Hi
It seems we got to a nice setup that resulted in enhancing the thumbnails
display in our DSpace.
1) Under dspace/config/dspace.cgf set the size of the image to be created:
thumbnail.maxwidth = 800
thumbnail.maxheight = 600
Note: Performance seems not to be an issue at this moment although the image
size increased from 2kb to around 70kb.
2) In our theme I've changed the following line to add a CSS class to the
thumbnail images:
From:
<img alt="Thumbnail">
To:
<img class="thumbnail" alt="Thumbnail">
3) And later I've added the .thumbnail definition to the CSS:
.thumbnail
{
max-width: 110px;
max-height: 110px;
}
Note: This way the larger resolution bigger image makes the thumbnail to look
better.
3) I've used the command dspace filter-media -f -n -i <item handle> to force
DSpace to recreate the thumbnail and it worked for most of the files I tried.
Thanks for your support on this.
Best regards
Rodrigo Calloni
System Librarian
Felipe Herrera Library
Knowledge and Learning Sector
Tel: 202-623-2952
Fax: 202-623-3183
1300 New York Avenue, N.W.
Washington, D.C. 20577
USA
www.iadb.org
"Knowledge for Development Challenges"
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of helix84
Sent: Wednesday, September 05, 2012 1:18 PM
To: Calloni, Rodrigo
Cc: [email protected]
Subject: Re: [Dspace-tech] Enhancing DSpace thumbnail image resolution
On Wed, Sep 5, 2012 at 7:01 PM, Calloni, Rodrigo <[email protected]> wrote:
> Thanks helix. I think I expressed myself in a wrong way.
>
> I think you got the idea of what I needed here:
>
> "An alternative to make a thumbnail look better (as opposed to increasing its
> resolution) would be to use a better downsampling method. But I didn't
> investigate if there are any other possibilities in the filter-media
> framework."
If you want to investigate improving downsampling quality, in the mentioned
BrandedPreviewJPEGFilter, this is where it takes place:
https://github.com/DSpace/DSpace/blob/master/dspace-api/src/main/java/org/dspace/app/mediafilter/BrandedPreviewJPEGFilter.java#L137
For starters, here's some pointers on how to change the sampling method:
http://stackoverflow.com/questions/4216123/how-to-scale-a-bufferedimage
If you find out that downsampling quality indeed can be improved, be sure to
share it back with us!
One thing I'm not sure about is which filter is used when (I'd guess
JPEGFilter, but BrandedPreviewJPEGFilter uses the
webui.preview.maxwidth/maxheight properties), so you may want to figure that
out, too.
> Anyway at this point we may see if by making the image larger and use CSS to
> make it show small in some pages (results list) and bigger in others (full
> view of item).
So you need both better quality and two thumbnail sizes?
Regards,
~~helix84
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