使用scikit图像计算图像中特定区域的平均灰度值

Question

我正在尝试计算下面显示的图像中5个区域的灰度。但是我没有在skimage中找到任何好的命令。

我首先通过处理以下代码来屏蔽图像：

import numpy as np
import matplotlib as mpl
from matplotlib.path import Path
from matplotlib import patches
import matplotlib.pyplot as plt

import skimage.io as io
from skimage import data_dir 

img = io.imread('/media/rene/Windows8_OS/PROMON/Recorded Sequences/PNG/0rpm_p000.png')

vertices = np.asarray([( 947, 1959),
                       (1762, 1959),
                       (1762, 2241),
                       ( 947, 2241),
                       ( 947, 1089),
                       (1762, 1089),
                       (1762, 1371),
                       ( 947, 1371),
                       ( 947,  797),
                       (1762,  797),
                       (1762, 1079),
                       ( 947, 1079),
                       ( 947,  505),
                       (1762,  505),
                       (1762,  787),
                       ( 947,  787),
                       ( 947,  213),
                       (1762,  213),
                       (1762,  495),
                       ( 947,  495)])

# reshape into smaller path for faster debugging
# vertices = vertices // 20

# matplotlib path
path = Path(vertices)
xmin, ymin, xmax, ymax = np.asarray(path.get_extents(), dtype=int).ravel()

# create a mesh grid of the shape of the final mask
x, y = np.mgrid[:img.shape[1], :img.shape[0]]
# mesh grid to points
points = np.vstack((x.ravel(), y.ravel())).T

# mask for the point included in the path
mask1 = path.contains_points(points)
path_points = points[np.where(mask1)]

# reshape mask for display 
img_mask1 = mask1.reshape(x.shape).T

# selecting all but black pixels
# black_pixels_mask = np.all(img_mask1 == [0, 0, 0], axis=-1)
# non_black_pixels_mask = ~black_pixels_mask

# plots
f, ax = plt.subplots()
# if more thn one plot 
# gs = mpl.gridspec.GridSpec(2,2)
# gs.update(wspace=0.2, hspace= 0.2)
# masked image 
ax.imshow(img * img_mask1, cmap="gray")
ixs = np.indices(img.shape)

但是现在我不知道如何获取5个区域中每个区域的灰度值。我的结果应该看起来像这样：Finding the average pixel values of a list of blobs identified by scikit-image's blob_log (Laplacian of Gaussian) method

蒙版图像：“>

我正在尝试计算下面显示的图像中5个区域的灰度。但是我没有在skimage中找到任何好的命令。我首先通过处理以下代码来掩盖图像：...

Answer 1

根据您的要求，这是一个玩具示例，向您展示如何计算由对角的坐标定义的两个矩形区域的平均值：