X-ray angiograms, which su er from low-contrast and noise, need to be improved by both the image enhancementand denoising techniques. However, the goals of these two tasks usually conict, which makes it di cult toe ciently combine the enhancement and denoising in one scheme. To solve this problem, we propose a novelspatial-frequency ltering (SFF) scheme to simultaneously enhance and denoise low-quality X-ray cardiovascularangiogram images. The proposed scheme includes three key components: Firstly, a relative total variationmethod is employed as a guide lter to separate an input image into two parts, including the base layer withstrong structures and the detail layer with weak structures and noise. Then the base layer is enhanced by aproposed improved histogram equalization (IHE) method while the detail layer is extracted by a short-timeFourier transform and is further enhanced by using a proposed adaptive correction parameter. Finally, theimproved image is the combination of results obtained by the two components. Both quantitative and qualitativeresults of experiments on real-world low-quality X-ray angiogram images demonstrate that the proposed methodoutperforms the state-of-the-arts in terms of contrast enhancement, structure preservation, and noise reduction.
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