Hi Andreas, This module has never been enhanced much and as you noticed there is room for such enhancements :) All of what you describe in your email makes sense to me, and I am sure the changes will be accepted if a patch is provided.
Cheers, Jonathan Le mer. 12 déc. 2018 à 06:42, Andreas Roussos <arouss1...@gmail.com> a écrit : > > Dear Developers, > > We use local cover images in our setup, and also resize the covers > we scan to a width of 160px before uploading and attaching them to > a Koha bibliographic record (we upload one cover per biblio). > > While using phpMyAdmin to view the contents of the 'biblioimages' > table (relevant screenshot here: https://imgur.com/a/cSEVLBI), we > noticed that the size of the BLOBs for the 'thumbnail' column was in > some cases twice as big as that of the 'imagefile' column. In fact, > this happens for more than 50% of uploaded covers as you can see > from the output of the SQL queries below: > > mysql> SELECT COUNT( * ) AS count > FROM biblioimages > WHERE LENGTH( thumbnail ) > ( LENGTH( imagefile ) * 2 ) ; > +-------+ > | count | > +-------+ > | 1356 | > +-------+ > > mysql> SELECT COUNT( * ) AS count, > SUM( LENGTH( imagefile ) ) AS images_size, > SUM( LENGTH( thumbnail ) ) AS thumbnails_size > FROM biblioimages ; > +-------+-------------+-----------------+ > | count | images_size | thumbnails_size | > +-------+-------------+-----------------+ > | 2347 | 68323933 | 115839686 | > +-------+-------------+-----------------+ > > It would appear that for each 160px-wide JPG with 24-bit depth that > we have uploaded, the 'imagefile' column has been populated with an > PNG of 8 bit depth with the same dimensions as the uploaded file, > whereas the 'thumbnail' column contains a 24-bit PNG image with a > width reduced to 140 pixels. > > I've tracked down the creation of resized 24-bit PNGs to this code: > https://github.com/Koha-Community/Koha/blob/master/C4/Images.pm#L182-L183 > > Do thumbnails for covers need to be true colour (24-bit) images? > > Also, why is it that _scale_image() returns an image of 8-bit depth > if the source image's dimensions are less than 600x800? (i.e. when > no resizing is performed) > > Thank you in advance for your time. > > Kind regards, > Andreas > _______________________________________________ > Koha-devel mailing list > Koha-devel@lists.koha-community.org > http://lists.koha-community.org/cgi-bin/mailman/listinfo/koha-devel > website : http://www.koha-community.org/ > git : http://git.koha-community.org/ > bugs : http://bugs.koha-community.org/ _______________________________________________ Koha-devel mailing list Koha-devel@lists.koha-community.org http://lists.koha-community.org/cgi-bin/mailman/listinfo/koha-devel website : http://www.koha-community.org/ git : http://git.koha-community.org/ bugs : http://bugs.koha-community.org/