* Approach of previewing latex fragement  with imagemagick is like this:
**  The original:

1. (emacs buffer font height) -> (evalue a density value) --> (imagemagick
destiny option)
2. (latex fragement) --> (tmp latex file) -> (pdf) -> (png) ( convert with
above destiny option)

** Advantages
1. It works well at the moment.
** disadvantages
2. we get the formula about (font height -> density value) by test and test
and test...


** A pontential approach:
1. (emacs buffer font height) -> (latex macros;
\fontsize{font-size}{fontsize*1.2}) -> (insert tmp latex file )-> pdf ->
png( convert with fixed density, for example: 96)

** Advantages
1. More intuition
2. This approach may be used  the feature "p-with-dvipng", by using this
approach,
    Maybe we can code a common function shared with imagemagick ang dvipng.

** disadvantages
1. depend latex command \fontsize.


Any comment?


Feng Shu