The actor was out and about in the Big Apple Saturday -- the first time he'd been seen in public since word of the ambush came down yesterday from his team ... and yes, the guy's rockin' a shiner on his left eye, which is where he's reported to have been hit.

As you can see ... he's got a pair of glasses on, and while the left side might look be a darker shade of lens -- that's not the case ... as the right side is totally clear.

In other words, these are normal glasses ... and the purple and black you're seeing is actually bruising -- and considering how noticeable it is, it just speaks to how vicious this attack was on Wednesday ... when Steve was struck by a dude out of nowhere.

Steve's team says he's okay now and on the mend -- but also lamented the fact this sort of thing seems to be happening to anyone and everyone in the city lately ... for doing nothing more than strolling down the street and minding one's own business.

Of course, SB is far from the first celeb to suffer this kind of violence at the hands of brutes in public -- in fact, this sort of thing (and worse) is happening to New Yorkers from all walks of life.

As you know ... a poor woman was recently strangled with a belt at night by a man who's been accused of raping her afterward -- and the video of that incident is absolutely horrific.

There's also a troubling trend of women who say they've been decked by random dudes in New York -- so like we said, this is just the tip of the iceberg on the assault crime spree.