Linearizing PDF scans

On Friday, August 13, 2021 at 17:23, Alexandre Souza wrote: I am not aware of any. I started with Al Kossow's basic recommendations, modified slightly: - scan at 600 dpi - use TIFF G4 where feasible - use tumble to convert to PDF I then wrote and use a couple of simple image-processing utilities based on the Leptonica image library: http://www.leptonica.org/ ...to clean up the scans (the library makes the programs pretty trivial). They start with the raw scans and: - mask the edges to remove hole punches, etc. - size to exactly 8.5" x 11" (or larger, for fold-out pages) - remove random noise dots (despeckle) - rotate to straighten (deskew) - descreen photos on pages into continuous-tone images - quantize and solidify screened color areas into solid areas - assign page numbers and bookmarks in the PDF A good example PDF produced by these programs is: http://www.bitsavers.org/pdf/hp/64000/software/64500-90912_Mar-1986.pdf The cover is a "solidified" black/gray/white image, manual pages 1-2 and 1-4 are continuous-tone JPEG images overlaying bilevel text images, and the rest of the pages are masked, deskewed, bilevel text images. The PDF bookmarks and logical page numbers are auto-generated from the original scan filenames. The final step is linearizing the PDFs, but I'm wondering whether this is still useful. -- Dave