This is a Photoshop Script to create all versions of launcher icon needed for Android from a chosen source image file. This Gist is inspired from: https://gist.github.com/appsbynight/3681050

Create Android Icons.jsx

// Prerequisite:
// First, create at least a 512x512 px PNG file 
// Install - Save Create Android Icons.jsx to:
//   Win: C:\Program Files\Adobe\Adobe Utilities - CS6\ExtendScript Toolkit CS6\SDK
//   Mac: /Applications/Utilities/Adobe Utilities/ExtendScript Toolkit CS6/SDK
// * Restart Photoshop
//
// Update:
// * Just modify & save, no need to resart Photoshop once it's installed.
//
// Run:
// * With Photoshop open, select File > Scripts > Create Icons
// * When prompted select the prepared Artwork file for your app.
// * The different version of the icons will get saved to the same folder that
//   the Artwork file is in.
//
// Adobe Photoshop JavaScript Reference
// http://www.adobe.com/devnet/photoshop/scripting.html


// Turn debugger on. 0 is off.
// $.level = 1;

try
{
  // Prompt user to select iTunesArtwork file. Clicking "Cancel" returns null.
  var Artwork = File.openDialog("Select a sqaure PNG file that is at least 512x512.", "*.png", false);

  if (Artwork !== null) 
  { 
    var doc = open(Artwork, OpenDocumentType.PNG);
    
    if (doc == null)
    {
      throw "Something is wrong with the file.  Make sure it's a valid PNG file.";
    }

    var startState = doc.activeHistoryState;       // save for undo
    var initialPrefs = app.preferences.rulerUnits; // will restore at end
    app.preferences.rulerUnits = Units.PIXELS;     // use pixels

    if (doc.width != doc.height)
    {
        throw "Image is not square";
    }
    else if ((doc.width < 512) && (doc.height < 512))
    {
        throw "Image is too small!  Image must be at least 512x512 pixels.";
    }
    else if (doc.width < 512)
    {
        throw "Image width is too small!  Image width must be at least 512 pixels.";
    }
    else if (doc.height < 512)
    {
        throw "Image height is too small!  Image height must be at least 512 pixels.";
    }
    
    // Folder selection dialog
    var destFolder = Folder.selectDialog( "Choose an output folder");

    if (destFolder == null)
    {
      // User canceled, just exit
      throw "";
    }

    // Save icons in PNG using Save for Web.
    var sfw = new ExportOptionsSaveForWeb();
    sfw.format = SaveDocumentType.PNG;
    sfw.PNG8 = false; // use PNG-24
    sfw.transparency = true;
    doc.info = null;  // delete metadata
    
    var icons = [
      {"name": "ic_launcher_Web", "size":512},
      {"name": "ic_launcher_xxxhdpi",    "size":192},
      {"name": "ic_launcher_xxhdpi",             "size":144},
      {"name": "ic_launcher_xhdpi",          "size":96},
      {"name": "ic_launcher_hdpi",          "size":72},
      {"name": "ic_launcher_mdpi",       "size":48},
      {"name": "ic_launcher_ldpi",       "size":36}
    ];

    var icon;
    for (i = 0; i < icons.length; i++) 
    {
      icon = icons[i];
      doc.resizeImage(icon.size, icon.size, // width, height
                      null, ResampleMethod.BICUBICSHARPER);

      var destFileName = icon.name + ".png";

      doc.exportDocument(new File(destFolder + "/" + destFileName), ExportType.SAVEFORWEB, sfw);
      doc.activeHistoryState = startState; // undo resize
    }

    alert("Android Launcher Icons Created!");
  }
}
catch (exception)
{
  // Show degbug message and then quit
	if ((exception != null) && (exception != ""))
    alert(exception);
 }
finally
{
    if (doc != null)
        doc.close(SaveOptions.DONOTSAVECHANGES);
  
    app.preferences.rulerUnits = initialPrefs; // restore prefs
}