Reduced number of bytes read

Author: radarhere

src/PIL/PcdImagePlugin.py

@@ -32,7 +32,7 @@ def _open(self) -> None:
         assert self.fp is not None
 
         self.fp.seek(2048)
-        s = self.fp.read(2048)
+        s = self.fp.read(1539)
 
         if not s.startswith(b"PCD_"):
             msg = "not a PCD file"