\begin{theindex}

  \item {height}
    \subitem {Picture}, \hyperpage{6}

  \indexspace

  \item {Picture}, \hyperpage{5}
    \subitem {height}, \hyperpage{6}
    \subitem {width}, \hyperpage{6}
  \item {Pixel}, \hyperpage{6}

  \indexspace

  \item {width}
    \subitem {Picture}, \hyperpage{6}

\end{theindex}