Using tensor as index for another tensor

I have a greyscale image batch (batch size = 16) of shape (16, 1, 240, 240) and a tensor of shape (16, 2, 100) with 100 points (x,y) which I want to use as index

output [b] [i] [j] = image_batch (index[b] [i] [j])

How to do this?