ABCPdf 8.1 webpage to PDF image compression issue

I've just recently upgraded from ABCPdf 6 to ABCPdf 8.1.
I've got this webpage that I need to convert into PDF format.
The whole reason for the upgrade is because ABCPdf 6 cannot read Chinese characters while version 8.1 could.
I did a test of the page on the ABCPdf demo site (http://www.abcpdfeditor.com/) and things looks fine. (1.2Mb pdf)

However, when I tried to either:

run my own backend code
or run the code provided in the examples
(C:\Program Files\WebSupergoo\ABCpdf .NET 8.1 x64\ExampleSite)
- Identical to www.abcpdfeditor.com

All PDF generated produces really pixelated/compressed images! (121Kb)

The page that I'm trying to convert is:
http://debug.webpromos.com.au/certificate.htm
As far as I can tell, there is no issue with the code, but I've attached it below anyway...
http://debug.webpromos.com.au/html2pdf.ashx.txt

I'm stuck and can't think of anything else that could make it generate a 1.2Mb PDF document with non-pixelated image as produced by www.abcpdfeditor.com!

I hope I have provided enough information!

Thanks! Wilfrid

Solution

Solved, all I need to do is to select the html engine specificly.

theDoc.HtmlOptions.Engine = EngineType.Gecko;