[NumLock]

примерно так:

Код:

procedure TForm1.IdHTTPServer1CommandGet(AThread: TIdPeerThread;
  ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
var
  stream: TStream;
begin
  stream:=TMemoryStream.Create;
  Image1.Picture.Bitmap.SaveToStream(stream);
  AResponseInfo.ContentText:='';
  AResponseInfo.ContentType:='image/jpeg';
  AResponseInfo.ContentLength:=stream.Size;
  AResponseInfo.ContentStream:=stream;
end;