Clean up old scanned books in PDF

I followed the instructions here and had good results 

https://graphicdesign.stackexchange.com/questions/136902/how-can-i-simultaneously-darken-all-black-text-in-a-pdf-of-an-old-scanned-book 

1. Extract all of the PDF pages as PNGs. I use pdftoppm for this. - It's part of Poppler. I found it here https://blog.alivate.com.au/poppler-windows/ I ran it in the cmd window pdftoppm -png Linux_For_Beginners.pdf Linux_For_Beginners 

2. Use ScanTailor to crop, straighten, standardize page sizes, and clean up the visual appearance of the pages. 

 URL: https://scantailor.org/ Run the program, load the pages, run the Auto, then manually tweak the fix. The tiff created will be sitting in the Out folder. 

3.ScanTailor outputs tif files. To combine these into PDFs, I use tiffcp and tiff2pdf from the libtiff library. (Optional) I use pdfnup to create a PDF with multiple pages per page, which can be convenient when printing the resulting file.

 I used this trail software: https://tiff-to-pdf-converter.com/ Seems to work, it will expire after 15 days. I used Group4 compression. It turned the pics to b/w but had better compression ration than LZW