Problem with math symbols in opencv-3.0.0 documentation

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I built opencv-3.0.0 on a an X86_64 computer (Linux lyta4 3.13.0-53-generic #88-Ubuntu SMP Wed May 13 18:10:29 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux) running Ubuntu 14.04.2 LTS. The build succeeded and OpenCV seems to work. The documentation was also built. Here is its configuration in the build log:

-- Documentation: -- Doxygen: /usr/bin/doxygen (ver 1.8.6) -- PlantUML: NO

I am able to view the documentation using Mozilla Firefox 38.0, but the "math markup" symbols, such as "\times", are not rendered but just displayed as is, e.g.:

In all cases except one, the (\texttt{ksize} \times \texttt{ksize})

Does anyone know what I can do to cause these symbols to be converted to the appropriate graphics for display?