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pic_feature.py
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#!/usr/bin/env python
# encoding:utf-8
"""
图像特征检测算法与相似图片搜索
基于SIFT,SURF,ORB特征结合opencv实现图片特征与相似图片搜索
author : @h-j-13
time : 2018-8-8
ref : https://blog.csdn.net/sinat_26917383/article/details/63306206?locationNum=6&fps=1
ref : https://blog.csdn.net/samkieth/article/details/49615669
ref : https://blog.csdn.net/eds95/article/details/70146689
>>>image = cv2.imread('test.jpg') # 通过OPENCV读取文件
>>>sfit(image) # 进行sfit特征变换
[[31. 1. 0. ... 92. 1. 0.]
...
[10. 30. 5. ... 0. 0. 0.]]
>>>orb(image) # 进行ORB特征变换
[[ 88 185 59 ... 0 230 186]
...
[116 221 63 ... 123 37 122]]
>>>surf(image,'surf_test.jpg') # 进行SURF特征变化,并保存提取特征后的图片
[[-3.3737912e-03 -1.9819981e-03 3.3737912e-03 ... 4.7051071e-04
4.5059556e-03 1.3064195e-03]
....
>>>i1 = cv2.imread('test.jpg')
>>>i2 = cv2.imread('test2.jpg')
>>>print compare_pic(i1,i2,show=True) # 进行特征比对
165
"""
import cv2
import numpy as np
# 特征变换全局对象
D = 200
SFIT = None
ORB = None
SURF = None
"""
SIFT
尺度不变特征转换(Scale-invariant feature transform或SIFT)
是一种电脑视觉的算法用来侦测与描述影像中的局部性特征，
它在空间尺度中寻找极值点，并提取出其位置、尺度、旋转不变量，
"""
def sfit(image, image_save_path=''):
"""
图片进行sfit变换,生成特征点返回特征矩阵
:param image: cv2.imread
:param image_save_path: 如果指定了保存地址,则会将特征提取过的图片保存到制定的地址中
:return:sfit变换后的特征向量(128维度xD)矩阵
"""
global SFIT, D
if SFIT is None:
SFIT = cv2.xfeatures2d.SIFT_create(D)
# 灰度化/sfit特征
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
kp, des = SFIT.detectAndCompute(gray, None)
# 保存特征图片
if image_save_path:
image = cv2.drawKeypoints(gray, kp, image)
cv2.imwrite(image_save_path, image)
return des
"""
一种新的具有局部不变性的特征 —— ORB特征，
从它的名字中可以看出它是对FAST特征点与BREIF特征描述子的一种结合与改进
"""
def orb(image, image_save_path=''):
"""
图片进行orb变换,生成特征点返回特征矩阵
:param image: cv2.imread
:param image_save_path: 如果指定了保存地址,则会将特征提取过的图片保存到制定的地址中
:return:orb变换后的特征向量(32维度xD)矩阵
"""
global ORB, D
if ORB is None:
ORB = cv2.ORB_create(D)
# 灰度化/sfit特征
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
kp, des = ORB.detectAndCompute(gray, None)
# 保存特征图片
if image_save_path:
image = cv2.drawKeypoints(gray, kp, image)
cv2.imwrite(image_save_path, image)
return des
"""
SURF
采用快速Hessian算法检测关键点+提取特征。
Surf在速度上比sift要快许多，这主要得益于它的积分图技术，
已经Hessian矩阵的利用减少了降采样过程，另外它得到的特征向量维数也比较少，
有利于更快的进行特征点匹配。
"""
def surf(image, image_save_path=''):
"""
图片进行surf变换,生成特征点返回特征矩阵
:param image: cv2.imread
:param image_save_path: 如果指定了保存地址,则会将特征提取过的图片保存到制定的地址中
:return:surf变换后的特征向量(64维度xn)矩阵
"""
global SURF
if SURF is None:
SURF = cv2.xfeatures2d.SURF_create()
# 灰度化/sfit特征
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
kp, des = SURF.detectAndCompute(gray, None)
# 保存特征图片
if image_save_path:
image = cv2.drawKeypoints(gray, kp, image)
cv2.imwrite(image_save_path, image)
return des
def drawMatchesKnn_cv2(img1_gray, kp1, img2_gray, kp2, goodMatch):
h1, w1 = img1_gray.shape[:2]
h2, w2 = img2_gray.shape[:2]
vis = np.zeros((max(h1, h2), w1 + w2, 3), np.uint8)
vis[:h1, :w1] = img1_gray
vis[:h2, w1:w1 + w2] = img2_gray
p1 = [kpp.queryIdx for kpp in goodMatch]
p2 = [kpp.trainIdx for kpp in goodMatch]
post1 = np.int32([kp1[pp].pt for pp in p1])
post2 = np.int32([kp2[pp].pt for pp in p2]) + (w1, 0)
for (x1, y1), (x2, y2) in zip(post1, post2):
cv2.line(vis, (x1, y1), (x2, y2), (0, 0, 255))
cv2.namedWindow("match", cv2.WINDOW_NORMAL)
cv2.imshow("match", vis)
def compare_pic(image1, image2, show=False):
"""
比较两张图片的特征
:param image1: cv2.imread
:param image2: cv2.imread
:param draw: 是否要显示匹配的结果
:return:匹配的特征点的个数
"""
global SFIT, D
if SFIT is None:
SFIT = cv2.xfeatures2d.SIFT_create(D)
# sift
kp1, des1 = SFIT.detectAndCompute(image1, None)
kp2, des2 = SFIT.detectAndCompute(image2, None)
# BFmatcher with default parms
bf = cv2.BFMatcher(cv2.NORM_L2)
matches = bf.knnMatch(des1, des2, k=2)
# 匹配点
goodMatch = []
for m, n in matches:
if m.distance < 0.50 * n.distance:
goodMatch.append(m)
# show
if show:
drawMatchesKnn_cv2(image1, kp1, image2, kp2, goodMatch)
cv2.waitKey(0)
cv2.destroyAllWindows()
return len(goodMatch)
if __name__ == '__main__':
import os
import time
class_name = 'data/normal/'
image_list = []
for file_name in os.listdir(class_name):
image_list.append(cv2.imread(class_name + file_name))
for i in xrange(len(image_list) - 1):
start = time.time()
print compare_pic(image_list[i], image_list[i + 1]),
print time.time() - start
# image = cv2.imread('test.jpg')
# print sfit(image)
# image = cv2.imread('test.jpg')
# print orb(image)
# image = cv2.imread('test.jpg')
# print surf(image)