How can I open images in a Google Colaboratory notebook cell from uploaded png files?

Try this

from IPython.display import Image
Image('bp.png')

You can set width and height as well

Image("bp.png", width=100, height=100)

To display more than 1 image, you need to call display. (it’s auto for just 1 image)

from IPython.display import Image, display
display(Image('1.png'))
display(Image('2.png'))

Update jan/2019

Put your image in /usr/local/share/jupyter/nbextensions/

Then display it from /nbextensions/, e.g.

%%html
<img src='/nbextensions/image.png' />