OpenCV的等高线画法
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2022-06-01 08:37:22
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用于圈出图片上颜色深浅不同的区域
处理步骤:gray + threshold + open + distanceTransform + medianBlur + find_contours
from skimage import io,color
import numpy as np
import cv2
from matplotlib import pyplot as plt
from IPython.display import display
from ipywidgets import interact,interactive,fixed
plt.style.use('classic')
1.读取图片,并二值化
img = io.imread('img.JPG')
img2 = io.imread('img2.JPG')
gray = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)
# ret 值多凭感觉
thresh = np.ones_like(gray)
ret = 168
thresh[gray < ret] = 255
thresh[gray > ret] = 0
fig = plt.figure(figsize=(16, 6))
plt.subplot(131),plt.imshow(img)
plt.subplot(132),plt.imshow(gray,'gray')
plt.subplot(133),plt.imshow(thresh,'gray')
plt.show()
2.降噪,扩张并获得距离参数
# noise removal
kernel = np.ones((3,3),np.uint8)
opening = cv2.morphologyEx(thresh,cv2.MORPH_OPEN,kernel, iterations = 2)
# sure background area
sure_bg = cv2.dilate(opening,kernel,iterations=3)
# Finding sure foreground area
dist_transform = cv2.distanceTransform(opening,cv2.DIST_L2,5)
# distanceTransform
fig = plt.figure(figsize=(16, 6))
plt.subplot(131),plt.imshow(opening,'gray')
plt.subplot(132),plt.imshow(sure_bg,'gray')
plt.subplot(133),plt.imshow(dist_transform,'gray')
plt.show()
3.滑动调节等高线高度,绘制等高线
def distance(dist_transform,thresh=0.1):
ret, sure_fg = cv2.threshold(dist_transform,thresh*dist_transform.max(),255,0)
sure_fg = np.uint8(sure_fg)
median_img = cv2.medianBlur(sure_fg,17)
fig = plt.figure(figsize=(20,18))
plt.subplot(121),plt.imshow(median_img,'gray'),plt.xticks([]),plt.yticks([])
im2, contours, hierarchy = cv2.findContours(median_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
img_ground = img2.copy()
cv2.drawContours(img_ground,contours,-1,(0,255,225),5)
plt.subplot(122),plt.imshow(img_ground),plt.xticks([]),plt.yticks([])
plt.show()
return median_img,img_ground
lims = (0.0,1.0,0.05)
w = interactive(distance,dist_transform = fixed(dist_transform),thresh = lims)
display(w)
可以拖动进度条调整阈值,以改变等高线位置