issue with org2html when using png images in org-file

A few issues here.
For one, I am unsure whether i am using the correct
way to specify certain \usepackages within org
(e.g.
#+LATEX_HEADER: \usepackage{tikz}
#+LATEX_HEADER: \usepackage{algorithm}
etc ...)
to generate a png image.

I specify :
#+BEGIN_SRC latex :exports results :file example.png
latex code here that might necessitate
certain packages such as tikz or algorithm
#+END_SRC

I run it and obtain the example.png file.

Now I would like to specify the example.png file within
the org file so that it can be accordingly exported to html.

When I run org2html now, the following error messages
appears:
........
........
executing Latex code block...
Attempt to calculate the dpi of a non-graphic display
org2html: Exported file wasn't produced
Recovering OLD file file.html...

What is happening ?