Use JPEG’s in Reporting Services if exporting to PDF

I recently made the mistake of using PNG’s for high-resolution background images in SQL Server Reporting Services (2008 R2). I wanted to use PNG’s as they were lossless, supported alpha transparency and actually generated smaller files than JPEG for the images I was using.  Unfortunately I ran into these problems when exporting to PDF:

SLOW export to PDF
PNG exported to PDF: 17 seconds.
JPEG exported to PDF: 2 seconds.
GIF’s also take the same ridiculously long amount of time as PNG’s to export to PDF.

No Alpha Transparency Support
I was initially planning to have a “DRAFT” watermark appear on the report based on a parameter.  I thought an easy way to do that would be to add a PNG with alpha transparency as an additional image object, and show/hide it as needed. This works great when exporting the report to a TIFF file, but it turns out the PDF renderer does not support transparency:

I finally concluded that JPEG’s are the only option if the report is going to be exported to PDF. In order to solve my DRAFT watermark issue, I ended up having to create two versions of each image, one with a draft watermark, one without.