I created a toy sheet of music and placed notes, rests in various places: low and high in the staff, to accommodate all the possible places symbols can be found in a sheet of music. The resulting template set was not exhaustive, but will do for now, as it contains the most common notes, rests, and clefs.
After a quick slice and dice on Photoshop, involving some heavy eyeballing, I boxed out the templates, making the box sizes as small as I possibly could.
I tried to make the template sizes consistent among symbol types, quarter notes and half notes being 32 x 22. However, there is more variety of sizes within our rest symbols. As you can see, a quarter rest (24 x 60 in the set) is larger than a eighth rest (22 x 40)
A problem I foresee with our set right now is that at least with handwritten scores, ignoring the stems (which I did for quarter and half note templates), half notes can look very much like whole notes. I left a little bit of the stem in the templates, but it might not be enough.
This bootstrap set is by no means final; I foresee a lot of resizing in the future. It depends on how our template matching algorithm goes.