#+OPTIONS: latex:t
#+LATEX_HEADER: \usepackage{bussproofs}

Hello Nick, hello everybody

Before using your  suggestion of debugging, I have made  another test to
convert formulas made with different  latex packages into png images for
a html file. 

At the beginning of my org file: 

#+LATEX_HEADER: \usepackage{fitch}
#+LATEX_HEADER: \usepackage{bussproofs}
#+OPTIONS: tex:imagemagick

All formulas used  with the equation environment have a  nice png image,
and the Fitch proofs also. 
But that is not  the case with proofs in Gentzen  tree style created via
bussproofs.sty : the png images are corrupted. 

That's strange  because it works  well with  LaTeX export and  even with
latex-preview-image   and  org-htmlize.    This  image   of  implication
elimination rule in my gnus-message should be nice: 

\begin{prooftree}
\AxiomC{$A \to B$}
\AxiomC{$A$}
\RightLabel{\scriptsize{$\to E$}}
\BinaryInfC{$B$}
\end{prooftree}


I am  afraid to be  not competent enough  to use correctly  the debugger
that  you suggest,  but  it is  probably  again a  problem  my setup  or
something missing in my headers and not a bug somewhere. 

Best wishes,

Jo. 

Le  dim. 06  juil. 2014  à 11:25:30  , Nick  Dokos <ndokos@gmail.com>  a
envoyé ce message:
> The process by which images are produced (for imagemagick: dvipng
> follows a slightly different path) is to wrap the latex fragment
> into a complete latex file, run pdflatex (or whatever your
> org-latex-pdf-process says) to produce a pdf file and then run
> the imagemagick `convert' program to produce the png.
>
> I'd suggest that you duplicate this process by hand and see where
> it goes wrong.
>
> I usually do that by adding a (debug) call into
> org-create-formula-image-with-imagemagick like this:
>
>     (let ((latex-header (org-create-formula--latex-header)))
>       (with-temp-file texfile
>         (insert latex-header)
>         (insert "\n\\begin{document}\n"
>                 "\\definecolor{fg}{rgb}{" fg "}\n"
>                 "\\definecolor{bg}{rgb}{" bg "}\n"
>                 "\n\\pagecolor{bg}\n"
>                 "\n{\\color{fg}\n"
>                 string
>                 "\n}\n"
>                 "\n\\end{document}\n")))
>     (org-latex-compile texfile t)
>     (debug)                                       <<<<<<<<<<<<<<ADDED THIS
>     (if (not (file-exists-p pdffile))
>         (progn (message "Failed to create pdf file from %s" texfile) nil)
>       (ignore-errors
>         (if (featurep 'xemacs)
>             (call-process "convert" nil nil nil
>                           "-density" "96"
>                           "-trim"
>                           "-antialias"
>                           pdffile
>                           "-quality" "100"
>                           ;; "-sharpen" "0x1.0"
>                           pngfile)
>           (call-process "convert" nil nil nil
>                         "-density" dpi
>                         "-trim"
>                         "-antialias"
>                         pdffile
>                         "-quality" "100"
>                         ;; "-sharpen" "0x1.0"
>                         pngfile)))
>
>
> I then reload the file (M-x load-file RET /path/to/org.el RET) to pick
> up the modified function and proceed normally to export the file. When
> the (debug) is executed, I get a debug buffer and I can examine things
> like `texfile' and `dpi', using the debugger's `e' command. I then copy
> the latex file named by `texfile' to some private directory and run
> pdflatex on it and then (using the dpi value the debugger showed me - in
> my case, it was "120.0"), I convert to png using the same command as the
> function does:
>
>     cp /tmp/orgtex3771B9p.tex foo.tex
>     pdflatex foo.tex
>     convert -density 120.0 -trim -antialias foo.pdf -quality 100 foo.png
>
> The whole thing is a bit fiddly but not really difficult: it takes more
> time to explain than to do.
>
> BTW, if you go this way, don't forget to delete the (debug) afterwards.
>
> HTH.