ScanLine работает некорректно

void __fastcall TForm1::Button1Click(TObject *Sender)
{
Graphics::TBitmap *pBitmap = new Graphics::TBitmap();
TColor *ptr; 
 double D,l1,l2;
try
  {
    pBitmap->Assign( Form1->Image1->Picture->Bitmap);
    double h = pBitmap->Height;
    double w =  pBitmap->Width ;
    for (int y1 = 0; y1 < 100; y1++)
    {
     for (int y = 0; y < pBitmap->Height; y++)
     { 
      ptr = (TColor *)pBitmap->ScanLine[y];
      for (int x = 0; x < pBitmap->Width; x++) 
      { 
         l1 = sqrt(((w/2)-x)*((w/2)-x)+((h/2)-y)*((h/2)-y))  ;
         l2 = sqrt(((w/2)-x)*((w/2)-x)+(((h/2)-5)-y)*(((h/2)-5)-y))  ;
         l1!=0 ? D = ((l2)  -  ( l1)) / (l1) : D = 0;
         ptr[x] = RGB(D*100*y1,0,0);
      }
     }    
    Form1->Image1->Picture->Bitmap->Assign(pBitmap) ;
    Application->ProcessMessages();
    }
  }
  catch (...)
  {
    ShowMessage("Could not load or alter bitmap");
  }
}

//---------------------------------------------------------------------------
void __fastcall TForm1::FormCreate(TObject *Sender)
{
Image1->Canvas->Pen->Color= clWhite;
Image1->Canvas->FillRect(Image1->ClientRect);
}
//---------------------------------------------------------------------------

Image1->Canvas->Brush->Color= clBlack;
Image1->Canvas->FillRect(Image1->ClientRect);

pBitmap->PixelFormat = pf24bit;

ptr[x] = (TColor)RGB(D*100*y1,0,0);

l1!=0 ? D = ((l2)  -  ( l1)) / (l1) : D = 0;

__property void * ScanLine[int Row];

ptr = (TColor *)pBitmap->ScanLine[y];/* Опасно! */

ptr = (Byte *)pBitmap->ScanLine[y];

void __fastcall TForm1::Button1Click(TObject *Sender)
 
{
  Graphics::TBitmap *pBitmap = new Graphics::TBitmap();
// This example shows drawing directly to the Bitmap
  Byte *ptr;
  try
  {
    pBitmap->LoadFromFile("C:\\Program Files\\Common Files\\Borland Shared\\Images\\Splash\\256color\\factory.bmp");
    for (int y = 0; y < pBitmap->Height; y++)
    {
      ptr = (Byte *)pBitmap->ScanLine[y];
 
      for (int x = 0; x < pBitmap->Width; x++)
        ptr[x] = (Byte)y;
    }
    Canvas->Draw(0,0,pBitmap);
  }
  catch (...)
  {
    ShowMessage("Could not load or alter bitmap");
  }
  delete pBitmap;
}

#include <memory>       //for STL auto_ptr class
#include <cmath>
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
using namespace std;
 
auto_ptr<Graphics::TBitmap> Bitmap(new Graphics::TBitmap);
 
TRGBTriple *ptr;
 
Bitmap->PixelFormat = pf24bit;
Image1->Picture->Bitmap->PixelFormat = pf24bit;
 
double D=100,l1,l2;
 
try
  {
    Bitmap->Assign( Image1->Picture->Bitmap);
    double h =  Bitmap->Height;
    double w =  Bitmap->Width ;
 
    for (int y1 = 0; y1 < 100; y1++)
    {
     for (int y = 0; y < h; y++)
     {
      ptr = reinterpret_cast<TRGBTriple *>(Bitmap->ScanLine[y]);
 
      for (int x = 0; x < w; x++)
      {
         l1 = sqrt(((w/2)-x)*((w/2)-x)+((h/2)-y)*((h/2)-y))  ;
         l2 = sqrt(((w/2)-x)*((w/2)-x)+(((h/2)-5)-y)*(((h/2)-5)-y))  ;
 
         l1!=0 ? D = ((l2)  -  ( l1)) / (l1) : D = 0;
 
         ptr[x].rgbtRed= D*100*y1;
         ptr[x].rgbtGreen= 0;
         ptr[x].rgbtBlue= 0;
      }
     }
    Image1->Picture->Bitmap->Assign(Bitmap.get()) ;
    Application->ProcessMessages();
    }
  }
  catch (...)
  {
    ShowMessage("Could not load or alter bitmap");
  }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormCreate(TObject *Sender)
{
  Image1->Canvas->Brush->Color= clBlack;
  Image1->Canvas->FillRect(Image1->ClientRect);
}
//---------------------------------------------------------------------------