Radiography Contrast Enhancement: Smoothed LHE Filter a Practical Solution for Digital X-Rays with Mach Band
Radiography Contrast Enhancement: Smoothed LHE Filter a Practical Solution for Digital X-Rays with Mach Band
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DOI：
10.1109/dicta47822.2019.8946114
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
P. Ambalathankandy;Yafei Ou;Jyotsna Kochiyil;Shinya Takamaeda-Yamazaki;M. Motomura;T. Asai;M. Ikebe
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文献类型：
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作者：
P. Ambalathankandy;Yafei Ou;Jyotsna Kochiyil;Shinya Takamaeda-Yamazaki;M. Motomura;T. Asai;M. Ikebe
在本文中，我们分析并提出了平滑LHE（局部直方图均衡化）滤波器在处理低对比度图像（如数字射线图像）中的实用性。众所周知，数字x射线具有马赫波段和背景对比效应等视错觉，这是由横向抑制现象引起的。我们观察到，在医学图像中使用带有最新边缘保持滤波器的多层（ML）方法进行对比度增强可能存在问题，并且可能导致由于用户自定义增益设置不受控制的纹理增强而导致的细节夸大而导致的错误诊断。机器学习滤波器设计时，主观选择的滤波器核大小很少，这可能导致输出图像的不自然。我们提出了一种光滑的lhe类滤波器，具有自适应增益控制，它更鲁棒，可以增强数字x射线中的精细细节，同时保持其固有的自然性。保持x射线图像的自然性是放射学诊断的基本特征。我们提出的滤波器具有0(1)复杂度，并且可以很容易地控制和操作连续变化的核大小，其功能类似于有源高通滤波器，放大核内的所有频率。
In this paper, we analyze and propose the usefulness of smoothed LHE (Local Histogram Equalization) filters for processing images with low contrast like digital radiographic images. Digital X-rays are known to have optical illusions like Mach bands and background contrast effects, which are caused by lateral inhibition phenomena. We observe that using multilayer (ML) methods with latest edge preserving filter for contrast enhancement in medical images can be problematic and could lead to faulty diagnosis from detail exaggeration which are caused by uncontrolled texture boosting from user defined gain settings. ML filters are designed with few subjectively selected filter kernel sizes, which can result in unnaturalness in output images. We propose a smoothed LHE-like filter with an adaptive gain control, that is more robust and can enhance fine details in digital X-rays while maintaining their intrinsic naturalness. Preserving naturalness in X-ray images are an essential feature for radiographic diagnostics. Our proposed filter has 0(1) complexity and can easily be controlled and operated with a continuously varying kernel size, which functions like an active high pass filter, amplifying all frequencies within the kernel.