Delphi: WIA to take image from digital Camera connected to USB

DelphiWIATakePicture

uses WIALib_TLB;

procedure TForm1.Button1Click(Sender: TObject);
var
  wia:IWia;
  wiad:OleVariant;
  wiax:IWiaDispatchItem;
  i:integer;
  tc1,tc2:cardinal;
begin
  tc1:=GetTickCount;
  wia:=CoWia.Create;
  if ComboBox1.ItemIndex=-1 then
   begin
    for i:=0 to wia.Devices.Count-1 do
      ComboBox1.Items.Add((wia.Devices.Item[i] as IWiaDeviceInfo).Name);
   end
  else
   begin
    wiad:=wia.Devices.Item[ComboBox1.ItemIndex] as IWiaDeviceInfo;
    wiax:=wia.Create(wiad).TakePicture;
    wiax.Transfer('C:\Data\R&D\Delphi\WIA\test.bmp',false);
    tc2:=GetTickCount;
    Image1.Picture.LoadFromFile('C:\Data\R&D\Delphi\WIA\test.bmp');
    Caption:=IntToStr(tc2-tc1)+'ms '+IntToStr(Image1.Picture.Width)+'x'+IntToStr(Image1.Picture.Height);
   end;
end;

Where are the declarations for the IWiaDeviceInfo and Iwia variables to be found, please?, also the cowia object?

Select "Project > Import Type Library" from the Menu
Select ""Microsoft Windows Image Acquisition 1.01 Type Library" from the list
Choose "Create Unit"
You will then get the unit "WIALib_TLB.pas