CODEWITHSUNDEEP
pythonopencv
tribute2power Official
tribute2power Official

Reputation: 23

Template match a screen capture using opencv

What I want to achieve is to capture my screen in real time and have it detect when a certain image is shown inside the frame. What I've come up with so far is:

Screen Capture:

last_time = time.time()
while(True):
    screen = np.array(ImageGrab.grab(bbox=(0,40, 800, 640)))
    print('Loop took {} seconds'.format(time.time()-last_time))
    last_time = time.time()
    cv2.imshow('window', cv2.cvtColor(screen, cv2.COLOR_BGR2RGB))
    if cv2.waitKey(25) & 0xFF == ord('q'):
        cv2.destroyAllWindows()
        break

Template Matching:

import cv2
import numpy as np

img_rgb = cv2.imread('frame.png')
img_gray = cv2.cvtColor(img_rgb, cv2.COLOR_BGR2GRAY)

template = cv2.imread('template.png',0)
w, h = template.shape[::-1]

res = cv2.matchTemplate(img_gray,template,cv2.TM_CCOEFF_NORMED)
threshold = 0.8
loc = np.where( res >= threshold)

for pt in zip(*loc[::-1]):
    cv2.rectangle(img_rgb, pt, (pt[0] + w, pt[1] + h), (0,255,255), 2)

cv2.imshow('Detected',img_rgb)

cv2.waitKey(0)
cv2.destroyAllWindows()

I got both of them working separately but cant manage to fuse them together. What I mainly struggled with was to imread() the current frame, as it returns as an nparray from the capturing, while cv2.imread() requires a picture file (png., jpg. ect.)

Upvotes: 2

Views: 1636

Answers (1)

karlphillip
karlphillip

Reputation: 93410

  • Load the template image before the while(True) loop;
  • Inside the loop, make sure to convert screen from RGB to GRAY;
  • Then, execute those 3 lines of the template matching code;
  • Finally, to display the output with the rectangles, draw them on screen, not on its grayscale counterpart.

Upvotes: 1

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