detect icon rotation

fix_rotation.py

# -*- coding: utf-8 -*-
import cv2
import numpy as np

def fix(name):
  src = cv2.imread(name)

  h,w = src.shape[:2]
  r = min(h,w)/2 - 1
  center = np.array([w/2,h/2])

  mask = np.zeros((w,h), dtype=np.uint8)
  cv2.ellipse(mask,((w/2,h/2),(r*2,r*2),0),(255,255,255),-1)

  best = [-1,0]

  for a in range(-90,90):
    trans = cv2.getRotationMatrix2D((w/2,h/2), a, 1)
    now = cv2.warpAffine(src, trans, (w,h))
    now = cv2.Canny(now,50,150,apertureSize = 3)
    now = now & mask

    tot = now.sum()
    cnt = (now & np.roll(now,1,0)).sum()

    per = 0
    if tot > 0:
      per = cnt/tot
    best = max(best, [per, a])

  trans = cv2.getRotationMatrix2D((w/2,h/2), best[1], 1)
  result = cv2.warpAffine(src, trans, (w,h))
  # result = cv2.Canny(result,50,150,apertureSize = 3)
  # result &= mask
  cv2.imwrite('result.jpg', result)

if __name__ == '__main__':
  fix('1.jpg')

fix_rotation_2.py

# -*- coding: utf-8 -*-
import cv2
import numpy as np

def fix(name):
  src = cv2.imread(name)

  h,w = src.shape[:2]
  r = min(h,w)/2 - 1
  center = np.array([w/2,h/2])

  # mask = np.zeros((w,h), dtype=np.uint8)
  mask = np.zeros(src.shape, dtype=np.uint8)
  cv2.ellipse(mask,((w/2,h/2),(r*2,r*2),0),(255,255,255),-1)

  best = [-1,0]

  for a in range(-90,90):
    trans = cv2.getRotationMatrix2D((w/2,h/2), a, 1)
    now = cv2.warpAffine(src, trans, (w,h))
    # now = cv2.Canny(now,50,150,apertureSize = 3)
    now = now & mask

    tot = now.sum()
    # cnt = (now & np.roll(now,1,0)).sum()
    cnt = (now & np.flip(now,1)).sum()

    per = 0
    if tot > 0:
      per = cnt/tot
    best = max(best, [per, a])

  trans = cv2.getRotationMatrix2D((w/2,h/2), best[1], 1)
  result = cv2.warpAffine(src, trans, (w,h))
  # result = cv2.Canny(result,50,150,apertureSize = 3)
  # result &= mask
  cv2.imwrite('result.jpg', result)

if __name__ == '__main__':
  fix('1.jpg')