[Digikam-users] keeping pictures in PNG instead of JPG format

[M. Fioretti]

First of all, thanks again to the DK developers for the software, and
to the list members for all their answers to my previous messages on
the same general theme.

I know I am going at this in a somehow confused way, but discussions
here help me just to get rid of that confusion. Or closer to that
point, at least.

What I am looking at now is THE format in which to save the
photographs.

Last week, Jean-Francois answered as follows to a question of mine:

On Sat, Feb 16, 2013 22:53:40 PM +0100, Jean-François Rabasse wrote:

> Marco:
> >2) wrt to metadata saved inside pictures, I have the feeling I read
> >  somewhere that digikam can save in XMP, ITPC and EXIF format, but
> >  only to jpg and tiff files. Am I wrong?
>
> Digikam uses the libexiv2 library for metadata handling. So,
> supported files types are/should be the types supported by exiv2.
> ... the complete info here (what is possible for which file format):
> http://dev.exiv2.org/wiki/exiv2/Supported_image_formats

According to that page for exiv2, hence for digiKam, Jpg and PNG are
perfectly equivalent when it comes to both read and write any of the
three metadata formats. At the same time, the digiKam handbook
recommends PNG before JPG because, of course, only the first is
lossless.

Combining these two informations, what I understand is that:

- I should save all my pictures in PNG format, so I'll still have all
  the metadata read/write/export capabilities as if they were JPG, but
  I'll be able to edit metadata, geotag, remove red eyes, rotate or do
  any other image processing I forgot to do before converting to PNG,
  without degrading the pictures

- and the ONLY thing I'd lose is that a backup DVD of those pictures
  would not be readable by today's living-room DVD players, that only
  read jpg. So if Aunt Mary ever asks for a copy of the pictures to
  see on her TV, I'd have to make a second DVD with the jpg versions

Does all this make sense? Did I miss something?

TIA,
Marco