ShowPrewittFilterDlg example for Delphi

procedure TForm1.ShowPrewittFilterDlg1Click(Sender: TObject); 
var
   nRet: L_INT; 
begin
   LEADDlgImgEffect1.SpatialFilterType:= FLT_PREWITT_HORZ; 
   LEADDlgImgEffect1.DlgFlags:= DLG_PREWITTFILTER_SHOW_PREVIEW Or
                                 DLG_PREWITTFILTER_SHOW_TOOL_ZOOMLEVEL; 
   LEADDlgImgEffect1.LEADImage:= LEADImage1; 

   nRet:= LEADDlgImgEffect1.ShowPrewittFilterDlg ( Self ); 
   if ( nRet = SUCCESS_DLG_OK ) then
   begin
      LEADImage1.SpatialFilter ( LEADDlgImgEffect1.SpatialFilterType ); 
   end; 
end;