[Digikam-users] Can "Sharpen" be parallelized?

Tue Apr 29 16:56:52 BST 2014

Hi Gilles,

sounds good; any progress here is highly appreciated; though a speedup
of a factor of 2 on an 8 core CPU calls for further improvement. BTW:
OpenMP is not 3rd party software;  libgomp1 (openMP runtime library) is
available across all Linux distributions.

Thanks and best regards,

Robert

On 04/29/2014 03:51 PM, Gilles Caulier wrote:
> Hi all,
>
> Good news here.
>
> I'm starting to review code wich can be paralleled in algorithm from
> digiKam core.
>
> The goal is to use QConcurrentRun when it's possible which will
> simplify multicore support port without to use a 3rd party library as
> OpenMP for ex. After all we use Qt which provide API for multicore
> support.
>
> The first one filter ported by me is LocalContrast. I use it everyday
> due to excelent image result generated.
>
> The algorithm is very time consuming in some part, and multicore port
> give excelent results. I use a 24Mpx image taken with my Sony A77,
> processing on my i7 CPU (8 cores). Look below the result :
>
> Without multicore :
>
> digikam(12729)/digikam (core)
> Digikam::EditorToolThreaded::slotPreview: Preview  "Local Contrast"
> started...
> digikam(12729)/digikam (core)
> Digikam::DImgThreadedFilter::startFilterDirectly: "LocalContrast" ::
> excecution time :  15530  ms
> digikam(12729)/digikam (core)
> Digikam::EditorToolThreaded::slotFilterFinished: Preview  "Local
> Contrast"  completed...
>
> I can see one core used during processing.
>
> With multicore :
>
> digikam(12729)/digikam (core)
> Digikam::EditorToolThreaded::slotPreview: Preview  "Local Contrast"
> started...
> digikam(12729)/digikam (core)
> Digikam::DImgThreadedFilter::startFilterDirectly: "LocalContrast" ::
> excecution time :
> 7359  ms
> digikam(12729)/digikam (core)
> Digikam::EditorToolThreaded::slotFilterFinished: Preview  "Local
> Contrast"  completed...
>
> I can see all cores used during processing in this case.
>
> To resume : processing time is divided by 2. It's not negligible...
>
> This will be a good base to work on other filter algorithms by a student.
>
> I will include this LocalContrast multicore support in next 4.0.0
>
> Best
>
> Gilles Caulier
>
> 2014-04-22 15:18 GMT+02:00 Robert Zeller <robert.zeller at robert-zeller.org>:
>> Hello,
>>
>> Rawtherapee also runs multithreaded on compute intensive tasks.
>> Since all modern PCs use a multicore cpu on shared memory, the
>> parallelization paradigm that comes in handy in my opinion would be
>> OpenMP. It should not be too difficult to insert an omp parallel pragma
>> in front of  time consuming loops and divide the loop in as many chunks
>> as cores are available on the CPU, assigning each chunk to an individual
>> core / thread.
>> Unfortunately I cannot step in and help coding since I don't have any
>> C++ knowledge; furthermore I have been out of the code writing business
>> for more than a decade. But I think, parallelizing the time consuming
>> parts of DK might be an interesting task for a student and most valuable
>> for us users. (There are several tutorials on the internet on how to
>> apply OpenMP).
>>
>> Regards,
>> Robert
>>
>> On 04/17/2014 01:35 PM, Martin (KDE) wrote:
>>> Hallo
>>>
>>> It is not digikam, but darktable is able to use gpgpu/openCL/cuda for
>>> raw processing. I use it for photo processing and digikam for photo
>>> management. Darktable handles multithreading as well.
>>>
>>> regards
>>> Martin
>>>
>>> Am 17.04.2014 13:05, schrieb ultimateclem:
>>>> I said CUDAs, but i mean opencl (or  your prefered lib using GPU/CPU
>>>> combination). I know this is a lot of work, and that is not possible
>>>> right now. But some times, when i'm waiting for the end of a routine
>>>> wathcing tv, i dream of a really speed version of digikam. I'm using
>>>> digikam for professionnal purpose, all my pictures (more than 400 pix
>>>> for a wedding) are done in digikam... so i'm very concerned with speed.
>>>> Gilles, i would love to help the team, but i'm really unable to write a
>>>> single line of code, sorry.
>>>>
>>>> --------------
>>>> Clément Moignard
>>>>
>>>>
>>>> 2014-04-17 7:20 GMT+02:00 Remco Viëtor <remco.vietor at wanadoo.fr
>>>> <mailto:remco.vietor at wanadoo.fr>>:
>>>>
>>>>     On Wednesday 16 April 2014 19:29:56 ultimateclem wrote:
>>>>     > Hi,
>>>>     > I would be very pleased too if some speed improvements were on the
>>>>     todo
>>>>     > list. Actually, i would love if some algorythms, most time consuming,
>>>>     were
>>>>     > ported on cudas too. For example, sharpening, local contrast, cimg...
>>>>     > Please, Gilles, tell us more about speed improvement in the future,
>>>>     thanks.
>>>>     >
>>>>     > Regards,
>>>>     >
>>>>     > --------------
>>>>     > Clément Moignard
>>>>
>>>>     One thing about CUDA is that it is specific for NVidia GPUs (afaik).
>>>>     So a
>>>>     CPU version of the routine would still be needed for users of other
>>>>     GPUs.
>>>>
>>>>     Remco
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>>>>
>>>>
>>>>
>>>>
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>>
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