Você pode experimentar o JPEGtoPDF , um programa portátil muito leve (236 kB) que converte imagens em pdf.
De acordo com sua página da web,
This is a program for converting image files into PDF files. The
program supports converting multiple image files to single or multiple
PDFs files. The program also supports image scaling and positioning.
This program is now written in VB.Net, and supports additional image
formats: BMP, GIF, PNG, TIF, WMF, EMF, in addition to JPG, JP2, J2K.
Also, This program now supports commandline execution, where the
syntax is: JPEGtoPDF.exe "pdfFileName" "imgFileName1" "imgFileName2"
(Note that every parameter should be a full path+filename, and be
enclosed in quotes)
This program now supports unicode filenames.
Latest addition: The program now supports multi-page images.