为什么改变参数后，斑点检测的结果没有变化？

Question

我在下面的网站上得到了blob检测程序：https://www.learnopencv.com/blob-detection-using-opencv-python-c/

这是非常有用的，但是在我改变参数值之后，我发现结果没有任何变化。 比如：即使我将color的参数设置为255（用于检测较浅的斑点），深色的斑点仍然可以检测到。另外，在改变最小面积的值后，也可以检测到最小的斑点。在

似乎没有什么变化，结果总是这样的： the result of blob detection 代码如下：

import cv2
import numpy as np;

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


# Set up the detector with default parameters.
detector = cv2.SimpleBlobDetector()

params = cv2.SimpleBlobDetector_Params()

# Change thresholds
params.minThreshold = 10;    # the graylevel of images
params.maxThreshold = 200;

params.filterByColor = True
params.blobColor = 255

# Filter by Area.
params.filterByArea = False
params.minArea = 10000

# 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([]), (0,0,255), cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)

# Show keypoints
cv2.imshow("Keypoints", im_with_keypoints)
cv2.waitKey(0)

有人能帮我吗？非常感谢！！！在

Answer 1

您可以更改参数，但探测器不使用这些参数。设置它们，然后设置探测器：

import cv2
import numpy as np

# Read image
im = cv2.imread('blob.jpg', cv2.IMREAD_GRAYSCALE)

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

# Change thresholds
params.minThreshold = 10    # the graylevel of images
params.maxThreshold = 200

# Filter by Area.
params.filterByArea = True
params.minArea = 1500

# 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([]), (0, 0, 255),
    cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)

# Show keypoints
cv2.imshow('Keypoints', im_with_keypoints)
cv2.waitKey(0)

注意：如果您希望使用此参数且不以segfault结尾，则必须将True用于params.filterByArea。在