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US 5,513,120 AGranted
Special interpolation filters
AssigneeElscint Ltd.
InventorGideon Berlad
Life of this patent
Estimating the term…
Abstract
An interpolation filter that enables interpolation without changing the values of the interpolated points coinciding with the sampled data points, the signal content of the original image, or the variance of the original image.
Claims17
A method of providing images of internal views of a patient for medical diagnostic purposes by sampling a radiation field emanating from said patient,
- said method comprising the steps of:
- providing an orthogonal grid of discrete points to define the location of sampling points and non-sampling points in the radiation field,
- sampling the radiation field to acquire initial sampled data at said sampling points which are at certain of said discrete points on said orthogonal grid with other of said discrete points being said non-sampling points where initially no sampled data is acquired,
- transforming said initial sampled data to image data,
- said transforming step including interpolating said initial sampled data at said certain of said sampling points to obtain interpolated data at certain of said non-sampling points,
- said interpolating step comprising doing four point interpolation using the acquired initial sampled data at said sampling points that are nearest neighbors and next nearest neighbors in a line with, and on both sides of the non-sampling point requiring interpolated data,
- deriving interpolation coefficients for each of the four sampling points,
- maintaining the signal content of initial sampled data by conserving variance in a location independent manner and by varying the interpolation coefficients so that the sum of the squared varied interpolation coefficients adds up to unity to provide images with reduced local texture artifacts, and
- using the provided images for medical diagnostic purposes.
6 more elements
A system for providing images of internal views of a patient for medical diagnostic purposes, said system comprising:
- an orthogonal grid of discrete points,
- a radiation detector for sampling a radiation field emanating from said patient on said orthogonal grid of discrete points to acquire initial sampled data at certain of said discrete points with other of said discrete points being non-sampling points where initially no sampled data is acquired,
- an image processor for transforming said initial sampled data to image data,
- said image processor including a four point interpolator for interpolating said initial data at said certain of said sampling points to obtain interpolated data at certain of said non-sampling points,
- said interpolator using normalized interpolation coefficients to obtain interpolated data,
- setting values of said interpolation coefficients so that the normalized interpolation coefficients add up to unity and so that the sum of squared interpolation coefficients add up to unity, said interpolator including:
- means for locating a non-sampling point requiring interpolated data,
- means for locating the nearest two sampling points to the non-sampling point requiring interpolated data, said nearest two sampling points and said non-sampling point being on a straight line in said orthogonal grid, one of said nearest two sampling points being on each side of said non-sampling point requiring said interpolated data;
- means for locating the next nearest two sampling points on the straight line, one point of each of said next nearest two sampling points being on each side of the non-sampling point requiring said interpolated data;
- means for determining the distance of the non-sampling point requiring said interpolated data to a midway point between the nearest two sampling points, the midway point being a zero point in relation to the other five points;
- and
- means for setting the values of the interpolation coefficients used in the interpolations so that the sum of all squared interpolation coefficients adds up to unity to conserve the variance in a location dependent manner.
9 more elements
Dependencies are inferred from the claim text.