DannyA

Yes, it absolutely will. There's a trade off you have to make here. If they're going to put your image in their search results, it's obviously not in their interest to put images that won't open up in their search results. They've also dealt with plenty of shenanigans in the past with cloaking, so even if you get away with some form now, know it's something they consider for your long term strategy. Cloaking of any sort is fucking tricky. They detect it all easily but it's really hard to predict. Redirecting to the page with the image on it was always a bad idea, but lots of people do it without that metric putting them over any tipping point. At the same time, the next update could change the weight of some other metric and all the sudden you're actually flagged and that's fucked.

I really think before anybody does this though, they should crunch numbers on their server logs. Hotlink protection is meant to keep some dickhead from embedding images in his site to leech your bandwidth. If you allow Google to hotlink, they're hosting your thumbnail so at least when you do use up some bandwidth it's a prequalified click. They're also providing a direct link to the image (which is already cached), but they're also giving a free link to your page. Calculate what you spend on bandwidth vs. dollars earned from that traffic if you really want to decide.

Now what I personally would just always do to keep the image search traffic but keep other dickheads from leeching

That returns a 403 (forbidden). You can do a 302 to a "no hotlinking" image, but 302 literally means "found" and is treated as a promise that the server is sending you to the requested content. I just wouldn't, because to the algorithm that's intentional deception.