I have a form with a .png image in a Custom HTML.  The image looks fine when filling out the form, shows correctly after submitting, and shows correctly as a TIF in Laserfiche.  The issue is if the submitter chooses to download a PDF or are emailed a PDF by Forms, then the .png image is blank.  It still saves the place where it would've been but does not show the image.  I've changed the image over to .jpeg and it is working fine.  Just thought I would throw that out there in case anyone else was having issues with .png images not showing correctly from Forms into PDF.