I have installed LB 1.3 and I I was going through the sample files. Grasshopper shows that LB Image Viewer is not installed.
I found this older post that had the same issue. I downloaded the LB legacy components from the forum post and dropped to GH canvas. Image viewer in latest LB release - #5 by minggangyin
This version of LB image viewer works with GIFs, but not with HDRs as it is shown to do in the post of the new release Ladybug Tools for Grasshopper 1.3.0 Release
It´s not a relevant issue, but I was curious.