to sampled point and X-axis angle,
The number of concentric ring up-sampling point is V0, V1……VN-1, the pixel value specific formula for calculation of intersection point is as follows：
The angle of the intersection point and X-axisWherein, (x, y) is the coordinate of the intersection point；
Concentric ring where the intersection point is divided into preset quantity part, per a corresponding central angle
Block where θ is
If n is integer, the number of the sampled point where the intersection point on concentric ring is n；If n be integer, by j≤
N≤j+1 can be obtained, and the number of the sampled point where the intersection point on concentric ring is j and j+1；
By linear interpolation mode, the pixel value of the calculated for pixel values of the corresponding sampled point of the number intersection point is utilized：
IV=interp (Vj, Vj+1)
In the present embodiment, after dividing an image into multiple concentric rings, it can be adopted on each concentric ring by elder generation
Sample obtains the pixel value of each sampled point, then again by under each rotation angle of the calculated for pixel values of sampled point, every ray with
The pixel value of the intersection point of each concentric ring.Due to picture size size all same, in each image the coordinate of sampled point and
The coordinate of the intersection point of ray and concentric ring is constant, so as to pre-recorded in storage medium, directly reads sampling every time
The coordinate of the coordinate and intersection point of point further simplifies calculating process, improves image calibration without calculating one time every time
Just with iterative approximation efficiency.
Corresponding with the embodiment of orthographic projection method of aforementioned image, present invention also provides the Orthographic projection devices of image
Embodiment.
The embodiment of the Orthographic projection device of the application image can be applied in CT equipment.Device embodiment can be by soft
Part is realized, can also be realized by way of hardware or software and hardware combining.For implemented in software, as a logical meaning
On device, be to be read corresponding computer program instructions in nonvolatile memory by the processor of equipment where it
Operation is formed in memory.For hardware view, as shown in figure 4, exemplified according to embodiment implementation for the application
A kind of hardware structure diagram of CT equipment, in addition to processor shown in Fig. 4, memory, network interface and nonvolatile memory it
Outside, the equipment in embodiment where device can also include other hardware, no longer to this generally according to the actual functional capability of the equipment
It repeats.
Fig. 5 is a kind of example structure of the Orthographic projection device of image of the application shown according to an exemplary embodiment
Figure, the device embodiment can be applied in CT equipment, and the Orthographic projection device of the image includes：
It determines sampling point module 51, for described image to be divided into the concentric ring using picture centre as the center of circle, and determines
The coordinate and pixel value of sampled point on each concentric ring, described image center is overlapped with the rotation center；
Determine intersection point module 52, obtain under each rotation angle, the coordinate of every ray and the intersection point of each concentric ring and
Pixel value；
Projection value module 53 is determined, under each rotation angle, for every ray, utilizing the friendship on this ray
The pixel value of point intercept corresponding with concentric ring where the intersection point determines the projection value of this ray.
In an optional realization method, described device further includes (being not shown in Fig. 5)：
It determines intercept module, is specifically used for one rotation angle of arbitrary selection, under the rotation angle of selection, for away from figure
First nearest concentric ring of inconocenter, using first concentric ring radius and picture centre to every ray distance, really
Fixed every ray passes through the corresponding intercept of the concentric ring；Since second concentric ring, for each concentric ring, by every ray
At a distance from the concentric ring, and two intersection points of the concentric ring adjacent with the concentric ring, it is determined as corresponding section of the concentric ring
Away from；Wherein, the radius of the concentric ring adjacent with the concentric ring is less than the radius of the concentric ring.
Fig. 6 is the example structure of the Orthographic projection device of another image of the application shown according to an exemplary embodiment
Figure, based on the basis of above-mentioned Fig. 5 shown devices, the determination samples point module 51, including：
Submodule 511 is sampled, for being directed to each concentric ring, sampling is determined according to the radius of the concentric ring and number of revolutions
Quantity, and choose on the concentric ring sampled point of the number of samples；
First determines pixel value submodule 512, the pixel for determining each sampled point using the pixel value of described image
Value；
The determining intersection point module 52, including：
It determines intersection point submodule 521, for being directed to each rotation angle, utilizes corresponding every ray under the rotation angle
Linear equation and each concentric ring radius, determine the intersection point of every ray and each concentric ring, and will be far from the ray
The intersection point in source abandons；
Second determines pixel value submodule 522, the pixel for determining each intersection point using the pixel value of the sampled point
Value.
In an optional realization method, described second determines pixel value submodule 522, is specifically used on the image
Pixel coordinate system is established, for the coordinate system using picture centre as origin, horizontal direction is X-axis, and vertical direction is Y-axis；For each
Concentric ring determines the angle that sampled point and X-axis are corresponded on the concentric ring, and by the angle according to sequence from small to large, right
Sampled point on the concentric ring is numbered；For each intersection point, the intersection point and the angle of X-axis are determined, and will be where the intersection point
Concentric ring be divided into preset quantity part, and determine per a corresponding central angle；It is true using the angle and the central angle
The number of sampled point where the fixed intersection point on concentric ring, and determine the intersection point using the pixel value of the corresponding sampled point of the number
Pixel value；Wherein, the preset quantity is the quantity of the sampled point on concentric ring where the intersection point.
The function of each unit and the realization process of effect specifically refer to and correspond to step in the above method in above-mentioned apparatus
Realization process, details are not described herein.
For device embodiments, since it corresponds essentially to embodiment of the method, so related place is referring to method reality
Apply the part explanation of example.The apparatus embodiments described above are merely exemplary, wherein described be used as separating component
The unit of explanation may or may not be physically separated, and the component shown as unit can be or can also
It is not physical unit, you can be located at a place, or may be distributed over multiple network units.It can be according to actual
It needs that some or all of module therein is selected to realize the purpose of application scheme.Those of ordinary skill in the art are not paying
In the case of going out creative work, you can to understand and implement.
The foregoing is merely the preferred embodiments of the application, not limiting the application, all essences in the application
With within principle, any modification, equivalent substitution, improvement and etc. done should be included within the scope of the application protection god.
Claims (11)
1. a kind of orthographic projection method of image, which is characterized in that the method is applied to be set in the CT including radiographic source and detector
Standby upper, the ray of the radiographic source transmitting is received after testee by the detector, the radiographic source and the detection
Device obtains the image of testee using rotation center as the center of circle, with predetermined angle rotating acquisition, the method includes：
Described image is divided into the concentric ring using picture centre as the center of circle, and determines the coordinate of the sampled point on each concentric ring
And pixel value, described image center are overlapped with the rotation center；
It obtains under each rotation angle, the coordinate and pixel value of every ray and the intersection point of each concentric ring；
It is same using the pixel value of the intersection point on this ray and intersection point place for every ray under each rotation angle
The corresponding intercept of thimble determines the projection value of this ray.
2. according to the method described in claim 1, it is characterized in that, the distance between neighboring concentric ring is less than the picture of described image
Plain width.
3. according to the method described in claim 1, it is characterized in that, determining the coordinate and pixel of the sampled point on each concentric ring
Value, including：
For each concentric ring, number of samples is determined according to the radius of the concentric ring and number of revolutions, and selected on the concentric ring
Take the sampled point of the number of samples；
The pixel value of each sampled point is determined using the pixel value of described image.
4. according to the method described in claim 1, it is characterized in that, obtain under each rotation angle, every ray with it is each same
The coordinate and pixel value of the intersection point of thimble, including：
For each rotation angle, the linear equation of corresponding every ray under the rotation angle and the half of each concentric ring are utilized
Diameter determines the intersection point of every ray and each concentric ring；
The pixel value of each intersection point is determined using the pixel value of the sampled point.
5. according to the method described in claim 4, it is characterized in that, determining each intersection point using the pixel value of the sampled point
Pixel value, including：
Pixel coordinate system is established on the image, and for the coordinate system using picture centre as origin, horizontal direction is X-axis, Vertical Square
To for Y-axis；
For each concentric ring, the angle of the sampled point and X-axis on the concentric ring is determined, and by the angle according to from small to large
Sequence, the sampled point on the concentric ring is numbered；
For each intersection point, the intersection point and the angle of X-axis are determined, and the concentric ring where the intersection point is divided into preset quantity
Part, and determine per a corresponding central angle；It is right on concentric ring where determining the intersection point using the angle and the central angle
The number of sampled point is answered, and determines the pixel value of the intersection point using the pixel value of the corresponding sampled point of the number；
Wherein, the preset quantity is the quantity of the sampled point on concentric ring where the intersection point.
6. according to the method described in claim 1, it is characterized in that, predetermined every ray is corresponding by each concentric ring
Intercept, including：
A rotation angle is arbitrarily chosen, under the rotation angle of selection, for first concentric ring nearest away from picture centre,
Using the radius and picture centre of first concentric ring to the distance of every ray, determine that every ray is corresponded to by the concentric ring
Intercept；
Since second concentric ring, for each concentric ring, by every ray and the concentric ring, and it is adjacent with the concentric ring
Concentric ring two intersection points distance, be determined as the corresponding intercept of the concentric ring；
Wherein, the radius of the concentric ring adjacent with the concentric ring is less than the radius of the concentric ring.
7. a kind of Orthographic projection device of image, which is characterized in that the method is applied to be set in the CT including radiographic source and detector
Standby upper, the ray of the radiographic source transmitting is received after testee by the detector, the radiographic source and the detection
Device obtains the image of testee using rotation center as the center of circle, with predetermined angle rotating acquisition, and described device includes：
It determines sampling point module, for described image to be divided into the concentric ring using picture centre as the center of circle, and determines each same
The coordinate and pixel value of sampled point on thimble, described image center are overlapped with the rotation center；
It determines intersection point module, obtains under each rotation angle, the coordinate and pixel value of every ray and the intersection point of each concentric ring；
Projection value module is determined, under each rotation angle, for every ray, utilizing the picture of the intersection point on this ray
Element value intercept corresponding with concentric ring where the intersection point determines the projection value of this ray.
8. device according to claim 7, which is characterized in that the determining sampling point module, including：
Submodule is sampled, for for each concentric ring, number of samples to be determined according to the radius of the concentric ring and number of revolutions, and
The sampled point of the number of samples is chosen on the concentric ring；
First determines pixel value submodule, the pixel value for determining each sampled point using the pixel value of described image.
9. device according to claim 7, which is characterized in that the determining intersection point module, including：
It determines intersection point submodule, for being directed to each rotation angle, utilizes the straight line of corresponding every ray under the rotation angle
The radius of equation and each concentric ring, determines the intersection point of every ray and each concentric ring, and will be far from the friendship of the radiographic source
Point abandons；
Second determines pixel value submodule, the pixel value for determining each intersection point using the pixel value of the sampled point.
10. device according to claim 9, which is characterized in that described second determines pixel value submodule, is specifically used for
Pixel coordinate system is established in described image, for the coordinate system using picture centre as origin, horizontal direction is X-axis, vertical direction Y
Axis；For each concentric ring, the angle of the sampled point and X-axis on the concentric ring is determined, and by the angle according to from small to large
Sequence, the sampled point on the concentric ring is numbered；For each intersection point, the intersection point and the angle of X-axis are determined, and should
Concentric ring where intersection point is divided into preset quantity part, and determines per a corresponding central angle；Utilize the angle and described
The number of sampled point is corresponded to where central angle determines the intersection point on concentric ring, and utilizes the pixel value of the corresponding sampled point of the number
Determine the pixel value of the intersection point；Wherein, the preset quantity is the quantity of the sampled point on concentric ring where the intersection point.
11. device according to claim 7, which is characterized in that described device further includes：
It determines intercept module, is specifically used for one rotation angle of arbitrary selection, under the rotation angle of selection, for away from image
First nearest concentric ring of the heart is arrived the distance of every ray using the radius and picture centre of first concentric ring, determined often
Ray passes through the corresponding intercept of the concentric ring；Since second concentric ring, for each concentric ring, by every ray and it is somebody's turn to do
At a distance from concentric ring, and two intersection points of the concentric ring adjacent with the concentric ring, it is determined as the corresponding intercept of the concentric ring；Its
In, the radius of the concentric ring adjacent with the concentric ring is less than the radius of the concentric ring.
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