[Digikam-users] how do you select images for slide show? A SOLUTION

[Remco Viëtor]

On Thursday 09 May 2013 17:19:30 Eildert Groeneveld wrote:
> Dear All
> along with the good suggestion in particular from Remco I have managed
> to setup a system that allows efficient definition and storage of
> "playlists" for slide shows for me. It is actually what Remco suggested:
> define hierarchical tags (see below). What I was not aware of is that
> the JPGs are not at all touched with the creation of new tags: instead
> they are apparently only stored in the database. Which is just fine as I
> do not want the upstream defined tags to get messed up. Perfect!
> 
> One little issue remains: for a slideshow I need to export the slide
> selection  which normally includes a resize. Ideally, digikam would just
> allow an export with the provision of being able to resize.
> Closest to this is the EXPORT TO REMOTE COMPUTER und EXPORTs. here at
> least you can specify any directory. But then I would need to used
> gwenview or something else to resize.
> 
> Any idea how that can be handled efficiently? This should be job for the
> batch queue manager, but I dont really know how.
> 
> Thanks again

That would indeed be a job for the batch queue manager, which can do the 
resizing and the conversion to JPG quite handily. What it /can't/ do (yet?) 
is 'export to remote computer', but it can write the converted file to a 
directory you specify (within Digikam's album structure). It can also apply 
a change to the name for the converted file.

Another option (easy under Linux): export the full-size images from Digikam 
to your slideshow directory and then use imagemagick to do a batch 
conversion of the exported files (from a command line, also easy to put in 
a script). Something like:
---------------------

#!/bin/bash
 for a in * 
  do     
    convert $a -resize '1800x800' -unsharp '0.3x0.1+1.0' ../${a%.*}.jpg ; 
  done

---------------------
[all files in the current working directory get resized to fit within 
1800*800, and a sharpening is applied, then the results is saved in the 
parent directory (don't ask...) with a .jpg extension.
*Try it first on a set of copies!* no guarantees that it works for you...]

That is actually what I prefer, as it allows me to generate different 
output sizes easily, and Imagemagick can resize in such a way that the 
converted image fits in the rectangle you specify, while respecting the 
aspect ratio of the original.

And, don't forget to apply a little bit of sharpening after down-sampling 
your images; they'll look a lot better (unsharp mask at radius 0.3 pixel 
and 50-100% is what has been suggested as a basis).

Hope this helps

Remco