Merge pull request #7872 from radarhere/webp_alpha_quality

Author: hugovk

Tests/test_file_webp_alpha.py

@@ -151,3 +151,15 @@ def test_write_unsupported_mode_PA(tmp_path: Path) -> None:
  target = im.convert("RGBA")
 
  assert_image_similar(image, target, 25.0)
+
+
+def test_alpha_quality(tmp_path: Path) -> None:
+ with Image.open("Tests/images/transparent.png") as im:
+ out = str(tmp_path / "temp.webp")
+ im.save(out)
+
+ out_quality = str(tmp_path / "quality.webp")
+ im.save(out_quality, alpha_quality=50)
+ with Image.open(out) as reloaded:
+ with Image.open(out_quality) as reloaded_quality:
+ assert reloaded.tobytes() != reloaded_quality.tobytes()

Tests/test_file_webp_animated.py

@@ -188,3 +188,21 @@ def test_seek_errors() -> None:
 
  with pytest.raises(EOFError):
  im.seek(42)
+
+
+def test_alpha_quality(tmp_path: Path) -> None:
+ with Image.open("Tests/images/transparent.png") as im:
+ first_frame = Image.new("L", im.size)
+
+ out = str(tmp_path / "temp.webp")
+ first_frame.save(out, save_all=True, append_images=[im])
+
+ out_quality = str(tmp_path / "quality.webp")
+ first_frame.save(
+ out_quality, save_all=True, append_images=[im], alpha_quality=50
+ )
+ with Image.open(out) as reloaded:
+ reloaded.seek(1)
+ with Image.open(out_quality) as reloaded_quality:
+ reloaded_quality.seek(1)
+ assert reloaded.tobytes() != reloaded_quality.tobytes()

docs/handbook/image-file-formats.rst

@@ -1234,11 +1234,15 @@ The :py:meth:`~PIL.Image.Image.save` method supports the following options:
  If present and true, instructs the WebP writer to use lossless compression.
 
 **quality**
- Integer, 0-100, Defaults to 80. For lossy, 0 gives the smallest
+ Integer, 0-100, defaults to 80. For lossy, 0 gives the smallest
  size and 100 the largest. For lossless, this parameter is the amount
  of effort put into the compression: 0 is the fastest, but gives larger
  files compared to the slowest, but best, 100.
 
+**alpha_quality**
+ Integer, 0-100, defaults to 100. For lossy compression only. 0 gives the
+ smallest size and 100 is lossless.
+
 **method**
  Quality/speed trade-off (0=fast, 6=slower-better). Defaults to 4.
 

src/PIL/WebPImagePlugin.py

@@ -217,6 +217,7 @@ def _save_all(im, fp, filename):
  verbose = False
  lossless = im.encoderinfo.get("lossless", False)
  quality = im.encoderinfo.get("quality", 80)
+ alpha_quality = im.encoderinfo.get("alpha_quality", 100)
  method = im.encoderinfo.get("method", 0)
  icc_profile = im.encoderinfo.get("icc_profile") or ""
  exif = im.encoderinfo.get("exif", "")
@@ -296,6 +297,7 @@ def _save_all(im, fp, filename):
  rawmode,
  lossless,
  quality,
+ alpha_quality,
  method,
  )
 
@@ -310,7 +312,7 @@ def _save_all(im, fp, filename):
  im.seek(cur_idx)
 
  # Force encoder to flush frames
- enc.add(None, round(timestamp), 0, 0, "", lossless, quality, 0)
+ enc.add(None, round(timestamp), 0, 0, "", lossless, quality, alpha_quality, 0)
 
  # Get the final output from the encoder
  data = enc.assemble(icc_profile, exif, xmp)
@@ -324,6 +326,7 @@ def _save_all(im, fp, filename):
 def _save(im, fp, filename):
  lossless = im.encoderinfo.get("lossless", False)
  quality = im.encoderinfo.get("quality", 80)
+ alpha_quality = im.encoderinfo.get("alpha_quality", 100)
  icc_profile = im.encoderinfo.get("icc_profile") or ""
  exif = im.encoderinfo.get("exif", b"")
  if isinstance(exif, Image.Exif):
@@ -343,6 +346,7 @@ def _save(im, fp, filename):
  im.size[1],
  lossless,
  float(quality),
+ float(alpha_quality),
  im.mode,
  icc_profile,
  method,

src/_webp.c

@@ -195,6 +195,7 @@ _anim_encoder_add(PyObject *self, PyObject *args) {
  char *mode;
  int lossless;
  float quality_factor;
+ float alpha_quality_factor;
  int method;
  WebPConfig config;
  WebPAnimEncoderObject *encp = (WebPAnimEncoderObject *)self;
@@ -203,7 +204,7 @@ _anim_encoder_add(PyObject *self, PyObject *args) {
 
  if (!PyArg_ParseTuple(
  args,
- "z#iiisifi",
+ "z#iiisiffi",
  (char **)&rgb,
  &size,
  &timestamp,
@@ -212,6 +213,7 @@ _anim_encoder_add(PyObject *self, PyObject *args) {
  &mode,
  &lossless,
  &quality_factor,
+ &alpha_quality_factor,
  &method)) {
  return NULL;
  }
@@ -229,6 +231,7 @@ _anim_encoder_add(PyObject *self, PyObject *args) {
  }
  config.lossless = lossless;
  config.quality = quality_factor;
+ config.alpha_quality = alpha_quality_factor;
  config.method = method;
 
  // Validate the config
@@ -578,6 +581,7 @@ WebPEncode_wrapper(PyObject *self, PyObject *args) {
  int height;
  int lossless;
  float quality_factor;
+ float alpha_quality_factor;
  int method;
  int exact;
  uint8_t *rgb;
@@ -601,13 +605,14 @@ WebPEncode_wrapper(PyObject *self, PyObject *args) {
 
  if (!PyArg_ParseTuple(
  args,
- "y#iiifss#iis#s#",
+ "y#iiiffss#iis#s#",
  (char **)&rgb,
  &size,
  &width,
  &height,
  &lossless,
  &quality_factor,
+ &alpha_quality_factor,
  &mode,
  &icc_bytes,
  &icc_size,
@@ -637,6 +642,7 @@ WebPEncode_wrapper(PyObject *self, PyObject *args) {
  }
  config.lossless = lossless;
  config.quality = quality_factor;
+ config.alpha_quality = alpha_quality_factor;
  config.method = method;
 #if WEBP_ENCODER_ABI_VERSION >= 0x0209
  // the "exact" flag is only available in libwebp 0.5.0 and later