I sorta read it to mean the level of impact the image made. Like if you turned the page and was all like "OH MY GOD!" Or cried or laughed or the best word for what I am saying is probably "moved" by the image. Or "impactful", like a tremendous change in the character happened in that moment or something. The Obito image fits that description.
How about this one. That's Kurama, Naruto is calling the ninetails by its name, the gate's open, he even has his back facing the open gate. It probably would have had more impact if I had been caught up to the manga at the time it happened and been able to be excited along with everyone else. Without that, there is only what the image creates on its own (even though it's a catalyst for however the community reacted to begin with).: