我正在尝试实现维纳滤波器来对模糊图像进行反卷积。我的实现方式如下:
import numpy as np
from numpy.fft import fft2, ifft2
def wiener_filter(img, kernel, K = 10):
dummy = np.copy(img)
kernel = np.pad(kernel, [(0, dummy.shape[0] - kernel.shape[0]), (0, dummy.shape[1] - kernel.shape[1])], 'constant')
# Fourier Transform
dummy = fft2(dummy)
kernel = fft2(kernel)
kernel = np.conj(kernel) / (np.abs(kernel) ** 2 + K)
dummy = dummy * kernel
dummy = np.abs(ifft2(dummy))
return np.uint8(dummy)
这个实现是基于维纳反卷积的Wiki页面。所用的TIFF图像来自:http://www.ece.rice.edu/~wakin/images/lena512color.tiff,这里有一个PNG版本:
![](https://istack.dev59.com/yCF9i.webp)
我的输入图像被对角线内核模糊,并添加了一些高斯噪声。Lena图片为512x512,模糊内核为11x11。
当我将维纳滤波器应用于此图像时,结果如下图所示。
![enter image description here](https://istack.dev59.com/wp7UA.webp)
我认为这张去模糊的图片质量不佳。所以我想问一下我的实现是否正确。
更新:我添加噪声的方式。
from scipy.signal import gaussian, convolve2d
def blur(img, mode = 'box', block_size = 3):
# mode = 'box' or 'gaussian' or 'motion'
dummy = np.copy(img)
if mode == 'box':
h = np.ones((block_size, block_size)) / block_size ** 2
elif mode == 'gaussian':
h = gaussian(block_size, block_size / 3).reshape(block_size, 1)
h = np.dot(h, h.transpose())
h /= np.sum(h)
elif mode == 'motion':
h = np.eye(block_size) / block_size
dummy = convolve2d(dummy, h, mode = 'valid')
return np.uint8(dummy), h
def gaussian_add(img, sigma = 5):
dummy = np.copy(img).astype(float)
gauss = np.random.normal(0, sigma, np.shape(img))
# Additive Noise
dummy = np.round(gauss + dummy)
# Saturate lower bound
dummy[np.where(dummy < 0)] = 0
# Saturate upper bound
dummy[np.where(dummy > 255)] = 255
return np.uint8(dummy)