From 33d62fc8a1a15f26376bfdd9fc292449a4e0827e Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Wed, 25 Mar 2026 23:11:59 +1100
Subject: [PATCH] Added error messages

---
 Tests/test_file_jpeg2k.py | 16 ++++++++++++++++
 src/decode.c              |  1 +
 src/encode.c              |  3 +++
 3 files changed, 20 insertions(+)

diff --git a/Tests/test_file_jpeg2k.py b/Tests/test_file_jpeg2k.py
index df686df32..85851ddad 100644
--- a/Tests/test_file_jpeg2k.py
+++ b/Tests/test_file_jpeg2k.py
@@ -148,6 +148,22 @@ def test_prog_res_rt(card: ImageFile.ImageFile) -> None:
     assert_image_equal(im, card)
 
 
+def test_unknown_progression(tmp_path: Path) -> None:
+    outfile = tmp_path / "temp.jp2"
+
+    im = Image.new("1", (1, 1))
+    with pytest.raises(ValueError, match="unknown progression"):
+        im.save(outfile, progression="invalid")
+
+
+def test_unknown_cinema_mode(tmp_path: Path) -> None:
+    outfile = tmp_path / "temp.jp2"
+
+    im = Image.new("1", (1, 1))
+    with pytest.raises(ValueError, match="unknown cinema mode"):
+        im.save(outfile, cinema_mode="invalid")
+
+
 @pytest.mark.parametrize("num_resolutions", range(2, 6))
 def test_default_num_resolutions(
     card: ImageFile.ImageFile, num_resolutions: int
diff --git a/src/decode.c b/src/decode.c
index c5c9cf56f..cda4ce702 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -905,6 +905,7 @@ PyImaging_Jpeg2KDecoderNew(PyObject *self, PyObject *args) {
     } else if (strcmp(format, "jp2") == 0) {
         codec_format = OPJ_CODEC_JP2;
     } else {
+        PyErr_SetString(PyExc_ValueError, "unknown codec format");
         return NULL;
     }
 
diff --git a/src/encode.c b/src/encode.c
index b9feb28d2..b268ad741 100644
--- a/src/encode.c
+++ b/src/encode.c
@@ -1346,6 +1346,7 @@ PyImaging_Jpeg2KEncoderNew(PyObject *self, PyObject *args) {
     } else if (strcmp(format, "jp2") == 0) {
         codec_format = OPJ_CODEC_JP2;
     } else {
+        PyErr_SetString(PyExc_ValueError, "unknown codec format");
         return NULL;
     }
 
@@ -1360,6 +1361,7 @@ PyImaging_Jpeg2KEncoderNew(PyObject *self, PyObject *args) {
     } else if (strcmp(progression, "CPRL") == 0) {
         prog_order = OPJ_CPRL;
     } else {
+        PyErr_SetString(PyExc_ValueError, "unknown progression");
         return NULL;
     }
 
@@ -1372,6 +1374,7 @@ PyImaging_Jpeg2KEncoderNew(PyObject *self, PyObject *args) {
     } else if (strcmp(cinema_mode, "cinema4k-24") == 0) {
         cine_mode = OPJ_CINEMA4K_24;
     } else {
+        PyErr_SetString(PyExc_ValueError, "unknown cinema mode");
         return NULL;
     }