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上面是两个原始图像;接下来进行拼接!
- import numpy as np
- import cv2
-
- class Stitcher:
- #拼接函数
- def stitch(self, images, ratio=0.75, reprojThresh=4.0,showMatches=False):
- #获取输入图片
- (imageB, imageA) = images
- #检测A、B图片的SIFT关键特征点,并计算特征描述子
- (kpsA, featuresA) = self.detectAndDescribe(imageA)
- (kpsB, featuresB) = self.detectAndDescribe(imageB)
-
- # 匹配两张图片的所有特征点,返回匹配结果
- M = self.matchKeypoints(kpsA, kpsB, featuresA, featuresB, ratio, reprojThresh)
-
- # 如果返回结果为空,没有匹配成功的特征点,退出算法
- if M is None:
- return None
-
- # 否则,提取匹配结果
- # H是3x3视角变换矩阵
- (matches, H, status) = M
- # 将图片A进行视角变换,result是变换后图片
- result = cv2.warpPerspective(imageA, H, (imageA.shape[1] + imageB.shape[1], imageA.shape[0]))
- # self.cv_show('result', result)
- # 将图片B传入result图片最左端
- result[0:imageB.shape[0], 0:imageB.shape[1]] = imageB
- # self.cv_show('result', result)
- # 检测是否需要显示图片匹配
- if showMatches:
- # 生成匹配图片
- vis = self.drawMatches(imageA, imageB, kpsA, kpsB, matches, status)
- # 返回结果
- return (result, vis)
-
- # 返回匹配结果
- return result
- # def cv_show(self,name,img):
- # cv2.imshow(name, img)
- # cv2.waitKey(0)
- # cv2.destroyAllWindows()
-
- def detectAndDescribe(self, image):
- # 将彩色图片转换成灰度图
- gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
-
- # 建立SIFT生成器
- descriptor = cv2.xfeatures2d.SIFT_create()
- # 检测SIFT特征点,并计算描述子
- (kps, features) = descriptor.detectAndCompute(image, None)
-
- # 将结果转换成NumPy数组
- kps = np.float32([kp.pt for kp in kps])
-
- # 返回特征点集,及对应的描述特征
- return (kps, features)
-
- def matchKeypoints(self, kpsA, kpsB, featuresA, featuresB, ratio, reprojThresh):
- # 建立暴力匹配器
- matcher = cv2.BFMatcher()
-
- # 使用KNN检测来自A、B图的SIFT特征匹配对,K=2
- rawMatches = matcher.knnMatch(featuresA, featuresB, 2)
-
- matches = []
- for m in rawMatches:
- # 当最近距离跟次近距离的比值小于ratio值时,保留此匹配对
- if len(m) == 2 and m[0].distance < m[1].distance * ratio:
- # 存储两个点在featuresA, featuresB中的索引值
- matches.append((m[0].trainIdx, m[0].queryIdx))
-
- # 当筛选后的匹配对大于4时,计算视角变换矩阵
- if len(matches) > 4:
- # 获取匹配对的点坐标
- ptsA = np.float32([kpsA[i] for (_, i) in matches])
- ptsB = np.float32([kpsB[i] for (i, _) in matches])
-
- # 计算视角变换矩阵
- (H, status) = cv2.findHomography(ptsA, ptsB, cv2.RANSAC, reprojThresh)
-
- # 返回结果
- return (matches, H, status)
-
- # 如果匹配对小于4时,返回None
- return None
-
- def drawMatches(self, imageA, imageB, kpsA, kpsB, matches, status):
- # 初始化可视化图片,将A、B图左右连接到一起
- (hA, wA) = imageA.shape[:2]
- (hB, wB) = imageB.shape[:2]
- vis = np.zeros((max(hA, hB), wA + wB, 3), dtype="uint8")
- vis[0:hA, 0:wA] = imageA
- vis[0:hB, wA:] = imageB
-
- # 联合遍历,画出匹配对
- for ((trainIdx, queryIdx), s) in zip(matches, status):
- # 当点对匹配成功时,画到可视化图上
- if s == 1:
- # 画出匹配对
- ptA = (int(kpsA[queryIdx][0]), int(kpsA[queryIdx][1]))
- ptB = (int(kpsB[trainIdx][0]) + wA, int(kpsB[trainIdx][1]))
- cv2.line(vis, ptA, ptB, (0, 255, 0), 1)
-
- # 返回可视化结果
- return vis
接下来进行测试;
- from Stitcher import Stitcher
- import cv2
-
- # 读取拼接图片
- imageA = cv2.imread("left_01.png")
- imageB = cv2.imread("right_01.png")
-
- # 把图片拼接成全景图
- stitcher = Stitcher()
- (result, vis) = stitcher.stitch([imageA, imageB], showMatches=True)
-
- def cv_show(name,img):
- cv2.imshow(name,img)
- cv2.waitKey(0)
- cv2.destroyAllWindows()
-
- # 显示所有图片
- # cv2.imshow("Image A", imageA)
- # cv2.imshow("Image B", imageB)
- cv2.imshow("Keypoint Matches", vis)
- # cv2.imshow("Result", result)
- cv2.waitKey(0)
- cv2.destroyAllWindows()
先看一下两张图片的关键点匹配图;
然后最后拼接后的图片;
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