Merge pull request #390 from wiredfool/webp-lossless

Lossless WEBP Support

PIL/WebPImagePlugin.py

@@ -12,6 +12,7 @@ _VALID_WEBP_MODES = {
 _VP8_MODES_BY_IDENTIFIER = {
     b"VP8 ": "RGB",
     b"VP8X": "RGBA",
+    b"VP8L": "RGBA", # lossless
     }
 
 

Tests/test_file_webp.py

@@ -66,6 +66,26 @@ def test_write_rgb():
     assert_image_similar(image, target, 20.0)
 
 
+def test_write_lossless_rgb():
+    temp_file = tempfile("temp.webp")
+
+    lena("RGB").save(temp_file, lossless=True)
+
+    image = Image.open(temp_file)
+    image.load()
+
+    assert_equal(image.mode, "RGB")
+    assert_equal(image.size, (128, 128))
+    assert_equal(image.format, "WEBP")
+    assert_no_exception(lambda: image.load())
+    assert_no_exception(lambda: image.getdata())
+
+
+    assert_image_equal(image, lena("RGB"))
+
+
+
+
 def test_write_rgba():
     """
     Can we write a RGBA mode file to webp without error. Does it have the bits we
@@ -111,3 +131,27 @@ def test_read_rgba():
     target = Image.open('Images/transparent.png')
     assert_image_similar(image, target, 20.0)
 
+
+
+def test_write_lossless_rgb():
+    temp_file = tempfile("temp.webp")
+    #temp_file = "temp.webp"
+    
+    pil_image = lena('RGBA')
+
+    mask = Image.new("RGBA", (64, 64), (128,128,128,128))
+    pil_image.paste(mask, (0,0), mask)   # add some partially transparent bits.
+    
+    pil_image.save(temp_file, lossless=True)
+    
+    image = Image.open(temp_file)
+    image.load()
+
+    assert_equal(image.mode, "RGBA")
+    assert_equal(image.size, pil_image.size)
+    assert_equal(image.format, "WEBP")
+    assert_no_exception(lambda: image.load())
+    assert_no_exception(lambda: image.getdata())
+
+
+    assert_image_equal(image, pil_image)

_webp.c

@@ -25,7 +25,7 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
     Py_ssize_t  exif_size;
     size_t ret_size;
 
-    if (!PyArg_ParseTuple(args, "s#iiOfss#s#",
+    if (!PyArg_ParseTuple(args, "s#iiifss#s#",
                 (char**)&rgb, &size, &width, &height, &lossless, &quality_factor, &mode,
                 &icc_bytes, &icc_size, &exif_bytes, &exif_size)) {
         Py_RETURN_NONE;
@@ -34,7 +34,7 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
         if (size < width * height * 4){
             Py_RETURN_NONE;
         }
-        if (PyObject_IsTrue(lossless)) {
+        if (lossless) {
             ret_size = WebPEncodeLosslessRGBA(rgb, width, height, 4* width, &output);
         } else {
             ret_size = WebPEncodeRGBA(rgb, width, height, 4* width, quality_factor, &output);
@@ -43,7 +43,7 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
         if (size < width * height * 3){
             Py_RETURN_NONE;
         }
-        if (PyObject_IsTrue(lossless)) {
+        if (lossless) {
             ret_size = WebPEncodeLosslessRGB(rgb, width, height, 3* width, &output);
         } else {
             ret_size = WebPEncodeRGB(rgb, width, height, 3* width, quality_factor, &output);

docs/handbook/image-file-formats.rst

@@ -271,6 +271,24 @@ WebP
 PIL reads and writes WebP files. The specifics of PIL's capabilities with this
 format are currently undocumented.
 
+The :py:meth:`~PIL.Image.Image.save` method supports the following options:
+
+**lossless** 
+    If present, instructs the WEBP writer to use lossless
+    compression.
+
+**quality** 
+    Integer, 1-100, Defaults to 80. Sets the quality level for
+    lossy compression.
+
+**icc_procfile** 
+    The ICC Profile to include in the saved file. Only supported if
+    the system webp library was built with webpmux support.
+
+**exif** 
+    The exif data to include in the saved file. Only supported if
+    the system webp library was built with webpmux support.
+
 XBM
 ^^^