无法检测到任何白色斑点-opencv python [英] unable to detect any white blobs - opencv python

问题描述

我正试图在图像中简单地找到白色的圆形斑点.当我尝试使用houghcircles时，我总是把字母和数字误认为圆圈，而我只需要完整的圆圈，即斑点.

I am trying to simply find white circular blobs in an image. When i tried going with houghcircles, I keep getting letters and digits mistaken for circles, whereas I only need complete circles, i.e. blobs.

因此，我使用自定义参数运行了该斑点检测器代码，以在左上角找到圆形的IC引脚标记.但是我一直在"9"和"0"内出现黑眼圈. 它根本检测不到任何白色斑点.

So I ran this blob detector code with custom params to find the circular IC pin mark on the upper left corner. But I keep getting dark circles inside '9' and '0'. It doesnt detect any white blobs at all.

这是我尝试的代码:

import cv2
import numpy as np;

# Read image
img = cv2.imread("C:\chi4.jpg", cv2.IMREAD_GRAYSCALE)
retval, threshold = cv2.threshold(img, 200, 255, cv2.THRESH_BINARY)

params = cv2.SimpleBlobDetector_Params()

# Change thresholds
params.minThreshold = 10;
params.maxThreshold = 255;

blur = cv2.GaussianBlur(img,(5,5),0)

params.filterByCircularity = True
params.minCircularity = 0.2

params.filterByArea = True;
params.minArea = 1000;

ver = (cv2.__version__).split('.')
if int(ver[0]) < 3 :
    detector = cv2.SimpleBlobDetector(params)
else :
    detector = cv2.SimpleBlobDetector_create(params)

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

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

# 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(img, keypoints, np.array([]), (0,0,255), cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)

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

这是我的输出图像:

Here is my output image:

红色圆圈是检测到的圆圈.我希望检测到顶部的白色圆形斑点，并用蓝色标记.

The red circles are the detected ones. I want the white circular blob, in the top marked in blue to be detected.

我尝试更改阈值参数，但仍然没有影响.请让我知道我要去哪里错了，或者提出改善输出的建议. 在此先感谢:D

I tried changing the threshold parameters, still no impact. Kindly let me know where I am going wrong or suggestions to improve the output. Thanks in advance :D

推荐答案

斑点通常假定为灰色/黑色.在您的情况下，字母旁边的斑点为黑色.但是，您想要的斑点是白色的.因此无法识别.

Blobs are generally assumed to be gray/black. In your case the blobs in side the letters are black. However the blob you have intended is white. Hence it Is not recognized.

在您的代码中，您必须将第四行更改为:

In your code you have to change the fourth line to:

retval, threshold = cv2.threshold(img, 200, 255, cv2.THRESH_BINARY_INV)

我在以下方面采用了相同的方法:

I followed the same approach for the following:

我对以下图像进行了斑点检测:

I performed blob detection on the following image:

但未找到任何斑点:

我将二进制图像反转为以下内容:

I inverted the binary image to the following:

现在我能够检测到它们，如下所示:

now I was able to detect them as shown:

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