cfpdf - Poor Image Quality

Hello,

I am using CF 9 and have tried various flavors of the below code.  The result jpg is always of poor quality while the source pdf is of high quality.  Any ideas?

<cfpdf action="thumbnail"  hires="yes" source="#fullPDFFormPath#" resolution="high"
                      destination="#tempPath#" overwrite="yes"
                      format="jpg" scale="100" transparent="no">
</cfpdf>

Thank you in advance...