\label{sec:format-jpeg}The
\textsc{jpeg} file format uses \textsc{dct} compression, a lossy
compression algorithm with variable compression rate.

It can be used for photos. It should not be used for logos, screenshots\ldots
or other images have large areas at the same color or sharp edges.

Some \textsc{jpeg} files can be used directly as \textsc{dct} encoded
data, bmeps only applies an additional ASCII-Hex- or ASCII85-encoding.
The following conditions must be fulfilled to do so:
\begin{itemize}
\item	The analysis function built into bmeps properly recognizes the
image.
\item	The \textsc{jpeg} file contains exactly one begin-image instruction.
\item	The \textsc{jpeg} file contains only allowed
\({\text{SOF}}_n\)-markers.
\item	No conversion from colored input to grayscaled output is necessary.
\end{itemize}
If the test for these conditions fails, bmeps uses the jpeglib library
to decode the image and uses the combination of run-length, flate
and ASCII-Hex/ASCII85 to encode output.
\clearpage