Python图像处理：最好在PIL或任何相关模块中进行角点检测所需的帮助

Question

I'm new to image processing and got to do corner detection for this image:

In this image, I need to extract the starting and end points of each line segment or the coordinates of the corners. This is just a small part in my project and I'm stuck on this because I've no experience in image processing.

Answer 1

Here's a solution, using scikit-image :

from skimage import io, color, morphology
from scipy.signal import convolve2d
import numpy as np
import matplotlib.pyplot as plt

img = color.rgb2gray(io.imread('6EnOn.png'))

# Reduce all lines to one pixel thickness
snakes = morphology.skeletonize(img < 1)

# Find pixels with only one neighbor
corners = convolve2d(snakes, [[1, 1, 1],
                              [1, 0, 1],
                              [1, 1, 1]], mode='same') == 1
corners = corners & snakes

# Those are the start and end positions of the segments
y, x = np.where(corners)

plt.imshow(img, cmap=plt.cm.gray, interpolation='nearest')
plt.scatter(x, y)
plt.axis('off')
plt.show()

Answer 2

The accepted answer does not find ALL the corners in the image.

Using Harris corner detection , one can find all the possible corners. Since OP's choice of modules is not restricted, I chose to perform the following using the OpenCV library.

RESULT:

Every single corner present in the image is identified correctly.

THIS PAGE provides details of the algorithm and the code.

Answer 3

我建议使用Harris拐角检测器和Shi-Tomasi拐角检测器随附的OpenCV 。

Answer 4

I don't know whether I understand the question correctly, but I think a low efficiency way to do it is to scan through each pixel and check the 4 directions around that pixel. If 2 non-opposite directions (ie up & left or up & right etc.) are coloured, then it is a corner.

Hope this helps.

Answer 5

This is a bit of a shot in the dark, but I'd assume that you could parse the png header to retrieve the width/height of the image (take a look at this RFC for png details ). Combine this with the bit depth of the image and you should be able to determine where each corner is with simple math. Once you've found the corner, you should be able to follow the line using a simple algorithm checking neighboring pixel data.

This also sounds like homework. If so, you should tag it as such.