Python OpenCV —— Arithmetic

# -*- coding: utf-8 -*-
"""
Created on Wed Sep 28 11:54:47 2016

@author: Administrator
"""

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Arithmetic(算术) Operations on Images

cv2.add(),cv2addWeighted()
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import numpy as np
import cv2

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There is a difference between OpenCV addition and Numpy addition.
OpenCV addition is a saturated operation while Numpy addition is a modulo operation.
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x = np.uint8([250])
y = np.uint8([10])
# 只有超过255时结果才不同
print(cv2.add(x,y))  # 250+10=260=>255
print(x+y)  # 250+10=260%256 = 4

# Image Blending
# dst = x*img1 + y*img2 + z

img1 = cv2.imread(‘ml.png‘)
img2 = cv2.imread(‘opencv_logo.png‘)

# 指定图片大小
size = (500, 500)
img1 = cv2.resize(img1,size)
img2= cv2.resize(img2, size)

# 可以理解为，第一个图片占70%的比重，第二个占30%，最后的0，是常数项
dst = cv2.addWeighted(img1,0.7,img2,0.3,0)

cv2.imshow(‘dst‘,dst)
cv2.waitKey(0)
cv2.destroyAllWindows()