Crop image

4. Crop image

import cv2
import matplotlib.pyplot as plt

image = cv2.imread("adrian.png")
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

plt.imshow(image);
../../../_images/opencv_crop_3_0.png 
face = image[85:250, 85:220]

plt.imshow(image);
../../../_images/opencv_crop_5_0.png 
plt.imshow(face);
../../../_images/opencv_crop_6_0.png 
body = image[90:450, 0:290]

plt.imshow(body);
../../../_images/opencv_crop_8_0.png

  • 如果是 bounding box，給的是 (xmin, ymin, xmax, ymax).

  • 那 crop image 時，就用 img[ymin:ymax, xmin:xmax]

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3. 影像梯度與邊緣偵測