尋找等高線

Python 影像處理

Rebeca Gonzalez

Data Engineer

尋找等高線

測量大小
分類形狀
判斷物件數量

多米諾上的總點數：29。

二值影像

可以用 thresholding 或 edge detection 取得二值影像

使用 scikit-image 尋找等高線

準備影像

將影像轉成 2D 灰階。

# Make the image grayscale
image = color.rgb2gray(image)

使用 scikit-image 尋找等高線

準備影像

將影像二值化

# Obtain the thresh value
thresh = threshold_otsu(image)

# Apply thresholding
thresholded_image = image > thresh

使用 scikit-image 尋找等高線

接著使用 find_contours()。

# Import the measure module
from skimage import measure

# Find contours at a constant value of 0.8
contours = measure.find_contours(thresholded_image, 0.8)

固定等高值

找出等高線的步驟

from skimage import measure
from skimage.filters import threshold_otsu

# Make the image grayscale
image = color.rgb2gray(image)

# Obtain the optimal thresh value of the image
thresh = threshold_otsu(image)

# Apply thresholding and obtain binary image
thresholded_image = image > thresh


# Find contours at a constant value of 0.8
contours = measure.find_contours(thresholded_image, 0.8)

找出等高線的步驟

產生結果

等高線的 shape

等高線：由多個 (n,2) 的 ndarray 組成的清單。

for contour in contours:
    print(contour.shape)

(433, 2)
(433, 2)
(401, 2)
(401, 2) 
(123, 2)
(123, 2) 
(59, 2)
(59, 2)
(59, 2)
(57, 2)
(57, 2)
(59, 2)
(59, 2)

等高線的 shape

for contour in contours:
    print(contour.shape)

(433, 2)
(433, 2) --> Outer border
(401, 2)
(401, 2)
(123, 2)
(123, 2)
(59, 2)
(59, 2)
(59, 2)
(57, 2)
(57, 2)
(59, 2)
(59, 2)

等高線的 shape

for contour in contours:
    print(contour.shape)

(433, 2)
(433, 2) --> Outer border
(401, 2)
(401, 2) --> Inner border
(123, 2)
(123, 2) 
(59, 2)
(59, 2)
(59, 2)
(57, 2)
(57, 2)
(59, 2)
(59, 2)

等高線的 shape

for contour in contours:
    print(contour.shape)

(433, 2)
(433, 2) --> Outer border
(401, 2)
(401, 2) --> Inner border
(123, 2)
(123, 2) --> Divisory line of tokens
(59, 2)
(59, 2)
(59, 2)
(57, 2)
(57, 2)
(59, 2)
(59, 2)

等高線的 shape

for contour in contours:
    print(contour.shape)

(433, 2)
(433, 2) --> Outer border
(401, 2)
(401, 2) --> Inner border
(123, 2)
(123, 2) --> Divisory line of tokens
(59, 2)
(59, 2)
(59, 2)
(57, 2)
(57, 2)
(59, 2)
(59, 2) --> Dots

點的數量：7。

一起來練習吧！

Python 影像處理