[tex4ht] Newbie question about converting *.tex files with PDF figure references

[John Helly]

Greetings.

I am enjoying learning htlatex's capabilities but find a puzzling behavior.  I think I understand that tex4ht tries to convert image files to *.png but I would like to retain the PDF's since they are higher quality.  The apparent attempt to produce the *.png files referred to below fails for reasons I don't understand but that's not the central question I have.

In the *.html that is produced by htlatex I find the following code:

<!--l. 113--><p class="noindent" ><img
src="BasemapProduction_201010010x.png" alt="PIC" class="graphics"><!--tex4ht:graphics                                                                                                                   
name="BasemapProduction_201010010x.png" src="/Users/hellyj/Active/Papers/2010_USN_SERDP_SLR/BasemapProduction/Tables/LIDAR_comparison_SIOxUSGS_HiRes.pdf"                                               
-->
<br />

can be changed to 

<!--l. 113--><p class="noindent" ><img
src="/Users/hellyj/Active/Papers/2010_USN_SERDP_SLR/BasemapProduction/Tables/LIDAR_comparison_SIOxUSGS_HiRes.pdf" alt="PIC" class="graphics"><!--tex4ht:graphics                                                                                                                   
name="BasemapProduction_201010010x.png" src="/Users/hellyj/Active/Papers/2010_USN_SERDP_SLR/BasemapProduction/Tables/LIDAR_comparison_SIOxUSGS_HiRes.pdf"                                               
-->
<br />

and the *.pdf file will display correctly.  

Is it possible to prevent tex4ht from making these replacements or is this something I have to do in post-processing? 
Thanks.

Cheers.
--------------
John Helly, University of California, San Diego / San Diego Supercomputer Center / Scripps Institution of Oceanography / 760 840 8660 mobile / stonesteps7 (Skype) / stonesteps7 (iChat) / http://www.sdsc.edu/~hellyj