Improved ImagePalette

Tests/test_file_apng.py

@@ -249,8 +249,8 @@ def test_apng_mode():
         assert im.mode == "P"
         im.seek(im.n_frames - 1)
         im = im.convert("RGBA")
-        assert im.getpixel((0, 0)) == (0, 255, 0, 255)
-        assert im.getpixel((64, 32)) == (0, 255, 0, 255)
+        assert im.getpixel((0, 0)) == (255, 0, 0, 0)
+        assert im.getpixel((64, 32)) == (255, 0, 0, 0)
 
     with Image.open("Tests/images/apng/mode_palette_1bit_alpha.png") as im:
         assert im.mode == "P"

Tests/test_file_gif.py

@@ -749,10 +749,10 @@ def test_rgb_transparency(tmp_path):
     # Single frame
     im = Image.new("RGB", (1, 1))
     im.info["transparency"] = (255, 0, 0)
-    pytest.warns(UserWarning, im.save, out)
+    im.save(out)
 
     with Image.open(out) as reloaded:
-        assert "transparency" not in reloaded.info
+        assert "transparency" in reloaded.info
 
     # Multiple frames
     im = Image.new("RGB", (1, 1))

Tests/test_image.py

@@ -582,6 +582,10 @@ def test_register_extensions(self):
         assert ext_individual == ext_multiple
 
     def test_remap_palette(self):
+        # Test identity transform
+        with Image.open("Tests/images/hopper.gif") as im:
+            assert_image_equal(im, im.remap_palette(list(range(256))))
+
         # Test illegal image mode
         with hopper() as im:
             with pytest.raises(ValueError):
@@ -606,7 +610,7 @@ def _make_new(base_image, im, palette_result=None):
             else:
                 assert new_im.palette is None
 
-        _make_new(im, im_p, im_p.palette)
+        _make_new(im, im_p, ImagePalette.ImagePalette(list(range(256)) * 3))
         _make_new(im_p, im, None)
         _make_new(im, blank_p, ImagePalette.ImagePalette())
         _make_new(im, blank_pa, ImagePalette.ImagePalette())

Tests/test_image_convert.py

@@ -93,7 +93,7 @@ def test_trns_p(tmp_path):
     im_l.save(f)
 
     im_rgb = im.convert("RGB")
-    assert im_rgb.info["transparency"] == (0, 0, 0)  # undone
+    assert im_rgb.info["transparency"] == (0, 1, 2)  # undone
     im_rgb.save(f)
 
 
@@ -128,8 +128,8 @@ def test_trns_l(tmp_path):
     assert "transparency" in im_p.info
     im_p.save(f)
 
-    im_p = pytest.warns(UserWarning, im.convert, "P", palette=Image.ADAPTIVE)
-    assert "transparency" not in im_p.info
+    im_p = im.convert("P", palette=Image.ADAPTIVE)
+    assert "transparency" in im_p.info
     im_p.save(f)
 
 
@@ -155,13 +155,19 @@ def test_trns_RGB(tmp_path):
     assert "transparency" not in im_p.info
     im_p.save(f)
 
+    im = Image.new("RGB", (1, 1))
+    im.info["transparency"] = im.getpixel((0, 0))
+    im_p = im.convert("P", palette=Image.ADAPTIVE)
+    assert im_p.info["transparency"] == im_p.getpixel((0, 0))
+    im_p.save(f)
+
 
 def test_gif_with_rgba_palette_to_p():
     # See https://github.com/python-pillow/Pillow/issues/2433
     with Image.open("Tests/images/hopper.gif") as im:
         im.info["transparency"] = 255
         im.load()
-        assert im.palette.mode == "RGBA"
+        assert im.palette.mode == "RGB"
         im_p = im.convert("P")
 
     # Should not raise ValueError: unrecognized raw mode

Tests/test_imageops.py

@@ -157,9 +157,16 @@ def test_scale():
 
 
 def test_expand_palette():
-    im = Image.open("Tests/images/hopper.gif")
-    im_expanded = ImageOps.expand(im)
-    assert_image_equal(im_expanded.convert("RGB"), im.convert("RGB"))
+    im = Image.open("Tests/images/p_16.tga")
+    im_expanded = ImageOps.expand(im, 10, (255, 0, 0))
+
+    px = im_expanded.convert("RGB").load()
+    assert px[0, 0] == (255, 0, 0)
+
+    im_cropped = im_expanded.crop(
+        (10, 10, im_expanded.width - 10, im_expanded.height - 10)
+    )
+    assert_image_equal(im_cropped, im)
 
 
 def test_colorize_2color():

Tests/test_imagepalette.py

@@ -2,27 +2,47 @@
 
 from PIL import Image, ImagePalette
 
-from .helper import assert_image_equal_tofile
+from .helper import assert_image_equal, assert_image_equal_tofile
 
 
 def test_sanity():
 
-    ImagePalette.ImagePalette("RGB", list(range(256)) * 3)
+    palette = ImagePalette.ImagePalette("RGB", list(range(256)) * 3)
+    assert len(palette.colors) == 256
+
     with pytest.raises(ValueError):
-        ImagePalette.ImagePalette("RGB", list(range(256)) * 2)
+        ImagePalette.ImagePalette("RGB", list(range(256)) * 3, 10)
+
+
+def test_reload():
+    im = Image.open("Tests/images/hopper.gif")
+    original = im.copy()
+    im.palette.dirty = 1
+    assert_image_equal(im.convert("RGB"), original.convert("RGB"))
 
 
 def test_getcolor():
 
     palette = ImagePalette.ImagePalette()
+    assert len(palette.palette) == 0
+    assert len(palette.colors) == 0
 
     test_map = {}
     for i in range(256):
         test_map[palette.getcolor((i, i, i))] = i
-
     assert len(test_map) == 256
+
+    # Colors can be converted between RGB and RGBA
+    rgba_palette = ImagePalette.ImagePalette("RGBA")
+    assert rgba_palette.getcolor((0, 0, 0)) == rgba_palette.getcolor((0, 0, 0, 255))
+
+    assert palette.getcolor((0, 0, 0)) == palette.getcolor((0, 0, 0, 255))
+
+    # An error is raised when the palette is full
     with pytest.raises(ValueError):
         palette.getcolor((1, 2, 3))
+    # But not if the image is not using one of the palette entries
+    palette.getcolor((1, 2, 3), image=Image.new("P", (1, 1)))
 
     # Test unknown color specifier
     with pytest.raises(ValueError):
@@ -116,7 +136,7 @@ def test_getdata():
     mode, data_out = palette.getdata()
 
     # Assert
-    assert mode == "RGB;L"
+    assert mode == "RGB"
 
 
 def test_rawmode_getdata():

src/PIL/GifImagePlugin.py

@@ -461,10 +461,10 @@ def _write_multiple_frames(im, fp, palette):
                 previous = im_frames[-1]
                 if encoderinfo.get("disposal") == 2:
                     if background_im is None:
-                        background = _get_background(
-                            im,
-                            im.encoderinfo.get("background", im.info.get("background")),
+                        color = im.encoderinfo.get(
+                            "transparency", im.info.get("transparency", (0, 0, 0))
                         )
+                        background = _get_background(im_frame, color)
                         background_im = Image.new("P", im_frame.size, background)
                         background_im.putpalette(im_frames[0]["im"].palette)
                     base_im = background_im
@@ -760,7 +760,15 @@ def _get_background(im, infoBackground):
             # WebPImagePlugin stores an RGBA value in info["background"]
             # So it must be converted to the same format as GifImagePlugin's
             # info["background"] - a global color table index
-            background = im.palette.getcolor(background)
+            try:
+                background = im.palette.getcolor(background, im)
+            except ValueError as e:
+                if str(e) == "cannot allocate more than 256 colors":
+                    # If all 256 colors are in use,
+                    # then there is no need for the background color
+                    return 0
+                else:
+                    raise
     return background
 
 

src/PIL/Image.py

@@ -833,7 +833,7 @@ def load(self):
             palette_length = self.im.putpalette(mode, arr)
             self.palette.dirty = 0
             self.palette.rawmode = None
-            if "transparency" in self.info:
+            if "transparency" in self.info and mode in ("RGBA", "LA", "PA"):
                 if isinstance(self.info["transparency"], int):
                     self.im.putpalettealpha(self.info["transparency"], 0)
                 else:
@@ -977,21 +977,28 @@ def convert_transparency(m, v):
                     if self.mode == "P":
                         trns_im.putpalette(self.palette)
                         if isinstance(t, tuple):
+                            err = "Couldn't allocate a palette color for transparency"
                             try:
-                                t = trns_im.palette.getcolor(t)
-                            except Exception as e:
-                                raise ValueError(
-                                    "Couldn't allocate a palette color for transparency"
-                                ) from e
-                    trns_im.putpixel((0, 0), t)
-
-                    if mode in ("L", "RGB"):
-                        trns_im = trns_im.convert(mode)
+                                t = trns_im.palette.getcolor(t, self)
+                            except ValueError as e:
+                                if str(e) == "cannot allocate more than 256 colors":
+                                    # If all 256 colors are in use,
+                                    # then there is no need for transparency
+                                    t = None
+                                else:
+                                    raise ValueError(err) from e
+                    if t is None:
+                        trns = None
                     else:
-                        # can't just retrieve the palette number, got to do it
-                        # after quantization.
-                        trns_im = trns_im.convert("RGB")
-                    trns = trns_im.getpixel((0, 0))
+                        trns_im.putpixel((0, 0), t)
+
+                        if mode in ("L", "RGB"):
+                            trns_im = trns_im.convert(mode)
+                        else:
+                            # can't just retrieve the palette number, got to do it
+                            # after quantization.
+                            trns_im = trns_im.convert("RGB")
+                        trns = trns_im.getpixel((0, 0))
 
             elif self.mode == "P" and mode == "RGBA":
                 t = self.info["transparency"]
@@ -1009,14 +1016,14 @@ def convert_transparency(m, v):
             new = self._new(im)
             from . import ImagePalette
 
-            new.palette = ImagePalette.raw("RGB", new.im.getpalette("RGB"))
+            new.palette = ImagePalette.ImagePalette("RGB", new.im.getpalette("RGB"))
             if delete_trns:
                 # This could possibly happen if we requantize to fewer colors.
                 # The transparency would be totally off in that case.
                 del new.info["transparency"]
             if trns is not None:
                 try:
-                    new.info["transparency"] = new.palette.getcolor(trns)
+                    new.info["transparency"] = new.palette.getcolor(trns, new)
                 except Exception:
                     # if we can't make a transparent color, don't leave the old
                     # transparency hanging around to mess us up.
@@ -1039,16 +1046,25 @@ def convert_transparency(m, v):
                 raise ValueError("illegal conversion") from e
 
         new_im = self._new(im)
+        if mode == "P" and palette != ADAPTIVE:
+            from . import ImagePalette
+
+            new_im.palette = ImagePalette.ImagePalette("RGB", list(range(256)) * 3)
         if delete_trns:
             # crash fail if we leave a bytes transparency in an rgb/l mode.
             del new_im.info["transparency"]
         if trns is not None:
             if new_im.mode == "P":
                 try:
-                    new_im.info["transparency"] = new_im.palette.getcolor(trns)
-                except Exception:
+                    new_im.info["transparency"] = new_im.palette.getcolor(trns, new_im)
+                except ValueError as e:
                     del new_im.info["transparency"]
-                    warnings.warn("Couldn't allocate palette entry for transparency")
+                    if str(e) != "cannot allocate more than 256 colors":
+                        # If all 256 colors are in use,
+                        # then there is no need for transparency
+                        warnings.warn(
+                            "Couldn't allocate palette entry for transparency"
+                        )
             else:
                 new_im.info["transparency"] = trns
         return new_im
@@ -1700,7 +1716,7 @@ def putpalette(self, data, rawmode="RGB"):
         Attaches a palette to this image.  The image must be a "P", "PA", "L"
         or "LA" image.
 
-        The palette sequence must contain either 768 integer values, or 1024
+        The palette sequence must contain at most 768 integer values, or 1024
         integer values if alpha is included. Each group of values represents
         the red, green, blue (and alpha if included) values for the
         corresponding pixel index. Instead of an integer sequence, you can use
@@ -1713,7 +1729,6 @@ def putpalette(self, data, rawmode="RGB"):
 
         if self.mode not in ("L", "LA", "P", "PA"):
             raise ValueError("illegal image mode")
-        self.load()
         if isinstance(data, ImagePalette.ImagePalette):
             palette = ImagePalette.raw(data.rawmode, data.palette)
         else:
@@ -1760,7 +1775,7 @@ def putpixel(self, xy, value):
             and len(value) in [3, 4]
         ):
             # RGB or RGBA value for a P image
-            value = self.palette.getcolor(value)
+            value = self.palette.getcolor(value, self)
         return self.im.putpixel(xy, value)
 
     def remap_palette(self, dest_map, source_palette=None):
@@ -1781,6 +1796,7 @@ def remap_palette(self, dest_map, source_palette=None):
 
         if source_palette is None:
             if self.mode == "P":
+                self.load()
                 real_source_palette = self.im.getpalette("RGB")[:768]
             else:  # L-mode
                 real_source_palette = bytearray(i // 3 for i in range(768))
@@ -1818,23 +1834,19 @@ def remap_palette(self, dest_map, source_palette=None):
         m_im = self.copy()
         m_im.mode = "P"
 
-        m_im.palette = ImagePalette.ImagePalette(
-            "RGB", palette=mapping_palette * 3, size=768
-        )
+        m_im.palette = ImagePalette.ImagePalette("RGB", palette=mapping_palette * 3)
         # possibly set palette dirty, then
         # m_im.putpalette(mapping_palette, 'L')  # converts to 'P'
         # or just force it.
         # UNDONE -- this is part of the general issue with palettes
-        m_im.im.putpalette(*m_im.palette.getdata())
+        m_im.im.putpalette("RGB;L", m_im.palette.tobytes())
 
         m_im = m_im.convert("L")
 
         # Internally, we require 768 bytes for a palette.
         new_palette_bytes = palette_bytes + (768 - len(palette_bytes)) * b"\x00"
         m_im.putpalette(new_palette_bytes)
-        m_im.palette = ImagePalette.ImagePalette(
-            "RGB", palette=palette_bytes, size=len(palette_bytes)
-        )
+        m_im.palette = ImagePalette.ImagePalette("RGB", palette=palette_bytes)
 
         return m_im
 

src/PIL/ImageDraw.py

@@ -70,6 +70,7 @@ def __init__(self, im, mode=None):
             self.palette = im.palette
         else:
             self.palette = None
+        self._image = im
         self.im = im.im
         self.draw = Image.core.draw(self.im, blend)
         self.mode = mode
@@ -108,13 +109,13 @@ def _getink(self, ink, fill=None):
                 if isinstance(ink, str):
                     ink = ImageColor.getcolor(ink, self.mode)
                 if self.palette and not isinstance(ink, numbers.Number):
-                    ink = self.palette.getcolor(ink)
+                    ink = self.palette.getcolor(ink, self._image)
                 ink = self.draw.draw_ink(ink)
             if fill is not None:
                 if isinstance(fill, str):
                     fill = ImageColor.getcolor(fill, self.mode)
                 if self.palette and not isinstance(fill, numbers.Number):
-                    fill = self.palette.getcolor(fill)
+                    fill = self.palette.getcolor(fill, self._image)
                 fill = self.draw.draw_ink(fill)
         return ink, fill