特征点检测算法

Harris角点检测

cv2.cornerHarris(gray,blockSize=4,ksize=5,k=0.04)

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

def cv_show(name,image):
    """图像显示函数
    name：字符串，窗口名称
    img：numpy.ndarray，图像
    """
    cv2.namedWindow(name,cv2.WINDOW_NORMAL)
    cv2.imshow(name,image)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

if __name__=="__main__":
    img = cv2.imread('.\data\Box.jpg')
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    gray = np.float32(gray)
    # 角点检测
    dst = cv2.cornerHarris(gray,blockSize=4,ksize=5,k=0.04)
    # 对角点进行膨胀操作
    dst = cv2.dilate(dst,None)
    img[dst>0.01*dst.max()] = [0,0,255]
    # 显示图像
    cv_show('Harris Corners',img)

harris_crners.jpg

SIFT特征检测

import cv2
import numpy as np

def cv_show(name,image):
    """图像显示函数
    name：字符串，窗口名称
    img：numpy.ndarray，图像
    """
    cv2.namedWindow(name,cv2.WINDOW_NORMAL)
    cv2.imshow(name,image)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

if __name__=="__main__":
    img = cv2.imread('.\data\975-1.jpg')
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    
    sift = cv2.xfeatures2d.SIFT_create()
    keypoints,descriptor = sift.detectAndCompute(gray,None)
    # 在图上绘制关键点
    img = cv2.drawKeypoints(image=img,outImage=img,keypoints=keypoints,flags=cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS,color=(255,255,0))
    cv_show('sift_keypoints',img)
    cv2.imwrite('.\opencv_python\SIFT.jpg',img)

SIFT.jpg

SURF特征检测

import cv2
import numpy as np

def cv_show(name,image):
    """图像显示函数
    name：字符串，窗口名称
    img：numpy.ndarray，图像
    """
    cv2.namedWindow(name,cv2.WINDOW_NORMAL)
    cv2.imshow(name,image)
    cv2.waitKey(0)
    cv2.destroyAllWindows()
if __name__=="__main__":
    img = cv2.imread('.\data\975-1.jpg')
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    
    surf = cv2.xfeatures2d.SURF_create(8000)
    keypoints,descriptor = surf.detectAndCompute(gray,None)
    
    img = cv2.drawKeypoints(image=img,outImage=img,keypoints=keypoints,flags=cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS,color=(255,255,0))
    cv_show('surf_keypoints',img)
    cv2.imwrite('.\opencv_python\SURF.jpg',img)

SURF.jpg

ORB特征检测

def img_show(name,image):
    """matplotlib图像显示函数
    name：字符串，图像标题
    img：numpy.ndarray，图像
    """
    if len(image.shape) == 3:
        image = cv2.cvtColor(image,cv2.COLOR_BGR2RGB)
    plt.imshow(image,'gray')
    plt.xticks([])
    plt.yticks([])
    plt.xlabel(name,fontproperties='FangSong',fontsize=12)
 
if __name__=="__main__":
    img1 = cv2.imread('.\data\974-1.jpg')
    img2 = cv2.imread('.\data\975-1.jpg')
    gray1 = cv2.cvtColor(img1,cv2.COLOR_BGR2GRAY)
    gray2 = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)
    orb = cv2.ORB_create()
    kp1,des1 = orb.detectAndCompute(gray1,None)
    kp2,des2 = orb.detectAndCompute(gray2,None)
    bf = cv2.BFMatcher(cv2.NORM_HAMMING,crossCheck=True)
    matches = bf.match(des1,des2)
    matches = sorted(matches,key=lambda x:x.distance)
    img3 = cv2.drawMatches(img1,kp1,img2,kp2,matches[:80],img2,flags=2)
    plt.figure(figsize=(60,80),dpi=80)
    img_show('',img3)
    

orb.png