image processing - How to remove the undesired border of the GeoGraphics?

I have created an image of Europe as below:-

g1 = (GeoPosition[{56, #}] & /@ Range[-10, 25, 5]);
g2 = (GeoPosition[{36, #}] & /@ Range[25, -10, -5]);
img = GeoGraphics[Polygon@Join[g1, g2], GeoProjection -> "CylindricalEqualArea"]

As you can see, the desired area in now in grey, and there's a border with lighter color there. How can I remove the border without using the trial-and-error approach of chopping img by pixels?

Many thanks!

Answer

Set GeoRangePadding -> None:

g1 = (GeoPosition[{56, #}] & /@ Range[-10, 25, 5]);
g2 = (GeoPosition[{36, #}] & /@ Range[25, -10, -5]);
img = GeoGraphics[Polygon@Join[g1, g2], 
  GeoProjection -> "CylindricalEqualArea", GeoRangePadding -> None]

By default, GeoGraphics with GeoRange -> Automatic uses a range that encloses your content, then GeoRangePadding adds some extra space around it. If you turn off the padding, you get just the area needed to include your content.