do not accept int in PIL._binary.i8

src/PIL/IptcImagePlugin.py

@@ -20,26 +20,29 @@
 import tempfile
 
 from . import Image, ImageFile
-from ._binary import i8, o8
 from ._binary import i16be as i16
 from ._binary import i32be as i32
 
 COMPRESSION = {1: "raw", 5: "jpeg"}
 
-PAD = o8(0) * 4
+PAD = b"\0\0\0\0"
 
 
 #
 # Helpers
 
 
+def _i8(c: int | bytes) -> int:
+    return c if isinstance(c, int) else c[0]
+
+
 def i(c):
     return i32((PAD + c)[-4:])
 
 
 def dump(c):
     for i in c:
-        print("%02x" % i8(i), end=" ")
+        print("%02x" % _i8(i), end=" ")
     print()
 
 
@@ -103,10 +106,10 @@ def _open(self):
                 self.info[tag] = tagdata
 
         # mode
-        layers = i8(self.info[(3, 60)][0])
-        component = i8(self.info[(3, 60)][1])
+        layers = self.info[(3, 60)][0]
+        component = self.info[(3, 60)][1]
         if (3, 65) in self.info:
-            id = i8(self.info[(3, 65)][0]) - 1
+            id = self.info[(3, 65)][0] - 1
         else:
             id = 0
         if layers == 1 and not component:

src/PIL/_binary.py

@@ -18,8 +18,8 @@
 from struct import pack, unpack_from
 
 
-def i8(c: int | bytes) -> int:
-    return c if c.__class__ is int else c[0]  # type: ignore[index, return-value]
+def i8(c: bytes) -> int:
+    return c[0]
 
 
 def o8(i: int) -> bytes: