Reduce size of thumbnail images

[tdb01r]

I just installed ImageMagick on the server for non-EPrints usage and thought: why not get those thumbnails working as well. I was suprised by the filesize of these thumbnails (actually I wasn't since I already read about it on the EPrints lists before). There's a very simple way to reduce the thumbnail size though, just one small change in /perl_lib/EPrints/Plugin/Convert/ImageMagick/ThumbnailDocuments.pm

From:
system($convert, "-thumbnail","400x300>", '-bordercolor', 'rgb(128,128,128)', '-border', '1', $src.'[0]', $dir . '/' . $fn);
To:
system($convert, "-thumbnail","400x300>", '-bordercolor', 'rgb(128,128,128)', '-border', '1', $src.'[0]', 'PNG8:'.$dir . '/' . $fn);

The added PNG8: forces it to use 256 color PNG format instead of 16 million colors. I tried it with one PDF, the filesize decreased from 160kb to 20kb without any visual changes (it's only a thumbnail after all). Small code change, huge space savings ;-)

Dennis
University of Twente

[cjg]

I'm not sure I'm comfortable changing this midstream as it is a format change and will also change the preview URLs. But big previews verges on a bug.

[tdb01r]

Fixed some time ago.