Merge pull request #3728 from radarhere/pa_mode

Improvements to PA and LA conversion and palette operations

Author: hugovk

Tests/test_image_convert.py

@@ -12,7 +12,8 @@ def convert(im, mode):
             self.assertEqual(out.mode, mode)
             self.assertEqual(out.size, im.size)
 
-        modes = "1", "L", "I", "F", "RGB", "RGBA", "RGBX", "CMYK", "YCbCr"
+        modes = ("1", "L", "LA", "P", "PA", "I", "F",
+                 "RGB", "RGBA", "RGBX", "CMYK", "YCbCr")
 
         for mode in modes:
             im = hopper(mode)

Tests/test_image_putpalette.py

@@ -14,8 +14,10 @@ def palette(mode):
                 return im.mode, p[:10]
             return im.mode
         self.assertRaises(ValueError, palette, "1")
-        self.assertEqual(palette("L"), ("P", [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))
-        self.assertEqual(palette("P"), ("P", [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))
+        for mode in ["L", "LA", "P", "PA"]:
+            self.assertEqual(palette(mode),
+                             ("PA" if "A" in mode else "P",
+                              [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))
         self.assertRaises(ValueError, palette, "I")
         self.assertRaises(ValueError, palette, "F")
         self.assertRaises(ValueError, palette, "RGB")

src/PIL/Image.py

@@ -1619,10 +1619,10 @@ def putdata(self, data, scale=1.0, offset=0.0):
 
     def putpalette(self, data, rawmode="RGB"):
         """
-        Attaches a palette to this image.  The image must be a "P" or
-        "L" image, and the palette sequence must contain 768 integer
-        values, where each group of three values represent the red,
-        green, and blue values for the corresponding pixel
+        Attaches a palette to this image.  The image must be a "P",
+        "PA", "L" or "LA" image, and the palette sequence must contain
+        768 integer values, where each group of three values represent
+        the red, green, and blue values for the corresponding pixel
         index. Instead of an integer sequence, you can use an 8-bit
         string.
 
@@ -1631,7 +1631,7 @@ def putpalette(self, data, rawmode="RGB"):
         """
         from . import ImagePalette
 
-        if self.mode not in ("L", "P"):
+        if self.mode not in ("L", "LA", "P", "PA"):
             raise ValueError("illegal image mode")
         self.load()
         if isinstance(data, ImagePalette.ImagePalette):
@@ -1643,7 +1643,7 @@ def putpalette(self, data, rawmode="RGB"):
                 else:
                     data = "".join(chr(x) for x in data)
             palette = ImagePalette.raw(rawmode, data)
-        self.mode = "P"
+        self.mode = "PA" if "A" in self.mode else "P"
         self.palette = palette
         self.palette.mode = "RGB"
         self.load()  # install new palette

src/_imaging.c

@@ -1569,7 +1569,8 @@ _putpalette(ImagingObject* self, PyObject* args)
     if (!PyArg_ParseTuple(args, "s"PY_ARG_BYTES_LENGTH, &rawmode, &palette, &palettesize))
         return NULL;
 
-    if (strcmp(self->image->mode, "L") != 0 && strcmp(self->image->mode, "P")) {
+    if (strcmp(self->image->mode, "L") && strcmp(self->image->mode, "LA") &&
+        strcmp(self->image->mode, "P") && strcmp(self->image->mode, "PA")) {
         PyErr_SetString(PyExc_ValueError, wrong_mode);
         return NULL;
     }