Are min and max lat/lon when loading a raster pixel edges or centers?

[mattwigway]

I'm using raster elevation data, converted to an Arc/INFO ASCII grid with the header stripped as described in the documentation. My question though is about the interpretation of minimum and maximum latitude and longitude. I've been just putting in the extents reported by GIS for these, but I think this may actually be wrong—as the extents reported by GIS are based on the edges of the pixels, but based on looking at the interpolation code (in raster_source.cpp) I think OSRM wants the minimum and maximum lat/lon of the centers of the pixels. Am I on the right track here?