opencv 基于形状的模板匹配

1.问题或需求描述

opencv 基于形状的模板匹配测试

2.解决方法或原理：

主要步骤：

1. 使用opencv查找轮廓(findContours)
2. 匹配轮廓（形状）(matchShapes)的相似度

python代码：

import cv2

# 读取目标图像
target_image = cv2.imread('target.png', cv2.IMREAD_COLOR)
# 读取模板图像
template_image = cv2.imread('template.png', cv2.IMREAD_COLOR)

# 转换为灰度图像
gray_target_image = cv2.cvtColor(target_image, cv2.COLOR_BGR2GRAY)
gray_template_image = cv2.cvtColor(template_image, cv2.COLOR_BGR2GRAY)
# 扩展通道数以绘制色彩
view = cv2.merge((gray_target_image, ) * 3)

# 二值化
_, gray_target_image = cv2.threshold(gray_target_image, 50, 255, cv2.THRESH_BINARY)
_, gray_template_image = cv2.threshold(gray_template_image, 50, 255, cv2.THRESH_BINARY)

# 显示图像
cv2.imshow('template', gray_template_image)
cv2.imshow('match', view)

# 提取图像轮廓
target_contours, target_hierarchy = cv2.findContours(gray_target_image, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)
template_contours, template_hierarchy = cv2.findContours(gray_template_image, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)

# 调试输出
print('target_contours num:',len(target_contours))
print('template_contours num:',len(template_contours))

# 存储各个形状匹配值
values = []
for v in range(len(target_contours)):
    # 计算形状匹配值
    match_value = cv2.matchShapes(target_contours[v], template_contours[0], cv2.CONTOURS_MATCH_I1, 0.0)
    print(f"形状匹配值: {match_value}")
    values.append(match_value)
    
    # 绘制当前匹配轮廓
    view_copy = view.copy()
    cv2.drawContours(view_copy, [target_contours[v]], -1, (0, 255, 0), thickness=cv2.FILLED)
    cv2.putText(view_copy, f"match value: {match_value}", (10,30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0,0,255), 2)
    cv2.imshow('match', view_copy)
    cv2.waitKey(500)


# 显示匹配结果
idx = values.index(min(values))
cv2.drawContours(view, [target_contours[idx]], -1, (0, 255, 0), thickness=cv2.FILLED)
cv2.putText(view, f"match value: {values[idx]}", (10,30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0,0,255), 2)
cv2.imshow('match', view)
cv2.waitKey(0)
cv2.destroyAllWindows()

3.结果演示：