Are there any updates on this topic? (since it’s been 8 years…) It would be really useful for contents that are not suitable for highlights! e.g., pictures in pdf.
Welcome @ElainaZ and no, there has been no change. There has also been no further discussion here in the last almost four years 
You could add e.g. a rectangular annotation enclosing the picture and then link to this annotation.
Any automaton to do this? I could only get highlights and comments when using Applescript.
An automation to do what specifically?
An automation to get item links of rectangular annotations.
The reference URL AppleScript property of windows/tabs returns such item links but the annotation has to be already selected.
I’ll give it a try. Thanks!