deprecate old rawmodes for 16-bit RGB data

Author: Yay295

docs/deprecations.rst

@@ -107,6 +107,23 @@ BGR;15, BGR 16 and BGR;24
 
 The experimental BGR;15, BGR;16 and BGR;24 modes have been deprecated.
 
+16-Bit RGB/BGR Rawmodes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. deprecated:: 10.4.0
+
+The following rawmodes have been deprecated and replaced with better-named rawmodes.
+
+RGB;15 → XBGR;1555
+RGB;16 → BGR;565
+BGR;5 → XRGB;1555
+BGR;15 → XRGB;1555
+BGR;16 → RGB;565
+RGB;4B → XBGR;4
+RGBA;4B → ABGR;4
+RGBA;15 → ARGB;1555
+BGRA;15 → ABGR;1555
+
 Support for LibTIFF earlier than 4
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

docs/releasenotes/10.4.0.rst

@@ -28,6 +28,21 @@ BGR;15, BGR 16 and BGR;24
 
 The experimental BGR;15, BGR;16 and BGR;24 modes have been deprecated.
 
+16-Bit RGB/BGR Rawmodes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+The following rawmodes have been deprecated and replaced with better-named rawmodes.
+
+RGB;15 → XBGR;1555
+RGB;16 → BGR;565
+BGR;5 → XRGB;1555
+BGR;15 → XRGB;1555
+BGR;16 → RGB;565
+RGB;4B → XBGR;4
+RGBA;4B → ABGR;4
+RGBA;15 → ARGB;1555
+BGRA;15 → ABGR;1555
+
 Support for LibTIFF earlier than 4
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

src/PIL/Image.py

@@ -276,6 +276,19 @@ def _conv_type_shape(im):
 # may have to modify the stride calculation in map.c too!
 _MAPMODES = ("L", "P", "RGBX", "RGBA", "CMYK", "I;16", "I;16L", "I;16B")
 
+# map of old deprecated rawmode to new replacement rawmode
+_DEPRECATED_RAWMODES = {
+    "RGB;15": "XBGR;1555",
+    "RGB;16": "BGR;565",
+    "BGR;5": "XRGB;1555",
+    "BGR;15": "XRGB;1555",
+    "BGR;16": "RGB;565",
+    "RGB;4B": "XBGR;4",
+    "RGBA;4B": "ABGR;4",
+    "RGBA;15": "ARGB;1555",
+    "BGRA;15": "ABGR;1555",
+}
+
 
 def getmodebase(mode: str) -> str:
     """
@@ -417,6 +430,13 @@ def _getdecoder(mode, decoder_name, args, extra=()):
     elif not isinstance(args, tuple):
         args = (args,)
 
+    if decoder_name == "raw" and args[0] in _DEPRECATED_RAWMODES:
+        deprecate(
+            f"rawmode {args[0]}",
+            12,
+            replacement=f"rawmode {_DEPRECATED_RAWMODES[args[0]]}",
+        )
+
     try:
         decoder = DECODERS[decoder_name]
     except KeyError:
@@ -1587,6 +1607,12 @@ def getpalette(self, rawmode: str | None = "RGB") -> list[int] | None:
             mode = self.im.getpalettemode()
         except ValueError:
             return None  # no palette
+        if rawmode in _DEPRECATED_RAWMODES:
+            deprecate(
+                f"rawmode {rawmode}",
+                12,
+                replacement=f"rawmode {_DEPRECATED_RAWMODES[rawmode]}",
+            )
         if rawmode is None:
             rawmode = mode
         return list(self.im.getpalette(mode, rawmode))