Contrast enhancement of CT images using a multiband filter

Abstract

Method for processing an initial image (I) of an object under investigation, wherein the initial image (I) was reconstructed from measurement data (pin) acquired during a relative rotational movement between a radiation source (C2, C4) of a computed tomography system (C1) and the object under investigation, wherein a frame rate splitting (Fk) of the initial image (I) into at least a first and a second image (Ik) is performed, the first image is modified by means of a first function (G1), wherein the first function (G1) causes a contrast increase within the first image, and the modified first image and the second image are combined (+), for the first image, before the frame rate splitting (Fk) is performed, wherein the non-linear function (Hk) causes a limitation of image values ​​with large absolute values, wherein the second image is modified by means of a second function (Gk).which effects noise reduction limited to an image value range of the second image, wherein the extent of the image value range is determined depending on the magnitude of the noise in the second image, and which includes pixel-dependent parameters so that adaptation to locally varying noise is achieved.

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