wiki: Compress images better when using JPEG format

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/src/backend/wiki.py b/src/backend/wiki.py
index 8075d0507416caecdb4a72211a8a5e5ac510ce5b..53fe6a97ead02389297d73e95b7fca2ffe15996f 100644 (file)
--- a/src/backend/wiki.py
+++ b/src/backend/wiki.py
@@ -1,6 +1,7 @@
 #!/usr/bin/python3
 
 import PIL
 #!/usr/bin/python3
 
 import PIL

+import PIL.ImageFilter

 import difflib
 import io
 import logging
 import difflib
 import io
 import logging


@@ -514,18 +515,39 @@ class File(misc.Object):
 
                return thumbnail
 
 
                return thumbnail
 

-       def _generate_thumbnail(self, size):
+       def _generate_thumbnail(self, size, **args):

                image = PIL.Image.open(io.BytesIO(self.blob))
 
                image = PIL.Image.open(io.BytesIO(self.blob))
 

+               # Remove any alpha-channels
+               if image.format == "JPEG" and not image.mode == "RGB":
+                       # Make a white background
+                       background = PIL.Image.new("RGBA", image.size, (255,255,255))
+
+                       # Flatten both images together
+                       flattened_image = PIL.Image.alpha_composite(background, image)
+
+                       # Remove the alpha channel
+                       image = flattened_image.convert("RGB")
+

                # Resize the image to the desired resolution
                # Resize the image to the desired resolution

-               image.thumbnail((size, size), PIL.Image.ANTIALIAS)
+               image.thumbnail((size, size), PIL.Image.LANCZOS)
+
+               if image.format == "JPEG":
+                       # Apply a gaussian blur to make compression easier
+                       image = image.filter(PIL.ImageFilter.GaussianBlur(radius=0.05))
+
+                       # Arguments to optimise the compression
+                       args.update({
+                               "subsampling" : "4:2:0",
+                               "quality"     : 70,
+                       })

 
                with io.BytesIO() as f:
                        # If writing out the image does not work with optimization,
                        # we try to write it out without any optimization.
                        try:
 
                with io.BytesIO() as f:
                        # If writing out the image does not work with optimization,
                        # we try to write it out without any optimization.
                        try:

-                               image.save(f, image.format, optimize=True, quality=98)
+                               image.save(f, image.format, optimize=True, **args)

                        except:
                        except:

-                               image.save(f, image.format, quality=98)
+                               image.save(f, image.format, **args)

 
                        return f.getvalue()
 
                        return f.getvalue()