CODEWITHSUNDEEP
opencvobject-detection
Stephen P
Stephen P

Reputation: 1

How to detect many small red laser dots correctly using CV?

I am working on a project, which needs to detect many small red laser dots correctly using Opencv. In the end, I want to find all the red laser dots out correctly. Now I changed the rgb to hsv and set the range to detect red dots, then used the canny and findContours function in the opencv to detect the edge and find countours. However, the result isn't very good. some red dots weren't detected well. you could see the picture below. Could you give me some advice about it? laser lights

detection result

below is my code:

cap = cv2.VideoCapture(0)
# set red thresh 
lower_red = np.array([0,0,255])
#156, 100, 40
upper_red = np.array([180,255,255])
while(1):
    ret, frame0 = cap.read()
    frame = cv2.flip(frame0,0)
    frame = frame[50:360,280:380]
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
    mask = cv2.inRange(hsv, lower_red, upper_red)   
    edged = cv2.Canny(mask, 30, 200)    
    cv2.imshow('Canny Edges After Contouring', edged)
    _, contours, hierarchy = cv2.findContours(edged, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    print("Number of Contours found = " + str(len(contours)))

    # Draw all contours
    # -1 signifies drawing all contours
    # for c in contours:
    #   M = cv2.moments(c)
    #   cX = int(M["m10"] / M["m00"])
    #   cY = int(M["m01"] / M["m00"])
    #   cv2.drawContours(frame, c, -1, (0, 255, 0), 3)
    #   cv2.circle(frame,(cX,cY),2,(255,255,255),-1)
    #   cv2.putText(frame,"center",(cX - 20, cY - 20),cv2.FONT_HERSHEY_SIMPLEX,0.5,(255,255,255),2)
    cv2.imshow('Capture',frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()

cv2.destroyAllWindows()

Upvotes: 0

Views: 639

Answers (1)

Felipe Cunha
Felipe Cunha

Reputation: 216

Have you tried to play with the individual channels of your image? you can get better contrast between the laser dots and the background if you use for example the green channel of your image.

import cv2 [enter image description here][1]

image = cv2.imread("cv2/images/laser.jpg")
b, g, r = cv2.split(image)
ret, newIm = cv2.threshold(g, 220, 255, cv2.THRESH_BINARY)
cv2.imshow('New Image', newIm)
cv2.waitKey()

Upvotes: 1

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