Python OpenCV Template Matching error
Question: I've been messing around with the OpenCV bindings for python for a while now
and i wanted to try template matching, i get this error and i have no idea why

    
    
    C:\builds\master_PackSlaveAddon-win64-vc12-static\opencv\modules\imgproc\src\templmatch.cpp:910: error: (-215) (depth == CV_8U || depth == CV_32F) && type == _templ.type() && _img.dims() <= 2 in function cv::matchTemplate
    

Anyone have any clues as to why this might be happening?

Source code:

    
    
    import win32gui
    from PIL import ImageGrab
    import win32api, win32con
    import numpy
    deckVar = "deck.png" # Temporary
    
    def click(x,y):
        win32api.SetCursorPos((x,y))
        win32api.mouse_event(win32con.MOUSEEVENTF_LEFTDOWN,x,y,0,0)
        win32api.mouse_event(win32con.MOUSEEVENTF_LEFTUP,x,y,0,0)
    
    margin = 10
    
    def OOO(): # Order Of Operations
        print None
    
    def main():
        deck = "test"
    
        img = ImageGrab.grab()
    
        HWNDHandle = win32gui.FindWindow(None, "Hearthstone");
        x,y,x2,y2 = win32gui.GetWindowRect(HWNDHandle)
        print x,y,x2,y2
        l = x2-x
        h = y2-y
        print l,h
    
        img_recog(img,"imgs/my_collection.png")
    
    def img_recog(img,templ):
        import cv2
        import numpy as np
        from matplotlib import pyplot as plt
    
    
        img2 = numpy.array(img.getdata()).reshape(img.size[0], img.size[1], 3)
        template = cv2.imread(templ,0)
        w, h = template.shape[::-1]
    
        # All the 6 methods for comparison in a list
        methods = ['cv2.TM_CCOEFF', 'cv2.TM_CCOEFF_NORMED', 'cv2.TM_CCORR',
                    'cv2.TM_CCORR_NORMED', 'cv2.TM_SQDIFF', 'cv2.TM_SQDIFF_NORMED']
    
    
        img = img2.copy()
        method = eval(methods[1])
    
        # Apply template Matching
        try:
            res = cv2.matchTemplate(img,template,method)
        except Exception as e:
            print str(e)
            raw_input()
        min_val, max_val, min_loc, max_loc = cv2.minMaxLoc(res)
    
    
        # If the method is TM_SQDIFF or TM_SQDIFF_NORMED, take minimum
        if method in [cv2.TM_SQDIFF, cv2.TM_SQDIFF_NORMED]:
            top_left = min_loc
        else:
            top_left = max_loc
        bottom_right = (top_left[0] + w, top_left[1] + h)
    
        return cv2.rectangle(img,top_left, bottom_right, 255, 2)
    
    
    main()  
    


Answer: Pay attention to the error message:

> error: (-215) (depth == CV_8U || depth == CV_32F) && type == _templ.type()
> && _img.dims() <= 2 in function cv::matchTemplate

It means the data type of the image should be CV_8U or CV_32F, and it should
have 3 or less channels.

If you don't know what CV_8U, CV_32F means, see [this
list](http://docs.opencv.org/modules/core/doc/basic_structures.html#mat-
depth).

Probably you are passing numpy objects other than np.uint8 or np.float32. you
can easily convert numpy dtype to 8-bit or 32-bit using:

    
    
    img.astype(np.float32)
    img.astype(np.uint8)
    

Just pay attention that OpenCV expect CV_8U 8-bit data to be in the range
0..255 and CV_32F can be in any range.

