How to export plots from matplotlib with transparent background?

I am using matplotlib to make some graphs and unfortunately I cannot export them without the white background.

In other words, when I export a plot like this and position it on top of another image, the white background hides what is behind it rather than allowing it to show through. How can I export plots with a transparent background instead?

Use the matplotlib savefig function with the keyword argument transparent=True to save the image as a png file.

In [30]: x = np.linspace(0,6,31)

In [31]: y = np.exp(-0.5*x) * np.sin(x)

In [32]: plot(x, y, 'bo-')
Out[32]: [<matplotlib.lines.Line2D at 0x3f29750>]            

In [33]: savefig('demo.png', transparent=True)

Result:

Of course, that plot doesn't demonstrate the transparency. Here's a screenshot of the PNG file displayed using the ImageMagick display command. The checkerboard pattern is the background that is visible through the transparent parts of the PNG file.

Png files can handle transparency. So you could use this question https://stackoverflow.com/questions/9622163/matplotlib-save-plot-to-image-file-instead-of-displaying-it-so-can-be-used-in-b so as to save you graph as a png file.

And if you want to turn all white pixel transparent, there's this other question : https://stackoverflow.com/questions/765736/using-pil-to-make-all-white-pixels-transparent

If you want to turn an entire area to transparent, then there's this question: And then use the PIL library like in this question https://stackoverflow.com/questions/4379978/python-pil-how-to-make-area-transparent-in-png so as to make your graph transparent.