As others have said, there is an "HD" button in the upper right corner which does what you want. It is always there, even if the background of the image obscures it.

There is also an option in "Advanced-->Media" that makes this behavior the default. You can also check if the data saver options for mobile and wifi are enabled.

I'm on Boost, check the little HD button on the top right of the image when you click on it and you can also finger pinch to zoom in. A slight inconvenience, but probably a data saver feature.

jerboa is pretty good too, though limited in search function.