Note: This post is 7 years old. Some information may no longer be correct or even relevant. Please, keep this in mind while reading.
ImageMagick’s convert tool is handy for converting a series of images into a PDF. Just for future reference, here is one method how you can achieve the same without convert. It is useful if you have 1-bit PBM images (e.g. scanned text) at hand:
cat *.pbm | pnmtops -setpage -width 6 -height 8 -imagewidth 3 - | ps2pdf -dEPSFitPage - > book.pdfThis command concatenates all .pbm files, pipes the data to pnmtops to create an intermediary PostScript file on-the-fly, and pipes this PostScript file to ps2pdf to create the final pdf.
With the -width and -height parameter you specify the paper size of the generated PDF in inches, which should correspond to the paper size of the original book. With the -imagewidth parameter you specify the width that your scan/photo takes up on the page.