Maximum maxval is 65535

src/PIL/PpmImagePlugin.py

@@ -166,26 +166,19 @@ def _save(im, fp, filename):
     elif im.mode == "L":
         rawmode, head = "L", b"P5"
     elif im.mode == "I":
-        if im.getextrema()[1] < 2**16:
-            rawmode, head = "I;16B", b"P5"
-        else:
-            rawmode, head = "I;32B", b"P5"
-    elif im.mode == "RGB":
-        rawmode, head = "RGB", b"P6"
-    elif im.mode == "RGBA":
+        rawmode, head = "I;16B", b"P5"
+    elif im.mode in ("RGB", "RGBA"):
         rawmode, head = "RGB", b"P6"
     else:
         raise OSError(f"cannot write mode {im.mode} as PPM")
-    fp.write(head + ("\n%d %d\n" % im.size).encode("ascii"))
+    fp.write(head + b"\n%d %d\n" % im.size)
     if head == b"P6":
         fp.write(b"255\n")
     elif head == b"P5":
         if rawmode == "L":
             fp.write(b"255\n")
-        elif rawmode == "I;16B":
+        else:
             fp.write(b"65535\n")
-        elif rawmode == "I;32B":
-            fp.write(b"2147483648\n")
     ImageFile._save(im, fp, [("raw", (0, 0) + im.size, 0, (rawmode, 0, 1))])
 
     # ALTERNATIVE: save via builtin debug function