使用python从二进制图像裁剪感兴趣的区域

时间:2019-02-24 14:58:24

标签: python image-processing

要求是从二进制图像裁剪感兴趣的区域。

我需要通过去除感兴趣区域周围的多余空间来从二进制图像中获取矩形图像。

例如: 从这个Original图像中,我只希望用黄色矩形标记的region of interest

注意:黄色矩形仅供参考,在要处理的图像中不存在。

我尝试了以下python代码,但未提供所需的输出。

from PIL import Image
from skimage.io import imread
from skimage.morphology import convex_hull_image
import numpy as np
from matplotlib import pyplot as plt
from skimage import io
from skimage.color import rgb2gray
im = imread('binaryImageEdited.png')
plt.imshow(im)
plt.title('input image')
plt.show()
# create a binary image
im1 = 1 - rgb2gray(im)
threshold = 0.8
im1[im1 <= threshold] = 0
im1[im1 > threshold] = 1
chull = convex_hull_image(im1)
plt.imshow(chull)
plt.title('convex hull in the binary image')
plt.show()
imageBox = Image.fromarray((chull*255).astype(np.uint8)).getbbox()
cropped = Image.fromarray(im).crop(imageBox)
cropped.save('L_2d_cropped.png')
plt.imshow(cropped)
plt.show()

谢谢。

2 个答案:

答案 0 :(得分:1)

由于两件事,您的图片实际上不是二进制的:

  • 首先,它有26种颜色,
  • 其次,它具有一个(完全不必要的)alpha通道。

您可以像这样修剪它:

#!/usr/bin/env python3

from PIL import Image, ImageOps

# Open image and ensure greysale and discard useless alpha channel
im = Image.open("thing.png").convert('L')

# Threshold and invert image as not actually binary
thresh = im.point(lambda p: p < 64 and 255)

# Get bounding box of thresholded image
bbox1 = thresh.getbbox()
crop1 = thresh.crop(bbox1)

# Invert and crop again
crop1n = ImageOps.invert(crop1)
bbox2  = crop1n.getbbox()
crop2  = crop1.crop(bbox2)  # You don't actually need this - it's just for debug

# Trim original, unthresholded, uninverted image to the two bounding boxes
result = im.crop(bbox1).crop(bbox2)
result.save('result.png')

enter image description here

答案 1 :(得分:0)

即使我也有类似的问题。如果保存的图像为32X32像素,也会很有帮助。