Moved decoder names out of MODES

src/PIL/PpmImagePlugin.py

@@ -23,20 +23,19 @@
 b_whitespace = b"\x20\x09\x0a\x0b\x0c\x0d"
 
 MODES = {
-    # standard, plain
-    b"P1": ("ppm_plain", "1"),
-    b"P2": ("ppm_plain", "L"),
-    b"P3": ("ppm_plain", "RGB"),
-    # standard, raw
-    b"P4": ("raw", "1"),
-    b"P5": ("raw", "L"),
-    b"P6": ("raw", "RGB"),
+    # standard
+    b"P1": "1",
+    b"P2": "L",
+    b"P3": "RGB",
+    b"P4": "1",
+    b"P5": "L",
+    b"P6": "RGB",
     # extensions
-    b"P0CMYK": ("raw", "CMYK"),
+    b"P0CMYK": "CMYK",
     # PIL extensions (for test purposes only)
-    b"PyP": ("raw", "P"),
-    b"PyRGBA": ("raw", "RGBA"),
-    b"PyCMYK": ("raw", "CMYK"),
+    b"PyP": "P",
+    b"PyRGBA": "RGBA",
+    b"PyCMYK": "CMYK",
 }
 
 
@@ -90,18 +89,16 @@ def _read_token(self):
     def _open(self):
         magic_number = self._read_magic()
         try:
-            decoder, mode = MODES[magic_number]
+            mode = MODES[magic_number]
         except KeyError:
             raise SyntaxError("not a PPM file")
 
-        self.custom_mimetype = {
-            b"P1": "image/x-portable-bitmap",
-            b"P2": "image/x-portable-graymap",
-            b"P3": "image/x-portable-pixmap",
-            b"P4": "image/x-portable-bitmap",
-            b"P5": "image/x-portable-graymap",
-            b"P6": "image/x-portable-pixmap",
-        }.get(magic_number)
+        if magic_number in (b"P1", b"P4"):
+            self.custom_mimetype = "image/x-portable-bitmap"
+        elif magic_number in (b"P2", b"P5"):
+            self.custom_mimetype = "image/x-portable-graymap"
+        elif magic_number in (b"P3", b"P6"):
+            self.custom_mimetype = "image/x-portable-pixmap"
 
         for ix in range(3):
             token = int(self._read_token())
@@ -127,14 +124,12 @@ def _open(self):
                         self.mode = "I"
                         rawmode = "I;32B"
 
+        decoder_name = "raw"
+        if magic_number in (b"P1", b"P2", b"P3"):
+            decoder_name = "ppm_plain"
         self._size = xsize, ysize
         self.tile = [
-            (
-                decoder,  # decoder
-                (0, 0, xsize, ysize),  # region: whole image
-                self.fp.tell(),  # offset to image data
-                (rawmode, 0, 1),  # parameters for decoder
-            )
+            (decoder_name, (0, 0, xsize, ysize), self.fp.tell(), (rawmode, 0, 1))
         ]