Abstract: A system for visualizing a 3D volume, in particular for medical applications, includes an input 1010 for receiving a three-dimensional set of data representing voxel values of the 3D volume. The data set is stored in a storage 1030. A processor projects the volume onto an imaginary 2D projection screen from a predetermined viewpoint. For each pixel of the 2D projection image a ray is cast through the pixel and through the volume. A protocol is used that, while traversing along ray positions within the volume, determines a rendering algorithm and/or rendering parameters in dependence on the ray position. For each ray position the determined rendering algorithm/parameters are used to calculate a contribution to a pixel value of the pixel based on at least one voxel value within a predetermined range of the ray position. An output 1040 is used for providing pixel values of a 2D image for rendering on a display.

Abstract: A method for matching grayvalued first elements of a first data set with grayvalued second elements of a second data set so that a first distribution of the first elements optimally matches a second distribution of the second elements, said method being characterized by the following steps: mapping said first elements on said second elements and evaluating a local grayvalue distribution difference between any mapped first element and its associated second element; from said local grayvalue distribution difference deriving for each said first element a force vector of a force field, said force vector indicating a preferred motion size and direction; combining said separate force vectors into a single force and a single torque value acting on said first elements collectively, for iteratively moving said first elements collectively to an amended mapping that improves a match between said first and second distributions.

Abstract: A method is presented to calculate the relative contribution of different tissues, or tissue mix, to at least one data element in a medical object data set, the medical object data set containing data elements, the data elements assigning data values to respective positions in a multi-dimensional geometrical space containing more than one tissue, by means by which parameters are calculated for the at least one data element, the parameters being dependent on the data value of the at least one data element and data values of surrounding data elements in the neighborhood of the at least one data element, the parameters being further compared to combinations of said parameters for data elements occurring in the region of boundaries between tissues.

Abstract: The present invention relates to the field of digital imaging, in particular to the field of estimating geometrical properties of an anatomical object. According to the present invention, geometrical properties are automatically measured and geometrical properties which have a definition based on sub-parts of the object are derived. To do this, additional geometrical information is integrated into a surface model. Geometrical properties are included into the surface model by identifying and labelling sub-parts of the surface model and fitting geometric primitives to these sub-parts. This advantageously allows to identify these sub-parts on an unseen object surface and to automatically extract relevant geometric properties.

Abstract: A method of constructing an object data set of data elements representing a physical property is described, in which the construction of the object data set includes assigning attributes to respective data elements. Such attributes are used, for example, in volume rendering. The construction of the object data set is achieved in such a way that the relative contributions of the physical property to the values of the respective data elements are derived on the basis of the relative contributions of the physical property to the data values of the data elements. These contributions are calculated by modeling transition changes in the image using a plot of grey value and gradient magnitude. Sampling of data points along the maximum gradient allows identification of the ranges of the physical property contributing to the selected voxel and calculation of the relative amounts.

Abstract: An apparatus 1000 includes an input 1010 for receiving an N-dimensional signal, N?2. A storage 1030 stores a composite model of a composite structure for estimating parameters of the model with respect to the signal. The composite model is based on constituent models 210-290 that each correspond to a constituent structure in the signal and that are incorporated in the composite structure. Each constituent model is designated for estimating parameters of the constituent model with respect to the signal based on prior knowledge of the constituent structure. At least two of the constituent models are based on differing technologies. Each constituent model is provided with a uniform interface for controlling the constituent model and for retrieving parameters estimated by it.

Abstract: The invention concerns a method of visualising an internal hollow organ (3) of a subject based on a volumetric scan thereof. A number of three-dimensional images of the internal surface of the hollow organ are reconstructed. For each image an image (Li) is calculated for the left eye from a first view point li. Next an image for the right eye (Ri) is calculated from a second view point ri that differs from the first view point. The left eye image and the right eye image are combined into a pair (Li, Ri) to form a stereoscopic image that is shown using stereoscopic imager means. The invention also refers to a system and a computer program to carry out the method according to the invention.

Abstract: The invention relates to a method for designing a template that removably fits to an object's surface, comprising the steps of: obtaining in a computer aided design system a digitized three-dimensional image of the object determining an approach direction for the template to be placed on the object manipulating the image for removal of undercuts related to the approach direction resulting in a modified image of the object defining the template depending on the shape of the modified image, in which the image is processed for visualization in a viewing direction that identifies with the approach direction, and that the so processed image is used as the modified image depending on which the template is designed.

Abstract: The invention relates to a method of measuring geometric variables of a three-dimensional structure contained in an object from at least on image representing the object, having the following steps:—use of a deformable first model describing the structure, the shape of which model can be described by parameters,—adjustment of the first model to the structure in the image,—determination of the parameters at which the first model exhibits optimum conformity with the structure,—use of a deformable second model describing the structure, which second model in shape corresponds to the first model, and which in addition contains at least one geometric variable,—modification of the second model according to the parameters determined, and—derivation of the geometric variable(s) from the modified second model.

Abstract: The invention relates to an image processing method with steps of acquiring (1) a sequence of translation overlapping images (11) representing an elongated scene; determining regions (ROI) in image pairs (Pk) and region sections (Bj) having dimensions suitable for matching (2); estimating region and section displacement fields (24, 25); regularizing (3) said region and section displacement fields (34, 35); interpolating pixel values of sections that have dimensions suitable for merging calculated from the regularized section displacement field, so as to evaluate the pixel values of corresponding regions and further scaling the sections in said regions to dimensions calculated from the regularized region displacement field, and reconstructing (4) an overview image (41) of the elongated scene (112) with said regions. The invention also relates to a system for implementing said method and a medical examination apparatus having said image processing system.

Abstract: The invention concerns a method of enhancing the quality of a radiographic image for medical purposes. Thereto at least one not relevant image area is defined in said radiographic image in which the image points are assigned different values such that a pattern is formed for masking off said image area. As an alternative or in combination therewith, the image points in the not relevant image area are assigned color values.

Abstract: Sub-images are merged in order to form an assembled image representing an elongate scene. In order to counteract artifacts in the assembled image such as disturbing transitions at the boundaries of adjacent sub-images in the image assembly method in accordance with the invention, pixel-values of overlapping portions of consecutive sub-images are interpolated so as to form pixel-values of the assembled image. The relative shift between consecutive sub-images with respect to the elongate scene is calculated from image information contained in the sub-images themselves. Correlations of pixel-values in overlapping portions of consecutive sub-images are determined as a function of the shift-value of the shift between consecutive sub-images with respect to the elongate scene. The actual shift between consecutive sub-images is found as the shift-value for which the correlation attains its maximum-value.

Abstract: Sub-images of an e.g. elongate scene are merged so as to form combined first and second portions on the basis of individual shifts of successive sub-images relative to the elongate scene. The first combined portion is distorted, notably compressed or expanded, on the basis of the dimensions of the first and second combined portions. The distorted first combined portion is merged with the combined second portion so as to form the composite image. The sub-images are formed, for example by irradiating a patient by means of an X-ray beam in different positions. For example, the distorted combined first portion shows a scale graduation and the combined second portion contains anatomic information of a patient.

Abstract: An image processing method is provided to remove areas from an image made by x-irradiation, said areas corresponding to absorption filters in the x-ray beam. Because such filters, also known as x-ray shutters, are inserted into the x-ray beam from the outside of the x-ray beam, x-ray shutter-areas extend from the periphery of the image. Therefore, once the edge of an x-ray shutter-areas has been determined, the part of the image located between the periphery and the x-ray shutter-edge is removed. X-ray shutter-edges are determined by locating transition-points in the image having brightness-transitions having maxima of both the first and second spatial derivatives of the brightness-value. An x-ray shutter-edge is then determined by fitting a curve through the transition-points. The curve fitting is performed with the use of weight-factors that are representative of the likelihood that a transition-point is on an actual x-ray shutter-edge.

Abstract: In a space having image parameter values, a contour (10) is defined consisting of vertices (11, 12, 13) connected by edges (14, 15, 16). By variation of the position and number of the vertices as a function of the variation of image parameter values in the space, the contour (10) is determined to follow features in the density variation. The movement of vertices is restricted to a direction (P.sub.i) perpendicular to the local direction (t.sub.i) of the contour (10). For smoothing the contour (10), an internal force or energy is defined at each of the vertices (11, 12, 13) which force or energy depends on the angle (c.sub.i) between the edges at the vertex, or of the variation of the angles along a sequence of adjacent vertices. A direct interaction between vertices is thereby avoided.

Abstract: In a computer tomography apparatus in accordance with the invention the advantages of the convolution calculation are combined with the advantages of recursive filtering. The processing unit for the measurement data includes a convolution filter which has only 64 convolution factors and which performs the central part of a convolution calculation (the number of measurement data amounts to, for example 512 or 1024) and a parallel-operating recursive filter which approximates the rests of the convolution calculation situated outside the central part by recursive filtering of the measurement data. Using five different multiplication factors and a corresonding number of attenuation factors, ample accuracy is achieved. By variable of only the 64 convolution factors, a large number of different filters can be realized, without it being necessary to change the factors for recursive filtering.

Abstract: A computer tomography device, in which the row of detectors has been rotated through the quarter of a detector angle (.DELTA..psi./4) with respect to the X-ray source. The invention filters selected parallel measurement values which were measured in a single direction instead of doing so with all the selected measurement values measured in parallel and antiparallel directions. The calculating time required for filtering is reduced by a factor of 2 and the values can be pipeline processed.