to allow non-ascii characters, encode strings as utf-16-be (big endian) and escape backslashes and parenthesis

CHANGES.rst

@@ -7,6 +7,7 @@ CHANGES
 
  - replace -x and -y option by combined option -s (or --pagesize) and use -S
    for --subject
+ - correctly encode and escape non-ascii metadata
 
 0.1.5
 -----

src/img2pdf.py

@@ -518,7 +518,15 @@ def valid_size(string):
 # is both, type str and type bytes (only the case in python2)
 def pdf_embedded_string(string):
     if type(string) is str and type(string) is not bytes:
-        string = string.encode("utf8")
+        # py3
+        pass
+    else:
+        # py2
+        string = string.decode("utf8")
+    string = b"\xfe\xff"+string.encode("utf-16-be")
+    string = string.replace(b'\\', b'\\\\')
+    string = string.replace(b'(', b'\\(')
+    string = string.replace(b')', b'\\)')
     return string
 
 parser = argparse.ArgumentParser(