Allow larger background images without scaling them down

[Warpsmith]

Reading the docs... https://docs.woothemes.com/document/sensei-certificates/#section-4

The certificate becomes a PDF file, right? Then it seems like the intention, at some point, have been to make it easy to print the certificate on paper.

That makes the choice of size for the background image pretty weird. The proportions of 1200x675px does not correspond with the European A4 paper format (or any other size in the A series), or the American Letter & Legal formats. Is it not reasonable to have the default certificate in the proportions of any of the known standard paper sizes?

Also... 1200x675px? It says in the docs that larger size than that becomes scaled down, which isn't promising if the desire is to have it print well.

• 1200x675px printed at 300dpi becomes smaller than a postcard: 10x5.7 cm.
• 1200x675px printed to fill the width of a landscape oriented A4 becomes only 100dpi which will look badly pixellated on paper.

If would be good if the plugin allowed larger background images without scaling them down.

[aheckler]

514865-zd-woothemes as well.

[Adminifhta]

It would be great if the plugin could use standard paper sizes (https://en.wikipedia.org/wiki/Paper_size) from graphics program outputs that are used for certificate graphics preparation.