我怎样才能创建一个自定义的带通滤波器? [英] How can I create a custom band-pass filter?
问题描述
在
其中,
现在,我已经实施如下所示:
请参阅下面的代码: In this research paper, in the Section 4.1(Preprocessing), an equation of a Bandpass filter is given: Where, Now, I have implemented this like the following: https://dotnetfiddle.net/ZhucE2 But, this code produces nothing. You need to create image of your kernel, then to convolve it with your image. fft is used for optimization of convolution for large images. You can use filter2D function to make opencv do everything for you. Kernel image: Please see code below:
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源图像:
应用卷积:
Trhesholding:
$
$ b
import cv2
import math
import numpy as np
class内核(对象):
def H_Function(self,Dh,Dv,u,v,centerX,centerY,theta,n):
返回1 /(1 + 0.414 * math.sqrt(math.pow(self.U_Star(u,centerX,centerY,theta)/ Dh + self.V_Star(v,centerX,centerY,theta)/ Dv,2 * n) ))
$ b $ def U_Star(self,u,centerX,centerY,theta):
return math.cos(theta)*(u + self.Tx(centerX,theta))+ math .sin(theta)*(u + self.Ty(centerY,theta))
def V_Star(self,u,centerX,centerY,theta):
return(-math.sin (theta))*(u + self.Tx(centerX,theta))+math.cosθ(u + self.Ty(centerY,theta))
def Tx(self,中心,theta):
返回中心* math.cos(theta)
def Ty(self,center,theta):
return center * math.sin(theta)
K = Kernel()
size = 40,40
kernel = np.zeros(size,dtype = np.float)
Dh = 2
Dv = 2
centerX = -size [0] / 2
centerY = -size [1] / 2
theta = 0.9
n = 4
(0,size [0])为
:
在范围内(0,size [1]):
kernel [u] [v] = K.H_Function d h,Dv,u,v,centerX,centerY,theta,n)
kernelNorm = np.copy(kernel)
cv2.normalize(kernel,kernel,1.0,0,cv2.NORM_L1)
cv2.normalize(kernelNorm,kernelNorm,0,255,cv2.NORM_MINMAX)
cv2.imwrite(kernel.jpg,kernelNorm)
imgSrc = cv2.imread('src .jpg',0)
convolved = cv2.filter2D(imgSrc,-1,kernel)
cv2.normalize(卷积,卷积,0,255,cv2.NORM_MINMAX)
cv2.imwrite(conv.jpg,卷积)
th thresholded = cv2.threshold(卷积,100,255,cv2.THRESH_BINARY)
cv2.imwrite(thresh.jpg,thresholded )
Source image:
Convolution applied:
Trhesholding:
import cv2
import math
import numpy as np
class Kernel(object):
def H_Function(self, Dh, Dv, u, v, centerX, centerY, theta, n):
return 1 / (1 + 0.414 * math.sqrt(math.pow(self.U_Star(u, centerX, centerY, theta) / Dh + self.V_Star(v, centerX, centerY, theta) / Dv, 2 * n)))
def U_Star(self, u, centerX, centerY, theta):
return math.cos(theta) * (u + self.Tx(centerX, theta)) + math.sin(theta) * (u + self.Ty(centerY, theta))
def V_Star(self, u, centerX, centerY, theta):
return (-math.sin(theta)) * (u + self.Tx(centerX, theta)) + math.cos(theta) * (u + self.Ty(centerY, theta))
def Tx(self, center, theta):
return center * math.cos(theta)
def Ty(self, center, theta):
return center * math.sin(theta)
K = Kernel()
size = 40, 40
kernel = np.zeros(size, dtype=np.float)
Dh=2
Dv=2
centerX = -size[0] / 2
centerY = -size[1] / 2
theta=0.9
n=4
for u in range(0, size[0]):
for v in range(0, size[1]):
kernel[u][v] = K.H_Function(Dh, Dv, u, v, centerX, centerY, theta, n)
kernelNorm = np.copy(kernel)
cv2.normalize(kernel, kernel, 1.0, 0, cv2.NORM_L1)
cv2.normalize(kernelNorm, kernelNorm, 0, 255, cv2.NORM_MINMAX)
cv2.imwrite("kernel.jpg", kernelNorm)
imgSrc = cv2.imread('src.jpg',0)
convolved = cv2.filter2D(imgSrc,-1,kernel)
cv2.normalize(convolved, convolved, 0, 255, cv2.NORM_MINMAX)
cv2.imwrite("conv.jpg", convolved)
th, thresholded = cv2.threshold(convolved, 100, 255, cv2.THRESH_BINARY)
cv2.imwrite("thresh.jpg", thresholded)