opencv实现抠图（单一背景），替换背景图

# coding=utf-8

import cv2
import  numpy as np

img=cv2.imread('lp.jpg')
img_back=cv2.imread('back.jpg')
#日常缩放
rows,cols,channels = img_back.shape
img_back=cv2.resize(img_back,None,fx=0.7,fy=0.7)
cv2.imshow('img_back',img_back)

rows,cols,channels = img.shape
img=cv2.resize(img,None,fx=0.4,fy=0.4)
cv2.imshow('img',img)
rows,cols,channels = img.shape#rows，cols最后一定要是前景图片的，后面遍历图片需要用到

#转换hsv
hsv=cv2.cvtColor(img,cv2.COLOR_BGR2HSV)
#获取mask
lower_blue=np.array([78,43,46])
upper_blue=np.array([110,255,255])
mask = cv2.inRange(hsv, lower_blue, upper_blue)
cv2.imshow('Mask', mask)

#腐蚀膨胀
erode=cv2.erode(mask,None,iterations=1)
cv2.imshow('erode',erode)
dilate=cv2.dilate(erode,None,iterations=1)
cv2.imshow('dilate',dilate)

#遍历替换
center=[50,50]#在新背景图片中的位置
for i in range(rows):
    for j in range(cols):
        if dilate[i,j]==0:#0代表黑色的点
            img_back[center[0]+i,center[1]+j]=img[i,j]#此处替换颜色，为BGR通道
cv2.imshow('res',img_back)

cv2.waitKey(0)
cv2.destroyAllWindows()