How to remove the black border around rotated & masked image in result? OpenCv Python

Question

I have the task of generating data for deep learning. I take seed images, rotate them and plot them randomly on a background. The issue is the rotation results in a broken line boundary around the image and I can't figure out why it appears or how to get rid of it.

def rotateSeed(img):
rotated = imutils.rotate_bound(img, randint(0,360))
for row in range(rotated.shape[0]):
    for col in range(rotated.shape[1]):
        if (rotated[row,col,0] == 0) and (rotated[row,col,1] == 0) and (rotated[row,col,2] == 0):
            rotated[row,col] = default[0,0]
return rotated

Code explanation: default is the background color in the seed image. Rotation produces a black region I cover with the default.

Only one other person has had this problem and the solution does not explain much. It did not even rotate: OpenCV

Original seed image Rotated seed image

you can take a look at this.. https://www.pyimagesearch.com/2017/01/02/rotate-images-correctly-with-opencv-and-python/ — Andy_101, Oct 21 '19 at 07:32
The issue may have been with the data rather than the code on rotation. — Muhammad Mubashirullah Durrani, Oct 12 '21 at 20:50

Andy_101 · Answer 1 · 2019-10-21T08:21:51.073

0

You can use this code for rotation:

import cv2
import numpy as np

img = cv2.imread('C:\\Code\\1.jpeg')
num_rows, num_cols = img.shape[:2]

rotation_matrix = cv2.getRotationMatrix2D((num_cols/2, num_rows/2), 30, 1)
img_rotation = cv2.warpAffine(img, rotation_matrix, (num_cols, num_rows))
cv2.imshow('Rotation', img_rotation)
cv2.waitKey()

edited Oct 21 '19 at 08:21

answered Oct 21 '19 at 07:39

Andy_101

1,246
10
20

Dear Andy_101, under the hood imutils uses these functions and the link you shared is precisely the one I followed because this approach directly cuts the seed in some rotations. It also did not solve the border issue as it is still there. :( – Muhammad Mubashirullah Durrani Oct 22 '19 at 09:19

How to remove the black border around rotated & masked image in result? OpenCv Python

1 Answers1