CN106652012A - Medical image volume rendering method and system - Google Patents

Abstract

The invention is suitable for the technical field of medical image volume rendering, and provides a medical image volume rendering method. The method comprises the following steps of performing re-sampling: performing sampling processing on a three-dimensional data field; performing classification mapping: classifying acquired data and performing visual mapping; and performing image synthesis: performing calculation based on a light ray gradient vector to obtain an image synthesis operator. The invention furthermore correspondingly provides a medical image volume rendering system. By the method and the system, the image volume rendering quality can be improved.

Description

The method and system of drafting medical image body

Technical field

The present invention relates to the Volume Rendering Techniques field of image, more particularly to a kind of drafting medical image body method and be System.

Background technology

The basic procedure of existing object plotting method is：Resampling, classification, image synthesis, it is described in detail below.Adopt again Sample：Because 3 d data field is all discrete, need to be reconstructed initial data when being visually imaged, obtain original company Continuous signal, resampling enters response with the functional value for obtaining current sampling point in continuous signal；Classification in volume drawing with Visualization mapping：Classification is that the data in data fields are divided into into different types, and each type represents a kind of material, then carries out Corresponding visualization mapping.These materials are assigned to into different colors, opacity or other physical characteristics so that final display As a result different effects are presented；The image synthesis of volume drawing：The final step of volume drawing is image synthesis.The calculation of image synthesis Method is derived according to certain optical model.It is assumed that small particles are filled with the 3 d data field of continuous distribution, due to The attributes such as the luminous of these small particles, absorption, reflection there occurs change when causing light by 3 d data field, adopt so as to draw Contribution of the sampling point to screen pixels color.The image composite operator that can be obtained by from front to back based on this hypothesis, formula is such as Under：

Wherein, the color value of k-th sampled point isOpacity value isInto the color value of k-th sampled point ForOpacity value isColor value after k-th sampled point isOpacity value is

For above-mentioned calculation, volume elements that light passes through only is the introduction of for the attenuation of light, in medical science three In the clinical practice of dimension imaging, for the positional structure relation of apparent display different organ and tissue, especially for organ The interior position that pathological changes occur, lesion tissue often has a greater change with the voxel values of neighbouring normal structure, but above-mentioned calculating side Formula is added without the gradients affect factor that will likely be produced, and causes computational accuracy not high.

In summary, prior art there will naturally be in actual use inconvenience and defect, it is therefore necessary to being improved.

The content of the invention

For above-mentioned defect, it is an object of the invention to provide a kind of method and system of drafting medical image body, its The quality of volume rendered images can be improved.

To achieve these goals, the present invention provides a kind of object plotting method of medical image, comprises the following steps：

Resampling steps：To 3 d data field sampling processing；

Classification map step：Data classification to gathering, and carry out visualization mapping；

Image composition step：Calculated based on light gradient vector and obtain image composite operator.

The object plotting method of medical image of the invention, in described image synthesis step, described image composite operator Obtained by the way that mode is calculated as below：

Wherein, the color value of k-th sampled point isOpacity value isInto the color value of k-th sampled point ForOpacity value isColor value after k-th sampled point isOpacity value isθ be gradient to The angle of amount and light vector, q is the gradients affect factor, and 0≤q≤1.

The object plotting method of medical image of the invention, the gradient vector in described image synthesis step is according to focus Organize to be calculated with the parameter difference of the voxel values of neighbouring normal structure and obtain.

The present invention also provides a kind of volume drawing system of medical image, including：

Data sampling module, for 3 d data field sampling processing；

Classification map module, for classifying to the data for gathering, and carries out visualization mapping；

Image synthesis unit, for obtaining image composite operator based on light gradient vector.

The volume drawing system of medical image of the invention, image composite operator is obtained by the way that mode is calculated as below：

Wherein, the color value of k-th sampled point isOpacity value isInto the color value of k-th sampled point ForOpacity value isColor value after k-th sampled point isOpacity value isθ be gradient to The angle of amount and light vector, q is the gradients affect factor, and 0≤q≤1.

The volume drawing system of medical image of the invention, described image synthesis module according to lesion tissue with nearby just Often the parameter difference of the voxel values of tissue is calculated and obtains light gradient vector.

The present invention is integrated into during volume drawing calculates by introducing gradient vector in volume drawing so that system can be with More accurately realize that volume drawing is calculated, for clinical diagnosises more accurate data image is provided.

Description of the drawings

Fig. 1 is existing one draw calculation principle schematic；

Fig. 2 is the volume drawing system structure diagram of the present invention；

Fig. 3 is the object plotting method flow chart of the present invention.

Specific embodiment

In order that the objects, technical solutions and advantages of the present invention become more apparent, it is right below in conjunction with drawings and Examples The present invention is further elaborated.It should be appreciated that specific embodiment described herein is only to explain the present invention, and It is not used in the restriction present invention.

At present for the direct volume drawing of the structural data such as medical image field mainly has following four basic skills：It is based on Light projection (Ray casting) method of image space scanning, footprint table (Splatting) method scanned based on object space, (Shear-warp) method, throe-dimensional temperature (the Hardware-assisted 3D texture- of hardware auxiliary are cut-deformed to mistake Mapping) method.The characteristics of these methods each have different and suitable application area, wherein light projection method is in medical image three There is superiority in dimension visualization application.

The ultimate principle of line projective method is as shown in Figure 1.From each pixel f (i, j)s, along the side of sight line of screen To a piece light I of projection, walked in 3 d data field with certain step-length d.During it advances, constantly adopted again Sample and color synthesize, till opacity α is sufficiently large or I has already passed through whole volume data space.When all on screen After the light projection process of pixel is all completed, final display image has just been obtained.

Referring to Fig. 2, the invention provides a kind of volume drawing system of medical image, the system is mainly based upon computer Data processing,

Data sampling module 10, for 3 d data field sampling processing.

Because 3 d data field is all discrete, need to be reconstructed initial data when being visually imaged, obtain original The continuous signal of beginning, resampling enters response with the functional value for obtaining current sampling point in continuous signal.

Classification map module 20, for classifying to the data for gathering, and carries out visualization mapping.Classification is by data fields Data be divided into different types, each type represents a kind of material, then carries out corresponding visualization mapping.By these materials It is assigned to different colors, opacity or other physical characteristics so that final display result presents different effects.

Image synthesis unit 30, for obtaining image composite operator based on light gradient vector.

The algorithm of image synthesis is derived according to certain optical model.It is assumed that the 3 d data field of continuous distribution In be filled with small particles, due to these small particles it is luminous, absorb, the attribute such as reflection causes light to send out when passing through 3 d data field Change is given birth to, so as to draw contribution of the sampled point to screen pixels color.

Image composite operator is obtained by the way that mode is calculated as below：

Wherein, the color value of k-th sampled point isOpacity value isInto the color value of k-th sampled point ForOpacity value isColor value after k-th sampled point isOpacity value isθ be gradient to The angle of amount and light vector, q is the gradients affect factor, and 0≤q≤1.

It is not difficult to find out by upper computing formula, q values are bigger, impact of the gradient to light attenuation is bigger, when q values are equal to 0, The computing formula of the present invention is equal to the formula of background technology.

For described image synthesis module 30, it is the parameter difference according to lesion tissue with the voxel values of neighbouring normal structure Light gradient vector Ji Suan not be obtained, and gradients affect factor q can also be calculated according to the parameter of zoning and obtained.By drawing Entering gradients affect can improve picture quality, make image apparent.

Fig. 3 is the object plotting method flow chart of the medical image of the present invention, and it can be by system reality as shown in Figure 2 Existing, the method includes：

Step S301, to 3 d data field sampling processing.

Because 3 d data field is all discrete, need to be reconstructed initial data when being visually imaged, obtain original The continuous signal of beginning, resampling enters response with the functional value for obtaining current sampling point in continuous signal.

Step S302, the data classification to gathering, and carry out visualization mapping.Classification is to be divided into the data in data fields Different types, each type represents a kind of material, then carries out corresponding visualization mapping.These materials are assigned to different Color, opacity or other physical characteristics so that final display result presents different effects.

Step S303, based on light gradient vector image composite operator is obtained.

The algorithm of image synthesis is derived according to certain optical model.It is assumed that the 3 d data field of continuous distribution In be filled with small particles, due to these small particles it is luminous, absorb, the attribute such as reflection causes light to send out when passing through 3 d data field Change is given birth to, so as to draw contribution of the sampled point to screen pixels color.

Image composite operator is obtained by the way that mode is calculated as below：

Wherein, the color value of k-th sampled point isOpacity value isInto the color value of k-th sampled point ForOpacity value isColor value after k-th sampled point isOpacity value isθ be gradient to The angle of amount and light vector, q is the gradients affect factor, and 0≤q≤1.

It is not difficult to find out by upper computing formula, q values are bigger, impact of the gradient to light attenuation is bigger, when q values are equal to 0, The computing formula of the present invention is equal to the formula of background technology.

For described image synthesis module 30, it is the parameter difference according to lesion tissue with the voxel values of neighbouring normal structure Light gradient vector Ji Suan not be obtained, and gradients affect factor q can also be calculated according to the parameter of zoning and obtained.By drawing Entering gradients affect can improve picture quality, make image apparent

In sum, it is of the invention by introducing gradient vector in volume drawing, in being integrated into volume drawing calculating so that System can more accurately realize that volume drawing is calculated, and for clinical diagnosises more accurate data image is provided.

Certainly, the present invention can also have other various embodiments, ripe in the case of without departing substantially from spirit of the invention and its essence Know those skilled in the art and work as and various corresponding changes and deformation, but these corresponding changes and change can be made according to the present invention Shape should all belong to the protection domain of appended claims of the invention.

Claims (6)

1. a kind of method of drafting medical image body, it is characterised in that comprise the following steps：

Resampling steps：To 3 d data field sampling processing；

Classification map step：Data classification to gathering, and carry out visualization mapping；

Image composition step：Calculated based on light gradient vector and obtain image composite operator.

2. the method for drafting medical image body according to claim 1, it is characterised in that in described image synthesis step, Described image composite operator is obtained by the way that mode is calculated as below：

$C_{out}^k{\mathrm{\α}}_{out}^k=C_{in}^k{\mathrm{\α}}_{in}^k+C_{now}^k{\mathrm{\α}}_{now}^k(1-{\mathrm{\α}}_{in}^k)*(qcos\mathrm{\θ}+1-q)$

${\mathrm{\α}}_{out}^k={\mathrm{\α}}_{in}^k+{\mathrm{\α}}_{now}^k(1-{\mathrm{\α}}_{in}^k)$

Wherein, the color value of k-th sampled point isOpacity value isColor value into k-th sampled point isOpacity value isColor value after k-th sampled point isOpacity value isθ is gradient vector With the angle of light vector, q is the gradients affect factor, and 0≤q≤1.

3. the method for drafting medical image body according to claim 1, it is characterised in that in described image synthesis step Gradient vector is calculated with the parameter difference of the voxel values of neighbouring normal structure according to lesion tissue and obtained.

4. a kind of system of drafting medical image body, it is characterised in that include：

Data sampling module, for 3 d data field sampling processing；

Classification map module, for classifying to the data for gathering, and carries out visualization mapping；

Image synthesis unit, for obtaining image composite operator based on light gradient vector.

5. the system of drafting medical image body according to claim 4, it is characterised in that image composite operator is by as follows Calculation is obtained：

$C_{out}^k{\mathrm{\α}}_{out}^k=C_{in}^k{\mathrm{\α}}_{in}^k+C_{now}^k{\mathrm{\α}}_{now}^k(1-{\mathrm{\α}}_{in}^k)*(qcos\mathrm{\θ}+1-q)$

${\mathrm{\α}}_{out}^k={\mathrm{\α}}_{in}^k+{\mathrm{\α}}_{now}^k(1-{\mathrm{\α}}_{in}^k)$

Wherein, the color value of k-th sampled point isOpacity value isColor value into k-th sampled point isOpacity value isColor value after k-th sampled point isOpacity value isθ is gradient vector With the angle of light vector, q is the gradients affect factor, and 0≤q≤1.

6. the system of drafting medical image body according to claim 4, it is characterised in that described image synthesis module according to Lesion tissue is calculated with the parameter difference of the voxel values of neighbouring normal structure and obtains light gradient vector.