Prevent anti-aliasing for imshow in matplotlib


When I use matplotlib's imshow() method to represent a small numpy matrix, it ends up doing some smoothing between pixels. Is there any way to disables this? It makes my figure's misleading in presentations.A 28x28 matrix plotted with imshow()

The figure above is a 28x28 image, so I should be seeing large squares of single colors representing each pixel (as matlab would display it when using imagesc()). But Instead, the pixels seem to be blurred with neighboring pixels. Is there a way to disable this behavior?

12/4/2011 4:12:32 PM

Accepted Answer

There is an interpolation option for imshow which controls how and if interpolation will be applied to the rendering of the matrix. If you try

imshow(array, interpolation="nearest") 

you might get something more like you want. As an example

A=10*np.eye(10) + np.random.rand(100).reshape(10,10)


compared with

A=10*np.eye(10) + np.random.rand(100).reshape(10,10)
imshow(A, interpolation="nearest")

enter image description here

12/4/2011 5:47:34 PM

you can also try the function


which name indicated that it does exactly what you asked - represent matrices. It is quite handy when you do not need to customise the figure too much.

BTW, one of the best resources for matplotlib is their Gallery

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