我在频域进行高通滤波之后，进行傅里叶逆变换获得轮廓，再进行了闭运算的操作，将输出图像作为查找轮廓的输入，结果提示报错，网上查阅说是因为输入图像没有进行灰度处理，但是读取的时候我已经灰度处理了。代码如下
import cv2
import cv2 as cv
import numpy as np
import matplotlib.pyplot as plt
img = cv.imread("1.png",0)
#傅里叶变换
ft = np.fft.fft2(img)
cft = np.fft.fftshift(ft)
res = 20*np.log(np.abs(cft))
plt.subplot(111)
plt.imshow(res,'gray')
plt.title('center')
plt.show()
r, c = img.shape
cr, cc = int(r/2), int(c/2)
cft[cr-30:cr+30,cc-30:cc+30] = 1
high = 20*np.log(np.abs(cft))
plt.subplot(111)
plt.imshow(high,"gray")
plt.title('high')
plt.show()
#反变换
fshift = np.fft.ifftshift(cft)
backimg = np.fft.ifft2(fshift)
backimg = np.abs(backimg)
plt.imshow(backimg)
plt.title("backimg")
plt.show()
plt.hist(backimg.ravel(),256,[0,256])
plt.show()
ret,th1 = cv.threshold(backimg,15,255,cv.THRESH_BINARY)
cv.imshow("win",th1)
kernel = cv.getStructuringElement(cv.MORPH_ELLIPSE, (20, 20))
opening = cv.morphologyEx(th1, cv.MORPH_CLOSE, kernel)
cv.imshow("openning",opening)
contours, hierarchy = cv.findContours(opening,cv.RETR_TREE,cv.CHAIN_APPROX_SIMPLE)
cv.waitKey(0)
l =len(contours)
print(l)
