JpegImagePlugin sets bufsize for optimized images

PIL/ImageFile.py

@@ -433,8 +433,9 @@ class Parser:
 # @param im Image object.
 # @param fp File object.
 # @param tile Tile list.
+# @param bufsize Optional buffer size
 
-def _save(im, fp, tile):
+def _save(im, fp, tile, bufsize=0):
     "Helper to save image based on tile list"
 
     im.load()
@@ -442,7 +443,10 @@ def _save(im, fp, tile):
         im.encoderconfig = ()
     tile.sort(key=_tilesort)
     # FIXME: make MAXBLOCK a configuration parameter
-    bufsize = max(MAXBLOCK, im.size[0] * 4) # see RawEncode.c
+	# It would be great if we could have the encoder specifiy what it needs
+	# But, it would need at least the image size in most cases. RawEncode is
+	# a tricky case. 
+    bufsize = max(MAXBLOCK, bufsize, im.size[0] * 4) # see RawEncode.c
     try:
         fh = fp.fileno()
         fp.flush()

PIL/JpegImagePlugin.py

@@ -554,7 +554,15 @@ def _save(im, fp, filename):
         info.get("exif", b"")
         )
 
-    ImageFile._save(im, fp, [("jpeg", (0,0)+im.size, 0, rawmode)])
+    # if we optimize, libjpeg needs a buffer big enough to hold the whole image in a shot.
+    # Guessing on the size, at im.size bytes. (raw pizel size is channels*size, this
+    # is a value that's been used in a django patch.
+    # https://github.com/jdriscoll/django-imagekit/issues/50
+    bufsize=0
+    if "optimize" in info:
+        bufsize = im.size[0]*im.size[1]    
+
+    ImageFile._save(im, fp, [("jpeg", (0,0)+im.size, 0, rawmode)], bufsize)
 
 def _save_cjpeg(im, fp, filename):
     # ALTERNATIVE: handle JPEGs via the IJG command line utilities.

Tests/test_file_jpeg.py

@@ -113,6 +113,13 @@ def test_optimize():
     assert_image_equal(im1, im2)
     assert_true(im1.bytes >= im2.bytes)
 
+def test_optimize_large_buffer():
+	#https://github.com/python-imaging/Pillow/issues/148
+	f = tempfile('temp.jpg')
+	# this requires ~ 1.5x Image.MAXBLOCK
+	im = Image.new("RGB", (4096,4096), 0xff3333)
+	im.save(f, format="JPEG", optimize=True)
+
 def test_progressive():
     im1 = roundtrip(lena())
     im2 = roundtrip(lena(), progressive=1)