python - 如何在python中删除图像的背景

Question

我有一个包含全宽人类图像的数据集我想删除这些图像中的所有背景，只留下全宽的人，

我的问题：

有没有这样做的python代码？

我是否需要每次指定人对象的坐标？

标签： pythonimageopencvimage-processingbackground

Answer 1

这是使用 Python/OpenCV 的一种方法。

• 读取输入
• 转换为灰色
• 阈值和反转作为掩码
• 可选择应用形态学以清理任何多余的斑点
• 边缘抗锯齿
• 将输入的副本转换为 BGRA 并将遮罩插入为 Alpha 通道
• 保存结果

输入：

import cv2
import numpy as np

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

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

# threshold input image as mask
mask = cv2.threshold(gray, 250, 255, cv2.THRESH_BINARY)[1]

# negate mask
mask = 255 - mask

# apply morphology to remove isolated extraneous noise
# use borderconstant of black since foreground touches the edges
kernel = np.ones((3,3), np.uint8)
mask = cv2.morphologyEx(mask, cv2.MORPH_OPEN, kernel)
mask = cv2.morphologyEx(mask, cv2.MORPH_CLOSE, kernel)

# anti-alias the mask -- blur then stretch
# blur alpha channel
mask = cv2.GaussianBlur(mask, (0,0), sigmaX=2, sigmaY=2, borderType = cv2.BORDER_DEFAULT)

# linear stretch so that 127.5 goes to 0, but 255 stays 255
mask = (2*(mask.astype(np.float32))-255.0).clip(0,255).astype(np.uint8)

# put mask into alpha channel
result = img.copy()
result = cv2.cvtColor(result, cv2.COLOR_BGR2BGRA)
result[:, :, 3] = mask

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

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

透明结果：