使用循环进行图像分割

Question

I need to do image segmentation using loops. That is, select a coin. But I have no idea how to do this. Here are my pathetic attempts:

import cv2

a=[]

image = cv2.imread(r'E:\coin.jpg')

for line in image:

   for elem in line:
       if elem >=60:
          a.append('1')
       else:
          a.append('0')
cv2.imshow('Gray image', a) 
cv2.waitKey(0)

As a result, I get this error

Traceback (most recent call last):
  File "C:\Users\den22\AppData\Local\Programs\Python\Python36\123.py", line 9, in <module>
    if elem >=60:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

Could you please tell me what I'm doing wrong?

Answer 1

You should try to avoid iterating over arrays if you possibly can.

import cv2
import numpy as np

image = cv2.imread(r'E:\coin.jpg', cv2.IMREAD_GRAYSCALE)
threshold = 60

binary_mask = np.zeros_like(image)
above_threshold = np.where(image >= 60)
binary_mask[above_threshold] = 1
cv2.imshow(binary_mask)

This shows the logic explicitly, creating an array of zeros and then identifying the values of interest and setting those values in the binary_mask to 1. You can also just plot a boolean array:

bool_array = image >= 60
cv2.imshow(bool_array)