Lossless convert PNG image stack to PDF
Converting an image to a PDF file with ImageMagick can be as simple as:
convert in.png out.pdf
For single images -page letter
can leave big margins, which may not be desirable.
convert image stack to PDF
This ImageMagick command puts one PNG image per page
convert -page letter -adjoin *.png joined.pdf
-page letter
- does not upsize images, so tiny images will be tiny on the page, one image per page.