Digikam image re-compression - is it reliable?

[Marc Volovic]

You do not say whether the originals are in JPG formst or in RAW format. If
the latter, they contain a lot of information that can be safely discarded
(it is used for photo-processing which - in re-compressing - you have
decided to forgo.

If your originals are JPG files, the re-compression is just that. Now, a
JPG compression on JPG compression adds more artefacts, depending on what
has been photographed.

And, you will not be able to enlarge and print anything really huge.

C'est touts.

M


---MAV
marc at bard.org.il




On Wed, Jun 20, 2012 at 6:13 AM, Amos Shapira <amos.shapira at gmail.com>wrote:

> Hi,
>
> I'm preparing a disk-on-key with family photos to send to my mum and
> noticed something a bit unexpected.
> Most of the photos were taken with a Canon EOS 300D, maximum resolution
> and minimum compression.
> Some were taken with Android phone and iPhone 4.
> I use Digikam on Debian to manage my photos.
> The total space of the original images (including movies, which weren't
> touched) was ~7.6Gb.
> The total space after re-compression using default parameters (75%, JPEG,
> no resizing) - < 1Gb.
>
> I think I saw before that simple re-compression saves a lot of disk space,
> but this is about 90% reduction (take into account that this includes
> copied untouched .mp4 movie files).
> From eye-balling the images on the computer screen (24", 1920x1280) they
> look just fine. They are going to be printed on regular sized photo paper,
> not made into bus-stop posters or anything.
>
> Am I missing something? Should I still send the larger images (I think I
> can just barely fit them into an old 8Gb disk-on-key) or will the smaller
> ones do fine?
>
> It also makes me wonder about my own photo stash - it takes a few dozens
> of Gb's now. If I can recompress them without losing noticeable quality
> (assume I never intend to display/print them larger than an A4 page) then
> this could save me a huge amount of disk (+backups, handling, easier
> shipping to relatives on the other side of the world etc).
>
> Thanks,
>
> --Amos
> --
>  [image: View my profile on LinkedIn]
> <http://www.linkedin.com/in/gliderflyer>
>
>
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