Merge pull request #49 from ykiu/reduce-memory-usage

Make processors.Resize memory-efficient

pilkit/processors/resize.py

@@ -1,4 +1,5 @@
 from .base import Anchor
+from .utils import resolve_palette
 from ..lib import Image
 
 
@@ -20,7 +21,7 @@ def __init__(self, width, height, upscale=True):
 
     def process(self, img):
         if self.upscale or (self.width < img.size[0] and self.height < img.size[1]):
-            img = img.convert('RGBA')
+            img = resolve_palette(img)
             img = img.resize((self.width, self.height), Image.ANTIALIAS)
         return img
 

pilkit/processors/utils.py

@@ -19,4 +19,14 @@ def histogram_entropy_py(image):
 
 # Select the Pillow native histogram entropy function - if
 # available - and fall back to the Python implementation:
-histogram_entropy = getattr(Image.Image, 'entropy', histogram_entropy_py)
+histogram_entropy = getattr(Image.Image, 'entropy', histogram_entropy_py)
+
+def resolve_palette(image):
+    """ Convert a palette image to a non-palette image. """
+
+    # We need to load the image before accessing the palette
+    image.load()
+
+    if image.palette is None:
+        return image
+    return image.convert(image.palette.mode)