matplotlib savefig in jpeg format

问题

I am using matplotlib (within pylab) to display figures. And I want to save them in .jpg format. When I simply use the savefig command with jpg extension this returns :

ValueError: Format \"jpg\" is not supported.

Supported formats: emf, eps, pdf, png, ps, raw, rgba, svg, svgz.

Is there a way to perform this ?

回答1:

You can save an image as 'png' and use the python imaging library (PIL) to convert this file to 'jpg':

import Image
import matplotlib.pyplot as plt

plt.plot(range(10))
plt.savefig('testplot.png')
Image.open('testplot.png').save('testplot.jpg','JPEG')

The original:

The JPEG image:

回答2:

To clarify and update @neo useful answer and the original question. A clean solution consists of installing Pillow, which is an updated version of the Python Imaging Library (PIL). This is done using

pip install pillow

Once Pillow is installed, the standard Matplotlib commands

import matplotlib.pyplot as plt

plt.plot([1, 2])
plt.savefig('image.jpg')

will save the figure into a JPEG file and will not generate a ValueError any more.

Contrary to @amillerrhodes answer, as of Matplotlib 3.1, JPEG files are still not supported. If I remove the Pillow package I still receive a ValueError about an unsupported file type.

回答3:

Just install pillow with pip install pillow and it will work.

回答4:

I just updated matplotlib to 1.1.0 on my system and it now allows me to save to jpg with savefig.

To upgrade to matplotlib 1.1.0 with pip, use this command:

pip install -U 'http://sourceforge.net/projects/matplotlib/files/matplotlib/matplotlib-1.1.0/matplotlib-1.1.0.tar.gz/download'

EDIT (to respond to comment):

pylab is simply an aggregation of the matplotlib.pyplot and numpy namespaces (as well as a few others) jinto a single namespace.

On my system, pylab is just this:

from matplotlib.pylab import *
import matplotlib.pylab
__doc__ = matplotlib.pylab.__doc__

You can see that pylab is just another namespace in your matplotlib installation. Therefore, it doesn't matter whether or not you import it with pylab or with matplotlib.pyplot.

If you are still running into problem, then I'm guessing the macosx backend doesn't support saving plots to jpg. You could try using a different backend. See here for more information.

回答5:

Matplotlib can handle directly and transparently jpg if you have installed PIL. You don't need to call it, it will do it by itself. If Python cannot find PIL, it will raise an error.

来源：https://stackoverflow.com/questions/8827016/matplotlib-savefig-in-jpeg-format

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matplotlib

jpeg

figure