[[rruz]]

Asumiendo que tu imagen es JPEG, si fuera de otro formato solo cambia
el TJpegImage.

Código Delphi [-]
procedure CargarImagen(DataSet: TDataSet);
  var
    Stream: TMemoryStream;
    Jpg   : TJpegImage;
  begin
    Jpg := nil;
    Stream := nil;
    try
      Stream := TMemoryStream.Create;
      TBlobField(DataSet.FieldByName('imagen')).SaveToStream(Stream);
      if Stream.Size > 0 then 
      begin
        Jpg := TJpegImage.Create;
        Stream.Position := 0;
        Jpg.LoadFromStream(Stream);
        Image1.Picture.Assign(Jpg);
      end 
      else
      Image1.Picture.Assign(nil);
    except
      Image1.Picture.Assign(nil);
    end;
    jpg.Free;
    Stream.Free;
  end;