Two-dimensional tomographic image data is binarized by a predetermined threshold value, and two-dimensional labeling numbers are sequentially given to areas formed by binarization. Data of adjacent tomographic images are bit-added to generate data of a double bit length. When a value of this doubled-bit data appears at a frequency over a predetermined value, it is determined that corresponding areas of the adjacent tomographic image data are connected three-dimensionally, and a three-dimensional labeling number is given.
This incudes means for forming tomographic images of multiple cross sections by subjecting a plurality of projection data items covering a three-dimensional area of an object to a re-construction process, means for converting the tomographic images of multiple cross sections into binary images of multiple cross sections by a threshold process, and means for forming a three-dimensional model by curing liquid resin based on an image area of the binary images of multiple cross sections. With the above construction, it is possible to form a three-dimensional model of a portion extracted by the threshold process from the plurality of projection data items covering the three-dimensional area of the object.
An apparatus for reducing image artifacts caused by over-ranging or clipping of the data collected in a tomographic scan fits a geometric model to the in-range data of each projection. The geometric model is sized to the in-range data by summing all of the data of the projection to obtain a value of the total slice volume. This geometric model is used to compute the slope of the over-range data from the last point of in-range data and this extrapolated data is substituted for the over-range data. The correction process is implemented in pipeline form by convolving an over-range mask indicating which data is in-range and which data is over-range with a box car convolution kernel which produces a trapezoidal correction mask. This correction mask, multiplied by the uncorrected projection data provides the appropriate slope to its clipped portions.
Method and apparatus for automatically detecting and sizing cystic objects in ultrasound imaging. The cystic objects can be automatically detected by the steps of reading an image frame from memory; defining a search region within the image frame or a decimated version of the image frame; binarizing the pixel values within the search region based on a pixel value threshold that is adaptive to local pixel value statistics; morphological filtering the binarized pixel values to eliminate structures smaller than the speckle size; counting the number of continuous objects and keeping track of their area; and rejecting objects that are outside a predetermined size range. Each detected cystic object is automatically sized and graphical information representing the results of the automatic sizing process may be displayed.
A method and apparatus are provided to allow threshold values needed for the desired number of gradations to be set through a simple process when converting image data with numerous values into a low number of gradations. The desired number of gradations is achieved without shading being noticeable even for images having shading. The cumulative frequency distribution of the pixels for each brightness is determined from image data having a brightness range with designated gradations. The average brightness and standard deviation of the portion that is primarily background is determined from this cumulative frequency distribution. The first threshold value is determined on the basis of this average brightness and standard deviation, the second through n- 1st threshold values corresponding to the meaningful information are determined on the basis of this first threshold value. An n value conversion process is accomplished using these threshold values. Furthermore, this n value conversion process accomplishes n value conversion through a dither method for background pixels in order to reduce the effects of shading.
To perform cone beam reconstruction by using projection data correctly corresponding to X-ray beam having passed through each pixel in the reconstruction area, data D1 is obtained which is plane projected to a plane based on projection data D0. Then, plane projection data D1 to the projection plane pp is projected to the reconstruction area in the direction of X-ray transmission to obtain back projection pixel data D2. Thereafter, back projection pixel data D2 will be added for each corresponding pixel for all views to obtain back projection data D3. The present invention provides reconstruction by device of projection data correctly corresponding to the X-ray beam having passed through the reconstruction area. Through the plane projection to a plane the operation will become simplified and faster.
