* 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.