[digiKam-users] How to rebuild RAW thumbnails?

[Cirrus]

As others have said, the value of seeing the b&w jpeg immediately after
taking a shot is nearly critical.  Plus the particular rendering this
camera produces is something I very much like.

The point about the impact on speed in DK if the embedded raw thumbnail is
regenerated is a serious concern.  Although doing so should be optional and
a user would likely understand they are invoking a penalty.

That said, darktable does this (as an option for a thumbnail outside of the
raw) and the penalty, to me, is quite minor. I'd very much like to have the
choice in DK.

Given all the information everyone has kindly provided here (Thank you!),
it doesn't seem like there's a easy solution.  I'll probably continue doing
organization and tagging in DK but move culling and rating over to
darktable.  So it goes.


On Sat, Sep 29, 2018, 04:59 Gilles Caulier <caulier.gilles at gmail.com> wrote:

> Hi,
>
> Changing the color space in camera while shooting will affect preview
> included in RAW.
>
> RAW preview are mostly a small JPEG image embedded in RAW container. DK
> extract this JPEG as well to render icon view thumbnails. It's very very
> fast as no post processing is required.
>
> Using RAW image data will be really slower to render large albums, and
> will decrease DK performances. Even if libraw decoder can use fast RAW
> extraction method without to much post processing, the democaising of bayer
> matrix will be a bottleneck.
>
> Using sidecar can be a solution. Here i don't talk about XMP sidecar file,
> but the .thm file coming with RAW file (Canon generate this kind of file,
> as i know)...
>
> But this will introduce another dysfunction, as THM file include also
> metadata which do not correspond well with RAW metadata (incomplete).
> THM cannot be used as metadata source, and this will increase the
> complexity of metadata workflow.
>
> Gilles Caulier
>
> 2018-09-29 9:12 GMT+02:00 Andrew Goodbody <ajg02 at elfringham.co.uk>:
>
>> On 29/09/18 07:55, Maik Qualmann wrote:
>>
>>> I did not understand the problem at first, but I can reproduce it with my
>>> Nikon. First of all, it is not a good idea to take a image in B&W
>>> digitally.
>>> There are many more ways to do it later, but for the JPEG the color
>>> information is lost. There is currently no option in digiKam to specify
>>> that a
>>> thumbnail should be created from the RAW image. It uses the "fastest"
>>> source
>>> and that is the preview image. That was of course stored by the camera
>>> in B&W.
>>>
>>> Maik
>>>
>>
>> Sounds like this could be a wishlist item for a 'sidecar-jpeg' which
>> could be used for raw files to contain a preview image developed using the
>> current edit settings for the raw file.
>>
>> Andrew
>>
>
>
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