关键点检测和图像拼接
Key-point Detection and Image Stitching
]2
所以如下图所示,我在图像上检测到了关键点,但是环绕透视后的输出图像忽略了左侧的第一张图像,无法弄清楚为什么!
import numpy as np
import imutils
import cv2
class Stitcher:
def __init__(self):
# determine if we are using OpenCV v3.X
self.isv3 = imutils.is_cv3()
def stitch(self, imageA,imageB, ratio=0.75, reprojThresh=10.0,
showMatches=False):
# unpack the images, then detect keypoints and extract
# local invariant descriptors from them
#(imageB, imageA) = images
(kpsA, featuresA) = self.detectAndDescribe(imageA)
(kpsB, featuresB) = self.detectAndDescribe(imageB)
# match features between the two images
M = self.matchKeypoints(kpsA, kpsB,
featuresA, featuresB, ratio, reprojThresh)
# if the match is None, then there aren't enough matched
# keypoints to create a panorama
if M is None:
return None
# otherwise, apply a perspective warp to stitch the images
# together
(matches, H, status) = M
#print(M)
#print(matches)
#print(H)
#print(status)
#cv2.imwrite('intermediate.jpg',matches)
result = cv2.warpPerspective(imageA, H,
(imageA.shape[1] + imageB.shape[1], imageA.shape[0]))
result[0:imageB.shape[0], 0:imageB.shape[1]] = imageB
#cv2.imshow('intermediate',result)
# check to see if the keypoint matches should be visualized
if showMatches:
vis = self.drawMatches(imageA, imageB, kpsA, kpsB, matches,
status)
# return a tuple of the stitched image and the
# visualization
return (result, vis)
# return the stitched image
return result
def detectAndDescribe(self, image):
# convert the image to grayscale
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# check to see if we are using OpenCV 3.X
if self.isv3:
# detect and extract features from the image
#SIFT Algorithm
descriptor = cv2.xfeatures2d.SIFT_create()
#SURF Algorithm
#descriptor = cv2.xfeatures2d.SURF_create()# 400 is hesian threshold, optimum values should be around 300-500
#upright SURF: faster and can be used for panorama stiching i.e our case.
#descriptor.upright = True
print(descriptor.descriptorSize())
(kps, features) = descriptor.detectAndCompute(image, None)
print(len(kps),features.shape)
# otherwise, we are using OpenCV 2.4.X
else:
# detect keypoints in the image
detector = cv2.FeatureDetector_create("SIFT")
kps = detector.detect(gray)
# extract features from the image
extractor = cv2.DescriptorExtractor_create("SIFT")
(kps, features) = extractor.compute(gray, kps)
# convert the keypoints from KeyPoint objects to NumPy
# arrays
kps = np.float32([kp.pt for kp in kps])
# return a tuple of keypoints and features
#print("features",features)
return (kps, features)
def matchKeypoints(self, kpsA, kpsB, featuresA, featuresB,
ratio, reprojThresh):
# compute the raw matches and initialize the list of actual
# matches
matcher = cv2.DescriptorMatcher_create("BruteForce")
rawMatches = matcher.knnMatch(featuresA, featuresB, 2)
matches = []
# loop over the raw matches
for m in rawMatches:
# ensure the distance is within a certain ratio of each
# other (i.e. Lowe's ratio test)
if len(m) == 2 and m[0].distance < m[1].distance * ratio:
matches.append((m[0].trainIdx, m[0].queryIdx))
print(len(matches))
# computing a homography requires at least 4 matches
if len(matches) > 4:
# construct the two sets of points
ptsA = np.float32([kpsA[i] for (_, i) in matches])
ptsB = np.float32([kpsB[i] for (i, _) in matches])
# compute the homography between the two sets of points
(H, status) = cv2.findHomography(ptsA, ptsB, cv2.RANSAC,
reprojThresh)
# return the matches along with the homograpy matrix
# and status of each matched point
return (matches, H, status)
# otherwise, no homograpy could be computed
return None
def drawMatches(self, imageA, imageB, kpsA, kpsB, matches, status):
# initialize the output visualization image
(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
# loop over the matches
for ((trainIdx, queryIdx), s) in zip(matches, status):
# only process the match if the keypoint was successfully
# matched
if s == 1:
# draw the match
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)
# return the visualization
return vis
以上是关键点检测和拼接使用的代码,
还有一个问题,除了旋转图像和执行水平拼接之外,是否有人可以帮助我进行垂直图像拼接。
非常感谢!
我更改了我的代码并使用@Alexander 的padtransf.warpPerspectivePadded 函数来执行包装和混合!你能帮我得到输出图像的照明统一吗?
我自己也遇到过这个问题。如果我没记错的话,您正在使用 this 博客作为参考。
问题是 warpPerspective
关于行:
result = cv2.warpPerspective(imageA, H,
(imageA.shape[1] + imageB.shape[1], imageA.shape[0]))
result[0:imageB.shape[0], 0:imageB.shape[1]] = imageB
这个方法是全方位的。我的意思是,您只是通过根据 .shape[0]
和 .shape[1]
表示的宽度和高度替换像素值,将 imageA 拼接在 imageB 上。我用 C++ 解决了这个问题,因此没有 python 代码可以显示,但可以给你一个 运行 必须完成的事情。
- 获取您正在使用的每个图像的四个角。
- 获取在步骤 1 中找到的每个图像的最小角和最大角。
- 创建一个垫子“HTR”,用于映射图像一,使其与已经变形的图像二一致。 HTR.at(0,2) 表示 mats 3x3 矩阵中的一个位置。 Numpy 可能是您在这里需要使用的。
Mat Htr = Mat::eye(3,3,CV_64F);
if (min_x < 0){
max_x = image2.size().width - min_x;
Htr.at<double>(0,2)= -min_x;
}
if (min_y < 0){
max_y = image2.size().height - min_y;
Htr.at<double>(1,2)= -min_y;
}
- 对每个图像的四个角执行透视变换,以查看它们在 space 中的最终位置。
perspectiveTransform(vector<Point2f> fourPointImage1, vector<Point2f> image1dst, Htr*homography);
perspectiveTransform(vector<Point2f> fourPointImage2, vector<Point2f> image2dst, Htr);
- 从
image1dst
个四个角和 iamge2dst
个四个角获取最小值和最大值。
- 获取
image1dst
和 iamge2dst
的最小值和最大值,并用于创建一个正确大小的新 blank image
来保存最终拼接的图像。
- 这次重复第 3 步的过程,以确定调整每个图像的四个角所需的
translation
,以确保将它们移动到 blank image
[ 的虚拟 space 中=48=]
- 最后把你拥有的所有单应图像都扔进去 found/made。
warpPerspective(image1, blankImage, (translation*homography),result.size(), INTER_LINEAR,BORDER_CONSTANT,(0));
warpPerspective(image2, image2Updated, translation, result.size(), INTER_LINEAR, BORDER_CONSTANT, (0));
最终目标和结果是确定图像将被扭曲到哪里,这样您就可以制作一个空白图像来容纳整个拼接图像,这样就不会裁剪掉任何内容。只有完成所有预处理后,您才真正将图像拼接在一起。我希望这对您有所帮助,如果您有任何疑问,请大声疾呼。
所以如下图所示,我在图像上检测到了关键点,但是环绕透视后的输出图像忽略了左侧的第一张图像,无法弄清楚为什么!
import numpy as np
import imutils
import cv2
class Stitcher:
def __init__(self):
# determine if we are using OpenCV v3.X
self.isv3 = imutils.is_cv3()
def stitch(self, imageA,imageB, ratio=0.75, reprojThresh=10.0,
showMatches=False):
# unpack the images, then detect keypoints and extract
# local invariant descriptors from them
#(imageB, imageA) = images
(kpsA, featuresA) = self.detectAndDescribe(imageA)
(kpsB, featuresB) = self.detectAndDescribe(imageB)
# match features between the two images
M = self.matchKeypoints(kpsA, kpsB,
featuresA, featuresB, ratio, reprojThresh)
# if the match is None, then there aren't enough matched
# keypoints to create a panorama
if M is None:
return None
# otherwise, apply a perspective warp to stitch the images
# together
(matches, H, status) = M
#print(M)
#print(matches)
#print(H)
#print(status)
#cv2.imwrite('intermediate.jpg',matches)
result = cv2.warpPerspective(imageA, H,
(imageA.shape[1] + imageB.shape[1], imageA.shape[0]))
result[0:imageB.shape[0], 0:imageB.shape[1]] = imageB
#cv2.imshow('intermediate',result)
# check to see if the keypoint matches should be visualized
if showMatches:
vis = self.drawMatches(imageA, imageB, kpsA, kpsB, matches,
status)
# return a tuple of the stitched image and the
# visualization
return (result, vis)
# return the stitched image
return result
def detectAndDescribe(self, image):
# convert the image to grayscale
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# check to see if we are using OpenCV 3.X
if self.isv3:
# detect and extract features from the image
#SIFT Algorithm
descriptor = cv2.xfeatures2d.SIFT_create()
#SURF Algorithm
#descriptor = cv2.xfeatures2d.SURF_create()# 400 is hesian threshold, optimum values should be around 300-500
#upright SURF: faster and can be used for panorama stiching i.e our case.
#descriptor.upright = True
print(descriptor.descriptorSize())
(kps, features) = descriptor.detectAndCompute(image, None)
print(len(kps),features.shape)
# otherwise, we are using OpenCV 2.4.X
else:
# detect keypoints in the image
detector = cv2.FeatureDetector_create("SIFT")
kps = detector.detect(gray)
# extract features from the image
extractor = cv2.DescriptorExtractor_create("SIFT")
(kps, features) = extractor.compute(gray, kps)
# convert the keypoints from KeyPoint objects to NumPy
# arrays
kps = np.float32([kp.pt for kp in kps])
# return a tuple of keypoints and features
#print("features",features)
return (kps, features)
def matchKeypoints(self, kpsA, kpsB, featuresA, featuresB,
ratio, reprojThresh):
# compute the raw matches and initialize the list of actual
# matches
matcher = cv2.DescriptorMatcher_create("BruteForce")
rawMatches = matcher.knnMatch(featuresA, featuresB, 2)
matches = []
# loop over the raw matches
for m in rawMatches:
# ensure the distance is within a certain ratio of each
# other (i.e. Lowe's ratio test)
if len(m) == 2 and m[0].distance < m[1].distance * ratio:
matches.append((m[0].trainIdx, m[0].queryIdx))
print(len(matches))
# computing a homography requires at least 4 matches
if len(matches) > 4:
# construct the two sets of points
ptsA = np.float32([kpsA[i] for (_, i) in matches])
ptsB = np.float32([kpsB[i] for (i, _) in matches])
# compute the homography between the two sets of points
(H, status) = cv2.findHomography(ptsA, ptsB, cv2.RANSAC,
reprojThresh)
# return the matches along with the homograpy matrix
# and status of each matched point
return (matches, H, status)
# otherwise, no homograpy could be computed
return None
def drawMatches(self, imageA, imageB, kpsA, kpsB, matches, status):
# initialize the output visualization image
(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
# loop over the matches
for ((trainIdx, queryIdx), s) in zip(matches, status):
# only process the match if the keypoint was successfully
# matched
if s == 1:
# draw the match
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)
# return the visualization
return vis
以上是关键点检测和拼接使用的代码,
还有一个问题,除了旋转图像和执行水平拼接之外,是否有人可以帮助我进行垂直图像拼接。
非常感谢!
我更改了我的代码并使用@Alexander 的padtransf.warpPerspectivePadded 函数来执行包装和混合!你能帮我得到输出图像的照明统一吗?
我自己也遇到过这个问题。如果我没记错的话,您正在使用 this 博客作为参考。
问题是 warpPerspective
关于行:
result = cv2.warpPerspective(imageA, H, (imageA.shape[1] + imageB.shape[1], imageA.shape[0])) result[0:imageB.shape[0], 0:imageB.shape[1]] = imageB
这个方法是全方位的。我的意思是,您只是通过根据 .shape[0]
和 .shape[1]
表示的宽度和高度替换像素值,将 imageA 拼接在 imageB 上。我用 C++ 解决了这个问题,因此没有 python 代码可以显示,但可以给你一个 运行 必须完成的事情。
- 获取您正在使用的每个图像的四个角。
- 获取在步骤 1 中找到的每个图像的最小角和最大角。
- 创建一个垫子“HTR”,用于映射图像一,使其与已经变形的图像二一致。 HTR.at(0,2) 表示 mats 3x3 矩阵中的一个位置。 Numpy 可能是您在这里需要使用的。
Mat Htr = Mat::eye(3,3,CV_64F); if (min_x < 0){ max_x = image2.size().width - min_x; Htr.at<double>(0,2)= -min_x; } if (min_y < 0){ max_y = image2.size().height - min_y; Htr.at<double>(1,2)= -min_y; }
- 对每个图像的四个角执行透视变换,以查看它们在 space 中的最终位置。
perspectiveTransform(vector<Point2f> fourPointImage1, vector<Point2f> image1dst, Htr*homography); perspectiveTransform(vector<Point2f> fourPointImage2, vector<Point2f> image2dst, Htr);
- 从
image1dst
个四个角和iamge2dst
个四个角获取最小值和最大值。 - 获取
image1dst
和iamge2dst
的最小值和最大值,并用于创建一个正确大小的新blank image
来保存最终拼接的图像。 - 这次重复第 3 步的过程,以确定调整每个图像的四个角所需的
translation
,以确保将它们移动到blank image
[ 的虚拟 space 中=48=] - 最后把你拥有的所有单应图像都扔进去 found/made。
warpPerspective(image1, blankImage, (translation*homography),result.size(), INTER_LINEAR,BORDER_CONSTANT,(0)); warpPerspective(image2, image2Updated, translation, result.size(), INTER_LINEAR, BORDER_CONSTANT, (0));
最终目标和结果是确定图像将被扭曲到哪里,这样您就可以制作一个空白图像来容纳整个拼接图像,这样就不会裁剪掉任何内容。只有完成所有预处理后,您才真正将图像拼接在一起。我希望这对您有所帮助,如果您有任何疑问,请大声疾呼。