Fix reading RGB and CMYK IPTC images

Tests/test_file_iptc.py

@@ -2,28 +2,87 @@
 
 from io import BytesIO
 
+import pytest
+
 from PIL import Image, IptcImagePlugin, TiffImagePlugin, TiffTags
 
 from .helper import assert_image_equal, hopper
 
 TEST_FILE = "Tests/images/iptc.jpg"
 
 
+def create_iptc_image(info: dict[str, int] = {}) -> BytesIO:
+    def field(tag, value):
+        return bytes((0x1C,) + tag + (0, len(value))) + value
+
+    data = field((3, 60), bytes((info.get("layers", 1), info.get("component", 0))))
+    data += field((3, 120), bytes((info.get("compression", 1),)))
+    if "band" in info:
+        data += field((3, 65), bytes((info["band"] + 1,)))
+    data += field((3, 20), b"\x01")  # width
+    data += field((3, 30), b"\x01")  # height
+    data += field(
+        (8, 10),
+        bytes((info.get("data", 0),)),
+    )
+
+    return BytesIO(data)
+
+
 def test_open() -> None:
     expected = Image.new("L", (1, 1))
 
-    f = BytesIO(
-        b"\x1c\x03<\x00\x02\x01\x00\x1c\x03x\x00\x01\x01\x1c\x03\x14\x00\x01\x01"
-        b"\x1c\x03\x1e\x00\x01\x01\x1c\x08\n\x00\x01\x00"
-    )
+    f = create_iptc_image()
     with Image.open(f) as im:
-        assert im.tile == [("iptc", (0, 0, 1, 1), 25, "raw")]
+        assert im.tile == [("iptc", (0, 0, 1, 1), 25, ("raw", None))]
         assert_image_equal(im, expected)
 
     with Image.open(f) as im:
         assert im.load() is not None
 
 
+def test_field_length() -> None:
+    f = create_iptc_image()
+    f.seek(28)
+    f.write(b"\xff")
+    with pytest.raises(OSError, match="illegal field length in IPTC/NAA file"):
+        with Image.open(f):
+            pass
+
+
+@pytest.mark.parametrize("layers, mode", ((3, "RGB"), (4, "CMYK")))
+def test_layers(layers: int, mode: str) -> None:
+    for band in range(-1, layers):
+        info = {"layers": layers, "component": 1, "data": 5}
+        if band != -1:
+            info["band"] = band
+        f = create_iptc_image(info)
+        with Image.open(f) as im:
+            assert im.mode == mode
+
+            data = [0] * layers
+            data[max(band, 0)] = 5
+            assert im.getpixel((0, 0)) == tuple(data)
+
+
+def test_unknown_compression() -> None:
+    f = create_iptc_image({"compression": 2})
+    with pytest.raises(OSError, match="Unknown IPTC image compression"):
+        with Image.open(f):
+            pass
+
+
+def test_getiptcinfo() -> None:
+    f = create_iptc_image()
+    with Image.open(f) as im:
+        assert IptcImagePlugin.getiptcinfo(im) == {
+            (3, 60): b"\x01\x00",
+            (3, 120): b"\x01",
+            (3, 20): b"\x01",
+            (3, 30): b"\x01",
+        }
+
+
 def test_getiptcinfo_jpg_none() -> None:
     # Arrange
     with hopper() as im:

src/PIL/IptcImagePlugin.py

@@ -34,10 +34,6 @@
     return i32((b"\0\0\0\0" + c)[-4:])
 
 
-def _i8(c: int | bytes) -> int:
-    return c if isinstance(c, int) else c[0]
-
-
 ##
 # Image plugin for IPTC/NAA datastreams.  To read IPTC/NAA fields
 # from TIFF and JPEG files, use the <b>getiptcinfo</b> function.
@@ -100,16 +96,18 @@
         # mode
         layers = self.info[(3, 60)][0]
         component = self.info[(3, 60)][1]
-        if (3, 65) in self.info:
-            id = self.info[(3, 65)][0] - 1
-        else:
-            id = 0
         if layers == 1 and not component:
             self._mode = "L"
-        elif layers == 3 and component:
-            self._mode = "RGB"[id]
-        elif layers == 4 and component:
-            self._mode = "CMYK"[id]
+            band = None
+        else:
+            if layers == 3 and component:
+                self._mode = "RGB"
+            elif layers == 4 and component:
+                self._mode = "CMYK"
+            if (3, 65) in self.info:
+                band = self.info[(3, 65)][0] - 1
+            else:
+                band = 0
 
         # size
         self._size = self.getint((3, 20)), self.getint((3, 30))
@@ -124,39 +122,44 @@
         # tile
         if tag == (8, 10):
             self.tile = [
-                ImageFile._Tile("iptc", (0, 0) + self.size, offset, compression)
+                ImageFile._Tile("iptc", (0, 0) + self.size, offset, (compression, band))
             ]
 
     def load(self) -> Image.core.PixelAccess | None:
-        if len(self.tile) != 1 or self.tile[0][0] != "iptc":
-            return ImageFile.ImageFile.load(self)
-
-        offset, compression = self.tile[0][2:]
-
-        self.fp.seek(offset)
-
-        # Copy image data to temporary file
-        o = BytesIO()
-        if compression == "raw":
-            # To simplify access to the extracted file,
-            # prepend a PPM header
-            o.write(b"P5\n%d %d\n255\n" % self.size)
-        while True:
-            type, size = self.field()
-            if type != (8, 10):
-                break
-            while size > 0:
-                s = self.fp.read(min(size, 8192))
-                if not s:
+        if self.tile:
+            args = self.tile[0].args
+            assert isinstance(args, tuple)
+            compression, band = args
+
+            self.fp.seek(self.tile[0].offset)
+
+            # Copy image data to temporary file
+            o = BytesIO()
+            if compression == "raw":
+                # To simplify access to the extracted file,
+                # prepend a PPM header
+                o.write(b"P5\n%d %d\n255\n" % self.size)
+            while True:
+                type, size = self.field()
+                if type != (8, 10):
                     break
-                o.write(s)
-                size -= len(s)
-
-        with Image.open(o) as _im:
-            _im.load()
-            self.im = _im.im
-        self.tile = []
-        return Image.Image.load(self)
+                while size > 0:
+                    s = self.fp.read(min(size, 8192))
+                    if not s:
+                        break
+                    o.write(s)
+                    size -= len(s)
+
+            with Image.open(o) as _im:
+                if band is not None:
+                    bands = [Image.new("L", _im.size)] * Image.getmodebands(self.mode)
+                    bands[band] = _im
+                    _im = Image.merge(self.mode, bands)
+                else:
+                    _im.load()
+                self.im = _im.im
+            self.tile = []
+        return ImageFile.ImageFile.load(self)
 
 
 Image.register_open(IptcImageFile.format, IptcImageFile)