After the gray transformation and the histogram equalization, these images were filtered by a frequency-domain homomorphic filter, hence noises in the images were greatly reduced.

利用自开发软件，对图像进行灰度变换和直方图均衡化处理后，采用频域同态滤波的方法对图像进行降噪滤波处理。

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The histogram equalization can enhance the contrast by redistributing the gray levels, it has the drawback that it reduces the information in the processed image.

直方图均衡可以使图像灰度分布接近均匀，提高图像对比度，但图像的信息量会有一定程度的损失。

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