Hough transformation for Kreise

[bernhard_LA]

sieht jemand einen Bug in dieser Version der Hough Transformation für Kreise ?
Das thema Hough und Lines gabe es bereits hier : http://www.delphipraxis.net/156893-h...formation.html

Delphi-Quellcode:

///
///   Hough transformation for line detection
///
///
///   AnalysisBitmap : TBitMap;      ->  the image  for hough tranmsformation
///   aHoughResult :  THoughResult   ->  the result of the Hough transformation
///   r  :  Integer;                 ->  the search radius
///
///


procedure Hough_CircleDetection ( AnalysisBitmap : TBitMap; var aHoughResult :  THoughResult ;  r  :  Integer  );
var x,y, a,b    : integer;
    ImageWidth  : integer;
    ImageHeight : Integer;
    max_d       : Integer;
    help        : Real;

begin


   ///  size of hough array
   ImageWidth := AnalysisBitmap.Width;
   ImageHeight:= AnalysisBitmap.Height;



                            //  a        //  b
   SetLength(aHoughResult,ImageWidth, ImageHeight );

   // For all rows in image:
   for y:=0 to AnalysisBitmap.Height-1 do
   begin

   // For all pixel in one row :
   for x:=0 to AnalysisBitmap.Width-1 do
   begin

      // Is there a point  ?
      if IsPixel(x,y, AnalysisBitmap, 128 ) then
      begin
           //   circle
           //   r *r =  ( x-a) *(x-a)  + (y-b) *( y-b)
           for a:=0 to ImageWidth do
           begin
                // r * r   := (x-a) * (x-a)  + (y-b) * (y-b);
                // solve equation and get y ...
                help :=   r * r - (x-a) * (x-a);

                if ( help >= 0 ) then
                    begin

                    b :=  Round(  sqrt (help) + y ) ;

                    Inc(aHoughResult [a, b]);

                    end;



           end;
      end;
   end;
  end;


end;