Image rotation in OpenCV

The rotation of the image is very similar to the translation of the image, and is also implemented using cv2.warpAffine . The transformation matrix needs to be obtained through the cv2.getRotationMatrix2D function first, and its function prototype is

 cv2.getRotationMatrix2D(center, angle, scale)

in

• center rotation center point coordinates
• angle The angle of rotation, the unit is angle, the positive number represents the counterclockwise direction, and the negative number represents the clockwise direction
• scale zoom factor

This function returns the affine transformation matrix M, and then we pass this affine transformation matrix to the next function:

Example

 import cv2 import numpy as np image = cv2.imread("lenna.png") cv2.imshow("original image", image) column, row, channel = image.shape M = cv2.getRotationMatrix2D((column/2,row/2), 45, 1) dst = cv2.warpAffine(image, M, (column, row)) cv2.imshow('dst', dst) cv2.waitKey(0) cv2.destroyAllWindows()

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