如何使用 OpenCV 根据 object 半径裁剪图像？

Question

我是 python 的新手。我了解 image-preprocessing 的基础知识。我不知道如何使用 OpenCV 删除背景和裁剪图像。

Answer 1

这是 Python/OpenCV 中的一种方法。

读取输入
转换为灰度
阈值并反转为掩码
将蒙版放入输入的 alpha 通道
保存结果

输入：

import cv2
import numpy as np

# load image
img = cv2.imread('black_circle.png')

# convert to grayscale
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

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

# invert so circle is white on black
mask = 255 - threshold

# put mask into alpha channel of image
result = np.dstack((img, mask))

# save resulting masked image
cv2.imwrite('black_circle_masked.png', result)

# display result, though it won't show transparency
cv2.imshow("MASK", mask)
cv2.imshow("RESULT", result)
cv2.waitKey(0)
cv2.destroyAllWindows()

结果：

注：下载结果看透明度

Answer 2

这是 Python/OpenCV 中对您的新图像的处理。

输入：

import cv2
import numpy as np

# load image as grayscale
img = cv2.imread('Diabetic-Retinopathy_G_RM_151064169.jpg')

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# threshold input image
mask = cv2.threshold(gray, 10, 255, cv2.THRESH_BINARY)[1]

# optional morphology to clean up small spots
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (3,3))
mask = cv2.morphologyEx(mask, cv2.MORPH_CLOSE, kernel)
mask = cv2.morphologyEx(mask, cv2.MORPH_OPEN, kernel)

# put mask into alpha channel of image
result = np.dstack((img, mask))

# save resulting masked image
cv2.imwrite('Diabetic-Retinopathy_G_RM_151064169_masked.png', result)

# display result, though it won't show transparency
cv2.imshow("mask", mask)
cv2.imshow("RESULT", result)
cv2.waitKey(0)
cv2.destroyAllWindows()

Result

如何使用 OpenCV 根据 object 半径裁剪图像？

How to crop image based on the object radius using OpenCV?

python

opencv

image-processing