How to insert a picture, which has a height of 30% of the height of the text?

Question

What is the use?

\begin{figure} 
 \item { \includegraphics[height=0.3\lineheight]{./images/filename} 
} 
\end{figure} 

Answer 1

The normal distance between base lines is \baselineskip:

\includegraphics[height=.3\baselineskip]{...}

Or the height can be calculated, e.g.:

\newdimen\MyLineHeight % goes into the preamble
...
\settoheight{\MyLineHeight}{H}%
\includegraphics[height=.3\MyLineHeight]{...}

Or with package calc:

\usepackage{calc}% goes into the preamble
...
\includegraphics[height=\heightof{H}*3/10]{...}