CODEWITHSUNDEEP
python-2.7opencvimage-processingvideo-processing
the_guy
the_guy

Reputation: 99

Find mean position of blackpixels using python

I have a binary image and I need to find the mean values of x and y of the black region. These values are calculated for a set of binary images and their mean values of x and y are plotted I don't know how to find this region and calculate their mean values of x and y. Any help is kindly appreciated.

enter image description here

Upvotes: 0

Views: 1351

Answers (2)

Jeru Luke
Jeru Luke

Reputation: 21203

You can obtain the mean positions using the moments of contours.

In order to find the mean you must calculate the first order moments of the contour.

CODE:

#---Read image and obtain threshold---
im = cv2.imread('1.jpg', 1)
img = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
ret, thresh = cv2.threshold(img, 120, 255, 1)

#---Obtain contours---
contours, hierarchy = cv2.findContours(thresh, cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
cnts = contours
cv2.drawContours(im, contours, -1, (0, 255, 0), 1)

#---Compute the center/mean of the contours---
for c in cnts:
    M = cv2.moments(c)
    cX = int(M["m10"] / M["m00"])
    cY = int(M["m01"] / M["m00"])
    print cX
    print cY

Values cX and cY have the mean positions of the contours.

Upvotes: 1

MBo
MBo

Reputation: 80232

If black pixels are not registered in some data structure, just calculate center of mass for black pixels:

sx = 0
sy = 0
black_cnt = 0
for y in y-range
  for x in x-range
     if black(x,y)
          sx = sx + x
          sy = sy + y
          black_cnt++

sx = sx / black_cnt
sy = sy / black_cnt

Upvotes: 1

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