我正在尝试检测并掩盖图像中的第二大轮廓,如图1所示(带有红色轮廓)。但是,我无法检测到图像中的第二大轮廓。我将得到如图2所示的内容。下面是我的代码。请能有人请指教。
im = cv2.imread('F:\EA-358-4-1.4\ea-580.png') # Reading image
blur = cv2.GaussianBlur(im,(5,5),cv2.BORDER_DEFAULT) # Smoothing image
img = cv2.cvtColor(blur, cv2.COLOR_BGR2GRAY) # Converting to greyscale image
ret, thresh = cv2.threshold(img,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
_, contours,_ = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE) # Finding contours, hierarchy et al.
print(len(contours))
# Masking image and drawing contour
cnt = contours
mask = np.zeros_like(im) # Masking the contour
second_largest_cnt = sorted(cnt, key = cv2.contourArea, reverse = True)[1] # Dtermine the second largest contour
cv2.drawContours(mask,[second_largest_cnt],-1,(255,255,255),-1) # Drawing the detected contour
# Copying mask of detected contour unto original image and canning edge detection
out = mask.copy() # Copying the mask nto the original image
out[mask == 255] = im[mask == 255]
canny = feature.canny(out[:, :, 0],sigma=1,low_threshold=5,high_threshold=10) # Detecting the egeds of the image
plt.subplot(121),plt.imshow(canny,cmap='gray')
plt.xticks([]),plt.yticks([])
plt.subplot(122),plt.imshow(out,cmap='gray')
plt.xticks([]),plt.yticks([])
图1
图2
图3
更新的代码 我已经按照@HansHirse的建议更新了代码,但无法得到任何结果。
im = cv2.imread('F:\EA-358-4-1.4\ea-580.png',cv2.IMREAD_GRAYSCALE)
#new = im[:,:,1]
mask = np.zeros_like(im)
th3 = cv2.adaptiveThreshold(im,255,cv2.ADAPTIVE_THRESH_GAUSSIAN_C,cv2.THRESH_BINARY,201,-1)
kernel = np.ones((5,5),np.uint8)
opening = cv2.morphologyEx(mask, cv2.MORPH_OPEN, cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(7,7)),kernel)
dilate = cv2.dilate(mask,cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(11,11)))
img = im-mask
thresh = cv2.threshold(img,0,255,cv2.THRESH_OTSU)
opening = cv2.morphologyEx(img, cv2.MORPH_CLOSE, cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(7,7)),kernel)
_, contours,_ = cv2.findContours(img,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
cv2.drawContours(im,contours,-1,255,1)
cv2.imshow('im',im)
答案 0 :(得分:3)
由于我(仍然)对Python中的OpenCV不太熟悉,因此我将使用C ++ OpenCV提供解决方案。我评论了每一行,以尽可能轻松地移植到Python。
// Read input image.
cv::Mat img = cv::imread("e9dzM.png", cv::IMREAD_GRAYSCALE);
// Initialize mask.
cv::Mat mask = img.clone();
// Adaptive thresholding, 201 x 201 neighbourhood.
cv::adaptiveThreshold(img, mask, 255, cv::ADAPTIVE_THRESH_GAUSSIAN_C, cv::THRESH_BINARY, 201, -1);
// Morphological opening, 7 x 7 ellipsoid.
cv::morphologyEx(mask, mask, cv::MORPH_OPEN, cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(7, 7)));
// Morphological dilating, 7 x 7 ellipsoid.
cv::dilate(mask, mask, cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(11, 11)));
// Temporary image: Subtract ring like structure from original image.
cv::Mat temp = img - mask;
// Plain thresholding using Otsu method.
cv::threshold(temp, temp, 0, 255, cv::THRESH_OTSU);
// Morphological closing, 7 x 7 ellipsoid.
cv::morphologyEx(temp, temp, cv::MORPH_CLOSE, cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(7, 7)));
// Find contours in temporary image.
std::vector<std::vector<cv::Point>> contours;
cv::findContours(temp, contours, cv::RETR_EXTERNAL, cv::CHAIN_APPROX_NONE);
// Draw found contours in input image.
cv::drawContours(img, contours, -1, cv::Scalar(255), 1);
// Save image.
cv::imwrite("output.png", img);
您将获得以下输出图像:
此解决方案可能适用于您提供的特定图像。我非常怀疑,此代码可用于更一般的问题。请记住这一点。
答案 1 :(得分:0)
似乎某些图像的照明不均匀,因此我使用初始代码在某些图像上应用了自适应阈值,并且效果很好。