Convert image in KMZ to polygon

Question

I have a KMZ file that contains several image overlays (RF coverage plots).

I would like to convert the image overlays to polygons to decrease loading time in Google Maps.

Currently I'm tracing a rough outline of the image but that is labor intensive and not very accurate.

Is there a way to automatically convert a image to a polygon?

I have Google Earth and Manifold GIS. ArcScan looks promising but it is outside of my budget.

Answer 1

You can use GDAL tool inside Quantum GIS. Its free and it works fine. Install Quantum GIS and Gdaltools and you'll have a set of tool for raster/image processing. The one you want would be vectorize (gdal_polygonize). Cheers