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I have a image which I have binarized and the problem is I want to remove the white spots in that image which are not connected in a loop i.e. small white dots. The reason is I want to take a measurement of that section like shown here.

I have tried some OpenCV morphology functions like erode, open, close but the results are not what I require. I have also tried using canny edge but some diagonal lines which I want for some processing are also gone. here is the result of both thresh(left) and canny(right)

I have read that pruning is a process in which we remove pixels which are not connected but I don't know how it works? Is there a function in Opencv for that?

th3 = cv2.adaptiveThreshold(gray_img,255,cv2.ADAPTIVE_THRESH_GAUSSIAN_C,cv2.THRESH_BINARY,11,2) th3=~th3 th3 = cv2.dilate(th3, cv2.getStructuringElement(cv2.MORPH_RECT,(3,3))) th3 = cv2.erode(th3, cv2.getStructuringElement(cv2.MORPH_RECT,(5,5))) edged = cv2.Canny(gray_img,lower,upper)
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This answer explains how to measure the diameter of the drill bit:

The first step is to read the image as 2 channel (grayscale) and find the edges using a Canny filter:

img = cv2.imread('/home/stephen/Desktop/drill.jpg',0) canny = cv2.Canny(img, 100, 100)

canny

The edges of the drill using np.argmax():

diameters = [] # Iterate through each column in the image for row in range(img.shape[1]-1): img_row = img[:, row:row+1] start = np.argmax(img_row) end = np.argmax(np.flip(img_row)) diameters.append(end+start) a = row, 0 b = row, start c = row, img.shape[1] d = row, img.shape[0] - end cv2.line(img, a, b, 123, 1) cv2.line(img, c, d, 123, 1)

outline

The diameter of the drill in each column is plotted here:

diameters

All of this assumes that you have an aligned image. I used this code to align the image.

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3 Comments

That could help me for extracting some features from thread part but I couldn't understand the graph. What is x-axis and what is y-axis, what are the peaks and valleys. If you are kind enough to explain that, and can I find some thread features of drill bit with this algorithm. Consider me a noob
Please review my edits. I superimposed the drill bit in the graph image.
Sir I am not able to align my image like yours could you please tell me the steps you used in that code link?

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