Set mode to L if palette is missing

Author: radarhere

Tests/test_file_tga.py

@@ -133,6 +133,11 @@ def test_small_palette(tmp_path: Path) -> None:
         assert reloaded.getpalette() == colors
 
 
+def test_missing_palette() -> None:
+    with Image.open("Tests/images/dilation4.lut") as im:
+        assert im.mode == "L"
+
+
 def test_save_wrong_mode(tmp_path: Path) -> None:
     im = hopper("PA")
     out = str(tmp_path / "temp.tga")

src/PIL/TgaImagePlugin.py

@@ -85,7 +85,7 @@ def _open(self) -> None:
             elif depth == 16:
                 self._mode = "LA"
         elif imagetype in (1, 9):
-            self._mode = "P"
+            self._mode = "P" if colormaptype else "L"
         elif imagetype in (2, 10):
             self._mode = "RGB"
             if depth == 32: