[Digikam-users] error compiling libs from svn

[Gilles Caulier]

Caspar,

I will post a new entry in my blog about libraw support in digiKam, to
describe a technical review.

But there is some report from users that i would to see in this room about
libkdcraw 0.1.6 based on libraw, especially about speed improvements:

- We don't use KProcess to fork dcraw program. forking take more time than
to use multithreading.
- Demosaiced Raw data are taken directly in memory. It's fast. before, with
dcraw, we use a pipe. It's more slow
- Auto gamma adjustment in 16 bits color depth is done by main demosaicing
loop from libraw. Before, it's done in digiKam Raw loader, because dcraw do
not support this mode. This is want mean that we have another loop in the
trash. It's faster
- The same way is done for thumbnail. we recieve image data from memory
without to use KProcess. It's faster.
- At startup, we don't check dcraw program installed on your computer. This
speed up this part a little.

BUT the best is for the future ! Libraw use now openmp to parallelize
demosaicing jobs !!! Can you feel it... More info here :

http://openmp.org/wp/

OpenMp extension for GCC is included by default with 4.2 version of
compiler...

This is want mean that RAW time loading will be decreased around 30-40%
(first test done here with a dual core processor). This is a major
improvement for digiKam and RAW workflow. This mode is not yet enabled by
default. I need to test indeep before...

This way have been possible with help of Holger Berger, who have written a
patch for dcraw to parallelize code. Note that this patch have never been
accepted by Dave Coffin, so dcraw will continue to use a non parallelized
code for a while (and same for UFRAW).

If you have already tested Bibblepro, it use also a parallelized code to
demosaic raw file (based on dcraw too, dixit dcraw web page). this is why
this program is fast to play with RAW... This will be the same with digiKam
in a near future (:=)))

Gilles Caulier



2008/9/16 Gilles Caulier <caulier.gilles at gmail.com>

>
>
> 2008/9/16 Caspar Maessen <cmaessen at casco.demon.nl>
>
>> Op dinsdag 16 september 2008, schreef Gilles Caulier:
>>
>>   > Fixed in svn
>> What a service! Thank you.
>>
>
> libraw is update to 0.6.0-beta2 in svn. please update, compile and test
> again
>
> Gilles
>
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