CODEWITHSUNDEEP
pythonnumpyopencvgraphicsgeometry
user5650029
user5650029

Reputation: 35

opencv create circle out of bounds

I am trying to create a function that adds a random circle on an image. The circle should not pass the boundaries of the image. I tried it this way:

def create_circle(image):
  found = False
  color = (np.random.randint(low=0, high=255),
           np.random.randint(low=0, high=255),
           np.random.randint(low=0, high=255))
  while not found:
    pos = (np.random.randint(low=0, high=image.shape[1]),
           np.random.randint(low=0, high=image.shape[0]))
    rad = np.random.randint(low=0, high=image.shape[0]//2)
    if( rad +pos[0]< image.shape[0] and rad +pos[1]< image.shape[1]
       and rad -pos[0] >= 0 and rad -pos[1]>= 0):
      found = True
  cv2.circle(image,pos,rad,color,-1)

the circle keep getting out of the image boundaries

enter image description here

Upvotes: 1

Views: 424

Answers (1)

William Miller
William Miller

Reputation: 10320

There is a small error in the logic for deciding if the generated position and radius are valid. The conditions

rad - pos[0] >= 0 and rad - pos[1] >= 0

are equivalent to 

rad >= pos[0] and rad >= pos[1]

Which is True only if the radius exceeds both the x and y coordinate of the center of the circle. You want the opposite, i.e.

pos[0] >= rad and pos[1] >= pos[1]
# or
pos[0] - rad >= 0 and pos[1] - rad >= 0

Which will evaluate True only if both the x and y coordinates of the center of the circle exceed the radius.

Upvotes: 1

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