Image Adjustment wipes out overplots?

Question

I'm having a problem where when I display lines over an image (using Show) it works fine, but if I adjust the image colors first (using either ImageAdjust[] or Lighter[]) the lines vanish. Am I misunderstanding how image adjustment works? Here's a simplified example:

g = Graphics @@ GeoGraphics[GeoRange -> "World", GeoProjection -> {"Orthographic", "Centering" -> GeoPosition[{-22, 110}]}, GeoGridLines -> Automatic, AspectRatio -> 1, GeoBackground -> "Satellite"];
h = Lighter[g, 1];
l1 = Plot[.18 x - .4, {x, -Pi/2, Pi/2}, Axes -> False];
Show[g, l1]
Show[h, l1]

Why does the second show not have the overplotted line?

Thanks much for any help you can provide...

Answer 1

The reason l1 is not visible in Show[h, l1] is that h has a vastly different plot range than l1:

PlotRange /@ {g, l1, Show[h]}

{{{-0.999874, 0.999371}, {-0.999977, 0.999573}}, {{-1.5708,    1.5708}, {-0.682743, -0.117257}}, {{0., 360.}, {0., 360.}}}

 Row[Show[#, Frame -> True, ImageSize -> 300]& /@ {h, g}]

To see h and l1 together, you can rescale h to the plot range of g using RescalingTransform:

Show[MapAt[GeometricTransformation[#, 
    RescalingTransform[PlotRange[Show[h]], PlotRange[g]]] &, 
  Show@h , {1}], l1, PlotRange -> All]