[Dvipng] Mssive PNGs generated with dvipng

[Nimish Telang]

Hello,
When I use dvipng to generate pngs of any latex using a valid \documentclass, the generated png is extremely large even if
the options '-T tight' are given. If the documentclass is invalid and latex generates a dvi file, (after pressing enter wherever it asks a question), dvipng crops the 
png to be as large as the mathematical figure.

example:

\documentclass{article}
\usepackage{amsmath,amssymb}
\begin{document}
$\frac{x}{y}$
\end{document}


will make a png of size 2140x7120

whereas 

\documentclass{}
\usepackage{amsmath,amssymb}
\begin{document}
$\frac{x}{y}$
\end{document}

will make a png containing just \frac{x}{y} typeset and cropped, after simply pressing enter to each of latex's questions regarding a missing class file.

How can I make a properly cropped png with no extraneous whitespace without any latex errors? (I'm trying to batch process quite a few files).

I'm running on Windows Vista x86, with dvipng version 1.9
; kpathsea 3.3.2


Thanks