Even though one can upload high-resolution photos to Yelp, the images Yelp shows on business pages seem limited to a resolution of 600×400. Sometimes that makes it impossible to see what someone means (example).
Is there some URL hack to access larger versions of a Yelp photo? Many sites store the original along with the sized-down version they present to the user, and the original is sometimes accessible by changing the photo's URL (e.g. Instagram, Flickr).
I've tweeted at them, but I doubt they'll do anything about it quickly.
Best Answer
Have you tried right-clicking and 'view image' or 'view image in new tab'? In the example you linked, I get a 568x1000 pixel image. That is larger than the 400x600 you mention.
http://s3-media2.fl.yelpcdn.com/bphoto/pdef4LUmnhwN1XCMc1OUxQ/o.jpg
It seems like there is no way to dynamically grab this with the API though. :(
There is some more detailed info in this post, which basically lists the 5 images you can get: