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

First build with automatic dewarping

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dtic
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Re: First build with automatic dewarping

Post by dtic » 10 Mar 2011, 16:08

Testing Beta10. So far only improvements on my testpages, no crashes.

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 01:12

These results are using the following snapshot:

last change Sat, 19 Mar 2011 18:58:18 +0000

This snapshot did an almost perfect job with a warped two-colum page that was previously a problem. That's good!

However, this snapshot did either a good job or a terrible job handling a perfect, unwarped page, depending on whether I chose to output in B&W or Color/Grayscale.

As you can see, this snapshot did not mess up the B&W output:
b&w.jpg
The board is not allowing me to attach more than one file to a message, so I need to spread this over three more messages, below.

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 01:16

Part 2 re: "last change Sat, 19 Mar 2011 18:58:18 +0000"

but it did mess up the Color/Grayscale output rather terribly:
cgs.jpg

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 01:21

Part 3: "last change Sat, 19 Mar 2011 18:58:18 +0000"

This is the grid over the Color/Grayscale version:
grid.jpg
The content selection is perfect and identical for both versions. (Remember, this page is unwarped to begin with.) Picture zones are not an issue HERE because I am not using mixed mode.

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 01:25

Part 4 re: "last change Sat, 19 Mar 2011 18:58:18 +0000"

When I switch to Mixed, the output is perfect again:
mixed.jpg
It appears that the dewarping is thrown off by the "noisier" background, the more "complex" pictures, or both in Color/Grayscale.

Does the dewarping function ignore picture zones in Mixed mode?

Rhetorical question: would improving automatic picture zones, so that people case use Mixed mode more easily, improve dewarping?

Tulon
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Re: First build with automatic dewarping

Post by Tulon » 20 Mar 2011, 05:33

That's probably the most hopeless case I've seen so far. No book edges, no long text lines, and each of them either starts or ends with a picture. If it produces good results in one of the modes, it's just pure luck.
I don't currently take picture zones into account for dewarping.
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.

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 07:08

Tulon wrote:That's probably the most hopeless case I've seen so far.
That's why I keep it handy for testing! :lol:

It actually worked well in 2 out of 3 modes. It failed to work only in the mode that retains the full detail of pictures but does not put them into picture zones. Hence, my impression that dewarping might benefit from better automatic picture zones. I'll just leave it at that.

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 19:47

I experimented a little with the latest snapshot:

"last change Sun, 20 Mar 2011 16:53:21 +0000"

I obtained essentially the same results as above (using a perfect, unwarped page), but I thought you might like to see the three grids corresponding to B&W, Mixed, and Color/Grayscale.

This is the grid for B&W mode:
grid-b&w.png
Looks good!

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 19:49

Part 2 re: "last change Sun, 20 Mar 2011 16:53:21 +0000"

This is the grid for Mixed mode:
grid-mixed.png
Again, looks good!

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jimboh
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Re: First build with automatic dewarping

Post by jimboh » 20 Mar 2011, 19:53

Part 3 re: "last change Sun, 20 Mar 2011 16:53:21 +0000"

This is the grid for Color/Grayscale mode:
grid-cgs.png
Odd how the mode and the use or non-use of picture zones can make such a huge difference.

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