On 2021-08-14 12:04 p.m., Al Kossow via cctalk wrote:
On 8/13/21 3:15 PM, J. David Bryan via cctech wrote:
On Friday, August 13, 2021 at 17:23, Alexandre Souza wrote:
Is any kind of standard, recomendation, group, mail list, to discuss
the subject?
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
I tend to have my PDF's on portable device, so PDF's need to be easy to
use on those devices.
Ben.
