[magick-users] Trouble Quantizating an Image [I was unable to get/set the proper values in RGB]

[Victor Silva]

Hi folks I'm here again bugging you :)
I have  the following function (to read better use 
http://pastey.net/847) wich holds the follwing piece of code

for (x=0; x < (long) source->columns; x++)
   {
     {
       q->red = (p->red) / tones;
       q->green = (p->green) / tones;
       q->blue= (q->blue) / tones;
       q->opacity= p->opacity;
       p++;
       q+
   }
  }

where p and q are pixel packets, but by some reason I get no change on 
the image.
Ive read on the boards and googled and found this 
http://support.imagiware.com/info/images/ImageMagick/quantize.html
and this 
http://www.imagemagick.org/discussion-server/viewtopic.php?p=21104&sid=8e26689ed4382c04cb39d2d2693d1128 

But none of the links where exactly what I'm looking for. So question is 
is there is any way of getting the pixel value it self, Ive looked the 
docs and maybe what I would need is Read/Write Stream but I can't 
understand why does my current approach fails.


Folks thanks a lot for all the support, docs, and disponibility. :)
P.S.:I have appended the whole source above if you have some problem 
with the link.


int quantizateImage(Image* source, ImageInfo* source_data, int tones)
{
 long x, y;

 const PixelPacket *p;

 PixelPacket* q;
 ExceptionInfo* exception;
 Image* destination;  ImageInfo* destination_data;
 Image* canvas;
 PixelPacket white = {MaxRGB, MaxRGB, MaxRGB, OpaqueOpacity};

 destination_data =  CloneImageInfo( source_data );
 exception = &source->exception;
 destination = CloneImage( source,0,0,MagickTrue, exception );
 if (destination  == (Image *) NULL)
   { return 0; } //@TODO: Provide a better exception handler
 for (y=0; y < (long) source->rows; y++)
 {
   p = AcquireImagePixels( source,0,y,source->columns,1, exception );
   q = GetImagePixels( destination,0,y,destination->columns,1 );
   if ((p == ( const PixelPacket* ) NULL) || (q == ( PixelPacket * ) NULL))
     break;
   for (x=0; x < (long) source->columns; x++)
   {
     {
       q->red = (p->red) / tones;
       q->green = (p->green) / tones;
       q->blue= (q->blue) / tones;
       q->opacity= p->opacity;
       p++;
       q++;
     }
    /* else
     {
       q->red = p->red;
       q->green= p->green;
       q->blue= p->blue;
       q->opacity= p->opacity;
       p++;
       q++;
     }
    */
   }
     if (SyncImagePixels(destination) == MagickFalse)
     break;
 }
 if (y < (long) source->rows)
   { return 0; } //@TODO: provide a better exception handler

   destination_data = CloneImageInfo( source_data );
   destination_data->size = AcquireMemory(sizeof ( "800x600" ) );
   strcpy( destination_data-> size , "800x600");
   destination_data->background_color = white;
   canvas=AllocateImage( destination_data );
   assert( canvas != NULL );
   SetImage( canvas, OpaqueOpacity );




   DisplayImages ( destination_data, destination );
   DestroyImageInfo( destination_data );

}