Added reading of JPEG2000 palettes

Tests/test_file_jpeg2k.py

@@ -364,6 +364,16 @@ def test_subsampling_decode(name: str) -> None:
         assert_image_similar(im, expected, epsilon)
 
 
+@pytest.mark.skipif(
+    not os.path.exists(EXTRA_DIR), reason="Extra image files not installed"
+)
+def test_pclr() -> None:
+    with Image.open(f"{EXTRA_DIR}/issue104_jpxstream.jp2") as im:
+        assert im.mode == "P"
+        assert len(im.palette.colors) == 256
+        assert im.palette.colors[(255, 255, 255)] == 0
+
+
 def test_comment() -> None:
     with Image.open("Tests/images/comment.jp2") as im:
         assert im.info["comment"] == b"Created by OpenJPEG version 2.5.0"

src/PIL/Jpeg2KImagePlugin.py

@@ -19,7 +19,7 @@
 import os
 import struct
 
-from . import Image, ImageFile, _binary
+from . import Image, ImageFile, ImagePalette, _binary
 
 
 class BoxReader:
@@ -162,6 +162,7 @@ def _parse_jp2_header(fp):
     bpc = None
     nc = None
     dpi = None  # 2-tuple of DPI info, or None
+    palette = None
 
     while header.has_next_box():
         tbox = header.next_box_type()
@@ -179,6 +180,14 @@ def _parse_jp2_header(fp):
                 mode = "RGB"
             elif nc == 4:
                 mode = "RGBA"
+        elif tbox == b"pclr" and mode in ("L", "LA"):
+            ne, npc = header.read_fields(">HB")
+            bitdepths = header.read_fields(">" + ("B" * npc))
+            if max(bitdepths) <= 8:
+                palette = ImagePalette.ImagePalette()
+                for i in range(ne):
+                    palette.getcolor(header.read_fields(">" + ("B" * npc)))
+                mode = "P" if mode == "L" else "PA"
         elif tbox == b"res ":
             res = header.read_boxes()
             while res.has_next_box():
@@ -195,7 +204,7 @@ def _parse_jp2_header(fp):
         msg = "Malformed JP2 header"
         raise SyntaxError(msg)
 
-    return size, mode, mimetype, dpi
+    return size, mode, mimetype, dpi, palette
 
 
 ##
@@ -217,7 +226,7 @@ def _open(self):
             if sig == b"\x00\x00\x00\x0cjP  \x0d\x0a\x87\x0a":
                 self.codec = "jp2"
                 header = _parse_jp2_header(self.fp)
-                self._size, self._mode, self.custom_mimetype, dpi = header
+                self._size, self._mode, self.custom_mimetype, dpi, self.palette = header
                 if dpi is not None:
                     self.info["dpi"] = dpi
                 if self.fp.read(12).endswith(b"jp2c\xff\x4f\xff\x51"):

src/libImaging/Jpeg2KDecode.c

@@ -615,6 +615,8 @@ j2ku_sycca_rgba(
 
 static const struct j2k_decode_unpacker j2k_unpackers[] = {
     {"L", OPJ_CLRSPC_GRAY, 1, 0, j2ku_gray_l},
+    {"P", OPJ_CLRSPC_SRGB, 1, 0, j2ku_gray_l},
+    {"PA", OPJ_CLRSPC_SRGB, 2, 0, j2ku_graya_la},
     {"I;16", OPJ_CLRSPC_GRAY, 1, 0, j2ku_gray_i},
     {"I;16B", OPJ_CLRSPC_GRAY, 1, 0, j2ku_gray_i},
     {"LA", OPJ_CLRSPC_GRAY, 2, 0, j2ku_graya_la},