of images onto a page, with specified input
       resolution, location and compression.
     * Write a mixed raster PDF, given an input image and a segmentation
       mask.  Non-image regions are written in G4 (fax) encoding.
     * Concatenate single-page PDF wrapped images into a single PDF file.
     * Build a PDF file of all images in a directory or array of file names.
   As examples of usage, see:
     * prog/converttopdf.c: fast pdf generation with one image/page.
       For speed, this avoids tran