How do I convert a JPG into a PDF, but make it a hi-res file for print?
The PDF italic file format is just a wrapper. It contains whatever you put into it. So you need to take care of getting a decent JPEG italic with lots of pixels and with not too much genuine detail lost by JPEG italic typical qualitypression. For hi-res printing you need images with a resolution of 2 to 3 dpi. So if you need a 5 by 8 inch print your JPEG needs at least 1 by 16 pixels.