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

Elle Stone l.elle.stone at gmail.com
Wed Feb 20 16:58:36 GMT 2013


If your original images are jpegs to begin with (they came from the
camera as jpegs or entered your image collection some other way as
jpegs), then as long as you don't modify the original jpeg in any way
(except for adding metadata if you trust digiKam to write metadata to
the image - some people don't, some people do), then there is no
reason to convert the image to png, as png will take up more storage
space. Of course if you don't mind the extra storage requirements,
then that's not a problem.

I mark all my original jpegs as read-only and never, ever modify them.
My originals are all marked "read-only", but I'm not sure if or to
what extent digiKam actually respects "read-only".

When I want to edit an original jpeg, then I save it as a png and edit
the png, but I don't delete the original jpeg. That way, if I totally
mess up the png, I can go back and start over with an untouched image.

Wrt your proposed workflow, I would suggest saving your original jpegs
as pngs before you start removing red eye, doing any rotations or
other image processing.

Unless you use digiKam's ability to remember all versions of an image?
I don't use that functionality, but perhaps that would allow you to go
back to the original, unedited jpeg, in which case I'm not sure what
the advantage of the increased png storage requirements would be.

Kind regards,
Elle

On 2/20/13, M. Fioretti <mfioretti at nexaima.net> wrote:
> 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-Fran├žois 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
>
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