procedure TForm1.SetDCPixelFormat;      
var
  DC: HDC;
  hHeap: THandle;
  Barvy, i: Integer;
  Paleta: PLogPalette;
  Cervena, Zelena, Modra: Byte;
  nPixelFormat: Integer;
  pfd: TPixelFormatDescriptor;

begin
  FillChar(pfd, SizeOf(pfd), 0);

  with pfd do begin
    nSize     := sizeof(pfd);                               // Velikost struktury pixelu
    nVersion  := 1;                                         // Èíslo verze
    dwFlags   := PFD_DRAW_TO_WINDOW or
                 PFD_SUPPORT_OPENGL or
                 PFD_DOUBLEBUFFER;                          // struktura pixelu
    iPixelType:= PFD_TYPE_RGBA;                             // RGBA pixelové hodnoty
    cColorBits:= 24;                                        // 24-bit barva
    cDepthBits:= 32;                                        // 32-bit depth buffer
    iLayerType:= PFD_MAIN_PLANE;                            // typ vrstvy
  end;

  nPixelFormat := ChoosePixelFormat(DC, @pfd);              
  SetPixelFormat(DC, nPixelFormat, @pfd);

  DescribePixelFormat(DC, nPixelFormat, sizeof(TPixelFormatDescriptor), pfd);   

  if ((pfd.dwFlags and PFD_NEED_PALETTE) <> 0) then begin
    Barvy   := 1 shl pfd.cColorBits;
    hHeap     := GetProcessHeap;
    Paleta := HeapAlloc(hHeap, 0, sizeof(TLogPalette) + (Barvy * sizeof(TPaletteEntry)));

    Paleta^.palVersion := $300;
    Paleta^.palNumEntries := Barvy;

    Cervena   := (1 shl pfd.cRedBits) - 1;
    Zelena := (1 shl pfd.cGreenBits) - 1;
    Modra  := (1 shl pfd.cBlueBits) - 1;

    for i := 0 to Barvy - 1 do begin
      Paleta^.palPalEntry[i].peRed   := (((i shr pfd.cRedShift)   and Cervena)   * 255) DIV Cervena;
      Paleta^.palPalEntry[i].peGreen := (((i shr pfd.cGreenShift) and Zelena) * 255) DIV Zelena;
      Paleta^.palPalEntry[i].peBlue  := (((i shr pfd.cBlueShift)  and Modra)  * 255) DIV Modra;
      Paleta^.palPalEntry[i].peFlags := 0;
    end;

    Palette := CreatePalette(Paleta^);
    HeapFree(hHeap, 0, Paleta);

    if (Palette <> 0) then begin
      SelectPalette(DC, Palette, False);
      RealizePalette(DC);
    end;
  end;
end;