Small size Color PDF

After years of struggling with color PDF-s, I realized today that color PS exists, which lead to a fast solution on the given problem.

Here's how it goes:

1. GSCAN2PDF
   scan image on 8-bit depth and 300 dpi resolution.
   save in PNM file format.
   this results in an approx. 20MB size file.
2. CONVERT
   resize to 50%
   convert bigimg.pnm -resize 50% smallimg.pnm
   file size abt. 5MB
3. PNMTOPS
   convert to ps
   pnmtops -equalpixels smallimg.pnm > smallimg.ps
   file size abt. 10MB
4. PS2PDF
   convert to pdf
   ps2pdf12 smallimg.ps smallimg.pdf
   */Sadly, I could not manage to have the pdf cropped to the proper size with ps2pdf, so I have to do it manually in the next step. However if You know the solution to this problem do not hold back on sharing it with me!/*
   file size abt. 200KB
5. PDFCROP
   crop pdf of unnecessary margin
   pdfcrop smallimg.pdf
   (resulting in smallimg-crop.pdf)
   final file size abt. 200KB

This is how you do a good quality color pdf from good quality large images.

...And a couple months later (19 May 2013) I realized that my method of producing black-and-white pdfs, which I use since years, is just as good to produce color pdfs as the above or even better because with the old method I do not have to use pdfcrop, ad the pdf page size of the color cover will be compatible with the b&w pages...