201121-将numpy数组等像素保存为图片

Specifying and saving a figure with exact size in pixels

# %% Demo
import matplotlib.pyplot as plt
from matplotlib.image import imread
import numpy

# Setting
w = 5
h = 5
im_np = numpy.random.rand(h, w)

# Plot and save
fig = plt.figure(frameon=False)
fig.set_size_inches(w,h)
ax = plt.Axes(fig, [0., 0., 1., 1.])
ax.set_axis_off()
fig.add_axes(ax)
ax.imshow(im_np, aspect='auto',cmap=plt.cm.jet)
fig.savefig('figure.png', dpi=1)

# Load and show
im = imread("figure.png")
plt.imshow(im[:,:,3])