"Focus is a bourgeois concept."
--H. Cartier Bresson
Why take an easy problem?
Let's count the pieces of flyS___ in the pepper. Let's finally get that number of angels that can dance on the head of a pin. Lets....
Seriously, the only measure I have a real sharpness is if the image makes things appear close to what I actually see with the naked eye. Obviously, no way to quantify that. One thing it suggests though, is that the image borders on approaching some 3D aspects.
One of the most telling things for image sharpness is often the most nebulous -- clouds. With the naked eye, clouds can often be seen in distinct layers, and that's almost never seen in photos, at least without going to HDR or some kind of layering in post. If I take a picture that has layering storm clouds, and I can see distinct layering, I know it's "sharp."
Okay, back to the kitchen for me.....