Python3+OpenCV2实现图像的几何变换(平移、镜像、缩放、旋转、仿射)

前言

总结一下最近看的关于opencv图像几何变换的一些笔记.

这是原图:

1.平移

import cv2import numpy as npimg = cv2.imread("image0.jpg", 1)imgInfo = img.shapeheight = imgInfo[0]width = imgInfo[1]mode = imgInfo[2]dst = np.zeros(imgInfo, np.uint8)for i in range( height ):  for j in range( width - 100 ):    dst[i, j + 100] = img[i, j]cv2.imshow('image', dst)cv2.waitKey(0)

demo很简单,就是将图像向右平移了100个像素.如图:

2.镜像

import cv2import numpy as npimg = cv2.imread('image0.jpg', 1)cv2.imshow('src', img)imgInfo = img.shapeheight= imgInfo[0]width = imgInfo[1]deep = imgInfo[2]dst = np.zeros([height*2, width, deep], np.uint8)for i in range( height ):  for j in range( width ):    dst[i,j] = img[i,j]    dst[height*2-i-1,j] = img[i,j]for i in range(width):  dst[height, i] = (0, 0, 255)cv2.imshow('image', dst)cv2.waitKey(0)

demo生成一个如下效果:

3.缩放

import cv2img = cv2.imread("image0.jpg", 1)imgInfo = img.shapeprint( imgInfo )height = imgInfo[0]width = imgInfo[1]mode = imgInfo[2]# 1 放大 缩小 2 等比例 非等比例dstHeight = int(height * 0.5)dstWeight = int(width * 0.5)# 最近邻域插值 双线性插值 像素关系重采样 立方插值dst = cv2.resize(img, (dstWeight,dstHeight))print(dst.shape)cv2.imshow('image', dst)cv2.waitKey(0)

使用resize直接进行缩放操作,同时还可以使用邻域插值法进行缩放,代码如下:

# 1 info 2 空白模板 3 重新计算x, yimport cv2import numpy as npimg = cv2.imread('image0.jpg', 1)imgInfo = img.shape # 先高度,后宽度height = imgInfo[0]width = imgInfo[1]dstHeight = int(height/2)dstWidth = int(width/2)dstImage = np.zeros([dstHeight, dstWidth, 3], np.uint8)for i in range( dstHeight ):  for j in range(dstWidth):    iNew = i * ( height * 1.0 / dstHeight )    jNew = j * ( width * 1.0 / dstWidth )    dstImage[i,j] = img[int(iNew),int(jNew)]cv2.imshow('image', dstImage)cv2.waitKey(0)

4.旋转

import cv2img = cv2.imread('image0.jpg', 1)cv2.imshow('src', img)imgInfo = img.shapeheight= imgInfo[0]width = imgInfo[1]deep = imgInfo[2]# 定义一个旋转矩阵matRotate = cv2.getRotationMatrix2D((height*0.5, width*0.5), 45, 0.7) # mat rotate 1 center 2 angle 3 缩放系数dst = cv2.warpAffine(img, matRotate, (height, width))cv2.imshow('image',dst)cv2.waitKey(0)

旋转需要先定义一个旋转矩阵,cv2.getRotationMatrix2D(),参数1:需要旋转的中心点.参数2:需要旋转的角度.参数三:需要缩放的比例.效果如下图:

5.仿射

import cv2import numpy as npimg = cv2.imread('image0.jpg', 1)cv2.imshow('src', img)imgInfo = img.shapeheight= imgInfo[0]width = imgInfo[1]deep = imgInfo[2]# src 3 -> dst 3 (左上角, 左下角,右上角)matSrc = np.float32([[0,0],[0,height-1],[width-1, 0]]) # 需要注意的是 行列 和 坐标 是不一致的matDst = np.float32([[50,50],[100, height-50],[width-200,100]])matAffine = cv2.getAffineTransform(matSrc,matDst) #mat 1 src 2 dst 形成组合矩阵dst = cv2.warpAffine(img, matAffine,(height, width))cv2.imshow('image',dst)cv2.waitKey(0)

需要确定图像矩阵的三个点坐标,及(左上角, 左下角,右上角).定义两个矩阵,matSrc 为原图的三个点坐标,matDst为进行仿射的三个点坐标,通过cv2.getAffineTransform()形成组合矩阵.效果如下:

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。