1982 | OriginalPaper | Buchkapitel
Projections
verfasst von : Theo Pavlidis
Erschienen in: Algorithms for Graphics and Image Processing
Verlag: Springer Berlin Heidelberg
Enthalten in: Professional Book Archive
Aktivieren Sie unsere intelligente Suche um passende Fachinhalte oder Patente zu finden.
Wählen Sie Textabschnitte aus um mit Künstlicher Intelligenz passenden Patente zu finden. powered by
Markieren Sie Textabschnitte, um KI-gestützt weitere passende Inhalte zu finden. powered by
In image processing, the term projection usually refers to mapping an image into a waveform whose values are the sums of the values of the image points along particular directions. (In graphics, as well as in some scene analysis problems, the term is commonly used to denote the mapping of a three-dimensional object to the plane with all depth information lost.) The reconstruction of gray scale images from their projections is one of the best known uses of computers for medical applications because it provides a strong diagnostic tool replacing some painful and dangerous techniques (see Bibliographical Notes). The technique can be extended to reconstruct a three-dimensional object from its two-dimensional projections. This is achieved by linking together a series of cross-sections. Typically, the object is a human organ (heart, brain, etc.) and the projections are radiographic or ultrasonic images, but the theory is applicable to any type of object and penetrating signal. Figure 5.1 (Plate 19) illustrates the results of such a reconstruction. We shall discuss here some of the simpler techniques, without going into any discussion of medical applications. Sections 5.2 and 5.3 describe a fundamental method for such reconstructions.