opencv-python（十一）：模板匹配

模板匹配，就是将模板在待匹配的图像上进行滑窗比对，按照预先设定的相似性准则，得到最相似的区域即为匹配结果，opencv中设定的相似性准则总共有6种。

import cv2 as cv
import numpy as np
import matplotlib.pyplot as plt

img = cv.imread('messi5.jpg', 0)
img2 = img.copy()
template = cv.imread('messi_face.jpg', 0)
w,h = template.shape[:2]

# All 6 methods for comparison
methods = ['cv.TM_CCOEFF', 'cv.TM_CCOEFF_NORMED',
            'cv.TM_CCORR', 'cv.TM_CCORR_NORMED',
            'cv.TM_SQDIFF', 'cv.TM_SQDIFF_NORMED']

for meth in methods:
    img = img2.copy()
    method = eval(meth)

    # Apply template Matching
    res = cv.matchTemplate(img, template, method)
    min_val, max_val, min_loc, max_loc = cv.minMaxLoc(res)

    # If the method is TM_SQDIFF or TM_SQDIFF_NORMED
    if method in [cv.TM_SQDIFF, cv.TM_SQDIFF_NORMED]:
        top_left = min_loc
    else:
        top_left = max_loc

    bottom_right = (top_left[0] + w, top_left[1] + h)

    cv.rectangle(img, top_left, bottom_right, 255, 2)

    plt.subplot(121), plt.imshow(res, cmap='gray')
    plt.title('Matching Result'), plt.xticks([]), plt.yticks([])
    plt.subplot(122), plt.imshow(img, cmap='gray')
    plt.title('Detected Point'), plt.xticks([]), plt.yticks([])
    plt.suptitle(meth)
    plt.show()

匹配结果如下：