Hi Roshan,

Roshan Shariff writes:
I can confirm this bug with dvipng --- with the "-bg Transparent"
option, dvipng ignores the background color from the input tex file,
whereas without that option it always produces an opaque background.
There's currently no way to dynamically change command line
parameters, so I'm not sure how to solve this problem while supporting
both use cases.

I asked about this behaviour on the dvipng mailing list, and the
maintainer doesn't consider it a bug, see
https://lists.nongnu.org/archive/html/dvipng/2021-05/msg00002.html.

Can you explain the use for a `Transparent` background ? Transparent
images are poorly supported in emacs, all it does is render it with
the background color of the default face -- which may not be the
expected result.

Regards,
-- 
Sébastien Miquel

On Wed, Apr 7, 2021 at 1:38 PM Sébastien Miquel
<sebastien.miquel@posteo.eu> wrote:

To reproduce with `emacs -Q` :
  - Open an org buffer
  - Call ~(setq org-format-latex-options '(:foreground default
    :background "Black" :matchers ("$")))~
  - Call =C-c C-x C-l= (org-latex-preview) on a latex fragment such as
    $abc$

This bug was introduced by the commit 2f9e1569f which adds the option
`-bg Transparent` to the arguments of `dvipng`. According to its
manual, this option should be ignored if a background is already set,
but it doesn't seem to be. Perhaps org should set it differently.

--
Sébastien Miquel