Re: OpenMP in CinePaint?

On Fri, 21 Nov 2008, Robin Rowe wrote:

> A batch program like GraphicsMagick would seem to get more benefit from 
> OpenMP. If you want to send a patch though, please do.

Robin,

Any C language program which spends substantial time in repetitive 
time consuming code (i.e. any C program which includes image 
processing) can benefit from OpenMP.  It does not matter at all if the 
program is more interactive or more batch oriented.  The key thing is 
that any code which is run in parallel needs to be thread safe, or 
able to be modified to become so.

For example, here is a bit of OpenMP enhanced code which saved 
considerable time via OpenMP and only required that one extra line 
(the pragma) be added:

#pragma omp parallel for schedule(guided)
   for (i=0; i <= (long) MaxMap; i++)
   {
     if (levels.level_red)
       levels.map[i].red=
         ScaleMapToQuantum(MaxMap*pow((double) i/MaxMap,1.0/gamma.red));
     if (levels.level_green)
       levels.map[i].green=
        ScaleMapToQuantum(MaxMap*pow((double) i/MaxMap,1.0/gamma.green));
     if (levels.level_blue)
       levels.map[i].blue=
         ScaleMapToQuantum(MaxMap*pow((double) i/MaxMap,1.0/gamma.blue));
   }

Bob

>
> Robin
>
> Bob Friesenhahn wrote:
>> Are there any plans to update CinePaint to take advantage of multiple CPU 
>> cores via OpenMP?  I have done this for GraphicsMagick with spectacular 
>> results (http://www.graphicsmagick.org/OpenMP.html). Maybe CinePaint can do 
>> the same?
>> 
>> Bob
>> ======================================
>> Bob Friesenhahn
>> [email protected], http://www.simplesystems.org/users/bfriesen/
>> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
>> 
>> 
>
>
> -- 
> Robin Rowe
> CinePaint Project Leader
> Beverly Hills, California
> www.CinePaint.org
> www.cinepaint.blogspot.com
> www.linkedin.com/in/robinrowe
>

======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


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