图片的透视变换perspective transform——旋转矫正

简介

一幅倾斜了的图片如何进行矫正，这也许比较有用，比如，传统的车牌中有将倾斜了的车牌文字，用　Radon变换进行矫正。如果我们知道了四个点的坐标，是否也可以进行矫正处理？

代码

'''
Created on 2017年8月20日

@author: XT
'''
# import the necessary packages
import matplotlib.pyplot as plt
import imutils
from imutils import perspective
import numpy as np
import cv2

# load the notecard code image, clone it, and initialize the 4 points
# that correspond to the 4 corners of the notecard
notecard = cv2.imread("../image/notecard.png")
clone = notecard.copy()
pts = np.array([(73, 239), (356, 117), (475, 265), (187, 443)])

# loop over the points and draw them on the cloned image
for (x, y) in pts:
    cv2.circle(clone, (x, y), 5, (0, 255, 0), -1)

# apply the four point tranform to obtain a "birds eye view" of
# the notecard
warped = perspective.four_point_transform(notecard, pts)

# show the original and warped images
cv2.imshow("Original", clone)
cv2.imshow("Warped", warped)
plt.figure("Original opencv2matplotlib")
plt.imshow(imutils.opencv2matplotlib(clone))
plt.show()
cv2.waitKey(0)

效果