Hi, I've been reading tutorials and I'm trying to detect rectangles from my webcam using OpenCV.

When I run this code, I see white specs on parts of the screen for a few frames. These white areas flicker in a familiar pattern to what I've seen image recognition do. Within 2 seconds the screen is entirely black.

Why is this happening? I'm trying to detect rectangles on the screen. Thanks!

Hi, I've been reading tutorials and I'm trying to detect rectangles from my webcam using OpenCV.

When I run this code, I see white specs on parts of the screen for a few frames. These white areas flicker in a familiar pattern to what I've seen image recognition do. Within 2 seconds the screen is entirely black.

Why is this happening? I'm trying to detect rectangles on the screen. Thanks!

# Do image processing here, using img
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
contours,h = cv2.findContours(img,1,2)

for cnt in contours:
        approx = cv2.approxPolyDP(cnt,0.01*cv2.arcLength(cnt,True),True)
        print len(approx)
        if len(approx)==4:
            cv2.drawContours(img,[cnt],0,(0,0,255, 0.1),-1)

# Display the resulting frame
cv2.imshow('img',img)
if cv2.waitKey(1) & 0xFF == ord('q'):
    break

Hi, I've been reading tutorials and I'm trying to detect rectangles from my webcam using OpenCV.

When I run this code, I see white specs on parts of the screen for a few frames. These white areas flicker in a familiar pattern to what I've seen image recognition do. Within 2 seconds the screen is entirely black.

Why is this happening? I'm trying to detect rectangles on the screen. Thanks!

import numpy as np
import cv2
 
cv2

cap = cv2.VideoCapture(0)
 
cv2.VideoCapture(0)

while(True):
    ret, img = cap.read()
 
cap.read()

    # Do image processing here, using img
 img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
 contours,h = cv2.findContours(img,1,2)

 for cnt in contours:
         approx = cv2.approxPolyDP(cnt,0.01*cv2.arcLength(cnt,True),True)
         print len(approx)
         if len(approx)==4:
             cv2.drawContours(img,[cnt],0,(0,0,255, 0.1),-1)

 # Display the resulting frame
 cv2.imshow('img',img)
 if cv2.waitKey(1) & 0xFF == ord('q'):
     break
 

# When everything done, release the capture
 
capture
cap.release()
cv2.destroyAllWindows()
```

Hi, I've been reading tutorials and I'm trying to detect rectangles from my webcam using OpenCV.

When I run this code, I see white specs on parts of the screen for a few frames. These white areas flicker in a familiar pattern to what I've seen image recognition do. Within 2 seconds the screen is entirely black.

Why is this happening? I'm trying to detect rectangles on the screen. Thanks!

import numpy as np
import cv2

cap = cv2.VideoCapture(0)

while(True):
    ret, img = cap.read()

    # Do image processing here, using img
    img ret = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    contours,h = cv2.findContours(img,1,2)
cv2.findContours(ret,1,2)

    for cnt in contours:
            approx = cv2.approxPolyDP(cnt,0.01*cv2.arcLength(cnt,True),True)
            print len(approx)
            if len(approx)==4:
                cv2.drawContours(img,[cnt],0,(0,0,255, 0.1),-1)
1),-1)

    # Display the resulting frame
    cv2.imshow('img',img)
cv2.imshow('frame', img)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

Hi, I've been reading tutorials and I'm trying to detect rectangles from my webcam using OpenCV.

When I run this code, I see white specs on parts of the screen for a few frames. These white areas flicker in a familiar pattern to what I've seen image recognition do. Within 2 seconds the screen is entirely black.

Why is this happening? I'm trying to detect rectangles on the screen. Thanks!

import numpy as np
import cv2
import copy

cap = cv2.VideoCapture(0)

while(True):
    ret, img = cap.read()

    ret = cv2.cvtColor(img,     clone = copy.copy(img)
    gray_image = cv2.cvtColor(clone, cv2.COLOR_BGR2GRAY)
    ret, thresh = cv2.threshold(gray_image,127,255,1)

    # contours,h = cv2.findContours(ret,1,2)
cv2.findContours(thresh,1,2)

    contours, h = cv2.findContours(thresh,1,2)

    for cnt in contours:
            approx = cv2.approxPolyDP(cnt,0.01*cv2.arcLength(cnt,True),True)
            print len(approx)
            if len(approx)==4:
                cv2.drawContours(img,[cnt],0,(0,0,255, 1),-1)

    # Display the resulting frame
    cv2.imshow('frame', img)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

Edited code. Now now I see the screen will with am seeing red flickering -- but when I hold up a red rectangle.solid colored object (a pink yoga block in front of a white mat) it does not show.