CN101596114A - A kind of digital scan converter - Google Patents

Abstract

The invention discloses a kind of digital scan converter, a kind of digital scan converter, comprise the line data buffer, the two field picture memorizer, scan conversion input controller, the scan conversion o controller, coordinate converter, described line data buffer links to each other with described two field picture memorizer, described coordinate converter links to each other with described two field picture memorizer with described scan conversion o controller respectively, described scan conversion input controller links to each other with described two field picture memorizer, also comprise selector and at least two interpolation submodules, the input of described selector links to each other with described two field picture memorizer with described coordinate converter respectively, the outfan of described selector links to each other with each interpolation submodule respectively, controls described selector by selector control signal the dateout of described coordinate converter and the dateout of described two field picture memorizer are sent to one of them interpolation submodule.

Description

A kind of digital scan converter

Technical field

The present invention relates to the ultrasonoscopy processing technology field, be specifically related to a kind of digital scan converter.

Background technology

The medical ultrasound image technology is complete owing to having, adaptation is wide, directly perceived, can repeat, the soft tissue resolving ability is reached advantages such as inexpensive by force, flexibly, so occupy very consequence in the modern diagnosis technology.Supersonic imaging apparatus is a kind of scope of application medical imaging devices widely, and its technology is very ripe.

As shown in Figure 1, supersonic imaging apparatus sends the emission excitation through high-voltage switch gear incentive probe emission sound wave, and sound wave is popped one's head in through the tissue reflected back, amplify through receiving, wave beam is synthetic, demodulation, carry out DSC (digital scan conversion) behind the signal processing, then deliver to display and show.

DSC is the very important ingredient of supersonic imaging apparatus, and as shown in Figure 2, shift process comprises input flow process and output flow process two parts.The input controller is received after the line data head, and the output flow process of interrupt scanning conversion immediately also starts the input flow process.In the input flow process, the input controller produces write address that input line data deposit to four fens frames, writes and enable according to wire size line style display mode, and closes the output enable that four fens frames are deposited.After one line data write and finish, the input controller cancelled interrupt requests, activate output enable that four fens frames deposit, switch read/write address.The output flow process is gone round and begun again, and exports the image of a frame 512 * 512 pixels weekly.The scan conversion o controller sequentially provides the rectangular coordinate of display element, reads address and interpolation coefficient through what coordinate transformation unit obtained that four fens frames deposit, reads four data then and draws a video data output through the secondary linear interpolations.

The interpolation method that is commonly used in the DSC device has: it is several to close on interpolation, bilinear interpolation, two cubes of interpolation etc. most, and they have oneself the pluses and minuses and the scope of application separately.Wherein neighbor interpolation method interpolation speed is fast, and mosaic phenomenon is serious behind the image interpolation, is applicable to the better simply image of lines; The bilinear interpolation method interpolation speed is slower, and obscurity boundary behind the image interpolation has crenellated phenomena, is interpolation method the most frequently used among the present DSC; Two cubes of interpolation method interpolation speed are slow, and the border has a little fuzzy behind the image interpolation, and crenellated phenomena has improvement, is applicable to image processing software.Prior art is a kind of interpolation method of fixing use in the DSC interpolating apparatus, can not select different interpolation methods according to the feature of image adjustment.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of digital scan converter, and the DSC interpolating apparatus that overcomes prior art can not be selected the defective of different interpolation methods according to the feature of image adjustment.

The present invention solves the problems of the technologies described above the technical scheme that is adopted to be:

A kind of digital scan converter, comprise the line data buffer, the two field picture memorizer, scan conversion input controller, the scan conversion o controller, coordinate converter, described line data buffer links to each other with described two field picture memorizer, described coordinate converter links to each other with described two field picture memorizer with described scan conversion o controller respectively, described scan conversion input controller links to each other with described two field picture memorizer, also comprise selector and at least two interpolation submodules, the input of described selector links to each other with described two field picture memorizer with described coordinate converter respectively, the outfan of described selector links to each other with each interpolation submodule respectively, controls described selector by selector control signal the dateout of described coordinate converter and the dateout of described two field picture memorizer are sent to one of them interpolation submodule.

Described digital scan converter, wherein said interpolation submodule comprises the bilinear interpolation submodule.

Described digital scan converter, wherein said interpolation submodule comprise neighbor interpolation submodule.

Described digital scan converter, wherein said interpolation submodule comprise expands the linear interpolation submodule.

Described digital scan converter, wherein said selector are made as three and select a selector.

Storage interpolation smoothing factor is selected different interpolation smoothing factors by the selection signal that is input to described expansion linear interpolation submodule in the described digital scan converter, wherein said expansion linear interpolation submodule.

Described digital scan converter, wherein said selector and described interpolation submodule are realized by field programmable gate array FPGA.

Beneficial effect of the present invention: digital scan converter of the present invention improves interpolating module, can select different digital scan conversion interpolation methods according to the characteristics of image, has optimized the effect of digital scan conversion.

Description of drawings

The present invention includes following accompanying drawing:

Fig. 1 is a prior art B ultrasonic system schematic;

Fig. 2 is a prior art digital scan converter sketch map;

Fig. 3 is a digital scan converter sketch map of the present invention;

Fig. 4 is an interpolation submodule embodiment sketch map of the present invention;

Fig. 5 is a sampled data memory module sketch map of the present invention;

Fig. 6 is a sweep parameter sketch map of the present invention;

Fig. 7 is the present invention's four point interpolation sketch maps;

Fig. 8 is the present invention's eight point interpolation sketch maps.

The specific embodiment

With embodiment the present invention is described in further detail with reference to the accompanying drawings below:

As shown in Figure 3, digital scan converter of the present invention, comprise the line data buffer, the two field picture memorizer, scan conversion input controller, the scan conversion o controller, coordinate converter, described line data buffer links to each other with described two field picture memorizer, described coordinate converter links to each other with described two field picture memorizer with described scan conversion o controller respectively, described scan conversion input controller links to each other with described two field picture memorizer, also comprise selector and at least two interpolation submodules, the input of described selector links to each other with described two field picture memorizer with described coordinate converter respectively, the outfan of described selector links to each other with each interpolation submodule respectively, controls described selector by selector control signal the dateout of described coordinate converter and the dateout of described two field picture memorizer are sent to one of them interpolation submodule.

As shown in Figure 4, in a specific embodiment of the present invention, the interpolation submodule is respectively bilinear interpolation submodule, neighbor interpolation submodule and expands the linear interpolation submodule, selector is three to select a selector, expand storage interpolation smoothing factor in the linear interpolation submodule, select different interpolation smoothing factors by the selection signal that is input to described expansion linear interpolation submodule.

As shown in Figure 5, the total Sr of the memory module of sampled data is capable among the DSC, the Sc row.The scan depths that sampled data on each is gone is all corresponding identical, capable to Sr from first row, corresponding scan depths is successively uniformly-spaced from the zero probe maximum scan degree of depth that is increased to setting.The scanning angle that each sampled data that lists is all corresponding identical is listed as the Sc row from first, and corresponding scanning angle is from-θ ₀Be increased to θ ₀In general, Sr is 512, and Sc size in diameter pitch scanning is that 80 (80 array elements) are to 128 (128 array elements); Is that 160 (80 array elements) are to 256 (128 array elements) at half-section in scanning.Generally speaking, the size of image area is 512*512, so DSC need carry out interpolation to original sampling data, just can obtain being used for data presented.

Shown each relevant parameter that needs in the DSC calculating among Fig. 6 and the table 1.

Table 1DSC relevant parameter

Parameter name	The definition of parameter	Symbol	Remarks
				The scanning angle of convex array probe	During the convex array probe scanning, become segmental angle	2θ 0	Unit is a radian
The radius of curvature of convex array probe	Radius of curvature is the fan-shaped radius of the physics of convex array probe	r 0	Unit is physical unit millimeter (mm)
				The scan depths that convex array probe is current	The scan depths of the convex array probe corresponding with sampled data	D 0	Unit is physical unit millimeter (mm)
The minimum scan depths that convex array probe can be set	Minima in the scan depths that convex array probe can use	D 0	Unit is physical unit millimeter (mm)
				The line number of sampled data		Sr	Dimensionless parameters
The columns of sampled data		Sc	Dimensionless parameters
				Be presented at the image area width on the screen	Carry out being presented at after the DSC image area width on the screen	W 0	With the pixel is unit
Be presented at the image area height on the screen	Carry out being presented at after the DSC image area height on the screen	H 0	Same W 0
				Vertical distance	The probe center of circle is to the vertical dimension of coordinate system x-y coordinate axes x	d	Unit is physical unit millimeter (mm)

The computing formula of the distance of hanging down:

d＝r ₀×cosθ ₀ (1)

The coordinate translation formula:

$\left\{\begin{array}{c}u=x+u_0\\ v=y+v_0\end{array}\right.---\left(2\right)$

And

$\left\{\begin{array}{c}{u}_0=-W_0/2\\ v_0=\frac{d}{r_0+D_0-d}\×H_0\end{array}\right.---\left(3\right)$

Can get by formula (2) and formula (3)

$\left\{\begin{array}{c}u=x-W_0/2\\ v=y+\frac{d}{r_0+D_0-d}\×H_0\end{array}\right.---\left(4\right)$

Formula (4) is the coordinate translation formula that finally is used for DSC.

With reference to Fig. 6, under the situation that each parameter is all determined, if the coordinate (x under the x-y coordinate system, y) through the coordinate under the u-v coordinate system corresponding after the coordinate translation be (u, v), and coordinate (u, be (R v) through corresponding coordinate under R-θ coordinate system after the coordinate transform, θ), can get coordinate (u, the transformation for mula that v) arrives coordinate R-θ as the formula (5):

$\left\{\begin{array}{c}R=\sqrt{v^2+u^2}\\ \mathrm{\θ}=\arctan \left(\frac{u}{v}\right)\end{array}\right.---\left(5\right)$

It is q that the utmost point directly quantizes the factor _r, the polar angle quantizing factor is q _θ, the polar coordinate after then quantizing are (R _q, θ _q):

$\left\{\begin{array}{c}{R}_q=R\×q_r\\ {\mathrm{\θ}}_q=\mathrm{\θ}\×q_{\mathrm{\θ}}\end{array}\right.---\left(\text{8}\right)$

As shown in Figure 7, for the polar coordinate after quantizing and the numbering of sampled data can be unified, need to give utmost point footpath and polar angle go partially, it is (R that the polar coordinate after inclined to one side are removed in quantification _Qf, θ _Qf).Wherein utmost point footpath and polar angle can be made up of integer part and fractional part.If R _QfInteger part be i, fractional part is α, establishes θ _QfInteger part be j, fractional part is β.Neighbor interpolation and bilinear interpolation all are based on four some P around the interpolated point _{I, j}, P _{I, j+1}, P _{I+1, j}, P _{I+1, j+1}Carry out interpolation.

The value of P is P in the neighbor interpolation method _{I, j}, P _{I, j+1}, P _{I+1, j}, P _{I+1, j+1}In 4 with the value of the nearest point of P point.

The computing formula of bilinear interpolation is:

P＝(1-α)×(1-β)×P _i，j+(1-α)×β×P _i，j+1+α×(1-β)×P _i+1，j+α×β×P _i+1，j+1 (9)

The amount of calculation of bilinear interpolation is moderate, and effect is also good, just can cause the fuzzy of image, and sawtooth can occur in some cases.In general, Sr is 512, and the Sc minimum is 80; And the size of image area is 512*512.So image vertically, do not need to optimize again interpolation method, and image laterally, because the deficiency of sound ray number needs to optimize interpolation method, in the present invention, used a kind of expansion linear interpolation method based on 8, this is the linear interpolation method after a kind of improvement.According to the less characteristics of ultrasonic sound ray number, laterally adopting four point interpolations, and vertically adopting two point interpolations, as shown in Figure 8.

In computational process, elder generation's basis two points longitudinally obtains a point by linear interpolation, and eight points can obtain four points, are respectively P _J-1, P _j, P _J+1, P _J+2, its computing formula as the formula (10).Interpolation by horizontal four points obtains the value that P is ordered again, and its computing formula as the formula (11).

P _j-1＝(1-α)×P _i，j-1+α×P _i+1，j-1

P _j＝(1-α)×P _i，j+α×P _i+1，j (10)

P _j+1＝(1-α)×P _i，j+1+α×P _i+1，j+1

P _j+2＝(1-α)×P _i，j+2+α×P _i+1，j+2

P＝k _j-1×P _j-1+k _j×P _j+k _j+1×P _j+1+k _j+2×P _j+2 (11)

The computing formula of horizontal four point interpolation coefficients is:

Wherein d is the lateral separation that each point is ordered apart from P, and η is the interpolation smoothing factor, and η is between 0-1, and η is big more, and interpolation is sharp keen more, and the more little interpolation of η is level and smooth more.P _J-1The lateral separation of ordering to P is 1+ β, P _jThe lateral separation of ordering to P is β, P _J+1The lateral separation of ordering to P is 1-β, P _J+2The lateral separation of ordering to P is 2-β.

Expand the linear interpolation submodule and expand linear interpolation as follows:

1) according to interpolation smoothing factor η, and formula (12), calculate two interpolation coefficient look-up tables;

2) because P _j, P _J+1The distance of ordering apart from P is between 0 and 1, and P _J-1, P _J+2The distance of ordering apart from P is between 1 and 2, and the computing formula of Shi Yonging is identical between any two;

3) according to displaing coordinate x, y tries to achieve i, j, α, β;

4) from data storage, read needed 8 points;

5) there are 8 points and α to try to achieve P _J-1, P _j, P _J+1, P _J+2

6), obtain interpolation coefficient k by look-up table according to β _J-1, k _j, k _J+1, k _J+2

7) by P _J-1, P _j, P _J+1, P _J+2And k _J-1, k _j, k _J+1, k _J+2Try to achieve the P point.

The embodiment of digital scan converter of the present invention can be realized by field programmable gate array FPGA: data are read address and α, and β is obtained by displaing coordinate.Interpolation method can be selected by the user, and control signal DSCSEL is responsible for three of interpolation method and selects one, and wherein " 00 " represents bilinear interpolation, and " 01 " represents neighbor interpolation, and linear interpolation is expanded in " 10 " representative.The default value of interpolation smoothing factor η is 0.2; The user can select totally five grades of 0.1-0.5, is selected the value of η in hardware by control signal SMSEL.Every kind of interpolation method is realized by different interpolation submodules that all behind a selected interpolation method, data and α, β are imported in this interpolation submodule, obtain video data through after the corresponding interpolation calculation, finally output to display module.

Those skilled in the art do not break away from essence of the present invention and spirit, can there be the various deformation scheme to realize the present invention, the above only is the preferable feasible embodiment of the present invention, be not so limit to interest field of the present invention, the equivalent structure that all utilizations description of the present invention and accompanying drawing content are done changes, and all is contained within the interest field of the present invention.

Claims (7)

1, a kind of digital scan converter, comprise the line data buffer, the two field picture memorizer, scan conversion input controller, the scan conversion o controller, coordinate converter, described line data buffer links to each other with described two field picture memorizer, described coordinate converter links to each other with described two field picture memorizer with described scan conversion o controller respectively, described scan conversion input controller links to each other with described two field picture memorizer, it is characterized in that: also comprise selector and at least two interpolation submodules, the input of described selector links to each other with described two field picture memorizer with described coordinate converter respectively, the outfan of described selector links to each other with each interpolation submodule respectively, controls described selector by selector control signal the dateout of described coordinate converter and the dateout of described two field picture memorizer are sent to one of them interpolation submodule.

2, digital scan converter according to claim 1 is characterized in that: described interpolation submodule comprises the bilinear interpolation submodule.

3, digital scan converter according to claim 2 is characterized in that: described interpolation submodule comprises neighbor interpolation submodule.

4, digital scan converter according to claim 3 is characterized in that: described interpolation submodule comprises expands the linear interpolation submodule.

5, digital scan converter according to claim 4 is characterized in that: described selector is made as three and selects a selector.

6, digital scan converter according to claim 5 is characterized in that: storage interpolation smoothing factor in the described expansion linear interpolation submodule, select different interpolation smoothing factors by the selection signal that is input to described expansion linear interpolation submodule.

7, digital scan converter according to claim 6 is characterized in that: described selector and described interpolation submodule are realized by field programmable gate array FPGA.

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