In an elliptical polar orbit Juno does not get particularly close to the galilean satellites. In the current mission plan the spacecraft is <400,000 km from Io 22 times. It is <300,000 km from Io just 8 times. Our closest flyby will be at PJ33 with a range of ~145,000 km.
We do not have the planning tools to precisely time our images of Io so we simply take a "full-spin" image. That means we image 360 deg of sky, which also includes Jupiter. The metadata on the image gallery page is for Jupiter, not Io.
In this section I'll record a few simple geometric parameters for the Io images. These are not precise for the moment the image was taken, so if you are planning to do more sophisticated analysis please use spice kernels.