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I want to make a map (of Germany) with certain positions marked. This is just a MWE, in fact there are much more positions. What I did: 

   positions = {{47.5`, 11.08`}, {47.57`, 8.03`}, {47.6`, 
   8.13`}, {47.65`, 7.6`}, {47.65`, 7.78`}, {47.66`, 9.48`}, {47.7`, 
   10.32`}, {47.73`, 12.1`}, {47.77`, 9.72`}, {47.77`, 11.62`}}

and

marker = Graphics[{Blue, PointSize[0.4], Point[{0, 0}]}];

then (this - Entity - is keyed in manually because of the complicated structure of the Entity in this command when done via copy and paste)

    map = GeoGraphics[{GeoStyling["StreetMap"], 
            Polygon[Entity["Country","Germany"]],
            GeoZoomLevel -> 9,
            GeoMarker[positions, marker]
            }, 
            GeoBackground -> None, ImageSize -> 2000]

If I do so the map looks fine:

enter image description here

If I export the image:

Export["germany-04.JPG", map, "JPG"];

and re-import the image it is much more coarse. I tried with something like 

Export["germany-04.JPG", map, "JPG", ImageResolution-> 300];

and explicit ImageSize, but I never get close to the the original resolution (same with export formats like SVG, EPS, PNG. If I copy the map (as graphics) and try to import in Photoshop.... Mathematica crashes (??).

My system: MacOS 10.13.5, Mathematica 11.3.0, my goal is to get an exported image good for print.

enter image description here

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  • 2
    $\begingroup$ JPEG ("JPG") image files has lossy compression, and Mathematica uses a "CompressionLevel" of 0.25 by default. $\endgroup$ – rhermans Jun 26 '18 at 7:43
  • $\begingroup$ @rhermans: JPG was just an example here - same problems with SVG, WMF, PNG etc. Picture dimensions are approx. 2000x2700, so this is too few to get the names of towns readable in a "pixel-environment". It seems that PDF is much better there. $\endgroup$ – mgamer Jun 26 '18 at 20:35
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Save it as pdf, then open in Acrobat and the resolution seems to be preserved.

Export["germany-04.pdf", map, "PDF"];

The pdf file is about 40 MB, so that may explain the instability when trying to copy/paste.

enter image description here

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