Normally if you set the white level low enough that the paper is "white" and the black level high enough that the letters are completely black and if you set the scan to 1 bit color depth and tell scantailor to suppress all speckles that are less than 4 pixels wide png compression should result in smaller files than a JPEG compression that is lossy enough to produce ringing at every change from black to white and vice versa.
Jpeg isn't very well-suited for black-and-white, anyway: it first splits the file into colour and brightness hoping that only one will contain much data, then optionally leave out 50 or 75% of the color information samples: in the end only 1 of 4. Camera pixels sees red or blue. Then it will do a fourier transform and leave out the high frequencies: they are only needed for sharp edges and 99% of a photo aren't sharp. And then it uses huffman-coding that makes small numbers shorter than long ones. Most of these steps aren't perfect for text-only pages. Kind regards, Gunter. Am 21.02.2018 3:45 nachm. schrieb "Rogier Wolff" < r.e.wo...@harddisk-recovery.nl>: > On Tue, Feb 20, 2018 at 09:32:52AM -0800, T. Modes wrote: > > > Am Dienstag, 20. Februar 2018 17:57:08 UTC+1 schrieb Toolforger: > > > > Ah, the joys of too much editing. > > > I tested with PNG and found that 300 dpi with the right settings are > small > > > enough. TIFF with one of its compression modes may work, too, > > > > > Sorry, but PNG and 300 dpi resolution have nothing in common. A JPEG and > a > > TIFF or a BMP can also have 300 dpi resolution. It seems you mix a lot > up. > > Well, I do understand that after a bunch of non-information and > wrong-writing, you start reading precisely what is written and nitpick > on everything. > > But in this case, it's is pretty clear what is meant: When scanning > the book at 300DPI, the resulting PNG is acceptable in (on-disk) size. > > PNG claims "lossless" compression. The question is: Is that relevant? > If, say you scan at 600 DPI, and use a high-enough-quality JPG > compression, I would expect that you can get better quality at > less-bits-on-disk..... > > Roger. > > -- > +-- Rogier Wolff -- www.harddisk-recovery.nl -- 0800 220 20 20 -- > - Datarecovery Services Nederland B.V. Delft. KVK: 30160549 - > | Files foetsie, bestanden kwijt, alle data weg?! > | Blijf kalm en neem contact op met Harddisk-recovery.nl! > > -- > A list of frequently asked questions is available at: > http://wiki.panotools.org/Hugin_FAQ > --- > You received this message because you are subscribed to the Google Groups > "hugin and other free panoramic software" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to hugin-ptx+unsubscr...@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/hugin-ptx/20180221144554.GP17324%40BitWizard.nl. > For more options, visit https://groups.google.com/d/optout. > -- A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ --- You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group. To unsubscribe from this group and stop receiving emails from it, send an email to hugin-ptx+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/hugin-ptx/CAMcFxV2XZ2JPOd%3DqndwOU9JO9mXWCFLepmv2ZjGtb7N-X0MCjQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
