Possible fix for python-pillow#664

PIL/Image.py

@@ -101,7 +101,7 @@ def __getattr__(self, id):
 import numbers
 
 # works everywhere, win for pypy, not cpython
-USE_CFFI_ACCESS = hasattr(sys, 'pypy_version_info')  
+USE_CFFI_ACCESS = hasattr(sys, 'pypy_version_info')
 try:
     import cffi
     HAS_CFFI=True
@@ -233,7 +233,7 @@ def isImageType(t):
     "CMYK": ('|u1', 4),
     "YCbCr": ('|u1', 3),
     "LAB": ('|u1', 3), # UNDONE - unsigned |u1i1i1
-	# I;16 == I;16L, and I;32 == I;32L  
+	# I;16 == I;16L, and I;32 == I;32L
     "I;16": ('<u2', None),
     "I;16B": ('>u2', None),
     "I;16L": ('<u2', None),
@@ -502,7 +502,7 @@ def __enter__(self):
         return self
     def __exit__(self, *args):
         self.close()
-        
+
     def close(self):
         """
         Closes the file pointer, if possible.
@@ -524,7 +524,7 @@ def close(self):
         # deferred error that will better explain that the core image
         # object is gone.
         self.im = deferred_error(ValueError("Operation on closed image"))
-        
+
 
     def _copy(self):
         self.load()
@@ -540,7 +540,7 @@ def _dump(self, file=None, format=None):
         if not file:
             f, file = tempfile.mkstemp(suffix)
             os.close(f)
-            
+
         self.load()
         if not format or format == "PPM":
             self.im.save_ppm(file)
@@ -672,7 +672,7 @@ def load(self):
         normal cases, you don't need to call this method, since the
         Image class automatically loads an opened image when it is
         accessed for the first time. This method will close the file
-        associated with the image. 
+        associated with the image.
 
         :returns: An image access object.
         """
@@ -777,7 +777,7 @@ def convert(self, mode=None, matrix=None, dither=None,
         if "transparency" in self.info and self.info['transparency'] is not None:
             if self.mode in ('L', 'RGB') and mode == 'RGBA':
                 # Use transparent conversion to promote from transparent
-                # color to an alpha channel.         
+                # color to an alpha channel.
                 return self._new(self.im.convert_transparent(
                                            mode, self.info['transparency']))
             elif self.mode in ('L', 'RGB', 'P') and mode in ('L', 'RGB', 'P'):
@@ -799,19 +799,19 @@ def convert(self, mode=None, matrix=None, dither=None,
                         trns_im = trns_im.convert(mode)
                     else:
                         # can't just retrieve the palette number, got to do it
-                        # after quantization. 
+                        # after quantization.
                         trns_im = trns_im.convert('RGB')
                     trns = trns_im.getpixel((0,0))
-                        
-                    
+
+
         if mode == "P" and palette == ADAPTIVE:
             im = self.im.quantize(colors)
             new = self._new(im)
             from PIL import ImagePalette
             new.palette = ImagePalette.raw("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. 
+                # The transparency would be totally off in that case.
                 del(new.info['transparency'])
             if trns is not None:
                 try:
@@ -826,7 +826,7 @@ def convert(self, mode=None, matrix=None, dither=None,
         # colorspace conversion
         if dither is None:
             dither = FLOYDSTEINBERG
-                
+
         try:
             im = self.im.convert(mode, dither)
         except ValueError:
@@ -837,6 +837,9 @@ def convert(self, mode=None, matrix=None, dither=None,
             except KeyError:
                 raise ValueError("illegal conversion")
 
+        if self.mode == 'P' and mode == 'RGBA' and 'transparency' in self.info:
+            delete_trns = True
+
         new_im = self._new(im)
         if delete_trns:
             #crash fail if we leave a bytes transparency in an rgb/l mode.
@@ -863,18 +866,18 @@ def quantize(self, colors=256, method=None, kmeans=0, palette=None):
         # quantizer interface in a later version of PIL.
 
         self.load()
-        
+
         if method is None:
             # defaults:
             method = 0
             if self.mode == 'RGBA':
                 method = 2
 
         if self.mode == 'RGBA' and method != 2:
-            # Caller specified an invalid mode. 
+            # Caller specified an invalid mode.
             raise ValueError('Fast Octree (method == 2) is the ' +
                              ' only valid method for quantizing RGBA images')
-        
+
         if palette:
             # use palette from reference image
             palette.load()
@@ -928,7 +931,7 @@ def crop(self, box=None):
     def draft(self, mode, size):
         """
         NYI
-        
+
         Configures the image file loader so it returns a version of the
         image that as closely as possible matches the given mode and
         size.  For example, you can use this method to convert a color
@@ -1277,7 +1280,7 @@ def point(self, lut, mode=None):
             if self.mode in ("I", "I;16", "F"):
                 # check if the function can be used with point_transform
                 # UNDONE wiredfool -- I think this prevents us from ever doing
-                # a gamma function point transform on > 8bit images. 
+                # a gamma function point transform on > 8bit images.
                 scale, offset = _getscaleoffset(lut)
                 return self._new(self.im.point_transform(scale, offset))
             # for other modes, convert the function to a table
@@ -1420,8 +1423,8 @@ def putpixel(self, xy, value):
             self._copy()
             self.pyaccess = None
             self.load()
-            
-        if self.pyaccess: 
+
+        if self.pyaccess:
             return self.pyaccess.putpixel(xy,value)
         return self.im.putpixel(xy, value)