Wednesday, 16 May 2007

attachment_fu and Rmagick FAT thumbnails

I'm using attachment_fu on the project I'm currently working on, using it to process the images the users upload.

As backend I use Rmagick, since it was already used in the same app. At some point I felt curious about the size in kb of the thumbnails generated, to estimate the increase of bandwidth the new feature would add on the server.

I quickly spotted the size of the generated jpegs was unreasonable for the pixel size of them.

It turned out that attachment_fu + Rmagick on Ubuntu 6.0.6 and Ruby 1.4 aren't compressing jpegs.

To fix here's a one line patch on attachment_fu.

this patch sets the jpeg quality to 85%

[~]$ cat atch_fu/attachment_fu_rmagick_compression.patch
Index: lib/technoweenie/attachment_fu/processors/rmagick_processor.rb
--- lib/technoweenie/attachment_fu/processors/rmagick_processor.rb (revision 2864)
+++ lib/technoweenie/attachment_fu/processors/rmagick_processor.rb (working copy)
@@ -45,9 +45,9 @@
img.change_geometry(size.to_s) { |cols, rows, image| image.resize!(cols, rows) }
- self.temp_path = write_to_temp_file(img.to_blob)
+ self.temp_path = write_to_temp_file(img.to_blob {self.quality = 85})
\ No newline at end of file

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