edgemoron:
There are dozens of different HESs, can you post a part # or datasheet link?
You will need to shop for a Hall Effect sensor with a LINEAR output. I don't recall what the digital ones are called but they are HIGH with no magnetic field and LOW with the South side of the magnet nearest the sensor.
Some time back I used a linear HE sensor and scanned a magnetic sign. (this was a large one about 14" x 10" like you would put on a Car or Truck
Scanning across the surface yielded a nice sine wave. This was not a graphic image but a series of digital data points,