python - 为什么 find_objects 会给出一堆无，然后是整个图像的范围？

Question

我试图找到在不同帧中检测到的所有对象，我认为这将给出阈值中检测到的每个区域的列表，但是 find_objects给出一堆“无”和整个图像的范围？

...
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
(slice(0, 972, None), slice(0, 1296, None))

相关代码可从here 测试

import numpy as np
import cv2
from matplotlib import pyplot as plt
import pylab

from scipy import ndimage
import os

for img in os.listdir('.'):
    if img.endswith('.jpg'):
        image = cv2.imread(img)
        gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
        gray_image = cv2.resize(gray_image, (int(gray_image.shape[1]/2), int(gray_image.shape[0]/2) ))
        ret, threshimg = cv2.threshold(gray_image,0,255,cv2.THRESH_BINARY)
        cv2.imshow('opening',threshimg)
        objects = ndimage.find_objects(threshimg)
        for ob in objects:
            print(ob)
        cv2.waitKey(0)                 # Waits forever for user to press any key   
        cv2.destroyAllWindows()

Answer 1

scipy.ndimage.find_objects函数返回

A list of tuples, with each tuple containing N slices (with N the dimension of the input array). Slices correspond to the minimal parallelepiped that contains the object. If a number is missing, None is returned instead of a slice.

我认为在您的数据中，标签不是从 1 开始的(0 是背景，被 find_objects 忽略)。不是 None 的条目的索引是对象的整数值。