OpenCV Assertion Failed with matchTemplate

Question

I'm new to python and I'm trying to follow a tutorial on object detection, but my code calling find (which calls cv.matchTemplate) this error:

import cv2 as cv
import numpy as np
from time import time
from random import randint
from windowcapture import WindowCapture
from vision import Vision


#points = get_click_points('img2.jpg', 'copper.jpg', threshold=0.55, debug_mode=True)

wincap = WindowCapture('OSBuddy - takeawayeoc')
vision_ore = Vision('orefixed.png')

loop_time = time()
while (True):
    screenshot = wincap.capture_window()

    #cv.imshow('Computer Vision', screenshot)
    vision_ore.find(screenshot, 0.6, 'rectangles')
    print('FPS{}'.format(1 / (time() - loop_time)))
    loop_time = time()

    if(cv.waitKey(1) == ord('q')):
        cv.destroyAllWindows()
        break


File "c:\Users\Daniel\Documents\Projects\bottests\vision.py", line 28, in find
    result = cv.matchTemplate(haystack_img, self.needle_img, self.method)
cv2.error: OpenCV(4.4.0) 
C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-h4wtvo23\opencv\modules\imgproc\src	emplmatch.cpp:1163: error: (-215:Assertion failed)
 (depth == CV_8U || depth == CV_32F) && type == _templ.type() && _img.dims() <= 2 in function 'cv::matchTemplate'

you can see links to the classes in question here (code for find function) and here (window capture).

EDIT: I'm assuming the reason this isn't working is also because a simple call to print(haystack_img) and print(self.needle_img) prints different size arrays, as well as my haystack_img prints to all 0. ie:

print(haystack_img)

...
[0 0 0]
[0 0 0]
[0 0 0]]]

print(self.needle_img)
...
  [ 40  76  87 255]
  [ 40  76  87 255]
  [ 40  76  87 255]]]

This is the code for the window capture function:

def capture_window(self):
    #hwnd = None
    #get the window image data
    wDC = win32gui.GetWindowDC(self.hwnd)
    dcObj = win32ui.CreateDCFromHandle(wDC)
    cDC = dcObj.CreateCompatibleDC()
    dataBitMap = win32ui.CreateBitmap()
    dataBitMap.CreateCompatibleBitmap(dcObj, self.w, self.h)
    cDC.SelectObject(dataBitMap)
    cDC.BitBlt((0, 0), (self.w, self.h), dcObj, (0,0), win32con.SRCCOPY)

    # convert the raw data into a format opencv can read
    #dataBitMap.SaveBitmapFile(cDC, 'debug.bmp')
    signedIntsArray = dataBitMap.GetBitmapBits(True)
    img = np.fromstring(signedIntsArray, dtype='uint8')
    img.shape = (self.h, self.w, 4)

    # free resources
    dcObj.DeleteDC()
    cDC.DeleteDC()
    win32gui.ReleaseDC(self.hwnd, wDC)
    win32gui.DeleteObject(dataBitMap.GetHandle())

    # drop the alpha channel
    img = img[:,:,:3]
    # make image C_CONTIGUOUS
    img = np.ascontiguousarray(img)
    print('IMG DIMS: ', img.shape) #returns 'IMG DIMS: (28, 160, 3) then my error
    return img

Am I on the right track? How can I make matchTemplate read my screenshots from a video feed?

OpenCV Assertion Failed with matchTemplate

0 Answers