Use "with" to open and close input files

src/img2pdf.py

@@ -206,7 +206,7 @@ def convert(images, dpi, x, y, title=None, author=None, creator=None, producer=N
 
     for imfilename in images:
         debug_out("Reading %s"%imfilename, verbose)
-        im = open(imfilename, "rb")
+        with open(imfilename, "rb") as im:
             rawdata = im.read()
             im.seek(0)
             try:
@@ -286,8 +286,6 @@ def convert(images, dpi, x, y, title=None, author=None, creator=None, producer=N
 
         pdf.addimage(color, width, height, imgformat, imgdata, pdf_x, pdf_y)
 
-        im.close()
-
     return pdf.tostring()