Merge pull request #6231 from radarhere/bmp_compression

Ignore compression value from BMP info dictionary when saving as TIFF

Tests/test_file_tiff.py

@@ -715,6 +715,13 @@ def test_save_icc_profile(self, tmp_path):
         with Image.open(outfile) as reloaded:
             assert reloaded.info["icc_profile"] == icc_profile
 
+    def test_save_bmp_compression(self, tmp_path):
+        with Image.open("Tests/images/hopper.bmp") as im:
+            assert im.info["compression"] == 0
+
+            outfile = str(tmp_path / "temp.tif")
+            im.save(outfile)
+
     def test_discard_icc_profile(self, tmp_path):
         outfile = str(tmp_path / "temp.tif")
 

src/PIL/TiffImagePlugin.py

@@ -1559,7 +1559,13 @@ def _save(im, fp, filename):
 
     encoderinfo = im.encoderinfo
     encoderconfig = im.encoderconfig
-    compression = encoderinfo.get("compression", im.info.get("compression"))
+    try:
+        compression = encoderinfo["compression"]
+    except KeyError:
+        compression = im.info.get("compression")
+        if isinstance(compression, int):
+            # compression value may be from BMP. Ignore it
+            compression = None
     if compression is None:
         compression = "raw"
     elif compression == "tiff_jpeg":