如何在opencv中填充canny边缘图像-python

Question

我有一张图片，例如：

我应用了 Canny 边缘检测器并得到了这张图片：

如何填充这张图片？我希望边缘包围的区域是白色的。我该如何实现？

Answer 1

您可以在 Python/OpenCV 中做到这一点，方法是获取轮廓并将其绘制为黑色背景上的白色填充。

输入：

import cv2
import numpy as np

# Read image as grayscale
img = cv2.imread('knife_edge.png', cv2.IMREAD_GRAYSCALE)
hh, ww = img.shape[:2]

# threshold
thresh = cv2.threshold(img, 128, 255, cv2.THRESH_BINARY)[1]

# get the (largest) contour
contours = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
contours = contours[0] if len(contours) == 2 else contours[1]
big_contour = max(contours, key=cv2.contourArea)

# draw white filled contour on black background
result = np.zeros_like(img)
cv2.drawContours(result, [big_contour], 0, (255,255,255), cv2.FILLED)

# save results
cv2.imwrite('knife_edge_result.jpg', result)

cv2.imshow('result', result)
cv2.waitKey(0)
cv2.destroyAllWindows()

结果：

Answer 2

形态学运算结果相似

img=cv2.imread('base.png',0)
_,thresh = cv2.threshold(img, 0, 255, cv2.THRESH_BINARY)
rect=cv2.getStructuringElement(cv2.MORPH_RECT, (3, 3))
dilation = cv2.dilate(thresh,rect,iterations = 5)
erosion = cv2.erode(dilation, rect, iterations=4)

Answer 3

这没有回答问题。
这只是我对该问题的评论的补充，评论不允许代码和图像。

示例图像具有透明背景。因此，alpha 通道提供了您正在寻找的输出。在没有任何图像处理知识的情况下，您可以按如下方式加载图像并提取 alpha 通道：

import cv2

img = cv2.imread('base.png', cv2.IMREAD_UNCHANGED)
alpha = img[:,:,3]

cv2.imshow('', alpha); cv2.waitKey(0); cv2.destroyAllWindows()

如何在opencv中填充canny边缘图像-python

How to fill canny edge image in opencv-python

python

opencv

image-processing

contour

image-segmentation