Merge pull request #8231 from radarhere/ppm_i16

Author: hugovk

Tests/test_file_ppm.py

@@ -95,7 +95,9 @@ def test_16bit_pgm_write(tmp_path: Path) -> None:
     with Image.open("Tests/images/16_bit_binary.pgm") as im:
         filename = str(tmp_path / "temp.pgm")
         im.save(filename, "PPM")
+        assert_image_equal_tofile(im, filename)
 
+        im.convert("I;16").save(filename, "PPM")
         assert_image_equal_tofile(im, filename)
 
 

src/PIL/PpmImagePlugin.py

@@ -333,7 +333,7 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
         rawmode, head = "1;I", b"P4"
     elif im.mode == "L":
         rawmode, head = "L", b"P5"
-    elif im.mode == "I":
+    elif im.mode in ("I", "I;16"):
         rawmode, head = "I;16B", b"P5"
     elif im.mode in ("RGB", "RGBA"):
         rawmode, head = "RGB", b"P6"