Patent ID: 7366334

Claim:
A method of extracting a region of interest from a plurality of cross-sectional images of a sliced three-dimensional object, comprising: specifying an initial region from a first cross-sectional image of the plurality of cross sectional images; calculating a first value based on pixel values of each pixel inside the initial region; calculating a second value based on pixel values of each pixel outside the initial region; selecting, as a first temporary region, a region that is at the same position as the initial region, from a second cross-sectional image corresponding to a second cross section next to a first cross section corresponding to the first cross-sectional image; obtaining a pixel value of a first pixel near a boundary of the first temporary region; determining whether the first pixel is inside the region of interest based on the pixel value of the first pixel, the first value, and the second value; obtaining a pixel value of a second pixel outside the first temporary region and near the first pixel, if the first pixel is determined to be inside the region of interest; obtaining a pixel value of a third pixel inside the first temporary region and near the first pixel, if the first pixel is determined to be outside the region of interest; determining whether the second pixel or third pixel is inside the region of interest based on the pixel value of the second pixel or third pixel obtained, the first value, and the second value; selecting, as a second temporary region, a region that is at the same position as the initial region including all pixels that have been determined to be inside the region of interest in the second cross-sectional image, from a third cross-sectional image corresponding to a third cross section next to the second cross section; obtaining a pixel value of a fourth pixel near the second temporary region; calculating a third value based on pixel values of each pixel inside the first temporary region and the initial region; calculating a fourth value based on pixel values of each pixel outside the first temporary region and the initial region; and determining whether the fourth pixel is inside the region of interest based on the pixel value of the fourth pixel, the third value, and the fourth value.