| 摘要 |
This invention relates to an apparatus and method for improved display of small dark structures such as in particular coronary blood vessels in digital X-ray images. A live image (S) is initially subjected to multiscale decomposition in which firstly multiple uses of low pass filtering with subsequent resolution reduction (RED), and secondly resolution increases using subsequent low pass filtration (EXP), give detailed images (D1, D2, D3, D4) of different resolution. In accordance with the first variant of the method, a mask (M) representative of the uninteresting image background is subtracted from the detailed image (D4) having the lowest degree of resolution. This ensures that the subtraction will only comprise correspondingly coarse structures with dimensions greater than the expected image motion. A further improvement can be achieved by applying a motion estimation (MOT EST) and motion compensation (MOT COMP) to the mask (M) and to the detailed image (D4) of the lowest degree of resolution. The detailed images (D1-D4) may be multiplied by factors (c2) before they are combined to form the overall image (G). For this purpose, asymmetrical intensification functions are preferably used, so that negative contrast values corresponding to small dark structures can be intensified and positive contrast values can be suppressed.
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