B/W source - how to keep format?

Scan Tailor specific announcements, releases, workflows, tips, etc. NO FEATURE REQUESTS IN THIS FORUM, please.

Moderator: peterZ

eL_PuSHeR
Posts: 125
Joined: 28 Jun 2010, 15:25

Re: B/W source - how to keep format?

Post by eL_PuSHeR »

In the interim I have made a 4bpp version that will suffice for now. Thank you very much for your replies. Still waiting Tulon's opinion.
Tulon
Posts: 687
Joined: 03 Oct 2009, 06:13
Number of books owned: 0
Location: London, UK
Contact:

Re: B/W source - how to keep format?

Post by Tulon »

eL_PuSHeR wrote:Still waiting Tulon's opinion.
I second pejuko's opinion - go with the Mixed mode.
I personally wouldn't care about the output size, as I would convert it to PDF or DJVU and then discard it.
Scan Tailor experimental doesn't output 96 DPI images. It's just what your software shows when DPI information is missing. Usually what you get is input DPI times the resolution enhancement factor.
eL_PuSHeR
Posts: 125
Joined: 28 Jun 2010, 15:25

Re: B/W source - how to keep format?

Post by eL_PuSHeR »

Tried mixed mode today but I don't understand what it does. A new button appears telling something about shape (free, rectangular). I tested it on a page (free) and it looked normal. What's the difference between mixed mode and grayscale mode for instance?
User avatar
Misty
Posts: 481
Joined: 06 Nov 2009, 12:20
Number of books owned: 0
Location: Frozen Wasteland

Re: B/W source - how to keep format?

Post by Misty »

Mixed mode will convert part of the image into pure black/white, and part of it into a greyscale or colour image with multiple shades. The advantage is that pure black/white text compresses much, much better than greyscale. If you use mixed mode, you can then use a program that will separate the two parts and use the optimal compression for each of them; that will get you much better compression than if you did the whole thing greyscale.

By default, Scan Tailor automatically detects where the greyscale or colour parts of the image are, and treats everything else as text. The shape tool lets you manually override that to define certain parts of the image as either being text or greyscale.
The opinions expressed in this post are my own and do not necessarily represent those of the Canadian Museum for Human Rights.
eL_PuSHeR
Posts: 125
Joined: 28 Jun 2010, 15:25

Re: B/W source - how to keep format?

Post by eL_PuSHeR »

Interesting. And how Scan Tailor decides which parts of a bitmap is text and which parts aren't?

Thank you very much for your replies all of you, honest.
User avatar
Misty
Posts: 481
Joined: 06 Nov 2009, 12:20
Number of books owned: 0
Location: Frozen Wasteland

Re: B/W source - how to keep format?

Post by Misty »

It does a visual analysis to try to pick out dark text on light background from illustrations. It's usually quite accurate, but does make mistakes.
The opinions expressed in this post are my own and do not necessarily represent those of the Canadian Museum for Human Rights.
eL_PuSHeR
Posts: 125
Joined: 28 Jun 2010, 15:25

Re: B/W source - how to keep format?

Post by eL_PuSHeR »

Thanks. It seems interesting for scanning text only using line art mode (600dpi-2bpp).
eL_PuSHeR
Posts: 125
Joined: 28 Jun 2010, 15:25

Re: B/W source - how to keep format?

Post by eL_PuSHeR »

I have made several tests more. I have found out that the way ST treats 2bpp source images defeates most of the reason about using 600dpi line-art mode. I don't know why ST cannot work with pure b/w 2bpp images but after processing some pages I get heavy artifacting no matter what output mode I use. B/W should preserve current pixels/palette but it doesn't. The other two remaining modes produce heavy artifacts clearly noticeable on output specially on dark areas, like rhombus-shaped patterns.

Any ideas are welcome by the way...
User avatar
daniel_reetz
Posts: 2812
Joined: 03 Jun 2009, 13:56
E-book readers owned: Used to have a PRS-500
Number of books owned: 600
Country: United States
Contact:

Re: B/W source - how to keep format?

Post by daniel_reetz »

Do you have a bitmap we can look at?
User avatar
dingodog
Posts: 110
Joined: 22 Jul 2010, 18:19
Number of books owned: 1000
Country: on the net
Location: on the net
Contact:

Re: B/W source - how to keep format?

Post by dingodog »

if eL_Pusher had not afraid to use command-line programs, he might get better results than with scantailor

using jbig2enc

I blurred image with radious 4 before to encode with jbig2enc, as I wrote here

http://www.diybookscanner.org/forum/vie ... 1395#11395

this is a typical fear induced by Micro$oft to avoid that users become too smart
Post Reply