How to save images using matplotlib without displaying them?

Question

I have multiple(in millions) numpy 2-D arrays which need to be saved. One can save an individual image like this:

import numpy as np
import matplotlib.pyplot as plt

surface_profile = np.empty((50,50)) #numpy array to be saved
plt.figure()
plt.imshow(surface_profile)
save_filename='filename.png'
plt.savefig(save_filename)

However this process also displays the image which I don't require. If I keep saving million images like this, I should somehow avoid imshow() function of matplotlib. Any help???

PS: I forgot to mention that I am using Spyder.

Shouldn't happen in general, but it might be related to Jupyter/Spyder. See this answer. — Josh Friedlander
– Josh Friedlander, Commented May 24, 2020 at 11:55
In what environment are you running this code? In a non-interactive environment you should not get any display until you run plt.show(). Try adding plt.ioff() at the beginning of your script. See matplotlib.org/tutorials/introductory/… — Diziet Asahi
– Diziet Asahi, Commented May 24, 2020 at 11:55

DrBwts · Accepted Answer · 2020-05-24 12:24:55Z

2

Your problem is using plt.imshow(surface_profile) to create the image as this will always display the image as well.

This can be done using PIL, try the following,

from PIL import Image
import numpy as np

surface_profile = np.empty((50,50)) #numpy array to be saved
im = Image.fromarray(surface_profile)
im = im.convert('RGB')
save_filename="filename.png"
im.save(save_filename, "PNG")

answered May 24, 2020 at 12:24

DrBwts

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