Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Output Background Color for Mixed & B/W

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univurshul
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Output Background Color for Mixed & B/W

Post by univurshul » 10 Nov 2010, 04:51

I've noticed that when using Adobe Reader to view ebooks with inverted colors (white text on black background), none of my ST-generated images invert their backgrounds. (They stay white). This only occurs on ST-generated ebook images. Other PDFs unaffiliated with ScanTailor production invert normally.

What could be a cause of ST white backgrounds not inverting within ereader software?

Tulon
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Re: Output Background Color for Mixed & B/W

Post by Tulon » 10 Nov 2010, 05:55

Acrobat Reader may be only inverting text not pictures. Or it may be able to invert B/W images but not color / grayscale ones, which ST is generating in Mixed mode.
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.

univurshul
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Re: Output Background Color for Mixed & B/W

Post by univurshul » 10 Nov 2010, 06:03

Can you clarify why the white background ST generates is not inverted, and remains white?

Adobe Reader can invert ST-generated B/W text well, pictures are not inverted for good reason. The issue is with ST's white generated background. It doesn't invert.

Could this be a error within PDF construction software that creates a colored background as opposed to white
Last edited by Anonymous on 10 Nov 2010, 06:18, edited 1 time in total.

Tulon
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Re: Output Background Color for Mixed & B/W

Post by Tulon » 10 Nov 2010, 06:15

univurshul wrote:Adobe Reader can invert ST-generated B/W text well, pictures are not inverted for good reason. The issue is with ST's white generated background.
ST outputs grayscale or color images in Mixed mode. It never outputs B/W ones, even for pages without any pictures. It's just an implementation detail. So depending on how you encode your PDFs, you may end up with text encoded as a color or grayscale picture. It's quite understandable that Acrobat Reader doesn't dare to try to invert that.

BTW, if you'd used PDFMaker by Misty, you supposedly wouldn't have this problem.
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.

univurshul
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Re: Output Background Color for Mixed & B/W

Post by univurshul » 10 Nov 2010, 06:20

This helps makes sense. Thanks.

Which means Misty has found a way to remove the background on mixed mode?

Tulon
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Re: Output Background Color for Mixed & B/W

Post by Tulon » 10 Nov 2010, 06:33

ST's Mixed output and in fact all other output modes follow a certain convention to make it easy to separate B/W content from pictures. The convention is to never use pure black and pure white colors in pictures. That's how PDFMaker and djvubind separate them.
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.

univurshul
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Re: Output Background Color for Mixed & B/W

Post by univurshul » 13 Nov 2010, 19:26

Some interesting notes here:

ST doesn't apply any backgrounds to the TIFFs. The white regions around text and imagery isn't actually a background.

Maybe this is what was tried to explained to me (Thanks Tulon).

What does achieve the inversion of colors in ereading apps is the addition of a background. You need to create a white background even if it appears white upon PDF binding. I didn't know this, and what this really speaks to is the capability to read without bright white light glaring into your eyes all the time, and ultimately conserve battery life. (Apps like Acrobat Pro can add backgrounds to your PDFs).
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dingodog
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Re: Output Background Color for Mixed & B/W

Post by dingodog » 13 Nov 2010, 19:43

Adobe is nothing, compared to power of the mighty

pdftk
- http://www.pdflabs.com/docs/install-pdftk/

simply:

- create a new background (e.g. in openoffice draw a rectangle equal, in size, to your images)
- export as pdf, named as back.pdf
- now:

Code: Select all

pdftk  yourscannedfile.pdf background  back.pdf output backgrounded.pdf
remember: Adobe is nothing; pdftk can do everything

since Adobe is a multi-millionaire company insisting to set, as default, in its products, ever the last PDF version (without good reason apart the fact of trying of inhibiting the freeware tools to operate on file) and produces very expensive apps without correct serious bugs, it is preferable do not recommend any adobe product, specially when other opensource tools exist, able to perform the same task or tasks adobe cannot perform

in addition to this, since not everybody has enough money to spend in adobian shopping, it is preferable linking a free alternatives, every time is possible

univurshul
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Re: Output Background Color for Mixed & B/W

Post by univurshul » 13 Nov 2010, 20:12

dingodog wrote:remember: Adobe is nothing; pdftk can do everything... it is preferable do not recommend any adobe product, specially when other opensource tools exist, able to perform the same task or tasks adobe cannot perform

in addition to this, since not everybody has enough money to spend in adobian shopping, it is preferable linking a free alternatives, every time is possible
OK, show me where pdftk vectorizes and runs OCR. Acrobat is $80. I personally find that a bargain, and it comes free with Creative Suite 4. Many of us use Adobe software. They employ good people who do good work.

Your tips are welcome. But it did not render as described in pdftk, and therefore the app isn't resourceful in this experiment.
Last edited by Anonymous on 15 Nov 2010, 09:13, edited 1 time in total.

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dingodog
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Re: Output Background Color for Mixed & B/W

Post by dingodog » 13 Nov 2010, 20:35

Adobe has no needs to be PROMOTED when there are excellent softwares (free) able to perform same tasks

what happens if we promote ever and only ADOBE when we can instead suggest, for same task, an opensource/free alternative?

Adobe increments its revenues

users, not knowing that a free alternative exist, goes to buy its adobian pack, while he can preserve his money using a free tool and a little of brain

in this specific case, there are no needs to BUY an adobian creature for this simple task (adding background)

I see a dangerous trends towards ADOBIAN PRODUCTS in this forum, by some users; you must ever remember that not everybody can spend his money in ADOBIAHOPPING (adobian shopping)

Adobe, for instance, has anything to equivalent to Tulon's Scantailor. WHY? Until users will buy an adobian product, also for very simple tasks that can be performed by free software, Adobe will have not the stimulus for innovate

so, buying not adobian products for very simple tasks, has two good effects: preserve money, convince Adobe to innovate or die

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