Saving a Numpy array as an image

python image numpy
M456 picture M456 · May 24, 2009 · Viewed 585.8k times · Source

I have a matrix in the type of a Numpy array. How would I write it to disk it as an image? Any format works (png, jpeg, bmp...). One important constraint is that PIL is not present.

Answer

Steve Tjoa picture Steve Tjoa · Nov 11, 2009

This uses PIL, but maybe some might find it useful:

import scipy.misc
scipy.misc.imsave('outfile.jpg', image_array)

EDIT: The current scipy version started to normalize all images so that min(data) become black and max(data) become white. This is unwanted if the data should be exact grey levels or exact RGB channels. The solution:

import scipy.misc
scipy.misc.toimage(image_array, cmin=0.0, cmax=...).save('outfile.jpg')

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