Nanozoomer annotation coordinate system to openslide pixels

[Benjamin Gilbert]

On Mon, November 10, 2014 10:40 pm, Ahmed Bassiouni wrote:
> In this way, we need the complete width+length of the whole slide to
> calculate coordinates.

We've been trying to do the calculation in the wrong order!  We don't 
need the slide size after all.  Here's the approach:

0. The point coordinates are in physical units, relative to the center 
of the entire slide
1. Add the [XY]OffsetFromSlideCentre ==> physical units, relative to the 
center of the main image
2. Divide by (mpp-[xy] * 1000) ==> pixel coordinates, relative to the 
center of the main image
3. Subtract (level-0 dimensions / 2) ==> level 0 pixel coordinates

--Benjamin Gilbert