Affine transformation – OpenCV 3.4 with python 3 Tutorial 14

by Sergio Canu February 15, 2018

import cv2
import numpy as np

img = cv2.imread("grid.jpg")
rows, cols, ch = img.shape

cv2.circle(img, (83, 90), 5, (0, 0, 255), -1)
cv2.circle(img, (447, 90), 5, (0, 0, 255), -1)
cv2.circle(img, (83, 472), 5, (0, 0, 255), -1)

pts1 = np.float32([[83, 90], [447, 90], [83, 472]])
pts2 = np.float32([[0, 0], [447, 90], [150, 472]])

matrix = cv2.getAffineTransform(pts1, pts2)
result = cv2.warpAffine(img, matrix, (cols, rows))

cv2.imshow("Image", img)
cv2.imshow("Affine transformation", result)
cv2.waitKey(0)
cv2.destroyAllWindows()

Files:

grid.jpg

2 Comments

karuppaiya September 7, 2018 at 9:02 am

I got a information about warpAffine method. But I want to know one more about warpAffine .

import cv2
import numpy as np

pic = cv2.imread(‘image.jpeg’)
print(pic.shape)
cols = pic.shape[1]
rows = pic.shape[0]

M = np.float32([[1,0,25],[0,1,10]]) # This line is passed to warpAffine method. But in your video, you have explained another way. can you tell me what is the difference between this line and your method in your code?

shifted = cv2.warpAffine(pic, M, (cols,rows))
cv2.imshow(‘shifted’,shifted)

cv2.waitKey(0)
cv2.destroyAllWindows()

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david October 16, 2018 at 4:50 pm

What if i want to translate back from the result to the original image ?

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