Rotate an image in python and fill the cropped area with image-CodePudding

Have a look at the image and it will give you the better idea what I want to achieve. I want to rotate the image and fill the black part of image just like in required image.

# Read the image
img = cv2.imread("input.png")

# Get the image size
h, w = img.shape[:2]

# Define the rotation matrix
M = cv2.getRotationMatrix2D((w/2, h/2), 30, 1)

# Rotate the image
rotated = cv2.warpAffine(img, M, (w, h))

mask = np.zeros(rotated.shape[:2], dtype=np.uint8)
mask[np.where((rotated == [0, 0, 0]).all(axis=2))] = 255
img_show(mask)

From the code I am able to get the mask of black regions. Now I want to replace these black regions with the image portion as shown in the image

CodePudding user response：

Use the borderMode parameter of warpAffine.

You want to pass the

CodePudding user response：

I have an approach. You can first create a larger image consisting of 3 * 3 times your original image. When you rotate this image and only cut out the center of this large image, you have your desired result.

import cv2
import numpy as np

# Read the image
img = cv2.imread("input.png")

# Get the image size of the origial image
h, w = img.shape[:2]

# make a large image containing 3 copies of the original image in each direction
large_img = np.tile(img, [3,3,1])

cv2.imshow("large_img", large_img)

# Define the rotation matrix. Rotate around the center of the large image
M = cv2.getRotationMatrix2D((w*3/2, h*3/2), 30, 1)

# Rotate the image
rotated = cv2.warpAffine(large_img, M, (w*3, h*3))

# crop only the center of the image
cropped_image = rotated[w:w*2,h:h*2,:]

cv2.imshow("cropped_image", cropped_image)
cv2.waitKey(0)