minimum blob size for opencv threshold in python

Question

is there a way to threshold only if the blob size is more than (height,width)?

Example

import cv2

img_1 = cv2.imread('my_image_1.jpg')
thresh = cv2.threshold(img_1, 200, 255, cv2.THRESH_BINARY)[1]

For the purposes of thresholding, I want to ignore all pixels that are not inside a blob of say, 6 x 6 pixels that also meet the thresholding condition.

What is the best way to do this?

Answer 1

Please check this tutorial. You can implement this by adding the following lines to your code,

params = cv2.SimpleBlobDetector_Params()

params.filterByArea = True
params.minArea = 20 #define minimum area

ver = (cv2.__version__).split('.')

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

keypoints = detector.detect(thresh)

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