How to export plots from matplotlib with transparent background?

Question

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?

Answer 1

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.

Answer 2

Png files can handle transparency. So you could use this question Save plot to image file instead of displaying it using Matplotlib 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 : 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 Python PIL: how to make area transparent in PNG? so as to make your graph transparent.