fix wrong pdf size

watermark.py

@@ -152,7 +152,7 @@ def watermark_img(img_file, template, dpi):
 
     # Save image as PDF and delete original image file
     pdf_file = os.path.splitext(img_file)[0] + '.pdf'
-    out.save(pdf_file)
+    out.save(pdf_file, resolution=dpi)
     if os.path.isfile(img_file):
         os.remove(img_file)