How to get threshold value from histogram?

Question

I\'m writing an Android app in OpenCV to detect blobs. One task is to threshold the image to differentiate the foreground objects from the background (see image).

It wo

Answer 1

If all your images are like this, or can be brought to this style, i think cv2.THRESHOLD_OTSU, ie otsu's tresholding algorithm is a good shot.

Below is a sample using Python in command terminal :

>>> import cv2
>>> import numpy as np
>>> img2 = cv2.imread('D:\Abid_Rahman_K\work_space\sofeggs.jpg',0)

>>> ret,thresh = cv2.threshold(img2,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)

>>> ret
122.0

ret is the threshold value which is automatically calculated. We just pass '0' as threshold value for this.

I got 124 in GIMP ( which is comparable to result we got). And it also removes the noise. See result below: