图片处理：对图片进行缩放

#实现图片缩放
#定义一个2*3的矩阵，[[A1 A2 B1],[A3 A4 B2]]
#[[A1 A2],[A3 A4]]   [B1 B2]
#newX = A1*x+A2*y+B1
#newY = A3*x+A4*y+B2
# x->0.5*x y->0.5*y
#把A1=0.5 A2=0 B1=0  =>  newX= 0.5*x
import cv2
import  numpy as np

img = cv2.imread('image0.jpg', 1)
cv2.imshow('src', img)
imgInfo = img.shape
height = imgInfo[0]
width = imgInfo[1]
#设置矩阵，其中A1=0.5，A4=0.5，其余为0
matScale = np.float32([[0.5, 0, 0],[0,0.5,0]])
#定义仿射方法
dst = cv2.warpAffine(img, matScale,(int(width/2),int(height/2)))
#图片展示
cv2.imshow('dst', dst)
cv2.waitKey(0)