Purchase Orders - How to enlarge product photo for PDF printing

[shoptube56]

Hiya,

I'm using the Purchase Orders app from Shopify in conjunction with Retail Barcode Labels app.  I'm trying to print purchase orders with everything needed for the warehouse to scan against with the shipments arrive.  Since printing barcodes from purchase orders isn't supported by Shopify currently, I print double-barcodes and stick them on the purchase order manually. 

e.g.

However, I would like to increase the quality of the product image that appears on the left side.  This will give a visual indicator to the warehouse to verify shipments and reduce errors.  Is this possible?  Any other ideas of what people have come up with compensate?  Thank you!