Support saving DDS images with pixel formats

Tests/test_file_dds.py

@@ -9,7 +9,13 @@
 
 from PIL import DdsImagePlugin, Image
 
-from .helper import assert_image_equal, assert_image_equal_tofile, hopper
+from .helper import (
+ assert_image_equal,
+ assert_image_equal_tofile,
+ assert_image_similar,
+ assert_image_similar_tofile,
+ hopper,
+)
 
 TEST_FILE_DXT1 = "Tests/images/dxt1-rgb-4bbp-noalpha_MipMaps-1.dds"
 TEST_FILE_DXT3 = "Tests/images/dxt3-argb-8bbp-explicitalpha_MipMaps-1.dds"
@@ -109,6 +115,32 @@ def test_sanity_ati1_bc4u(image_path: str) -> None:
  assert_image_equal_tofile(im, TEST_FILE_ATI1.replace(".dds", ".png"))
 
 
+def test_dx10_bc2(tmp_path: Path) -> None:
+ out = str(tmp_path / "temp.dds")
+ with Image.open(TEST_FILE_DXT3) as im:
+ im.save(out, pixel_format="BC2")
+
+ with Image.open(out) as reloaded:
+ assert reloaded.format == "DDS"
+ assert reloaded.mode == "RGBA"
+ assert reloaded.size == (256, 256)
+
+ assert_image_similar(im, reloaded, 3.81)
+
+
+def test_dx10_bc3(tmp_path: Path) -> None:
+ out = str(tmp_path / "temp.dds")
+ with Image.open(TEST_FILE_DXT5) as im:
+ im.save(out, pixel_format="BC3")
+
+ with Image.open(out) as reloaded:
+ assert reloaded.format == "DDS"
+ assert reloaded.mode == "RGBA"
+ assert reloaded.size == (256, 256)
+
+ assert_image_similar(im, reloaded, 3.69)
+
+
 @pytest.mark.parametrize(
  "image_path",
  (
@@ -370,7 +402,7 @@ def test_not_implemented(test_file: str) -> None:
 def test_save_unsupported_mode(tmp_path: Path) -> None:
  out = str(tmp_path / "temp.dds")
  im = hopper("HSV")
- with pytest.raises(OSError):
+ with pytest.raises(OSError, match="cannot write mode HSV as DDS"):
  im.save(out)
 
 
@@ -389,5 +421,93 @@ def test_save(mode: str, test_file: str, tmp_path: Path) -> None:
  assert im.mode == mode
  im.save(out)
 
- with Image.open(out) as reloaded:
- assert_image_equal(im, reloaded)
+ assert_image_equal_tofile(im, out)
+
+
+def test_save_unsupported_pixel_format(tmp_path: Path) -> None:
+ out = str(tmp_path / "temp.dds")
+ im = hopper()
+ with pytest.raises(OSError, match="cannot write pixel format UNKNOWN"):
+ im.save(out, pixel_format="UNKNOWN")
+
+
+def test_save_dxt1(tmp_path: Path) -> None:
+ # RGB
+ out = str(tmp_path / "temp.dds")
+ with Image.open(TEST_FILE_DXT1) as im:
+ im.convert("RGB").save(out, pixel_format="DXT1")
+ assert_image_similar_tofile(im, out, 1.84)
+
+ # RGBA
+ im_alpha = im.copy()
+ im_alpha.putpixel((0, 0), (0, 0, 0, 0))
+ im_alpha.save(out, pixel_format="DXT1")
+ with Image.open(out) as reloaded:
+ assert reloaded.getpixel((0, 0)) == (0, 0, 0, 0)
+
+ # L
+ im_l = im.convert("L")
+ im_l.save(out, pixel_format="DXT1")
+ assert_image_similar_tofile(im_l.convert("RGBA"), out, 6.07)
+
+ # LA
+ im_alpha.convert("LA").save(out, pixel_format="DXT1")
+ with Image.open(out) as reloaded:
+ assert reloaded.getpixel((0, 0)) == (0, 0, 0, 0)
+
+
+def test_save_dxt3(tmp_path: Path) -> None:
+ # RGB
+ out = str(tmp_path / "temp.dds")
+ with Image.open(TEST_FILE_DXT3) as im:
+ im_rgb = im.convert("RGB")
+ im_rgb.save(out, pixel_format="DXT3")
+ assert_image_similar_tofile(im_rgb.convert("RGBA"), out, 1.26)
+
+ # RGBA
+ im.save(out, pixel_format="DXT3")
+ assert_image_similar_tofile(im, out, 3.81)
+
+ # L
+ im_l = im.convert("L")
+ im_l.save(out, pixel_format="DXT3")
+ assert_image_similar_tofile(im_l.convert("RGBA"), out, 5.89)
+
+ # LA
+ im_la = im.convert("LA")
+ im_la.save(out, pixel_format="DXT3")
+ assert_image_similar_tofile(im_la.convert("RGBA"), out, 8.44)
+
+
+def test_save_dxt5(tmp_path: Path) -> None:
+ # RGB
+ out = str(tmp_path / "temp.dds")
+ with Image.open(TEST_FILE_DXT1) as im:
+ im.convert("RGB").save(out, pixel_format="DXT5")
+ assert_image_similar_tofile(im, out, 1.84)
+
+ # RGBA
+ with Image.open(TEST_FILE_DXT5) as im_rgba:
+ im_rgba.save(out, pixel_format="DXT5")
+ assert_image_similar_tofile(im_rgba, out, 3.69)
+
+ # L
+ im_l = im.convert("L")
+ im_l.save(out, pixel_format="DXT5")
+ assert_image_similar_tofile(im_l.convert("RGBA"), out, 6.07)
+
+ # LA
+ im_la = im_rgba.convert("LA")
+ im_la.save(out, pixel_format="DXT5")
+ assert_image_similar_tofile(im_la.convert("RGBA"), out, 8.32)
+
+
+def test_save_dx10_bc5(tmp_path: Path) -> None:
+ out = str(tmp_path / "temp.dds")
+ with Image.open(TEST_FILE_DX10_BC5_TYPELESS) as im:
+ im.save(out, pixel_format="BC5")
+ assert_image_similar_tofile(im, out, 9.56)
+
+ im = hopper("L")
+ with pytest.raises(OSError, match="only RGB mode can be written as BC5"):
+ im.save(out, pixel_format="BC5")

setup.py

@@ -68,6 +68,7 @@ def get_version() -> str:
  "Reduce",
  "Bands",
  "BcnDecode",
+ "BcnEncode",
  "BitDecode",
  "Blend",
  "Chops",

src/PIL/DdsImagePlugin.py

@@ -419,6 +419,14 @@ def _open(self) -> None:
  self._mode = "RGBA"
  self.pixel_format = "BC1"
  n = 1
+ elif dxgi_format in (DXGI_FORMAT.BC2_TYPELESS, DXGI_FORMAT.BC2_UNORM):
+ self._mode = "RGBA"
+ self.pixel_format = "BC2"
+ n = 2
+ elif dxgi_format in (DXGI_FORMAT.BC3_TYPELESS, DXGI_FORMAT.BC3_UNORM):
+ self._mode = "RGBA"
+ self.pixel_format = "BC3"
+ n = 3
  elif dxgi_format in (DXGI_FORMAT.BC4_TYPELESS, DXGI_FORMAT.BC4_UNORM):
  self._mode = "L"
  self.pixel_format = "BC4"
@@ -518,30 +526,68 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
  msg = f"cannot write mode {im.mode} as DDS"
  raise OSError(msg)
 
- alpha = im.mode[-1] == "A"
- if im.mode[0] == "L":
- pixel_flags = DDPF.LUMINANCE
- rawmode = im.mode
- if alpha:
- rgba_mask = [0x000000FF, 0x000000FF, 0x000000FF]
+ flags = DDSD.CAPS | DDSD.HEIGHT | DDSD.WIDTH | DDSD.PIXELFORMAT
+ bitcount = len(im.getbands()) * 8
+ pixel_format = im.encoderinfo.get("pixel_format")
+ args: tuple[int] | str
+ if pixel_format:
+ codec_name = "bcn"
+ flags |= DDSD.LINEARSIZE
+ pitch = (im.width + 3) * 4
+ rgba_mask = [0, 0, 0, 0]
+ pixel_flags = DDPF.FOURCC
+ if pixel_format == "DXT1":
+ fourcc = D3DFMT.DXT1
+ args = (1,)
+ elif pixel_format == "DXT3":
+ fourcc = D3DFMT.DXT3
+ args = (2,)
+ elif pixel_format == "DXT5":
+ fourcc = D3DFMT.DXT5
+ args = (3,)
  else:
- rgba_mask = [0xFF000000, 0xFF000000, 0xFF000000]
+ fourcc = D3DFMT.DX10
+ if pixel_format == "BC2":
+ args = (2,)
+ dxgi_format = DXGI_FORMAT.BC2_TYPELESS
+ elif pixel_format == "BC3":
+ args = (3,)
+ dxgi_format = DXGI_FORMAT.BC3_TYPELESS
+ elif pixel_format == "BC5":
+ args = (5,)
+ dxgi_format = DXGI_FORMAT.BC5_TYPELESS
+ if im.mode != "RGB":
+ msg = "only RGB mode can be written as BC5"
+ raise OSError(msg)
+ else:
+ msg = f"cannot write pixel format {pixel_format}"
+ raise OSError(msg)
  else:
- pixel_flags = DDPF.RGB
- rawmode = im.mode[::-1]
- rgba_mask = [0x00FF0000, 0x0000FF00, 0x000000FF]
+ codec_name = "raw"
+ flags |= DDSD.PITCH
+ pitch = (im.width * bitcount + 7) // 8
+
+ alpha = im.mode[-1] == "A"
+ if im.mode[0] == "L":
+ pixel_flags = DDPF.LUMINANCE
+ args = im.mode
+ if alpha:
+ rgba_mask = [0x000000FF, 0x000000FF, 0x000000FF]
+ else:
+ rgba_mask = [0xFF000000, 0xFF000000, 0xFF000000]
+ else:
+ pixel_flags = DDPF.RGB
+ args = im.mode[::-1]
+ rgba_mask = [0x00FF0000, 0x0000FF00, 0x000000FF]
 
+ if alpha:
+ r, g, b, a = im.split()
+ im = Image.merge("RGBA", (a, r, g, b))
  if alpha:
- r, g, b, a = im.split()
- im = Image.merge("RGBA", (a, r, g, b))
- if alpha:
- pixel_flags |= DDPF.ALPHAPIXELS
- rgba_mask.append(0xFF000000 if alpha else 0)
-
- flags = DDSD.CAPS | DDSD.HEIGHT | DDSD.WIDTH | DDSD.PITCH | DDSD.PIXELFORMAT
- bitcount = len(im.getbands()) * 8
- pitch = (im.width * bitcount + 7) // 8
+ pixel_flags |= DDPF.ALPHAPIXELS
+ rgba_mask.append(0xFF000000 if alpha else 0)
 
+ fourcc = D3DFMT.UNKNOWN
  fp.write(
  o32(DDS_MAGIC)
  + struct.pack(
@@ -556,11 +602,16 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
  )
  + struct.pack("11I", *((0,) * 11)) # reserved
  # pfsize, pfflags, fourcc, bitcount
- + struct.pack("<4I", 32, pixel_flags, 0, bitcount)
+ + struct.pack("<4I", 32, pixel_flags, fourcc, bitcount)
  + struct.pack("<4I", *rgba_mask) # dwRGBABitMask
  + struct.pack("<5I", DDSCAPS.TEXTURE, 0, 0, 0, 0)
  )
- ImageFile._save(im, fp, [ImageFile._Tile("raw", (0, 0) + im.size, 0, rawmode)])
+ if fourcc == D3DFMT.DX10:
+ fp.write(
+ # dxgi_format, 2D resource, misc, array size, straight alpha
+ struct.pack("<5I", dxgi_format, 3, 0, 0, 1)
+ )
+ ImageFile._save(im, fp, [ImageFile._Tile(codec_name, (0, 0) + im.size, 0, args)])
 
 
 def _accept(prefix: bytes) -> bool:

src/_imaging.c

@@ -4041,6 +4041,8 @@ PyImaging_ZipDecoderNew(PyObject *self, PyObject *args);
 
 /* Encoders (in encode.c) */
 extern PyObject *
+PyImaging_BcnEncoderNew(PyObject *self, PyObject *args);
+extern PyObject *
 PyImaging_EpsEncoderNew(PyObject *self, PyObject *args);
 extern PyObject *
 PyImaging_GifEncoderNew(PyObject *self, PyObject *args);
@@ -4109,6 +4111,7 @@ static PyMethodDef functions[] = {
 
  /* Codecs */
  {"bcn_decoder", (PyCFunction)PyImaging_BcnDecoderNew, METH_VARARGS},
+ {"bcn_encoder", (PyCFunction)PyImaging_BcnEncoderNew, METH_VARARGS},
  {"bit_decoder", (PyCFunction)PyImaging_BitDecoderNew, METH_VARARGS},
  {"eps_encoder", (PyCFunction)PyImaging_EpsEncoderNew, METH_VARARGS},
  {"fli_decoder", (PyCFunction)PyImaging_FliDecoderNew, METH_VARARGS},

src/encode.c

@@ -27,6 +27,7 @@
 
 #include "thirdparty/pythoncapi_compat.h"
 #include "libImaging/Imaging.h"
+#include "libImaging/Bcn.h"
 #include "libImaging/Gif.h"
 
 #ifdef HAVE_UNISTD_H
@@ -350,6 +351,31 @@
  return 0;
 }
 
+/* -------------------------------------------------------------------- */
+/* BCN */
+/* -------------------------------------------------------------------- */
+
+PyObject *
+PyImaging_BcnEncoderNew(PyObject *self, PyObject *args) {
+ ImagingEncoderObject *encoder;
+
+ char *mode;
+ int n;
+ if (!PyArg_ParseTuple(args, "si", &mode, &n)) {
+ return NULL;
+ }
+
+ encoder = PyImaging_EncoderNew(0);
+ if (encoder == NULL) {
+ return NULL;
+ }
+
+ encoder->encode = ImagingBcnEncode;
+ encoder->state.state = n;
+
+ return (PyObject *)encoder;
+}
+
 /* -------------------------------------------------------------------- */
 /* EPS */
 /* -------------------------------------------------------------------- */