Base64 ModPE

var path = android.os.Environment.getExternalStorageDirectory().getAbsolutePath() + "/games/com.mojang/minecraftpe/mods";
var imageIcon = " /*Base64 code here*/ ";
Base64Decode(android.util.Base64.decode(imageIcon, 0), path + "/imagename.png");

function Base64Decode(byteArray, Path) {
    try {
        var File = new java.io.File(Path);
        if (!File.exists()) {
            File.createNewFile();
            var Stream = new java.io.FileOutputStream(File);
            Stream.write(byteArray);
            Stream.close();
        }

    } catch (err) {
        print(err);
    }
}

var imageBtn = new android.graphics.BitmapFactory.decodeFile(android.os.Environment.getExternalStorageDirectory().getAbsolutePath() + "/games/com.mojang/minecraftpe/mods/imagename.png");

var imageButton = new android.graphics.drawable.BitmapDrawable(imageBtn);

//Now use button.setBackgroundDrawable(imageButton);