Nonlinear multiresolution gradient adaptive filter for medical images
Nonlinear multiresolution gradient adaptive filter for medical images
复制标题
用于医学图像的非线性多分辨率梯度自适应滤波器
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
T. Aach
中科院分区：
文献类型：
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作者：
D. Kunz;K. Eck;H. Fillbrandt;T. Aach
我们提出了一种新颖的方法，用于框内图像处理，该方法适用于多种医学成像方式，例如X射线血管造影，X射线荧光镜，磁共振或超声。大约4.5 dB及更多 - 保留尖锐的图像细节。多分辨率金字塔的单个带层的非线性自适应滤波。适应性是由从下一个更粗的多分辨率金字塔表示的图像梯度来控制的。梯度仅垂直于梯度进行过滤，即沿边缘或线条进行多分辨率方法。频率小滤波器内核被应用，从而限制了计算成本并允许对标准硬件进行实时实现。通过选择性衰减或扩增相应的频带通过系数来增强边缘。
We present a novel method for intra-frame image processing, which is applicable to a wide variety of medical imaging modalities, like X-ray angiography, X-ray fluoroscopy, magnetic resonance, or ultrasound. The method allows to reduce noise significantly - by about 4.5 dB and more - while preserving sharp image details. Moreover, selective amplification of image details is possible. The algorithm is based on a multi-resolution approach. Noise reduction is achieved by non-linear adaptive filtering of the individual band pass layers of the multi-resolution pyramid. The adaptivity is controlled by image gradients calculated from the next coarser layer of the multi-resolution pyramid representation, thus exploiting cross-scale dependencies. At sites with strong gradients, filtering is performed only perpendicular to the gradient, i.e. along edges or lines. The multi-resolution approach processes each detail on its appropriate scale so that also for low frequency noise small filter kernels are applied, thus limiting computational costs and allowing a real-time implementation on standard hardware. In addition, gradient norms are used to distinguish smoothly between “structure” and “noise only” areas, and to perform additional noise reduction and edge enhancement by selectively attenuating or amplifying the corresponding band pass coefficients.