Add 'mct' and 'use_jp2' options for J2K saving

Tests/test_file_jpeg2k.py

@@ -209,6 +209,37 @@ def test_layers():
         assert_image_similar(im, test_card, 0.4)
 
 
+def test_use_jp2():
+    out = BytesIO()
+    test_card.save(out, "JPEG2000", use_jp2=False)
+    out.seek(0)
+    assert out.read(2) == b"\xff\x4f"
+
+
+def test_mct():
+    # Three component
+    for val in (0, 1):
+        out = BytesIO()
+        test_card.save(out, "JPEG2000", mct=val, use_jp2=False)
+        out.seek(0)
+        with Image.open(out) as im:
+            im.load()
+            assert_image_similar(im, test_card, 1.0e-3)
+            assert out.getvalue()[59] == val
+
+    # Single component
+    for val in (0, 1):
+        out = BytesIO()
+        with Image.open("Tests/images/16bit.cropped.jp2") as jp2:
+            jp2.save(out, "JPEG2000", mct=val, use_jp2=False)
+
+        out.seek(0)
+        with Image.open(out) as im:
+            im.load()
+            assert_image_similar(im, jp2, 1.0e-3)
+            assert out.getvalue()[53] == 0
+
+
 def test_rgba():
     # Arrange
     with Image.open("Tests/images/rgb_trns_ycbc.j2k") as j2k:

docs/handbook/image-file-formats.rst

@@ -502,9 +502,14 @@ The :py:meth:`~PIL.Image.Image.save` method supports the following options:
     and must be greater than the code-block size.
 
 **irreversible**
-    If ``True``, use the lossy Irreversible Color Transformation
-    followed by DWT 9-7.  Defaults to ``False``, which means to use the
-    Reversible Color Transformation with DWT 5-3.
+    If ``True``, use the lossy discrete waveform transformation DWT 9-7.
+    Defaults to ``False``, which uses the lossless DWT 5-3.
+
+**mct**
+    If ``0`` then don't use multiple component transformation when encoding,
+    otherwise use ``1`` to apply to components 0, 1 and 2. MCT works best
+    with a ``mode`` of ``RGB`` and is only available for 3 component image
+    data.
 
 **progression**
     Controls the progression order; must be one of ``"LRCP"``, ``"RLCP"``,
@@ -524,6 +529,10 @@ The :py:meth:`~PIL.Image.Image.save` method supports the following options:
     for compliant 4K files, *at least one* of the dimensions must match
     4096 x 2160.
 
+**use_jp2**
+    If ``False`` then don't wrap the codestream in the JP2 file format when
+    saving. Defaults to ``True``.
+
 .. note::
 
    To enable JPEG 2000 support, you need to build and install the OpenJPEG

src/PIL/Jpeg2KImagePlugin.py

@@ -320,6 +320,10 @@ def _save(im, fp, filename):
     irreversible = info.get("irreversible", False)
     progression = info.get("progression", "LRCP")
     cinema_mode = info.get("cinema_mode", "no")
+    mct = info.get("mct", 0)
+
+    kind = "jp2" if info.get("use_jp2", True) else "j2k"
+
     fd = -1
 
     if hasattr(fp, "fileno"):
@@ -340,6 +344,7 @@ def _save(im, fp, filename):
         irreversible,
         progression,
         cinema_mode,
+        mct,
         fd,
     )
 

src/encode.c

@@ -1187,11 +1187,12 @@ PyImaging_Jpeg2KEncoderNew(PyObject *self, PyObject *args) {
     OPJ_PROG_ORDER prog_order;
     char *cinema_mode = "no";
     OPJ_CINEMA_MODE cine_mode;
+    char *mct = 0;
     Py_ssize_t fd = -1;
 
     if (!PyArg_ParseTuple(
             args,
-            "ss|OOOsOnOOOssn",
+            "ss|OOOsOnOOOssbn",
             &mode,
             &format,
             &offset,
@@ -1205,6 +1206,7 @@ PyImaging_Jpeg2KEncoderNew(PyObject *self, PyObject *args) {
             &irreversible,
             &progression,
             &cinema_mode,
+            &mct,
             &fd)) {
         return NULL;
     }
@@ -1302,6 +1304,7 @@ PyImaging_Jpeg2KEncoderNew(PyObject *self, PyObject *args) {
     context->irreversible = PyObject_IsTrue(irreversible);
     context->progression = prog_order;
     context->cinema_mode = cine_mode;
+    context->mct = mct;
 
     return (PyObject *)encoder;
 }

src/libImaging/Jpeg2K.h

@@ -82,6 +82,9 @@ typedef struct {
     /* Compression style */
     int irreversible;
 
+    /* Set multiple component transformation */
+    char mct;
+
     /* Progression order (LRCP/RLCP/RPCL/PCRL/CPRL) */
     OPJ_PROG_ORDER progression;
 

src/libImaging/Jpeg2KEncode.c

@@ -435,6 +435,9 @@ j2k_encode_entry(Imaging im, ImagingCodecState state) {
     }
 
     params.irreversible = context->irreversible;
+    if (components == 3) {
+        params.tcp_mct = context->mct;
+    }
 
     params.prog_order = context->progression;