SimpleBlobDetector Blob Count

Question

如何确定在Python 2.7中使用SimpleBlobDetector找到的blob数量？我有示例代码查找和标记图像中的blob，但也需要知道有多少blob匹配我的参数。

#!/usr/bin/python

# Standard imports
import cv2
import numpy as np;
from matplotlib import pyplot as plt

# Read image
im = cv2.imread("blob.jpg")

# Setup SimpleBlobDetector parameters.
params = cv2.SimpleBlobDetector_Params()

# Change thresholds
params.minThreshold = 10
params.maxThreshold = 200

# Filter by Area.
params.filterByArea = True
params.minArea = 15

# Filter by Circularity
params.filterByCircularity = True
params.minCircularity = 0.1

# Filter by Convexity
params.filterByConvexity = True
params.minConvexity = 0.87

# Filter by Inertia
params.filterByInertia = True
params.minInertiaRatio = 0.01

# Create a detector with the parameters
detector = cv2.SimpleBlobDetector(params)

# Detect blobs.
keypoints = detector.detect(im)

# Draw detected blobs as red circles.
# cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS ensures
# the size of the circle corresponds to the size of blob

im_with_keypoints = cv2.drawKeypoints(im, keypoints, np.array([]), (255,0,0), cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS

titles = ['Blobs Detected']
images = [im_with_keypoints]


for i in xrange(1):    
    plt.subplot(1,1,i+1), plt.imshow(images[i],'gray')
    plt.title(titles[i])
    plt.xticks([]), plt.yticks([])  # to hide tick values on X and Y axis    
plt.show()

Answer 1

你只需要

nblobs = len(keypoints)