Opencv 使用绝对值差和进行模式匹配|极客教程

在这里我们使用绝对值差和进行模式匹配。将imori_part.jpg在imori.jpg中匹配的图像使用红框框出来。

绝对值差和（Sum of Absolute Differences，简称SAD）计算像素值差的绝对值之和，选取 $S$ 最小的位置作为匹配。
$S=\sum\limits_{x=0}^w\ \sum\limits_{y=0}^h\ |I(i+x,j+y)-T(x,y)|$

python实现：

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

# Read image
img = cv2.imread("imori.jpg").astype(np.float32)
H, W, C = img.shape

# Read templete image
temp = cv2.imread("imori_part.jpg").astype(np.float32)
Ht, Wt, Ct = temp.shape


# Templete matching
i, j = -1, -1
v = 255 * H * W * C
for y in range(H-Ht):
    for x in range(W-Wt):
        _v = np.sum(np.abs(img[y:y+Ht, x:x+Wt] - temp))
        if _v < v:
            v = _v
            i, j = x, y

out = img.copy()
cv2.rectangle(out, pt1=(i, j), pt2=(i+Wt, j+Ht), color=(0,0,255), thickness=1)
out = out.astype(np.uint8)

# Save result
cv2.imwrite("out.jpg", out)
cv2.imshow("result", out)
cv2.waitKey(0)
cv2.destroyAllWindows()