const
  SHIL_LARGE = $00;
  // The image size is normally 32x32 pixels. However, if the Use large icons option is selected from the Effects section of the Appearance tab in Display Properties, the image is 48x48 pixels.
  SHIL_SMALL = $01;
  // These images are the Shell standard small icon size of 16x16, but the size can be customized by the user.
  SHIL_EXTRALARGE = $02;
  // These images are the Shell standard extra-large icon size. This is typically 48x48, but the size can be customized by the user.
  SHIL_SYSSMALL = $03;
  // These images are the size specified by GetSystemMetrics called with SM_CXSMICON and GetSystemMetrics called with SM_CYSMICON.
  SHIL_JUMBO = $04;
  // Windows Vista and later. The image is normally 256x256 pixels.
  IID_IImageList: TGUID = '{46EB5926-582E-4017-9FDF-E8998DAA0950}';

procedure GetIconFromFile(AFile: String; var AIcon: TIcon;
  SHIL_FLAG: Cardinal);
{ Get the system image icon for small, large, extra large and jumbo. }
var
  iImgList: HIMAGELIST;
  iSFI: TSHFileInfo;
  iIndex: integer;
begin // Get the index of the imagelist
  SHGetFileInfo(PChar(aFile), FILE_ATTRIBUTE_NORMAL, iSFI, SizeOf(TSHFileInfo),
    SHGFI_ICON or SHGFI_LARGEICON or SHGFI_SHELLICONSIZE or
    SHGFI_SYSICONINDEX or SHGFI_TYPENAME or SHGFI_DISPLAYNAME);
  if not Assigned(AIcon) then
    AIcon := TIcon.Create;
  // get the imagelist
  iImgList := GetImageListSH(SHIL_FLAG);
  // get index
  iIndex := iSFI.iIcon;
  // extract the icon handle
  AIcon.Handle := ImageList_GetIcon(iImgList, iIndex, ILD_NORMAL);
end;

procedure TForm1.GetIcon1Click(Sender: TObject);
var
  iIcon: TIcon;
begin
  {SHIL_JUMBO- 256x256}
  iIcon := TIcon.Create;
  try
    GetIconFromFile(Filename1.Text, iIcon, SHIL_JUMBO);
    { Assign to TImage }
    Image1.Picture.Icon.Assign(iIcon);
    Image1.Update;
  finally
    iIcon.Free;
  end;
end;