如何从此类图像中删除背景?

时间:2015-03-28 04:23:27

标签: python opencv image-processing scikit-image

Image_1

我想删除此图片的背景以仅获取此人。我有这样的数千张图像,基本上是一个人,有点白色背景。

我所做的是使用边缘检测器,如canny边缘检测器或sobel过滤器(来自skimage库)。那么我认为可以做的是,使边缘内的像素变白并使像素变黑。之后,原始图像可以被掩盖以获取该人的图片。

然而,使用canny边缘检测器很难获得封闭边界。使用Sobel滤波器的结果并不差,但我不知道如何从那里开始。

Sobel_result

编辑:

是否也可以去除右手和裙子之间以及头发之间的背景?

6 个答案:

答案 0 :(得分:63)

以下代码可以帮助您入门。您可能想要使用程序顶部的参数来微调提取:

import cv2
import numpy as np

#== Parameters =======================================================================
BLUR = 21
CANNY_THRESH_1 = 10
CANNY_THRESH_2 = 200
MASK_DILATE_ITER = 10
MASK_ERODE_ITER = 10
MASK_COLOR = (0.0,0.0,1.0) # In BGR format


#== Processing =======================================================================

#-- Read image -----------------------------------------------------------------------
img = cv2.imread('C:/Temp/person.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

#-- Edge detection -------------------------------------------------------------------
edges = cv2.Canny(gray, CANNY_THRESH_1, CANNY_THRESH_2)
edges = cv2.dilate(edges, None)
edges = cv2.erode(edges, None)

#-- Find contours in edges, sort by area ---------------------------------------------
contour_info = []
_, contours, _ = cv2.findContours(edges, cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)
# Previously, for a previous version of cv2, this line was: 
#  contours, _ = cv2.findContours(edges, cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)
# Thanks to notes from commenters, I've updated the code but left this note
for c in contours:
    contour_info.append((
        c,
        cv2.isContourConvex(c),
        cv2.contourArea(c),
    ))
contour_info = sorted(contour_info, key=lambda c: c[2], reverse=True)
max_contour = contour_info[0]

#-- Create empty mask, draw filled polygon on it corresponding to largest contour ----
# Mask is black, polygon is white
mask = np.zeros(edges.shape)
cv2.fillConvexPoly(mask, max_contour[0], (255))

#-- Smooth mask, then blur it --------------------------------------------------------
mask = cv2.dilate(mask, None, iterations=MASK_DILATE_ITER)
mask = cv2.erode(mask, None, iterations=MASK_ERODE_ITER)
mask = cv2.GaussianBlur(mask, (BLUR, BLUR), 0)
mask_stack = np.dstack([mask]*3)    # Create 3-channel alpha mask

#-- Blend masked img into MASK_COLOR background --------------------------------------
mask_stack  = mask_stack.astype('float32') / 255.0          # Use float matrices, 
img         = img.astype('float32') / 255.0                 #  for easy blending

masked = (mask_stack * img) + ((1-mask_stack) * MASK_COLOR) # Blend
masked = (masked * 255).astype('uint8')                     # Convert back to 8-bit 

cv2.imshow('img', masked)                                   # Display
cv2.waitKey()

#cv2.imwrite('C:/Temp/person-masked.jpg', masked)           # Save

输出继电器: enter image description here

答案 1 :(得分:28)

如果您希望填充的背景不是红色而是透明,您可以在解决方案中添加以下行:

# split image into channels
c_red, c_green, c_blue = cv2.split(img)

# merge with mask got on one of a previous steps
img_a = cv2.merge((c_red, c_green, c_blue, mask.astype('float32') / 255.0))

# show on screen (optional in jupiter)
%matplotlib inline
plt.imshow(img_a)
plt.show()

# save to disk
cv2.imwrite('girl_1.png', img_a*255)

# or the same using plt
plt.imsave('girl_2.png', img_a)

如果您愿意,可以调整一些png压缩参数以使文件更小。

下面的白色背景上的图像。或者是黑色的 - http://imgur.com/a/4NwmH

enter image description here

答案 2 :(得分:14)

作为替代方案,您可以使用像这样的神经网络:CRFRNN

它给出了如下结果:

enter image description here

答案 3 :(得分:5)

enter image description here vs2017的工作示例 设置红色背景但保存蓝色。
还添加了transperent示例。

如何删除女孩的身体,只留下照片中的连衣裙? 有什么想法吗?

# == https://stackoverflow.com/questions/29313667/how-do-i-remove-the-background-from-this-kind-of-image

import cv2
import numpy as np
from matplotlib import pyplot as plt

#== Parameters =======================================================================
BLUR = 21
CANNY_THRESH_1 = 10
CANNY_THRESH_2 = 200
MASK_DILATE_ITER = 10
MASK_ERODE_ITER = 10
MASK_COLOR = (0.0,0.0,1.0) # In BGR format


#== Processing =======================================================================

#-- Read image -----------------------------------------------------------------------
img = cv2.imread('img/SYxmp.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

#-- Edge detection -------------------------------------------------------------------
edges = cv2.Canny(gray, CANNY_THRESH_1, CANNY_THRESH_2)
edges = cv2.dilate(edges, None)
edges = cv2.erode(edges, None)

#-- Find contours in edges, sort by area ---------------------------------------------
contour_info = []
_, contours, _ = cv2.findContours(edges, cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)
for c in contours:
    contour_info.append((
        c,
        cv2.isContourConvex(c),
        cv2.contourArea(c),
    ))
contour_info = sorted(contour_info, key=lambda c: c[2], reverse=True)
max_contour = contour_info[0]

#-- Create empty mask, draw filled polygon on it corresponding to largest contour ----
# Mask is black, polygon is white
mask = np.zeros(edges.shape)
cv2.fillConvexPoly(mask, max_contour[0], (255))



#-- Smooth mask, then blur it --------------------------------------------------------
mask = cv2.dilate(mask, None, iterations=MASK_DILATE_ITER)
mask = cv2.erode(mask, None, iterations=MASK_ERODE_ITER)
mask = cv2.GaussianBlur(mask, (BLUR, BLUR), 0)

mask_stack = np.dstack([mask]*3)    # Create 3-channel alpha mask

#-- Blend masked img into MASK_COLOR background --------------------------------------
mask_stack  = mask_stack.astype('float32') / 255.0          # Use float matrices, 
img         = img.astype('float32') / 255.0                 #  for easy blending

masked = (mask_stack * img) + ((1-mask_stack) * MASK_COLOR) # Blend
masked = (masked * 255).astype('uint8')                     # Convert back to 8-bit 

plt.imsave('img/girl_blue.png', masked)
# split image into channels
c_red, c_green, c_blue = cv2.split(img)

# merge with mask got on one of a previous steps
img_a = cv2.merge((c_red, c_green, c_blue, mask.astype('float32') / 255.0))

# show on screen (optional in jupiter)
#%matplotlib inline
plt.imshow(img_a)
plt.show()

# save to disk
cv2.imwrite('img/girl_1.png', img_a*255)

# or the same using plt
plt.imsave('img/girl_2.png', img_a)

cv2.imshow('img', masked)                                   # Displays red, saves blue

cv2.waitKey()

答案 4 :(得分:4)

根据@jedwards答案,当与opencv4一起使用时,会出现以下错误:

Traceback (most recent call last):
  File "save.py", line 26, in <module>
    _, contours, _ = cv2.findContours(edges, cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)
ValueError: not enough values to unpack (expected 3, got 2)

功能cv2.findContours()已更改为仅返回轮廓和层次结构

您应该更改为此:

contours, _ = cv2.findContours(edges, cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)

答案 5 :(得分:1)

  • 获得不完整的边缘(如你所知)后,你可以运行一个闭合形态学(一系列扩张和侵蚀)(必须根据需要/边缘状态设置大小和迭代)。

  • 现在假设你在主体周围有一个恒定的边缘,使用任何类型的填充算法(blob)来组合边缘对象之外的所有点,然后采取负面的方法为你提供掩模对象内部。