[Digikam-users] How does digiKam do raw conversions for the slide shows ?

Gilles Caulier caulier.gilles at gmail.com
Wed Dec 23 17:46:33 GMT 2009

2009/12/23 Linuxguy123 <linuxguy123 at gmail.com>:
> On Wed, 2009-12-23 at 18:14 +0100, Gilles Caulier wrote:
>> 2009/12/23 Mark Greenwood <fatgerman at ntlworld.com>:
>> > On Wednesday 23 Dec 2009 16:59:45 Linuxguy123 wrote:
>> >>
>> >> How does digiKam generate the images for the raw files it displays in
>> >> the slide shows ?   How could I easily generate jpegs that look as good
>> >> as the images in the slideshow ?
>> >>
>> >
>> > I would assume that for the slideshow Digikam is using the embedded
>> JPEG data from the RAW file and not the RAW data. You can extract the
>> embedded JPEG using exiftool (though I forget how, try googling it)
> Thanks for the tip.
>>  but that really defeats the object of using RAW. When you use RAW you
>> are expected to do all the white balance etc adjustments yourself. The
>> embedded JPEG has the camera's built-in adjustments already applied.
>> If you're going to use the embedded JPEG you may as well just shoot
>> JPEG in the first place.
> Thanks for the explanation about raws.  I never would have known that
> from shooting over 20,000 of them and converting them to jpegs.
>> Yes, it use JPEG preview. Fast and usefull...
> Are you serious/ sure this is the case ?  I always thought the preview
> jpegs were thumbnails.  I displayed the slideshow images on a 52" LCD TV
> at 1920x1080.  There was no way they were thumbnails.

YES. I'm serious !

RAW are containers. camera record a reduced version (and somethime the
full version) of JPEG image processed at the same time than RAW file.
Why ? to reder quicly the image on screen device and TV of course.

This is why preview in digiKam sound always better (in the first
approach) than the decoded RAW : all the algorithm from camera are
processed there...

This is not the case of RAW. You need to reproduce the camera job. And
as each camera maker and model use different algorithm, it's a worse !

I'm waiting JPEGXR from M$ encluded in camera to save my image using
waveltes compression and 16 bits color depth support. Bye bye RAW and
 Note : there is no others alternative than JPEGXR from M$, and
especially in open source, excepted PGF format, but promotion of this
do not exist...

Gilles Caulier

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