Image analysis – Image transformation or preprocessing – Changing the image coordinates
Reexamination Certificate
1998-02-25
2001-02-20
Couso, Yon J. (Department: 2723)
Image analysis
Image transformation or preprocessing
Changing the image coordinates
C382S128000
Reexamination Certificate
active
06192164
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to digital scan conversion in an ultrasonic system, and more particularly, to a digital scan conversion method and apparatus for interpolating sampled data whose position is represented by a polar coordinate system, and thus calculating pixel data whose position is represented by a rectangular coordinate system.
A general ultrasonic system emits an ultrasonic signal to an object to be tested, and receives and samples the ultrasonic signal reflected from the object at a predetermined period, to thereby obtain tested data. A digital scan converter used in the ultrasonic system has various functions such as image information display and image processing, in addition to a basic function for storing the ultrasonic signal acquired from the object to be tested, and supplying the stored data to a display device. The digital scan converter stores digital data obtained from the ultrasonic signal according to scan modes provided by the ultrasonic system, for example, a B mode, an M mode, a D mode, a CD mode, in a memory, and reads the data stored in the memory if necessary, to then display the read data via a display device.
A conventional ultrasonic system uses coordinate conversion in order to represent data whose position is represented by a polar coordinate system into that represented by a rectangular coordinate system. The coordinate conversion creates degradation of picture quality and artifact. To solve this problem, many studies for interpolating a pixel position having no data on a rectangular coordinate system and filling data therein have been performed.
FIG. 1
is a graphical view for explaining an interpolation method which is performed in a conventional digital scan converter. In
FIG. 1
, a symbol “◯” represents an actual sampling point which is positioned on a scan line represented by a polar coordinate system, and a symbol “⋄” represents a pixel point on which data stored in a memory is displayed. The data in the pixel points (I
0
, I
1
) shown in
FIG. 1
is calculated using a predetermined interpolation equation which is made by four data sampled at the sampling points A, B, C and D on mutually neighboring scan lines and a distant ratio between the sampling points A, B, C and D. However, such an interpolation method is not ideal but approximates only an ideal interpolation method, and thus remains the degradation of picture quality and artifact.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a digital scan conversion method and apparatus in an ultrasonic system capable of providing an ultrasonic image having no degradation of picture quality and artifact, by interpolating sampled data having the same radial distance as that of a desired pixel position of pixel data to then obtain the pixel data of the desired pixel position.
To accomplish the above object of the present invention, there is provided a digital scan conversion method in an ultrasonic system having a probe, the digital scan conversion method comprising the step of:
interpolating sampled data obtained from sampling points which are positioned on two scan lines neighboring to a particular pixel point and have the same radius as that of the pixel point, in order to obtain pixel data corresponding to a particular pixel point.
There is also provided a digital scan conversion apparatus for use in an ultrasonic system having a probe, the digital scan conversion apparatus comprising: interpolation data calculation means for calculating pixel points positioned between two neighboring scan lines, sampling points for obtaining sampled data positioned on the two scan lines in correspondence to the pixel points, and interpolation data corresponding to the pixel points; storage means for storing the sampling clock representing the sampling points and the interpolation data therein; an input memory for storing the sampled data corresponding to the pixel point among the ultrasonic echo signal received by the probe, using the sampling clock stored in the storage means as write clock, and outputting the stored sampled data according to read clock; a radial interpolation table for outputting pixel data with respect to the pixel point using the corresponding interpolation coefficient supplied from the storage means and the sampled data output from the input memory; a frame memory for storing the pixel data output from the radial interpolation table; and an address controller for generating read clock for reading the sampled data corresponding to the interpolation data stored in the storage means from the input memory and a write address for storing the pixel data output from the radial interpolation table in the frame memory, on the basis of the pixel points output from the interpolation data calculation means.
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Couso Yon J.
Dilworth & Barrese LLP
Medison Co. Ltd.
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